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Ἴ ἤν ἣν | on Noe oe im γν 
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PROCKEDINGS 


OF THE 


AMERICAN ACADEMY 


OF 


ARTS AND SCIENCES. 


Vion. Guilt. 


FROM MAY, 1907, TO MAY, 1908. 


BOSTON: 
PUBLISHED BY THE ACADEMY. 
1908. 


Hk 
γα 


Wniversity ress : 


Joun Witson anp Son, Campripce, U.S. A. 


Il. 


Ill. 


ΠῚ 


ὙΠ]. 


IX. 


LIBRARY 


IN}: ἣν ἣ OR 


K 


CONTENTS.  BOranica 


GARDEN 


. Studies on Fluorite: (IV.) The Kathodo-Luminescence of Fluorite. 


By H. W. Morse . 


(1.) New Species of Senecio and Schoenocaulon from Mexico. By 
J.M. GreenMan. (II.) New or otherwise Noteworthy Sper- 
matophytes, chiefly from Mexico. By B. L. Rosrnson. (III.) 
New Plants from Guatemala and Mexico collected chiefly by 
C. C. Deam. By B. L. Rosryson anp H. H. BArtiert. 
(1V.) Diagnoses of New Spermatophytes from Mexico. By 
M. L. FERNALD oe ee aoe ἢ 


Maturation Stages in the Spermatogenesis of Vespa maculata Linn. 
By E. L. Mark anp Manton CopELAND 


. The Physiological Basis of Illumination. By Louis BELL 


On the Determination of the Magnetic Behavior of the Finely Divided 
Core of an Electromagnet while a Steady Current is being 
Established in the Exciting Coil, By B. O. PErrcr 


. The Demagnetizing Factors for Cylindrical Iron Rods. By C. L. B. 


SHUDDEMAGEN . 


Outlines of a New System of Thermodynamic Chemistry. By 
GaN sowwis “sas 


The Quantitive Determination of Arsenic by the Gutzeit Method. 
By C. R. Sancer anv O. F. BLack 


The Determination of Arsenic in Urine. By C. R. SANGER AND 
O. F. Back 


PAGE 


17 


69 


97 


183 


to 
oo 
or 


325 


X. 


XI. 


XII. 


XIII. 


XIV. 


XVI. 


XVII. 


XVIII. 


XIX. 


XXII. 


CONTENTS. 


The Transition Temperature of Manganous Chloride: A New 
Fixed Point in Thermometry. By T. W. Ricuarps anp 
F. Wrepr 


Difference in Wave-Lengths of Titanium dX 3900 and 3913 in 
Arc and Spark. By Ν. A. Kent anp A. H. Avery . 


A Revision of the Atomic Weight of Lead. Preliminary Paper. 
— The Analysis of Lead Chloride. By G. P. Baxter 
AnD J. H. Witson 


A Simple Method of Measuring the Intensity of Sound. By 
G. W. Pierce 


Longitudinal Magnetic Field and the Cathode Rays. By Joun 
TROWBRIDGE 


. Note on Some Meteorological Uses of the Polariscope. By 


Louis Bett . 
The Sensory Reactions of Amphiorus. By G. H. PARKER . 


On Delays before ἀναγνωρίσεις in Greek Tragedy. By W. P. 
Dickry 


A New Method for the Determination of the Specific Heats of 
Liquids. By T. W. Ricnarps anp A. W. Rowe . 


Pisistratus and his Edition of Homer. By ὃ. H. New- 
HALL 


. Positive Rays. By Joun TrowsriGe 


. Concerning the Use of Electrical Heating in Fractional Distilla- 


tion. By T. W. Ricuarps anp J. H. Matnrews 


Recorps oF MEETINGS . 


Report oF THE COUNCIL . 


BioGRAPHICAL ΝΌΤΙΟΝ 


Samuel Cabot . 


PAGE 


941 


351 


363 


397 


457 


473 


489 


511 


CONTENTS. 


OFFICERS AND COMMITTEES FoR 1908-09 . .... . 
List oF FELLOWS AND ForEIGN Honorary MEMBERS 
STATUTES AND STANDING VOTES 

RUMFORD. Ἐπελίσ.,., - ss ws 


EN DEX ee MEE! OP ore jen a eh aS Pw he 


43—1 


Proceedings of the American Academy of Arts and Sciences. 


Vou. XLIII. No. 1.— June, 1907. 


CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY, 
HARVARD UNIVERSITY, 


STUDIES ON FLUORITE. 


IV.—THE KATHODO-LUMINESCENCE OF FLUORITE. 


By Harry W. Morse. 


Wirnu a Pate, 


INVESTIGATIONS ON LIGHT AND HEAT MADE AND PUBLISHED, WHOLLY OR IN PART, WITH APPROPRIATION 
FROM THE RumforD Funp. 


A, Monss, H. W. —Studies on Fluorite: (IV.) The 
; pl June, 1907, 35e. ae 


© 


* ‘4 


Proceedings of the American Academy of Arts and Sciences. 


Vou. XLIII. No. 1.— June, 1907. 


CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY, 
HARVARD UNIVERSITY. 


STUDIES ON FLUORITE. 


IV.— THE KATHODO-LUMINESCENCE OF FLUORITE. 


By Harry W. Morse. 

LIBRARY 
NEW YORK 
BOTANICAL 


GARDEN. 


Wiru a PLATE, 


INVESTIGATIONS ON LIGHT AND HEAT MADE AND PUBLISHED, WHOLLY OR IN PART, WITH APPROPRIATION 
FROM THE RumForD Funb, 


Ns ae Tine. 


(Velie is 


JUL 5 - 1907 


CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY, 
HARVARD UNIVERSITY. 


STUDIES ON FLUORITE. 
IV. THE KATHODO-LUMINESCENCE OF FLUORITE. 


By HARRY W. MORSE. 


Presented by John Trowbridge. Received March 20, 1907. 


I. In previous papers which have been presented to the American 
Academy by the author, data on the light emitted by crystals of fluor- 
ite from various localities, excited by hight? and by heat,? have been 
discussed. ‘The present research contains data on the spectra of the 
light emitted by various fluorites under excitation by kathode rays. 

It was found in the first research that many fluorites, if not all, give 
discontinuous spectra when excited by the light from certain sparks. 
The metals which have strong ultra-violet lines in their spark spectra, 
used as terminals for the passage of a strong spark, excite lines of 
fluorescence in these fluorites ; and while these lines are in most cases 
somewhat diffuse and broad in appearance, they are in other cases 
apparently as sharp as the metallic lines which excite them. 

In the later paper, data has been given on the light emitted, in two 
typical cases, by fluorites under excitation by heat alone. Here again 
the spectra are discontinuous, and contain, beside broad-banded por- 
tions, lines which are quite sharp. 

The spectroscopic side of the luminescence of fluorite is not ex- 
hausted by a study of the fluorescence and thermo-luminescence 
spectra. This mineral is most remarkable in the great variety of 
ways by which its luminescence can be excited, and it is known to 
emit light under the influence of kathode rays, X-rays, and radium 
radiation, as well as by simply rubbing or breaking a crystal. 

Parallel with the spectroscopic investigation of the light emitted by 
the erystals under various excitations, a careful series of investigations 


1 The Fluorescence Spectrum of Fluorite, Astrophysical Journal, 21, 83 
(Mar. 1905) ; Studies on Fluorite, I. These Proceedings, 41, 587 (Mar. 1906). 
2 Studies on Fluorite, II. These Proceedings, 41, 593 (Mar. 1906). 


4 PROCEEDINGS OF THE AMERICAN ACADEMY. 


has been made on the impurities which are present in the natural min- 
eral. ‘The first of these investigations? was made on the gases con- 
tained in fluorite, and the results of this research are wholly negative 
as far as the question of the source of luminescence is concerned. 
Nothing other than the ordinary gases was found in any case, and no 
relation between the occluded gases and the emission of light under 
excitation was discovered. 

At the present time, careful chemical analyses of a series of fluorites - 
from many parts of the world are being carried out, in the hope of find- 
ing a clue to the source of the light-emission. The results of these. 
analyses, as far as they have gone, are most interesting. Many fluorites 
are found to contain quite evident amounts of rare earths,* and from 
one specimen, at least, enough neodymium and praseodymium have 
been separated to give a quite measurable absorption spectrum. ‘The 
author intends to report the results of these investigations to the 
American Academy as soon as possible. 

II. The spectra of a large number of fluorites, excited by kathode 
rays, have been examined and photographed. Of this large number, 
seven will be described in this paper. The crystals examined were : 

1. Fluorite from Amelia Court-House, Virginia. ‘his region is a 
famous one because of the occurrence of this fluorite, which has re- 
markable properties, and also for many other minerals containing rare 
earths. Very large microlite crystals were found near the fluorite de- 
posits. The crystals of fluorite from this region are what are called 
“chlorophanes,” par excellence. 'They are very sensitive to heat, emit- 
ting light strongly at the temperature of boiling water, and so strongly 
at 300° as to be bright objects even in a well-lighted room. The fluor- 
ites occur in colors varying from dark brown and dark purple to light 
green. All show the same thermo-luminescence spectrum, and the 
same kathodo-luminescence spectrum. ‘The spectrum of thermo-lumi- 
nescence of this variety has been given at length in a previous paper.® 
The details of the kathodo-luminescence spectrum are given in 'T'able I, 
and the appearance of this spectrum is seen in Figure 1, Plate o. 

2. Fluorite from Trumbull, Conn. ‘This is also a brilliant “‘chloro- 
phane,” which shows the same thermo-luminescence spectrum as the 
Virginia crystals, and a kathodo-luminescence spectrum which is very 
closely related to that of the other mineral. Details of the latter 
spectrum are given in 'l'able II, and the appearance of the spectrum is 
seen in Figure 2 of the plate. 


3 Studies on Fluorite, III. These Proceedings, 41, 601 (Mar. 1906). 
# See also Humphreys, Astrophysical Journal, 20, 266 (1904). 
5 Studies on Fluorite, 11. These Proceedings, 41, 593 (Mar. 1906). 


MORSE. — THE KATHODO-LUMINESCENCE OF FLUORITE. 5 


3. Fluorite from Westmoreland, N. H. This is a clear, light-green 
fluorite, which shows no very strong fluorescence, but which is most 
brilliant in thermo-luminescence, giving out a purple light, the spec- 
trum of which has been fully described in a previous paper.€ Its 
kathodo-luminescence spectrum is in many respects very different from 
all the others described. The details of this spectrum are given in 
Table III, and a photograph of the spectrum is reproduced in Figure 3 
of the plate. 

4. Fluorite from Hardin County, Ohio. This is a clear pink variety 
of no very strong fluorescence or thermo-luminescence, but which 
shows a fairly strong kathodo-luminescence. Its spectrum is shown in 
Figure 4, and the detail of the lines is given in Table IV. 

5. Purple fluorite from Weardale, England. ‘This locality has fur- . 
nished some of the most beautiful fluorspar crystals of the world, and 
this particular crystal was cut from a large and perfect natural crystal. 
It is the same crystal as No. 5 of the paper on the fluorescence of 
fluorite”? and it is characterized by a fine series of layers of different 
colors, in planes parallel to the natural faces of the crystal. (Table V 
and Figure 5.) 

6. Green Weardale crystal. A deep green variety from the same 
locality, showing a kathodo-luminescence spectrum very much like that 
of the purple variety, but different in some strong lines. ‘Table VI, of 
wave-lengths, and Figure 6 of the plate, show its characteristics. 

7. Yellow Weardale crystal. From the same locality, but of deep 
straw-yellow color. Not very strong in fluorescence or thermo-lumi- 
nescence, but giving a fine purple kathodo-luminescence. Shown in 
Figure 7 and described in Table VII. 

III. After the preliminary study of the method, exposure, condi- 
tions for brightest luminescence, etc., the crystals described were cut 
from the natural crystals and their faces polished. This treatment 
permits of excluding the lines of gases in the tube as completely as 
possible, and gives a field of light which is regular and smooth. ‘The 
crystals were then mounted in the vacuum tube so that one of the 
polished faces was exposed directly to the kathode bombardment, 
the spectroscope being so placed that it would take in all the light 
possible from the polished face of the crystal. 

The form of tube shown in the figure (Figure A) is convenient 
for this special purpose. The crystal is mounted on the little table 
which forms the end of the stop-cock, and so mounted it can be turned 


6 Studies on Fluorite, II. These Proceedings, 41, 593 (Mar. 1906). 
7 The Fluorescence Spectrum of Fluorite, Astrophysical Journal, 21, 83 
(Mar. 1905); Studies on Fluorite, I. These Proceedings, 41, 587 (Mar. 1906). 


6 PROCEEDINGS OF THE AMERICAN ACADEMY. 


to any desired position in front of the rays, or a new face can be ex- 
posed when this is necessary, without loss of time. In the preliminary 
examination, a number of small bits of fluorite were mounted on the 
revolving table, near the edge, and these could then be brought one 
after the other into the kathode rays, and their spectra studied with 
a hand spectroscope. During the entire research the kathode stream 
was controlled by means of a permanent magnet, and with it the 
brightest luminescence could be brought out near the slit; or, if the 
crystal had been mounted a little too low or too high, the kathode 
stream was brought into the most favorable position for bright lumi- 
nescence by means of the magnet. 


FIGure A. 


The large aperture spectroscope already described § was used for the 
photography of the spectra, and Cramer 'l'ri-chromatic plates were found 
to give a fairly flat spectrum down as far as wave-length 6000. 

It was found that the time of exposure could not be increased beyond 
a certain point with any advantage. ‘The well-known phenomenon 
of discoloration of the crystal faces takes place, and before long the 
layer of color becomes so dense that practically no more kathode excita- 
tion gets through it, and the luminescence stops. About half an hour 
is the limit of profitable exposure for a single crystal face under the 
conditions of excitation used in this work, and if the intensity of the 
kathode stream is greatly increased, this time is reduced to a few min- 
utes. The time varies with different crystals, and some of them remain 
unattacked for a much longer period than others. When a longer 
exposure than half an hour was found necessary, the crystal was simply 


8 The Fluorescence Spectrum of Fluorite, Astrophysical Journal, 21, 83 
(Mar. 1905); Studies on Fluorite, I. These Proceedings, 41, 587 (Mar. 1906). 


MORSE. — THE KATHODO-LUMINESCENCE OF FLUORITE. T 


turned through 90° and a new face presented, so that the exposure 
could. be continued to about two hours with a single crystal. The 
luminescence light passes almost undimmed through the thin layer of 
color on the face of the crystal, so that a face which has been completely 
protected from further excitation by the kathode beam is still quite 
transparent to light, and may therefore be turned toward the slit, while 
a new face is exposed to excitation. 

The tube was kept connected with the pump during the entire series 
of experiments, and the vacuum was brought back to the most favorable 
point whenever necessary. For some crystals no pumping was required, 
and the vacuum remained at the right point for many hours. In other 
cases constant use of the pump was necessary. ‘The Westmoreland 
erystal (No. 3), although one of the clearest and least colored of the 
series, gave off hydrogen in measurable “quantities, and the spectrum 
of the gases in the tube changed slowly after this crystal was introduced, 
until finally the original nitrogen (air) spectrum had almost entirely dis- 
appeared and only hydrogen was visible. ‘I'his is evidently closely con- 
nected with the fact that this same Westmoreland fluorite contains a 
considerable percentage of hydrogen in the gases which it holds oc- 
cluded. Analysis of the gases given off from this fluorite on heating 
showed that while the amount of gas present was small compared with 
some other fluorites, it contained about 52 per cent of hydrogen.? ‘The 
evolution of hydrogen at room temperature, under the influence of 
the kathode discharge, is an interesting qualitative confirmation of the 
analyses. 

IV. In the following tables the abbreviations 


sh., sharp v. sh., very sharp 
dif., diffuse v. dif., very diffuse 
4. sh., quite sharp max., Maximum 


are used. Bands are indicated by brackets enclosing the numbers 
representing their boundaries. 

Intensities are given on a scale of 1 to 10, increasing. 

In tables IX and X the strong’ lines and those common to several 
crystals have been collected. A few important relations may be men- 
tioned. 

The band from » 5570 to X 5610 is a universal constituent of all 
these spectra. 

The strong line at 5667 is present in all but one. It is just as cer- 


9 See also Humphreys, Astrophysical Journal, 20, 266 (1904). 


8 PROCEEDINGS OF THE AMERICAN ACADEMY. 


tainly absent from the spectrum of the Ohio crystal, and it is replaced 
by the line at A 5676. 

Table X shows the most common lines and their occurrence in the 
seven spectra under analysis. Comparison with the tables of wave- 


TABLE I. 


AmELIA Court Houser (Va.) FLuorire. 


Wave-length. Intensity. Remarks. Wave-length. Intensity. Remarks. 
4310 2 [5875 
4332 1 to strong band. 
4350 3 q. sh. (5407 
(4360 5455 2 dif. 
to rather weak band. 5535 2 dif. 
4378 5608 2 dif. 
4415 2 dif. 5665 10 
4544 2 to 
4663 2 | 5733 max. strong band. 
4775 2 to 
4800 5780 sharp edge. 
to rather weak band. 5804 
l 1530 | to weak band. 
4857 3 4. sh. 5886 3 
5295 1 dif. 5962 2 dif. 
5332 1 dif. 6040 3 dif. 
TABLE II. 


TRUMBULL, Conn., FLuoRITE. 


Wave-length. Intensity. Remarks. Wave-length. Intensity. Remarks. 
4145 1 dif. 5666 8 rather dif. 
4335 3 dif. 5693 2 
4350 5 q. sh. 5710 2 dif. 

(4365 5731 3 v. sh. 

ὶ to strong flat band 5750 5 v. sh. 
4380 5774 8 v. sh. 
4417 5 dif. 5795 
4510 1 dif. to band. 
5398 5 broad 5837 
5433 1 5860 
5487 2 to band. 
5506 2 5890 
5539 4 broad. 6055 2 dif. 
5555 

| to rather weak band. 


5610 sharp edge 


MORSE. — THE KATHODO-LUMINESCENCE OF FLUORITE. 


lengths of the spectra produced by fluorescence 19 and by thermo-lum- 
inescence 11 shows immediately that while the spectra are similar in 
general appearance, and while the strong lines in the kathodo-spectra are 
in about the same part of the spectrum as those in the fluorescence- 


spectra, there are no coincidences of importance. 


The three 


lumines- 


cences are totally different as far as the wave-lengths of the principal 


lines are concerned. And a moment’s consideration of the facts about 


Wave-length. 


4722 
4777 
4857 
4892 
5142 
5187 
5244 
5332 
5370 
5398 
5433 
5468 
5513 


Wave-length. 
4898 
5192 
5202 
5345 
5375 
5400 
5434 
5468 
5517 
5538 

\ 5572 


Intensity. 


2 


SNR are NN μι bO 


TABLE III. 
WESTMORELAND, N. H., FLuoritTe. 
Remarks. Wave-length. Intensity. Remarks. 

v. dif. 5573 3 

v. dif. ! to band. 

q. sh. 5608 

dif. 5667 4 dif. 

dif. 5727 4 q. sh. 

dif. 5767 max. or sh. edge 

dif. to band. 
5822 

q. sh. \ 5870 

q. sh. to diffuse band. 
5912 

q. sh. ᾿ 5980 

dif. to weak band with 2 max. 
6055 


TABLE IV. 


FLUORITE FROM HarpIN Co., Itt. 


Intensity. 


μι Ὁ We οι ὧι μὶ μὶ db be 


Remarks. 
dif. 
dif. 
dif. 


Ὁ: sh: 
q. sh. 


q. sh. 
dif. 
q. sh. 


ἴο fairly strong band. 


5619 


10 The Fluorescence Spectrum of Fluorite, Astrophysical Journal, 21, 83, 


Wave-length. 


5978 


Intensity. 


max, 


Remarks. 


fairly strong band. 


max. 


band. 


(Mar. 1905) ; Studies on Fluorite, I. These Proceedings, 41, 587 (Mar. 1906). 
11 Studies on Fluorite, I. These Proceedings, 41, 593 (Mar. 1906). 


10 PROCEEDINGS OF THE AMERICAN ACADEMY. 


the fluorescence spectra makes this result necessary as far as that 
method of excitation is concerned. The /luorescence spectrum of a crys- 
tal of fluorite is a function of the exciting source,and changes completely 
when the exciting wave-lengths are changed. It is therefore improbable 
that any one of the fluorescence spectra should show more than approx- 
imate or accidental coincidences with many lines excited by either heat 
or kathode luminescence. ‘There are lines which appear in the fluores- 
cence spectra of a crystal under excitation by several different sources, 


TABLE V. 
PurePLE WeARDALE (ENG.) FLUORITE. 

Wave-length. Intensity. Remarks. Wave-length. Intensity. Remarks, 
4727 1 5669 10 rather dif. 
4782 1 5754 max. in band. 
4796 1 5780 4 max. of band. 
4944 2 5810 max. 

5337 1 } to band. 
5374 3 5857 
5407 5 5871 
5467 3 } to rather weak band. 
5509 2 5908 
5542 3 GO45 5 
5571 6114 1 
to band. 
5612 


TABLE VI. 


GREEN WEARDALE (ENG.) FLuoRITE. 


Wave-length. Intensity. Remarks. Wave-length. Intensity. Remarks. 
4730 4 q. sh. 5517 1 dif. 
4780 3 sh. 5537 3 q. sh. 
4795 4 sh. 5575 2 
4854 | to 

to rather weak band. 5606 2 band. 
4867 5667 10 sh. and strong. 
4890 1 dif. 5726 3 q. sh. 
4915 3 broad. 5761 1 
4947 ! dif. 5774 δ΄. 4. sh. 
5333 1 broad. 5809 5 4. sh. 
5370 3 q. sh. 5833 5 q- sh. 
5396 1 q. sh. 5861 sharp edge here. 
5408 5 q. sh. ) to strong band. 
5439 2 broad. 5893 

5470 5 broad. 6040 8 q. sh. 
5506 2 q. sh. _ 6110 1 q. sh. 


MORSE. — THE KATHODO-LUMINESCENCE OF FLUORITE. 11 

and these might be expected to be a property of the crystal, and to per- 

sist under other forms of excitation. None of these lines appear in 

either the thermo-luminescence or kathodo-luminescence of these crys- 

tals. That the same substance can, however, give the same spectrum 

under excitation by light and by heat has been shown by Becquerel,!* 
and Urbain 18 has proven that the same spectrum, modified only slightly, 

is shown by the same substance under excitation by kathode rays. 
The necessary conclusion from the author’s experiments is, however, 

that this is by no means always the case. ‘he purple Weardale fluorite 

(No. 5) has been most carefully studied both in fluorescence and in 

kathodo-luminescence, and there is no relation whatever between these 

spectra as far as the wave-lengths of lines are concerned. ‘The West- 

moreland fluorite, and that from Amelia Court-House, have been inves- 

tigated in both thermo-luminescence and kathodo-luminescence, and 

no coincidences of importance are visible. 

Plate 0 gives a very good idea of the relation between the kathodo- 

luminescence spectra of the seven crystals examined. ‘The two upper 
spectra are very evidently similar. ‘They are both “chlorophanes,” 


TABLE VII. 


YELLOW WEARDALE (ENG.) FLuoRITE. 


Wave-length. Intensity. Remarks. Wave-length. Intensity. Remarks. 
4332 2 4946 1 dif. 
4350 8 sh. 5372 2 
4365 5400 1 

to broad flat band. 5408 2 
4382 5437 1 
4419 8 dif. 5470 3 q. sh. 
4512 2 5508 2 ᾳ. 5ἢ. 
᾿ 4542 4 dif. ! to band between. 
to 5540 2 q. sh. 
4705 2 dif. 5570 
4736 8 q. sh. to 
4752 2 5602 max. a broad band. 
4767 1 to 
4785 5 sh. 5615 
4796 5 sh. 5669 10 q. sh. 
4814 2 5730 2 q. sh. 
to band. 5773 3 q. sh. 
4833 1 5811 2 q. sh. 
4860 4 dif. 5837 1 q. sh 
4917 4 dif. 5885 3 dif. 


12 Journal de physique, 68, 444, and 69, 169. 


13 Comptes rendus, 143, 825 (1906). 


12 PROCEEDINGS OF THE AMERICAN ACADEMY. 
TABLE VIII. 


SUMMARY. 


4, 5 6. | ie 


| 

Ϊ 
Wave-length. Am. C-H. Trumb. West. Ohio. P. Wr. G. Wr. Y. Wr. 

| 


4145 1 d. 
4310 
4333 
4350 
4360 
to 
4380 
4416 
4511 
4543 
4663 
4705 
4722 
4728 
4736 
4752 
4767 
4776 
4781 
4785 
4796 
4800 \ 
4814 ὁ w. bnd. 
4832 ( 
4856 3 8. 4 ( 
4860 bnd. 
4867 Ι 
4891 ν᾽ 1d. 
4898 
4917 3. Ὁ. 
1d. 


5b. 


bnd. 


| st. 


MORSE. — THE KATHODO-LUMINESCENCE OF FLUORITE. 19 


TABLE VIII. (Continued.) 


ile 


Wave-length. | Am. C-H. 


5435 
5455 
5469 


2d 
4b. Ik 3 


} 
st. bnd. ae y ᾿ (bnd. 
10 : 10 s. 


ὁ w. "πα. 


10 s. 


3 5. 


bnd. 


m. 
m. 


Ὡ 


Joa 


(In the above summary s., sharp; d., diffuse; m., maximum in band; 
w., weak; bnd., band; st., strong; are used. Bands are indicated by 
brackets.) 


14 PROCEEDINGS OF ΤῈ AMERICAN ACADEMY. 


TABLE IX. 
STRONG LINES. 


AND THOSE CoMMON TO SEVERAL CRYSTALS. 


Wave-length. | Am. σης, Trumb. Weat. P. Wr. | G. Wr. 


4350 
4416 
4730 
4780 
4785 
4796 
4856 
4917 
5372 
5398 
5408 
5470 
5512 
5538 4 
5570 
to bnd. bnd. 
5610 
5667 
5676 
5730 3 
5775 8 
5810 bnd. 
5885 bnd. 
6040 ‘ bnd. 


= CO 00 
a 8 


w= wm Or δι 
a. 
: 


w 


~ 


νι 
woe © 


Οὐ ὃ w 
τῷ 


wm wh 


(s., sharp; d., diffuse; m., maximum in band; bnd., band; intensities on 
increasing scale of 1 to 10.) 


TABLE X. 


Tue Most Common LINES OF THR 7 CRYSTALS. 


in 5 5810 
5 5SS85 
6 6050 


60r 7 5570 
5 to 


7 5610 


MORSE. —- THE KATHODO-LUMINESCENCE OF FLUORITE. 15. 


and the spectrum is therefore concealed in some degree beneath the 
broad green band which is characteristic of both. ‘The similarity in 
many of the sharper lines is, however, perfectly apparent. 

The spectra of Figures 3 and 4 are quite different from each other 
and from the other spectra shown. The larger part of the luminescence 
lines are in the same part of the spectrum as in the others, but the 
lines are not the same. Figure 4 is more like the spectra 5, 6, and 7 
than it is like the ones preceding it in the plate. The three lower 
figures are all of fluorites from Weardale. ‘They are very similar in 
most of their lines, but show evident differences in the strength of 
individual lines and groups of lines. 

In none of these spectra are the lines quite as sharp as the lines of 
fluorescence. ‘They are all diffuse in comparison with sharp metallic 
lines. 

V. While work on this research was in progress, a paper by Urbain 18 
appeared in which the cause of the luminescence of fluorite was definitely 
connected with the presence of the rare earths terbium, samarium, and 
dysprosium. ‘he particular fluorite which was cited by Urbain was 
one which had been examined several years before by Becquerel,}® both 
in the phosphoroscope and in thermo-luminescence. It is a ‘“chloro- 
phane” which gives a brilliant green luminescence under all of the va- 
rious methods of excitation, and from the table of wave-lengths which 
accompanies the paper it is quite evident that the spectrum of this 
chlorophane in kathodo-luminescence is very similar in all important de- 
tails to the spectra of the chlorophanes of the author’s Tables I and II, 
and of Figures 1 and 2. But the resemblance of this spectrum to the 
kathodo-luminescence spectra of terbium, samarium, and dysprosium, 
dissolved in various oxides and sulphates, is very slight indeed, and 
Urbain’s conclusions from this resemblance may possibly be unjustified. 
He prepared from the fluorite in question substances which did give 
spectra corresponding in every detail with the spectra of the rare earths, 
and also synthesized a fluorite, which was like the original one, from 
such preparations. The proof seems a very strong one, but it is one 
which requires further test. ‘lhe kathodo-luminescence spectra of the 
rare earths, in spite of their perfectly definite appearance and their 
evident persistence as a property of some definite substance or element, 
have proven most elusive. Crookes1§ spent some fifteen years in fol- 


14 Comptes rendus, 143, 825 (1906). 

15 Journal de physique, 68, 444, and 69, 169. 

16 A large number of papers by Crookes on this subject are to be found in the 
Proceedings of the Royal Society, the Transactions, and in the Chemical News, 
from 1880 to 1890 especially. 


16 PROCEEDINGS OF THE AMERICAN ACADEMY. 


lowing certain definite bands in these spectra. Lecoq 17 about as long 
Baur and his students thought that they had settled the matter finally.18 
Urbain 19 has done wonderful work in separating the elements of the 
rare earths, and his opinion is undoubtedly of more importance than 
that of any one else. An explanation along these lines must include 
not only the case of a single chlorophane, but it must cover also the 
cases where the fluorescence, thermo-luminescence, and kathodo-lumi- 
nescence of the same crystal of fluorite are all different, even in their 
minute details. . 

While the author cannot expect to test the question by synthesis, 
further study of the rare elements which are present in fluorites is 
already under way, and examination of the light emitted by these same 
fluorites under excitation by other means will also be taken up as soon 
as possible. 

The author’s thanks are due to the American Academy for a gener- 
ous appropriation from the Rumford Fund, which has been of the 
utmost assistance in this work. 


Tue Jerrerson PuysicALt Laporatory, 
Harvarp University. March 20, 1907. 


17 Papers by Lecoqg de Boisbaudran on this subject, to the number of thirty or 
more, are to be found in the Comptes rendus, beginning with volume 100, and 
continuing for many years. 

18 Ber. d. d. Chem, Ges., 33, 1748, and 34, 2460. 

19 A very complete bibliography of all the literature on the yttrium and cerium 
earths is that of Meyer, Bibliographie der seltenen Erden. (Leopold Voss, 
Leipzig, 1905.) 


ae 


* 


‘ 


EXPLANATION OF PLATE. 


The upper spectrum is that of the spark between cadmium terminals, and the 
numbers indicate wave-lengths. 
The seven numbered spectra are kathodo-luminescence spectra of the fol- 
lowing : 
Fluorite from Amelia Court-House, Virginia. 
Fluorite from Trumbull, Conn. 
Fluorite from Westmoreland, N. H. 
Fluorite from Hardin Co., Ohio. 
Purple fluorite from Weardale, England. 
Green fluorite from Weardale, England. 
Yellow fluorite from Weardale, England. 


ore oY 


oe 


> 


~ 


ae 
sti 2 


8 


Fs ᾿ 


rook 


io 


1. 


2. 


8. 


20. 
21. 


VOLUME 42. 


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New Sante. — - ΝΟ. XXXIV. 


ἧς ‘New gjeties ὩΣ ‘Sinecio di Schoenoaauion’ from eMaxing By 
aa mM. GREENMAN. | ; 


en or. See was N oteworthy Spermatophytes, mores from 
eee, By B. L. Rosinson.. 


A 


and Se? 
‘New Plants from Ga 
Stages in the 8 


of ἢ π 4 a } | 
ΗΝ ΠῊΝ Byatt 
tan ; 
HAE ea 
‘apy 
ee ; ' 


Proceedings of the American Academy of Arts and Sciences. 


Vou. XLIII. No. 2.— συ ΧΕ, 1907. 


CONTRIBUTIONS FROM THE GRAY HERBARIUM OF 
HARVARD UNIVERSITY. 


LIBRARY 
NEW YORK 
4 Τ σσυ 
New Series. —- No. XXXIV. BOTANICAL 
GARDEN 


I. New Species of Senecio and Schoenocaulon from Mexico. By 
J. M. GREENMAN. ; 


Il. New or otherwise Noteworthy Spermatophytes, chiefly from 
Mexico. By B. L. Ropryson. 


III. New Plants from Guatemala and Mexico collected chiefly by 
C. C. Deam. By B. L. Rosryson anv H. H. Bartuert. 


IV. Diagnoses of New Spermatophytes from Mexico, By Μ. L. 
FERNALD. 


᾿ ᾿ ry. δ ὁ 
f ; . ᾿ ὟΝ aie νη “δ et Ὧν Ὕ ᾿ ᾿ ᾿ 


ν a μιν τὰ ἌΡ 
᾿ of κοντα 1h ee Oh 
iS | “ων yan ye x aA Hf i 4) nw ᾿ ie rhe 
5 - ἽΝ a A To i ἂν ' *) Lis ory "1 ; re A 
νι ᾿ ΟΝ "hl 4! < 4 is 


vid 


CONTRIBUTIONS FROM THE GRAY HERBARIUM OF HARVARD 
UNIVERSITY.— NEW SERIES, NO. XXXIV. 


Presented by B. L. Robinson, February 13, 1907. Received February 23, 1907. 


I. NEW SPECIES OF SENECIO AND SCHOENOCAULON 
FROM MEXICO. 


By J. M. GREENMAN. 


Schoenocaulon calcicola Greenman, ἢ. sp., bulbis ovoideis 1.5-2 
cm. diametro ; caudice erecto cylindrato 5-10 cm. longo a reliquis atro- 
brunneis vel nigrescentibus fibrosis squamarum foliorumque exterio- 
rum circumdato; folis lineari-attenuatis 3-10 dm. longis 2-5 mm. 
latis 7-13-nerviis utrinque laevibus margine paulo hirtellis ; scapo 
nudo 5.5-7.5 dm. alto aliquanto flexuoso subancipiti glabro basin 
versus purpureo ; inflorescentia laxiflora 1-2 dm. longa 8-10 mm. an- 
thesi diametro ; bracteis parvis late ovatis tenuibus brunnescentibus ; 
floribus sessilibus vel breviter pedicellatis ; perianthio 6-partito, seg- 
mentis linearibus 2.5-3 mm. longis acutiusculis saepissime basi 
bidentatis ; staminibus perianthio longioribus; capsulis maturis ob- 
longo-lanceolatis ca. 1 cm. longis glabris reflexis. — Hillsides, Las 
Sedas, Oaxaca, Mexico, alt. 1830 m., 1 August, 1894, C. G. Pringle, 
no. 5754 (type, in hb. Gray); calcareous banks, Las Sedas, alt. 1830 m., 
19 July, 1897, C. G. Pringle, no. 6740 (hb. Gray, hb. Field Mus.). 
The latter number was distributed as S. intermedium Baker, a species 
from which WS. ca/cicola is readily separated by its reflexed fruit. 


ν΄  Schoenocaulon caricifolium Greenman, n. comb. Veratrum cari- 


cifolium Schlecht. Ind. Sem. Hort. Hal. 8 (1838). Asagraea carici- 
Jolia Kunth, Enum. Pl. iv. 666 (1843). Although this species has 
been treated by several authors as conspecific with Schoenocaulon 
officinale Gray, yet an examination of some of the original material, 
collected by Ehrenberg, of which there is now a specimen in the Gray 
Herbarium, shows very clearly that it can scarcely be regarded as iden- 


p tical with Dr. Gray’s species. S. caricifolium differs from S. officinale 
= in having narrower leaves, shorter scapes and inflorescence, and rela- 
*—~ tively shorter and distinctly inflated capsules. — Mexico, without defi- 


JUL 5- 


20 PROCEEDINGS OF THE AMERICAN ACADEMY. 


nite locality, Khrenberg (hb. Gray). Specimens secured by C. Conzatti 
and V. Gonzalez at Etla, Cafiada de San Gabriel, State of Oaxaca, alt. 
3000 m., 8 August, 1897, no. 323 (hb. Gray), are apparently referable 
to this species. 

Sthoenocaulon Ghiesbreghtii Greenman, τι. sp., caudice erecto 
10-12 cm. alto reliquis brunneis aut nigrescentibus fibrosis squamarum 
et folioram primorum obtecto; foliis linearibus attenuatis 4-8 dm. 
longis 2-6 mm. latis 7-13-nerviis utrinque glabris ; inflorescentia 
1-1.2 dm. vel ultra longa 1.5-2 cm. diametro densiflora ; bracteis late 
ovatis 2.5 mm. longis obtusis 5-nerviis; floribus sessilibus vel breviter 
pedicellatis ; perianthio profunde 6-partito, lobis anguste oblongis 
4-4.5 mm. longis obtusis integris vel subintegris 3-5-nerviis; fila- 
mentis perianthio duplo vel ultra longioribus uniforme recurvatis ; 
fructu ignoto. — State of Chiapas, Mexico, without more precise lo- 
cality, Dr. Ghiesbreght, no. 672 (type, in hb. Gray); without definite 
locality, alt. 2130 m., Berendt (hb. Gray). This species is rather strik- 
ing on account of the recurved filaments. In this respect it resembles 
S. tenuifolium Robinson & Greenman, but in other and more essential 
characters it is amply distinct. 

Schoenocaulon jaliscense Greenman, ἢ. sp., bulbis oblongo- 
ovoideis 2.5-3.5 cm. diametro; caudice erecto cylindrato 1-1.5 dm. 
alto a reliquis atrobrunneis vel nigrescentibus fibrosis squamarum 
foliorumque exteriorum obtecto; foliis gramineis 6-10 dm. longis 
2-7 mm. latis 9-13-nerviis utrinque glabris margine inconspicue hir- 
tellis ; scapo erecto 8 dm. vel ultra alto nudo subancipiti aliquid 
glauco; inflorescentia elongata 1 usque ad fere 5 dm. longitudine 
1-1.5 cm. diametro simplici vel raro ramum lateralem gerenti ; bracteis 
parvis scariosis suberoso-marginatis ; floribus breviter pedicellatis ; 
perianthio alte 6-partito, segmentis lineari-oblongis ca. 2.5 mm. longis 
integris vel basi bidentatis apicem obtusum versus paulo ampliatis 
incrassatisque ; staminibus perianthio longioribus ; filamentis persis- 
tentibus ; capsulis immaturis nee non pedicellis et segmentis perianthii 
plus minusve glaucis et purpurascentibus ; fructu erecto oblongo-ovato 
quam 1 cm. breviore. — Cool grassy sides of cafions, near Guadalajara, 
Jalisco, Mexico, 11 November, 1889, C. G. Pringle, no. 2938 (type, in 
hb. Gray); Rio Blanco, Guadalajara, 1903, ΟἹ G. Pringle, no. 11,853 
(hb. Gray); Cerro de San Felipe, Oaxaca, Mexico, alt. 2000 m., 29 

August, 1897, C. Conzatti & V. Gonzalez, no. 449 (hb. Gray). 
‘Senecio (§ Eremophili) ctenophyllus Greenman, n. sp., herbaceus 
annuus vel perennis basi saepe lignosus ; caulibus erectis 3-4 dm. altis 
simplicibus vel ramosis arachnoideo-tomentosis ; foliis lanceolatis 2-9 cm. 
longis 1-2.5 cm. latis plus minusve pectinato-divisis arachnoideo- 


ROBINSON. — NEW SPERMATOPHYTES, CHIEFLY FROM MEXICO. 21 


tomentulosis ; foliis inferioribus petiolatis, summis sessilibus ; inflores- 
centiis terminalibus corymboso-cymosis tomentosis ; capitulis numerosis 
8-9 mm. altis heterogamis calyculatis ; involucri campanulati squamis 
ca. 13 lineari-lanceolatis 5 mm. longis acutis nigro-penicillatis ceterum 
glabratis vel sparsissime tomentulosis ; floribus femineis liguliferis 5-8, 
corollis glabris, ligulis flavis ; floribus disci ca. 25 ; achaeniis cano- 
hirtellis. — Barranca below Sandia Station, Durango, Mexico, alt. 2135 
m., 15 October, 1905, C. G. Pringle, no. 10,105 (type, in hb. Gray). 
This species has the general aspect of S. eremophilus Richards., S. chi- 
huahuensis Wats. and S. MacDougalii Heller, but differs from all of 
them in being tomentulose throughout and in having narrower leaves 
with mostly simple slender and entire lateral teeth or divisions. 

4 Senecio (§ Tomentosi) loratifolius Greenman, n. sp., herbaceus 
perennis ; caulibus erectis 3 dm. altis lanato-tomentosis ; foliis alternis 
elongato-lanceolatis vel subloratis 0.5-1.7 dm. longis 4-12 mm. latis 
acutis vel obtusis integris membranaceis juventate supra arachnoideo- 
tomentosis denique glabratis subtus persistenter albo-tomentosis ; foliis 
inferioribus basi sensim angustatis et subpetiolatis, superioribus sessili- 
bus et amplexicaulibus ; inflorescentiis cymosis terminalibus ; capitulis 
paucis 8-9 mm. altis heterogamis calyculatis ; involucris campanulatis 
tomentosis, squamis ca. 13 lineari-lanceolatis 6-7 mm. longis ; flori- 
bus femineis ligulatis 8-12, corollis glabris flavis; floribus disci ca. 
35 quam squamis involucri vix longioribus ; achaeniis hispidulis. — 
Mountains near Saltillo, Coahuila, Mexico, alt. 2133 m., 5 October, 
1905, C. G. Pringle, no. 13,676 (type, in hb. Gray). This species is 
related to S. umbraculiferus Watson, but differs amply in foliar char- 
acters, especially in having thinner leaf-texture, glabrate upper leaf- 
surface, and more distinctly amplexicaul upper leaves. 


Il. NEW OR OTHERWISE NOTEWORTHY SPERMATO- 
PHYTES, CHIEFLY FROM MEXICO. 


By B. L. Rospryson. 


ν΄ Tigridia morelosana Robinson, n. sp., bulbo ovoideo acuminato 4-- 
6 cm. longo 2-3.2 em. diametro atrobrunneo, radicibus fibrosis ; caule 
gracillimo flexuoso 3 dm. alto saepissime 1-2-foliato glabro modice 
compresso ; foliis basilaribus anguste lanceolato-linearibus attenuatis 
plicato-nervosis ca. 3 dm. longis ca. 8 mm. latis utrinque viridibus 
glabris laevibus ; foliis caulinis linearibus vel anguste spathiformibus ; 


22 PROCEEDINGS OF THE AMERICAN ACADEMY. 


spathis saepissime 2 longipedunculatis 3-6-floris, foliolis oblongo-lance- 
olatis acutissimis 2-4 cm. longis margine tenuibus subscariosis ; pedi- 
cellis gracillimis 2-3 cm. longis glabris; sepalis purpureis 14 mm, 
longis 6 mm. latis anguste obovatis obtusis basi angustatis in media 
parte atromaculatis ; petalis ovatis 12 mm. longis acutiusculis cordatis 
brevissime stipitatis supra mediam partem purpurascentibus tenuibus 
infra mediam partem flavescentibus firmiusculis 6 mm. latis ; columna 
4 mm. alta ; antheris oblongis apiculatis in summa columna sessilibus ; 
ramis styli 6 filiformibus antheras subaequantibus. — Sierra de T'e- 
poxtlan, Morelos, Mexico, alt. 2350 m., 5 September, 1905, C. G. 
Pringle, no. 13,657 (type, in hb. Gray). 

Amaranthus squamulatus Robinson, n. comb. Scleropus squam- 
ulatus Anderss. Om Galapagos-darnes Veg., Stockh. Akad. Handl. 
1853, 162 (1854), & Om Galapagos-darnes Veg. 60 (1859). Seleropus 
sguarrulosus Anderss. ex Gray, Proc. Am. Acad. v. 169 (1861), by cler- 
ical error. Amblogyne squarrulosa Gray, 1. ὁ. (1861). Amaranthus 
squarrulosus Uline & Bray, Bot. Gaz. xix. 170 (1894) ; Rob. & Greenm, 
Am. Jour. Sci. 1. 147 (1895); Rob. Proc. Am. Acad. xxxviii. 136 
(1902). 

Schoepfia Pringlei Robinson, n. sp., fruticosa vel arborescens 5 m. 
alta ramosa ; ramis teretibus leviter flexuosis a cortice griseo rugoso 
tectis ; ramulis plus minusve angulatis fuscescenti-puberulis ; foliis al- 
ternis coriaceis ovato-lanceolatis obtusis vel acutiusculis vel etiam 
falcato-acuminatis integerrimis opacis utrinque viridibus glaberrimis 
subtus vix pallidioribus obscure pinnatinerviis 4—5.5 cm. longis 1.5-2.3 
cm. latis ; basi cuneatis brevissime petiolatis ; pedunculis axilkaribus 4 
mm. longis puberulis cupulas 2-4 plus minusve racemosas gerentibus, 
pedicellis vix ullis ; cupulis puberulis saepissime 2-partitis, lobo majore 
obscure 2-3-dentato floram solitariam subtendente; calyce carnoso 
rugoso turbinato ; corolla extus glaberrima 6 mm. longa 5-6 mm. di- 
ametro viridescenti-flava, tubo 4 mm. longo subgloboso, lobis 5 ovato- 
deltoideis acutiusculis 3 mm. longis recurvis ; staminibus 5 ; filamentis 
omnino corollae adnatis ; antheris breviter oblongis albidis ; eorum in- 
sertionibus pubentibus ; ovario fere supero, parte libera ovoidea sub- 
carnosa ruguloso-papillosa ; stylo 3.3 mm. longo; stigmate disciformi 
obscure 3-lobato; fructu ignoto.— Uruapan, Michoacan, Mexico, alt. 
1525 m., | November, 1905, C. α΄. Pringle, no. 10,123 (type, in hb. Gray). 
This species differs in its much larger corolla and more lanceolate leaves 
from the plant of the West Indies and Florida, which has generally 
passed as S. Schreberi Lam. or S. arborescens R. & 8. From S. mewi- 
cana DC. (known to the writer only from description) it appears to dif- 
fer in its leaves, which are often fully twice as long as those described 


ROBINSON. — NEW SPERMATOPHYTES, CHIEFLY FROM MEXICO. 23 


by DeCandolle and in its decidedly urceolate almost globose rather 
than cylindric corolla; also in the fact that the corolla-lobes are more 
than half as long as the tube. S. parvifolia Planch., to judge from 
Nelson’s n. 1836, so identified at the Royal Gardens at Kew, has a 
much more slender corolla. δ. angulata Planch. is described by Hems- 
ley, Biol. Cent.-Am. Bot. i. 185, as having flowers only one and one- 
half lines long and branches angled, while in the present species the 
branches are terete and even the branchlets are scarcely angled, the 
flowers being furthermore fully 3 lines long. The genus, however, is 
much in need of a thorough revision. 

Mimosa (§ Habbasia) buceragenia Robinson, n. sp., valde armata 
3-5 m. alta; ramulis viridibus albido-costatis puberulis in costis acu- 
leatis ; aculeis sparsis recurvatis 4 mm. longis basi albidis compressis 
4—5 mm. latis apice brunnescentibus induratis ; foliis 10-12 cm. longis 
5-6 cm. latis; petiolo et rhachibus et rhachillis breviter molliterque 
pubescentibus ; petiolo 2 cm. longo supra cum glandulo conspicuo ob- 
longo sessili ca. 2 mm. longo instructo subtus cum aculeo saepius uno 
armato; rbachi aculeis 2-3 parvis instructa ; stipulis binis subulato- 
filiformibus ca. 3 mm. longis erectis ; pinnis ca. 11-jugis; foliolis ca. 
25-jugis linearibus utrinque viridibus glabris acutiusculis 4-5 mm. 
longis ca. 0.8 mm. latis saepe leviter falcatis basi valde obliquis ; 
floribus virescentibus spicatis ; spicis densis saepissime in axillis binis 
pedunculatis ca. 4.5 cm. longis 8 mm. diametro; calyce cupulato 
brevissime 5-dentato; petalis 5 anguste lanceolatis; staminibus 10 ; 
ovario stipitato ; fructu ignoto. — Valley near 'reinte Station, in the 
vicinity of Cuernavaca, Morelos, Mexico, alt. 1220 m., 26 September, 
1905, C. G. Pringle, no. 10,073. A species which, to judge from its in- 
florescence, belongs in the series Leptostachyae, but well marked in this 
series by its conspicuous petiolar glands. 
ν΄ Pedilanthus spectabilis Robinson, n. sp., caulibus teretibus cras- 

sis foliosis griseis minute granuloso-pulverulis vix 1 τὴ. altitudine ; 

foliis ovato-oblongis brevissime crassiusculeque petiolatis 8-9 cm. 
longis 4-6 cm. latis integris supra glabriusculis subtus breviter molli- 
terque pubescentibus apice rotundatis saepissime retusis distincte 
mucronulatis basi breviter cordatis ; inflorescentia terminali dichotoma 
bracteosissima densiuscula ca. 1.6 dm. lata; bracteis late ovatis cor- 
datis sessilibus oppositis integris 4-5 em. longis et latis internodia 
valde superantibus acute acuminatis caudato-attenuatis utrinque puber- 
ulis rubro-purpureis margine tomentellis ; pedicellis griseo-tomentosis ; 
involucro albido 18 mm. longo ‘basi: leviter invaginato, labio superiore 
profunde bipartito, lobis linearibus acutiusculis 6-7 mm. longis quam 
labio inferiore multo brevioribus margine tomentellis ; stipite ovarii 


24 PROCEEDINGS OF THE AMERICAN ACADEMY. 


glabro nutanti ; filamentis glabris ; stylo 1 cm. longo; capsula ca. 1 em. 
diametro obtuse 3-lobata subsphaerica ; seminibus virklescenti-griseis 
angulatis 6 mm. longis. —Cafon walls of limerock, Iguala Cafon, 
near Iguala, Guerrero, Mexico, alt. 760 m., 28 December, 1906, C. G. 
Pringle, no. 13,914 (type, in hb. Gray). This noteworthy species is 
probably the most showy of the genus. It differs from P. bracteatus 
(Jacq.) Boiss. in having pubescent leaves, denser inflorescence, and 
larger much more caudate-acuminate and strongly colored bracts. 
Bonplandia linearis Robinson, n. sp., herbacea ramosa dense caes- 
pitosa gracilis 4 dm. vel ultra alta ubique glanduloso-pubescens ; ramis 
erectis vel ascendentibus ; foliis alternis anguste linearibus 3-4.5 cm. 
longis vix 2 mm. latis sessilibus attenuatis cum lobis lateralibus 2 an- 
gustis late patentibus instructis; racemis erectis laxifloris 1-1.5 dm. 
longis ; floribus saepissime geminis in pedicellis erectis ca. 1 cm. longis 
nutantibus ; calyce tubuloso 15-striato et venoso-reticulato anthesi 8 
fructifero 11 mm. longo leviter curvato paulo nigrescenti, dentibus 
lanceolato-deltoideis acutis ; corolla cyanea ca. 2 cm. longa; tubo gra- 
cili ad orem calycis leviter deflexis ; lobis anguste obovatis retusis late 
patentibus ca. 12 mm. longis ; filamentis subaequalibus glabris longe 
exsertis ; stylo filiformi glabro, ramis stigmatiferis 3 linearibus papil- 
losis 1.2 mm. longis ; ovario ovoideo glabro. — Lava fields, near Coru 
Station, above Uruapan, Michoacan, Mexico, 26 January, 1907, C. G. 
Pringle, no. 10,364 (type, in hb. Gray). ‘This species obviously belongs 
to the hitherto monotypic genus Bonplandia. It differs strikingly from 
the common #. geminiflora Cav. in its narrowly linear leaves. 
Brittonastrum Barberi Robinson, n. sp., herbaceum 4—6 dm. vel ul- 
tra altum ; caulibus gracilibus suberectis simplicibus basi rubescentibus 
alibi pallide viridibus ubique crispe griseo-puberulis ; foliis ovato-lance- 
olatis crenatis obtusis vel superioribus acutis vel etiam subattenuatis 
2-3.5 cm. longis 1-2 em. latis subtus pallidioribus utrinque crispe griseo- 
puberulis superioribus distantibus ; petiolis 2-5 mm. longis ; inflore- 
scentia anguste paniculata 8-22 cm. longa 5 cm. diametro superne 
densiuscula ; bracteis inferioribus lanceolatis subsessilibus 1-1.5 em. 
longis superioribus valde reductis; inflorescentiis secundariis ascen- 
dentibus multifloris griseo-puberulis vel -pulverulis inferioribus plus 
minusve distantibus; bracteolis subulatis minimis et pedicellis pur- 
purascentibus; calyce anguste tubulato anthesi deorsum attenuato 
fructifero deinde turgido 10-12 mm. longo pulcherrime purpureo 
griseo-puberulo et atomifero, dentibus lanceolatis parvis acutis erectis 
1.5-2 mm. longis; corolla molliter puberula anguste tubulata leviter 
curvata 2.6 cm. longa, limbo valde ringenti, labio superiore erecto sub- 
-cucullato inferiore deflexo ca. 2 mm. longo; staminibus juxta labium 


ROBINSON. — NEW SPERMATOPHYTES, CHIEFLY FROM MEXICO. 25 


superius exsertis. — Near Colonia Garcia in Sierra Madres, Chihuahua, 
Mexico, alt. 2290 m., 17 July, 1899, C. H. 7. Townsend & C. M. Bar- 
ber, no. 79 (type, in hb. Gray). Previously collected in imperfect speci- 
mens at Los Pinitos, Sonora, Mexico, alt. 2000 m., 11 October, 1890, 
C. V. Hartman, no. 122 (hb. Gray), and in southwestern Chihuahua, 
August to November, 1885, Dr. 4. Palmer, no. FF in part. This 
species differs from the nearly related B. neo-mexicanum Briq. in its 
much longer corolla, more pedicellate flowers, shorter petioles, etc., 
from B. canum (Gray) Briq. in its shorter pedicels, longer less acutely 
toothed calyx, etc., from B. pallidum (Lindl.) Brig. by its ovate-lance- 
olate relatively narrower leaves, longer deep crimson calyx, and longer 
corolla. 

Brittonastrum ionocalyx Robinson, n. sp., herbaceum; caulibus 
quadrangularibus breviter molliterque canescenti-puberulis ; foliis del- 
toideo-ovatis sinu patulo cordatis grosse crenatis obtusis 3-5.5 em. 
longis 2.5-4 em. latis ubique molliter puberulis supra pallide viridibus 
subtus vix pallidioribus albo-nervosis, petiolo 6-10 mm. longo ; inflo- 
rescentia 11-17 cm. longa terminali 5-6 cm. diametro densiuscula ; 
bracteis infimis ovatis serrato-dentatis ca. 1 cm. longis, ceteris gradatim 
minoribus ; cymis furcatis compositis minute granuliferis vel glanduloso- 
puberulis ; floribus erectis vel paulo nutantibus ; calyce cylindrato pul- 
cherrime purpureo griseo-puberulo et atomifero anthesi 1 cm. longo 
fructifero vix accrescenti dentibus lanceolatis acutis 2 mm. longis erectis 
nec patulis nec induratis ; corolla purpureo-coccinea 2.5 cm. longa 
leviter curvata externe molliter puberula, faucibus vix dilatatis, limbo 
ringenti, labio superiore erecto, inferiore pendulo ; staminibus sub labio 
superiore modice exsertis. — Sandia Station, Durango, Mexico, alt. 
2288 m., 15 October, 1905, C. G. Pringle, no. 10,146 (type, in hb. 
Gray). This species differs from 25. pallidum (Lindl.) Briq. in its deep 
purple calyx and much more exserted corolla, as well as in its more 
compound inflorescence ; from 7. coccineum (Greene) Briq. in its much 
shorter calyx-teeth ; from 2B. betonicoides (Lindl.) Briq. in its much 
shorter petioles ; and from the real B. mexicanum (HBK.) Briq. in its 
very different foliage. To B. ‘onocalyx should be referred with scarcely 
a doubt Wright’s no. 1532 from mountains east of Santa Cruz, Sonora, 
which appears to differ only in the fact that the leaves are a trifle less 
cordate at base. 

Brittonastrum Palmeri Robinson, n. sp., herbaceum a basi hori- 
zontali radicanti erectum 6-9 dm. altum ; caule unico simplici acute 
quadrangulari saepius flexuoso vel torto ubique breviter crispeque 
griseo-puberulo ; foliis deltoideo-ovatis grosse crenatis acutiusculis vel 
subacuminatis utrinque griseo-tomentellis vel glabriusculis subtus paulo 


26 PROCEEDINGS OF THE AMERICAN ACADEMY. 


pallidioribus 3-6 cm. longis 2.4-3.6 em. latis basi cordatis ; petiolis 
4-10 mm. longis ; inflorescentia terminali ca. 1.5 dm. longa interrupte 
spiciformi, verticellastris inferne subremotis superne approximatis densis 
multifloris, cymulis brevibus densissimis, bracteis inferioribus foliaceis 
ovatis vel ovato-lanceolatis 2-2.5 em. longis petiolatis superioribus 
lanceolatis vel linearibus; pedicellis brevissimis purpureis griseo- 
puberulis, calyce subcylindrato anthesi 1 cm. longo puberulo inferne 
viridi superne laete purpureo vel violaceo, dentibus argutissimis 
lineari-lanceolatis ca. 3 mm. longis maturitate subinduratis saepe cur- 
vatis plus minusve patentibus ; corolla purpurea gracili griseo-puberula 
apicem versus deorsum curvata 2 cm. longa, labiis brevibus superiore 
subgaleato ; staminibus breviter exsertis. — Alvarez, San Luis Potosi, 
Mexico, 5-10 September, 1902, Dr. Hdward Palmer, no. 53 (type, in 
hb. Gray), distributed as Cedronella mexicana Benth. Previous col- 
lections of what appears to be the same species have been made as 
follows : Mexico, without precise locality, Swmichrast (hb. Gray), Coul- 
ter, no. 1078 (hb. Gray) ; in mountains near Morales in valley of San 
Luis Potosi, 1876, Schaffner, no. 682 (hb. Gray); region of San Luis 
Potosi, 1878, Purry & Palmer, no. 762 (hb. Gray). This species 
differs clearly from B. mexicanum (ABK.) Briq. in its deltoid-ovate 
leaves, shorter corolla, ete. It appears to differ in the same respects 
from B. coccineum (Greene) Briq., known to the writer from descrip- 
tion, —a characterization which fails to convince the reader that 
B. coccineum is distinct from the real B. mexicanum. B. Palmeri 
differs from B. betonicoides (Lindl.) Briq. in its much shorter petioles, 
longer calyx-teeth, ete. 

Brittonastrum Wrightii (Greenman) Robinson, n. comb. Cedro- 
nella Wrightii Greenman, Proc. Am. Acad. xli. 244 (1905). The sep- 
aration of the American simple-leaved species of Cedronella as a new 
genus Brittonastrum now generally accepted necessitates the transfer 
of Dr. Greenman’s excellent species C. Wrightiz. 

Russelia Pringlei Robinson, n. sp., caulibus subsimplicibus 1 m. 
vel ultra longitudine teretibus ca. 8-costatis niveo-tomentosis ; inter- 
nodiis 5-6 em. longis ; ramis elongatis gracilibus 4—6-angulatis griseo- 
tomentosis ; foliis oppositis vel ternis inaequalibus lanceolato-ovatis 
1.5-2 em. longis 6-10 mm. latis acutatis basi subeuneatis serrato-den- 
tatis supra viridibus crispe puberulis et squamiferis rugosis subtus 
pallidioribus densius squamiferis et praesertim in venis nervisque 
griseo-tomentellis ; inflorescentia 3-4 dm. longa 3-4 em. lata ; cymulis 
oppositis vel ternis; verticellis 3-5 cm. distantibus; pedicellis fili- 
formibus griseo-pubescentibus 3-4 mm. longis; calycis 5 mm. longi 
lobis ovato-lanceolatis caudato-acuminatis dorso squamiferis ; corolla 


γέ 


v 


ROBINSON. — NEW SPERMATOPHYTES, CHIEFLY FROM MEXICO. 27 


coccinea tubiformi 16 mm. longa glaberrima, lobis rotundatis 1.5 mm. 
longis ; capsula ovoidea acuminata 6 mm. longa glabra. — On vertical 
walls of limerock, Iguala Cafion, near Iguala, Guerrero, Mexico, 28 
December, 1906, C. G. Pringle, no. 10,367 (type, in hb. Gray). A 
species peculiar in its terete canescent-tomentose stem. 

Stemodia macrantha Robinson, n. sp., suffrutescens 1 m. vel ultra 
alta ; caulibus decumbentibus gracilibus teretibus pubescentibus ; ramis 
saepius simplicibus erectis vel ascendentibus viridibus patenter pilosis 
3-6 dm. longis, internodiis 3-10 cm. longis; foliis lanceolato-ovatis 
utroque angustatis 5-6 cm. longis 2.5-3 em. latis basi cuneata excepta 
crenato-serratis supra atroviridibus adpresse pilosis subtus paulo palli- 
dioribus in costis et venis lateralibus pinnatis hirsutulis ; petiolis 1 em. 
longis hirsutulis superne alatis ; inflorescentia terminali 1-4 dm. longa 
perlaxa folioso-bracteata, pedicellis filiformibus flexuosis glanduloso- 
pubescentibus unifloris 2-4 cm. longis ascendentibus ex axillis brac- 
tearum saepissime ternis vel quaternis orientibus ; calycis lacinis 
glanduloso-pulverulis et hispidulis lanceolato-linearibus superioribus 
anthesi usque ad 7 mm. longis infimis paulo brevioribus omnibus a 
basi gradatim angustatis sed apice vero obtusiusculis ; corolla 1.8—-2 
em. longis, tubo viridi-flavescenti cylindrato ca. 13 mm. longo 4 mm. 
diametro purpureo-nervio intus externeque piloso ad fauces distincte 
sursum curvato, limbo laete purpureo, lobis suborbicularibus subae- 
qualibus apice saepissime retusis ; staminibus brevioribus mediae parti 
tubi affixis 3 mm. longis longioribus paulo supra basin tubi affixis 
§ mm. longis omnibus inclusis antheriferis glabris ; capsula ovoidea 
5 mm. longa atrobrunnea a calyce persistenti circumdata. — Shaded 
bluffs of the deep barranca, near the foot of the Falls of T'zardracua, 
below Uruapan, Michoacan, Mexico, 28 January, 1907, C. G. Pringle, 
no. 10,356 (type, in hb. Gray). This species is amply distinguished 
from its Mexican congeners by its much larger flowers, which in fact 
are decidedly showy for the genus. 

Lopetta Netsonit Fernald, var. fragilis Robinson & Fernald, n. var. 
a forma typica recedit foliis utrinque viridibus juventate sparse pilo- 
sulis mox omnino glabratis lineari-lanceolatis multo brevioribus, maxi- 
mis ca. 7 cm. longis 8-10 mm. tantum latis. — Mexico, C. G. Pringle, 
no. 10,360 (type, in hb. Gray). This variety shares with the typical 
form the soft woody stems and branches as well as all the more impor- 
tant characteristics of the inflorescence. ‘The varietal name is suggested 
by the extreme brittleness of the branches, at least when dried. 'The 
variety, like the typical form, has numerous showy flowers with bright 
scarlet corolla. Both plants seem worthy of cultivation. 

Piqucria (Subg. Phalacraea) longipetiolata Robinson, n. sp., 


28 PROCEEDINGS OF THE AMERICAN ACADEMY. 


repens subglabra ; caule tenui flexuoso prostrato nodis radicante, inter- 
nodiis saepius perlongis (ad 1 dm.) glabris ‘angulato-costatis ; foliis 
oppositis, limbo late ovato 1.8-3.5 cm. longo 1.2-2.7 cm. lato supra 
basin integram crenato-dentato supra viridi sparse hispidulo subtus 
paulo pallidiore glabro basi obtuso vel breviter acuminato apice obtuso, 
petiolo obecompresso (dorsoventraliter) limbum longitudine aequante ; 
capitulis parvis ca. 9-floris cymosis, cymis ca. 7—-13-capituliferis termi- 
nalibus ; involucri campanulati squamis ca. 6 obovatis viridibus obtusis 
ciliatis 3 mm. longis ; corollae tubo proprio brevi glanduloso-puberulo, 
faucibus campanulatis quam tubo longioribus subglabris, limbi denti- 
bus 5 late ovatis obtusis ; achaeniis immaturis sursum hispidulis basi 
rectiusculis.— Colombia, near R. Flautas, R. Paez Valley, Tierra Aden- 
tro, Central Cordillera, alt. 2900 m., 26 January, 1906, H/. Pittier, no. 
1208 (hb. U. 8. Nat. Mus. ; fragment in hb. Gray). This species stands 
nearest P. callitricha Robinson, Proc. Am. Acad. xlii. 15 (1906), but 
differs in having smaller more coarsely and simply toothed leaves with 
much longer petioles. It is also a smoother plant and has fewer- 
flowered heads. 

Stevia alatipes Robinson, n. sp., herbacea perennis ca. 1 cm. alta 
hirsuta ; radice fibrosa; foliis radicalibus ovatis vel obovatis crenato- 
serratis ca. 8 cm. longis 4-5 em. latis pinnatinerviis utrinque hirsutis 
haud vel vix punctatis apice rotundatis basi angustatis in petiolum 
alatum decurrentibus; foliis caulinis oppositis 2-4-jugis oblanceo- 
latis vel fere spatulatis in petiolum alatum basi attenuatis ; intloresceutia 
laxissime pauciramosa ; ramis nudiusculis, capitula pauca parva sacpe 
aggregata ferentibus ; bracteis 7 mm. longis lanceolatis sessilibus her- 
baceis ; pedicellis ad 1 em. longis filiformibus glanduloso-puberulis ; 
capitulis ca. 12 mm. longis 4-floris ; involucri squamis 5 viridibus lan- 
ceolato-linearibus acutis inaequalibus ca. 7 mm. longis ; corollis 7 mm. 
longis, tubo viridescenti puberulo, limbo albo ; achaeniis nigrescentibus 
3.2 mm. longis minute puberulis ; pappo e squamis 3 brevibus albis et 
aristis 3 albidis 5-6 mm. longis barbellatis composito. — Pine forests, 
Uruapan, Michoacan, Mexico, alt. 1680 m., 14 November, 1905, C. G@. 
Pringle, no. 10,124 (type, in hb. Gray). Near S. elatior HBK. but 
readily separable by its much larger basal leaves with long-attenuate 
base, its aggregated heads, ete. 

Stevia Lozanoi Robinson, n. sp., caule tereti purpureo pilis crispis 
griséis brevibus pubescenti supra laxe ramoso folioso; ramis divergenti- 
ascendentibus subsimplicibus gracilibus ca. 1 dm. longis foliosis in 
corymbos subdensos capitiformis terminantibus; foliis inferioribus 
ignotis, superioribus linearibus sessilibus alternis integris 4-5 cm. longis 
3-7 mm. latis utrinque obscure viridibus punctatis 1-3-nerviis sparse 


ROBINSON. — NEW SPERMATOPHYTES, CHIEFLY FROM MEXICO, 29 


pubescentibus margine saepe purpurascenti-hispidulis apice obtusis basi 
attenuatis ; corymbis 3-4 cm. diametro convexis 10-20-capitulatis ; ca- 
pitulis 1.5 cm. longis breviter pedicellatis vel etiam sessilibus, bracteis 
linearibus 3-6 mm. longis herbaceis ; squamis involucri ca. 6 linearibus 
acutis purpureis 7 mm. longis pilis crispis atomisque resinosis tectis ; 
flosculis 5 ; corollis 8 mm. longis, tubo purpureo pubescenti gradatim a 
basi sursum leviter ampliato, limbo albo patenti 5-lobo, lobis oblongis 
obtusiusculis ; achaeniis gracilibus 5 mm. longis sursum praesertim in 


 angulis hispidulis ; pappo 6 squamulis 5 albidis brevissimis et aristis 5 


purpureis divergentibus scabratis composito. — Sandia Station in moun- 
tains of northwest Durango, Mexico, alt. 2290 m., 12 October, 1905, 
C. G. Pringle, no. 10,092 (type, in hb. Gray). A species evidently re- 
lated to S. laxiflora DC. and S. serrata DC., but readily distinguished 
by its numerous separate dense corymbs and entire leaves. Named for 
Sr. Filemon L. Lozano, faithful and efficient companion and assistant 
of Mr. Pringle in his recent journeys to Mexico. 


- Stevia PLUMMERAE Gray, var. durangensis Robinson, n. var., foliis 
ν΄ ’ ’ ᾽ 


Y 


tenuibus lanceolato-oblongis 6—9 cm. longis 1.5-2 em. latis supra mediam 
partem serratis nec dentatis supra pilis brevissimis crispis griseo-puber- 
ulis subtus molliter pubescentibus; corollis albis. — Barranca below 
Sandia Station, Durango, Mexico, alt. 2135 m., 13 October, 1905, C. G. 
Pringle, no. 10,106 (type, in hb. Gray). Nearer var. alba Gray, Syn. 
Fl. i. pt. 2, 92, than to the typical form, but differing in its thinner 


larger less strongly reticulated and much more pubescent leaves. 


EKupatorium acutidentatum Robinson, n. sp., herbaceum erectum 
6 dm. altum ; caule gracili tereti striato viridi vel purpurascenti crispe 
puberulo subsimplici vel modice oppositirameo ; foliis oppositis ovato- 
lanceolatis tenuibus argute serrato-dentatis basi cuneata et apice at- 
tenuato integris a basi 3-5-nerviis 3.6—-5 em. longis-1.8—2.2 em. latis 


“supra laete viridibus scabriusculis subtus vix pallidioribus i in nerviis 


sparse pubescentibus, petiolo puberulo ca. 5 mm. longo ; capitulis ca. 
12-floris 1 em. longis numerosis graciliter pedicellatis in eorymbos valde 
convexos collectis, pedicellis 5-8 mm. longis griseo-puberulis ; invo- 
lucri squamis anguste oblongis vel lanceolatis attenuatis herbaceis 
griseo-puberulis inaequalibus laxe imbricatis interioribus quam flosculis 
dimidio brevioribus ; corollis albis glabris, tubo proprio gracili quam 
faucibus gradatim sed valde ampliatis distincte breviore ; achaeniis 
nigrescentibus 3 mm. longis prismaticis deorsum paululo angustatis 
sursum hispidulis; pappi setis minute barbellatis corolla fere aequi- 
longis basin versus roseis. — Barranca below Sandia Station, Durango, 
Mexico, alt. 2135 m., 15 October, 1905, C. G. Pringle, no. 10,095 (type, 
in hb. Gray). This species is obviously close to E. betulaefolium 


50 PROCEEDINGS OF THE AMERICAN ACADEMY. ἃ 
(Greene) Robinson, n. comb. (Ayrstenia betulaefolia Greene, Leafl. i. 
10, 1903.) It differs, however, in having decidedly narrower leaves, 
which are entire at the attenuate apex ; the bracts are also of different 
form, being narrowly lanceolate, quite entire, and strongly attenuate ; 
furthermore the involucral scales are of a more herbaceous texture. 
Whether these distinctions will prove constant cannot be foretold ; but 
on the whole they appear rather too significant to permit the placing 
of the present plant under Μ΄. betulaefolium as a variety. 
' Eupatorium campechense Robinson, ἢ. sp., subglabrum ; ramis 
teretibus striatulis glaberrimis lignescentibus modice medullosis ; foliis 
oppositis petiolatis lanceolatis attenuatis saepe falcatis 3-nerviis crassi- 
usculis nitidulis 8-10 cm. longis 2.4-3 em. latis glabris vel in nerviis 
primariis obscure puberulis subremote serratis ; petiolo ca. 1 em. longo 
obecompresso supra canaliculato glabro vel papilloso ; inflorescentiis 
amplis oppositirameis ; capitulis numerosis ca. 5-floris graciliter pedi- 
cellatis subdense corymbosis ; ramulis paniculae et pedicellis gracil- 
limis puberulis; involucri squamis 5-stachyis imbricatis stramineis 
glaberrimis obtusis, extimis brevissimis ovatis ca. 1 mm. longis inter- 
mediis gradatim longioribus ovato-oblongis, intimis (numero ca. 5) 
anguste oblongis 7 mm. longis ; corollis tubulosis sine faucibus dis- 
tinctis 6 mm. longis, dentibus limbi ca. 1 mm. longis lanceolatis re- 
curvatis; achaeniis prismaticis 5-angulatis fuscis in faciebus et in 
costis pubescentibus 3.3 mm. longis deorsum modice angustatis ; pappi 
setis ca. 20 levibus albidis 4-5 mm. longis. — Apazoli near Yohaltun, 
Campeche, Mexico, 30 December, 1900, 2. A. Goldman, no. 504 (type, 
in hb. U.S. Nat. Mus. ; fragments in hb. Gray). A species well marked 
and apparently without close ally. 

Eupatorium chrysostyloides Robinson, ἢ. sp., herbaceum sub- 
erectum 1.3-4 dm. altum pilis crispis griseis brevibus hine inde glan- 
duliferis puberulum ; caule solitario modice curvato vel flexuoso obtuse 
angulato pallide viridi folioso, in parte inferiore subsimplici ; foliis 
oppositis longe petiolatis concoloribus viridibus nee lucidis late del- 
toideo-ovatis 3-6 cm. longis 2.4—5 em. latis obtusis vel modice acutis 
grosse crenato-dentatis basi subtruncatis 3-nerviis in petiolum breviter 
decurrentibus ; petiolo 1-4.5 em. longo; corymbis rotundatis multi- 
capitulatis densiusculis ramos terminantibus ; pedicellis filiformibus 
griseo-pubescentibus ; capitulis ca. 20-floris ca. 1 em. longis 6 mm. 
diametro ; involucri turbinato-cylindrati squamis numerosis anguste 
lanceolatis viridibus pallide nervatis hispidulis acutissimis valde inae- 
qualibus multiseriatis ; corollis viridi-albidis angustissimis brevissime 
5-dentatis, faucibus nullo modo ampliatis ; styli ramis longissimis aureis 
valde exsertis ; achaeniis 5-angulatis prismaticis 2.56 mm. longis basi 


ROBINSON. — NEW SPERMATOPHYTES, CHIEFLY FROM MEXICO. 51 


angustatis albo-callosis sursum paulo hispidulis, pappi setis ca. 25 
laete albis minute barbellatis. — On limerock, Sierra Madre, above 
Monterey, | Mexico, alt. 915 m., 27 April, 1906, C. G. Pringle, no. 10,231 
(type, in hb. Gray). This species belongs to a small but increasing 
group of very nearly related plants, including μι Purryi Gray, 
E. chrysostylum Robinson, and Μ΄. sphenopodum Robinson. From all 
these species, the present one differs in its exceedingly short crisped 
pubescence. 

γ᾽  Bupatorium durangense Robinson, ἢ. sp., herbaceum 6-9 dm. 
altum ; caule tereti oppositirameo folioso purpurascenti ubique minu- 
teque crispo-puberulo ; foliis oppositis ovatis deflexis breviter petio- 
latis firmiusculis obtusis vel vix acutis paulo supra basin 3—5-nerviis 
supra viridibus pilosellis subtus vix pallidioribus leviter reticulato- 
venosis in nervis venisque sparse pubescentibus serratis 2-3 cm. longis 
1.3-2.2 em. latis scabrido-ciliolatis, petiolo puberulo supra concavo 
2-3 mm. longo; capitulis ca. 12-floris numerosis in corymbis convexis 
terminalibus collectis, pediceliis 5-12 mm. longis filiformibus griseo- 
puberulis ; involucri squamis pallide viridibus griseo-puberulis oblongo- 
linearibus acutis valde inaequalibus sed laxe imbricatis interioribus ca. 
4—5 mm. longis; corollis albis 6-7 mm. longis, tubo proprio gracili 
fauces gradatim sed distincte ampliatos subcylindratos subaequanti; 
achaeniis nigris gracilibus 5-angulatis in angulis sursum hispidulis ; 
pappi setis simplicibus corollam aequantibus superne laete albis basin 
versus roseis. — Barranca below Sandia Station, Durango, Mexico, alt. 
2135 m., 15 October, 1905, C. G. Pringle, no. 10,096 (type, in hb. 

στῶ). 

ν Var. angustius Robinson, n. var., foliis angustioribus ovato-lance- 
olatis attenuatis maximis 3.2 em. longis 1.7 cm. latis supremis saepe 
alternantibus. — Mesa de Sandia, northwestern Durango, Mexico, alt. 
2745 m., 14 October, 1905, C. G. Pringle, no. 10,097 (type, in hb. 
Gray). This variety has something the appearance of Μ΄. Robinsoni- 
anum Greene, but may be readily distinguished by its more herba- 
ceous involucre, thickish more pubescent and regularly deflexed leaves, 
Shorter stouter petioles, ete. 

ν΄ Eupatorium erythrocomum Robinson, n. sp., suffrutescens laxe 
procumbens ; caulibus ee teretibus arcuatis ramosis atropurpu- 
reis striatulis plerumque ca. 2 mm. diametro cum pilis moniliformibus 
adpresse villosulis ; foliis oppositis ovatis vel ovato-lanceolatis breviter 
petiolatis, limbo 2-2.8 em. longo 1-1.2 cm. lato supra basin subrotun- 
datam integram argute serrato apice acuto 3-nervio supra viridi glabri- 
usculo subtus saepissime purpurascenti praesertim in nervis venisque 
adpresse pilosis, petiolo tereti purpureo ca. 2 mm. longo, venis supra 


32 PROCEEDINGS OF THE AMERICAN ACADEMY. 

impressis, dentibus limbi utroque ca. 5; capitulis ca. 30-floris paucis 
4-11 in corymbo terminali, pedicellis ca. 1 em. longis erectis vel ascen- 
dentibus subfiliformibus atropurpureis adpresse villosulis, bracteis 
linearibus ; involucri campanulati squamis ca. 15 lanceolati-linearibus 
subaequalibus vix imbricatis obtusis vel acutiusculis pilosis ca. 5 mm. 
longis margine praesertim apicem versus pulcherrime ciliatis ; corollis 
albis 4 mm. longis, tubo proprio gracili fauces ampliatos subcylindratos 
subaequanti, dentibus limbi 5 acutiusculis hispido-pilosis ; achaeniis 
prismaticis praesertim in angulis breviter hispidulis ; pappi setis pul- 
cherrime roseis. — Steep rocks, Ixtaccihuatl, Mexico, alt. 2440 m., 
January, 1906, C. A. Purpus, no. 1578 (type, in hb. Gray). This - 
attractive species of Kwpatorium was submitted to the writer by Mr. 
T. S. Brandegee. It approaches Μὲ prunel/ifolium HBK., but differs 
in its slender flexuous procumbent stems, and more evenly and sharply 
serrate leaves, which are essentially glabrous above. δ. oligocephalum 
DC., an imperfectly known species, may also be of this affinity ; but it 
is described as having glabrous involucral scales. 

Eupatorium hospitale Robinson, n. sp., arboreum ; ramis 6-angu- 
latis striatis molliter lignosis medullosis glabris ; foliis oppositis lance- 
olato-oblongis serratis vel subintegris petiolatis penninerviis utrinque 
glabris crassis siccitate nigrescentibus pellucide punctatis lineolatis- 
que caudato-acuminatis basi attenuatis 16-18 cm. longis 5-6 cm. latis ; 
panicula terminali pyramidata oppositiramea patenter ramosa obsolete 
pilosiuscula vel glabra multicapitulata ; capitulis in summis partibus 
ramulorum sessilibus parvis ca. 6-floris ; squamis involucri valde inae- 
qualibus, interioribus oblongis obtusis 5 mm. longis paucis caducis- 
simis, exterioribus multo brevioribus imbricatis dorso margineque 
pilosiusculis apice rotundatis persistentibus aetate patentibus ; flos- 
culis vero similiter albidis vel viridescentibus ; corollis 4 mm. longis, 
tubo proprio gracili, faucibus cylindratis saepius vix ampliatis ; achae- 
niis ca. 3 mm. longis brunneis acute 5-angulatis basi attenuatis in 
faciebus concavis pilosis ad angulos etiam hispidulis ; pappi setis sor- 
didis ca. 35 corollam subaequantibus. — /. vanillosmoides Hemsl., Biol. 
Cent.-Am. Bot. ii. 102 (1881), not Sch. Bip. ex Bak. in Mart. ΕἸ. Bras. vi. 
pt. 2, p. 346 (1876). — Mirador, Vera Cruz, Mexico, Liebmann, no. 43 
(type, in hb. Gray), Sartorius (hb. Gray) ; Orizaba, Mexico, October, 
1855, Schaffner (hb. Gray), Botter7, no. 613 (hb. Gray). This well 
marked species appears never to have been described. The plant in 
question has been repeatedly distributed as Lupatorium vanillosmoides 
Sch. Bip., but the species to which Schultz really gave this name was 
a Brazilian plant of entirely different affinity, referred by Mr. Baker 
(ΕἸ. Bras. vi. pt. 2, p. 346) to the synonymy of 27. pyrifolium DC. It 


\ 


ROBINSON. — NEW SPERMATOPHYTES, CHIEFLY FROM MEXICO. 33 


is true Schultz well knew the Mexican plant, and ascribed to it the 
same specific name (vanillosmoides), but under another generic name. 
In describing this hitherto uncharacterized Mexican plant it seems 
unwise to take up the nomen nudum /. vanillosmoides Hemsl., a name 
inadvertently ascribed by Mr. Hemsley to Schultz, although, as we 
have seen, Schultz used this binominal combination for quite a differ- 
ent plant of Brazil. To avoid probable confusion the Mexican plant is 
herewith given a new and distinctive name. ‘The designation chosen 
is suggested by the fact that some of the internodes below the inflo- 
rescence are often, swollen, hollowed, and provided with a somewhat 
regular rounded ingress for small insects, probably ants. These en- 
largements are not always present, and are doubtless of the nature of 
galls developing through insect irritation, and later serving as nesting 
places for the insects. 

Hupatorium hymenolepis Robinson, ἢ. sp., gracile patente ramo- 
sum; caule tereti nigrescenti obsolete strigilloso; ramis gracillimis 
flexuosis ; foliis oppositis longe petiolatis ovatis vel rhomboideis basi 
abrupte angustata acuta excepta grosse serratis apice caudato-attenuatis 
6-7.5 cm. longis 2-3.5 cm. latis tenuibus utrinque viridibus in nervis 
adpresse pilosiusculis subtus haud pallidioribus supra sparse strigillo- 
sis; cymis parvis 6-10-capitulatis graciliter pedunculatis saepissime 
nutantibus ; capitulis parvis 3.5 mm. longis ca. 18-floris ; involuerj 
companulati squamis valde inaequalibus albo-scareosis in media parte 
tantum viridi-striatis, interioribus lineari-oblongis obtusissimis, exterior- 
ibus brevioribus acutis vel acuminatis ; corollis albis 2.5 mm. longis 
glabris basin versus modice angustatis ; dentibus 5 ovato-deltoideis 
brevibus patentibus ; styli ramis albis paulo clavellatis ; achaeniis ni- 
gris 5-angulatis 1.3 mm. longis basi albo-callosis sursum minute his- 
pidulis, costis albidis ; pappi setis gracillimis ca. 20 corolla distincte 
brevioribus. — Falls of Tzararacua, near Uruapan, Mexico, 28 January, 
1907, C. G. Pringle, no. 10,355 (type, in hb. Gray). This species 
somewhat resembles μ΄. hymenophyllum Klatt, but has slightly firmer 
leaves 3-nerved from the very base instead of from a point somewhat 
above the base; it differs also in its involucre. From /. Gonzalezii 
Robinson, to which-it also bears some resemblance, it may be readily 
distinguished by its more attenuate leaves and scarious involucral 
scales. 

Eupatorium isolepis Robinson, ἢ. sp., suffruticosum ; caulibus te- 
retibus flexuosis oppositirameis brunneo-purpureis pubescentibus, pilis 
moniliformibus transverse purpureo-striatis ; foliis oppositis graciliter 
petiolatis ovatis acuminatis serratis tenuibus subpellucidis subconcol- 
oribus supra glabris subtus in nervis sparse pilosis penninerviis bast 

VOL. XLIII.—3 


94 PROCEEDINGS OF THE AMERICAN ACADEMY. 


rotundatis paululo in petiolum saepe subdecurrentibus 3-6.5 em. longis 
1.6-4 cm. latis ; petiolo 1-4 em. longo subtus convexo subglabro supra 
canaliculato villoso; capitulis 9 mm. longis 6 mm. diametro 20-floris 
numerosis ad apices ramorum glomerato-aggregatis, corymbis rotun- 
datis densiusculis ca. 4 cm. diametro ; pedicellis filiformibus puberulis 
2-6 min. longis ; involucri campanulati squamis ca. 10 elliptico- vel obo- 
vato-oblongis aequilongis apice rotundatis saepius pulcherrime ciliatis 
dorso pubescentibus 3.2 mm. longis 1.5 mm. latis pallide viridibus ; 
corollis albis, tubo proprio gracili 2 mm. longo glabro, faucibus cam- 
panulatis glabris, dentibus limbi 5 deltoideis pilosiusculis; antheris 
vix connatis apice longe appendiculatis; achaeniis nigrescentibus 5- 
angulatis 1.5 mm. longis sursum praesertim in angulis hispidulis apice 
cupula albida coronatis ; pappi setis capillaribus vix barbellatis laete 
albis vel saepissime pulcherrime roseis corollam fere aequantibus ca- 
ducis. — Open moist places, rocks of barranca, Ixtaccihuatl, Mexico, alt. 
2440 m., C. A. Purpus, no. 1496 (type, in hb. Gray) ; also in the Valley 
of Mexico, Schaffner, no. 201 (hb. Gray). This species differs from 2. 
pazcuarense HBK. in its very obtuse involucral scales; from 2. photinum 
Robinson, in its thin pubescent less attenuate leaves. It is perhaps 
most nearly related to Μ΄. Schaffneri Gray, but it differs from that 
species in its more attenuate-acuminate and more regularly serrate 
leaves which are pinnately veined, while in μ᾽ Schaffneri they are 
palmately nerved from the very base. 

EvpatORIUM PHOENICOLEPIS Robinson, var. guatemalensis Robinson, 
n. var., foliis quam eis formae typicae multo majoribus 12-14 em. longis 
9-10 em. latis tenuioribus cordatis supra scabriusculis subtus in nervis 
venisque laxiuscule pubescentibus nec tomentosis ; involucri squamis 
et floribus necnon achaeniis formae typicae simillimis. — Vol. Atitlan, 
Department of Solaldé, Guatemala, alt. 2500-2700 m., 16 February, 
1906, W. A. Kellerman, no. 5199 (type, in hb. Field Museum of Natural 
History ; fragment in hb. Gray); between Patahil and San Lucas, De- 
partment of Solald, Guatemala, 15 February, 1906, W. A. Kellerman, 
no. 5194 (hb. Field Mus.). 

Eupatorium saltillense Robinson, n. sp., fruticosum 9-15 dm. 
altum oppositirameum ; ramis teretibus late patentibus arcuato-ascen- 
dentibus a cortice brunneo-griseo obtectis foliosis ; foliis ovatis tenuibus 
translucentibus integris vel obsolete serratis vel plus minusve distincte 
serrato-dentatis vix discoloribus supra sparse pilosulis obscurissime 
punctatis vel omnino epunctatis subtus minute glanduloso-punctatis et 
praesertim in nervis venisque puberulis apice obtusis vel obtusiusculis 
numquam attenuatis basi angustatis in petiolo decurrentibus et margine 
saepissime revolutis, limbo 4-5.8 em. longis 2.3-3.3 cm. latis, nervis 


ROBINSON. —- NEW SPERMATOPHYTES, CHIEFLY FROM MEXICO. 309 


subtus albidis prominulis, venis lateralibus utrinque ca. 5 inaequidis- 
tantibus maximis supra basin orientibus ; petiolis 5-8 mm. longis levi- 
ter marginatis basi linea transversa connexis ; inflorescentiis corymbosis 
valde convexis oppositirameis multicapitulatis; bracteis inferioribus 
petiolatis ovatis foliis similibus sed multo minoribus superioribus 
anguste linearibus sessilibus; pedicellis rectis filiformibus patenti- 
ascendentibus pilis crispis obtectis ; capitulis parvis numerosissimis 
saepissime 5-floris 8 mm. longis ; squamis involucri ca. 8 linearibus 
vix imbricatis sordide puberulis acutiusculis interioribus 4-5 mm. 
longis extimis 1-3 multo brevioribus; corollis glabriusculis 4.6 mm. 
longis albidis vel roseis, tubo proprio gracili quam faucibus subcylindratis 
breviore, dentibus limbi ovato-deltoideis ; achaeniis nigris prismaticis 
griseo-puberulis 3 mm. longis ; pappi setis praesertim basi pulcherrime 
roseis corollam vix aequantibus. — Mountains near Saltillo, Coahuila, 
Mexico, alt. 2135 m., 5 October, 1905, C. G. Pringle, no. 10,080 (type, 
in hb. Gray). This species is obviously related to Δ micranthum Less. 
It differs, however, in many small characters. ‘The leaves are thin and 
translucent while in 2. micranthum they are thickish and quite opaque. 
In £. saltillense they are also much broader relatively to their length 
and not attenuate. The nervation is furthermore quite different, for 
in Μὰ micranthum the lateral veins leave the midnerve in a pretty reg- 
ular pinnate fashion, while in /. sa/til/ense they are less numerous and 
less regular and give the leaves somewhat the appearance of being 3- 
_nerved from a point above the base. 

Eupatorium sexangulare (Klatt) Robinson, n. comb. Piptocarpha 
sevangularis Klatt, Botanisches Beiblatt zur Leopoldina, 1895, p. 1. 
Mr. H. A. Gleason, during a recent examination of the Vernonicae in 
the Gray Herbarium, called my attention to the type of Dr. Klatt’s 
Piptocarpha sexangularis, which appeared wholly irreconcilable with 
the genus in which it had been placed and indeed with any other genus 
of the Vernonieae. Unfortunately the specimen, although showing well 
the stem, leaves, inflorescence, involucral scales, etc., has but very few 
flowers, and these have been so damaged by decay or insects that it is 
impossible to state precisely the form of the anthers or style-tips ; nev- 
ertheless there can be no doubt that the plant is a Hupatorium, and as 
it appears to be unlike any species previously referred to that genus, it 
may be simply transferred thither. In its sharply angled stem and 
large thickish lanceolate leaves it bears considerable resemblance to the 
plant here described as Δ΄. hospitale. It may be readily distinguished, 
however, by the different venation of the leaves, entirely glabrous 
achenes, ete. 

γ Hupatorium sphenopodum Robinson, n. sp., herbaceum oppositi- 


86 PROCEEDINGS OF THE AMERICAN ACADEMY. 


rameum molliter hirsutum, pilis longis patentibus plus minusve monili- 
formibus albis viscidulis inaequalibus ; foliis oppositis deltoideis vel 
ovato-deltoideis longe petiolatis late cordatis grosse duplicateque cren- 
ato-dentatis tenuibus utrinque praesertim subtus in nervis pubescenti- 
bus, limbo 11-12 em. longo 8-10 em. lato, petiolo sursum alato ca. 7 cm. 
longo hirsuto ; panicula oppositiramea ; capitulis ca. 11-floris 10-11 mm. 
longis 4-5 mm. diametro ; pedicellis gracilibus rectis valde inaequalibus 
2-12 mm. longis ; involucri squamis lanceolatis attenuatis peracutis 
3—4-seriatis valde imbricatis viridibus albo-nerviis hispidulis adpressis ; 
corollis angustissime tubulosis 3.5 mm. longis viridiscenti-albidis, 
faucibus vix ullis; dentibus limbi brevissimis erectis ; styli ramis valde 
exsertis aurantiacis vel maturitate brunnescentibus valde clavatis ; 
achaeniis fuscis prismaticis 2.7 mm. longis deorsum modice angustatis 
basi callosis plus minusve curvatis in faciebus et in costis sursum his- 
pidulis ; pappi setis inaequalibus ca. 20 vix scabratis laete albis co- 
rollam fere aequantibus. — On shaded cliffs of limerock, Sierra Madre, 
above Monterey, Mexico, 1000 m. alt., 16 July, 1906, C. G. Pringle, no. 
10,259 (type, in hb. Gray). his species is closely related on the one 
hand to Δ᾽ chrysostylum Robinson and on the other to &. Parryi Gray. 
From the former it differs in its more slender freely branched less pu- 
bescent stems, large bluntly toothed leaves and much longer pedicels. 
From δὶ Parryi it differs in having much larger leaves (of which 
even the uppermost are opposite), winged petioles, and smaller fewer- 
flowered heads. 

Eupatorium thyrsiflorum (Greene) Robinson, n. comb. A’yrstenia 
thyrsiflora Greene, Leafl. i. 9 (1903). The genus AKyrstenia Neck, 
does not seem to the writer in any way satisfactorily separable from 
Eupatorium. When all species are duly considered the two groups 
appear to merge by imperceptible gradations. ‘There seems, however, 
to be little doubt that Professor Greene’s A. thyrsiflora is specifically 
distinct and may be appropriately transferred to the older genus. 
From the more typical material of the species, with leaves in varying 
degree toothed and somewhat narrowed at the base, the following plant 
may be varietally separated. 

Var. holoclerum Robinson, n. var., foliis ovatis integris vel obsolete 
crenato-serratis basi fere rotundatis. — Near the city of Durango, 
Mexico, April to November, 1896, Dr. #. Palmer, no. 755 (type, in hb. 
Gray). Distributed as δὶ occidentale, var. arizonicum Gray. 

Eupatorium triangulatum Alam. ex DC. Prod. v. 172 (1836). After 
a careful examination of the types of this species in the DeCandollean 
herbarium at Geneva, and of /. rubricaule HBK. at the Museum of 
Natural History at Paris, the writer can find no differences of moment. 


ROBINSON. —- NEW SPERMATOPHYTES, CHIEFLY FROM MEXICO. 91 


DeCandolle does not appear to have seen the plant of Humboldt and 
Bonpland, and the distinctions on which he attempted to separate 
E. triangulatum were deduced from the description of Kunth, but on 
comparison of the plants themselves these distinctions do not appear 
to be definite or important. ‘The species should certainly be united and 
stand under the older name E. ruBricAuLE HBK. 

BRICKELLIA BETONICAEFOLIA Gray, Pl. Wright. ii. 72 (1853). In the 
typical form of this rather variable species the leaves are ovate-oblong 
and flat, the larger 6 cm. long, 3 cm. wide ; petioles very short, scarcely 
over 2 mm. long; longer scales of the involucre rather attenuate. 

Var. HUMILIS Gray, in ce. Leaves ovate-oblong, flat, essentially sessile, 
the largest 3.8 em. long, 1.5 cm. wide; longer scales of the involucre 

linear, attenuate. 

_ Var. elliptica Robinson, n. var., foliis late ellipticis planis 3-4 em. 
longis 1.8-3 cm. latis subsessilibus ; squamis involucri_atropurpureis 
interioribus lanceolati-linearibus attenuatis. — Barranca below Sandia 
Station, Durango, Mexico, alt. 2135 m., 13 October, 1905, C. G. Pringle, 
no. 10,102 (type, in hb. Gray). 

Var. conduplicata Robinson, n. var., caule 6-9 dm. alto ; foliis 2=3 
cm. longis 1.4—-1.8 cm. latis saepissime conduplicatis ; petiolo gracile 
4—5 mm. longo; squamis involucri interioribus oblongi-linearibus atro- 
purpureis vix attenuatis. —San Luis Potosi, Mexico, on rocky hills, 
San José Pass, 16 August, 1890, C. G. Pringle, no. 3171 (distributed as 
B. betonicaefolia Gray 1). Mountains near General Cepeda, Coahuila, 
Mexico, alt. 1920 m., 7 October, 1905, C. G. Pringle, no. 10,081 (type, 
in hb. Gray). 

Brickellia saltillensis Robinson, n. sp., caulibus ΓΝ 9-12 dm. 
altis gracilibus striatulis pallide viridibus vel leviter purpurascentibus 
molliter breviterque pubescentibus foliosis ; foliis alternis petiolatis in 
axillis proliferis, laminis late ovatis obtusis vel subacutis serratis tenui- 
bus utrinque viridibus brevissime pubescentibus basi rotundatis 4-5.5 
cm. longis 2-4 cm. latis a basi 3-nerviis laxe reticulato-venosis ; petiolo 
1-1.4 em. longo pilis crispis glanduloso-puberulo ; foliis parvis ellipticis 
2-4 in axillis; panicula angusta 7-30cm. longa 4-7 cm. diametro fol- 
ioso-bracteata ; cymulis saepissime 3-capitulatis ; pedicellis gracillimis 
filiformibus glanduloso-puberulis nutantibus ; capitulis ca. 14-floris 1.8 
cm. longis ; involucri subturbinati squamis exterioribus viridibus striatis 
lanceolatis attenuatis dorso puberulis, interioribus lanceolati-linearibus 
attenuatis purpureo-tinctis 1-1.2 cm. longis; corollis albidis angustis- 
sime tubulosis 8-9 mm. longis glabris, faucibus nullis, limbi dentibus 
brevissimis erectis; styli ramis nigrescentibus vix clavatis longe ex- 
sertis ; achaeniis columnaribus 4.5 mm. longis adpresse pubescentibus 


38 PROCEEDINGS OF THE AMERICAN ACADEMY. 


fuscis basi callosis, pappi setis ca. 22 aequalibus tenuibus laete albis 5 
mm. longis vix scabratis. — On mountains, Saltillo, Mexico, alt. 2135 
m., 5 October, 1905, C. G. Pringle, no. 10,082 (type, in hb. Gray), 

LAGASCEA HELIANTHIFOLIA HBK., var. adenocaulis Robinson, 
n. var., caule (3-4 m. alto) usque ad summam partem dense glandu- 
loso-puberulo nee piloso; foliis longiuscule oblanceolato-oblongis at- 
tenuatis supra scabris subtus paulo pallidioribus molliter tomentellis, — 
Hedgerows, Uruapan, Michoacan, Mexico, 24 January, 1907, (@. G. 
Pringle, no. 13,907 (type, in hb. Gray). <A transition between this 
variety and the typical spreading-pilose form is shown by L. C. Smith’s 
no. 964 from the mountains of San Juan del Estado, Oaxaca. 

LAGASCEA HELIANTHIFOLIA HBK., var. levior Robinson, n. comb. 
Nocca helianthifolia Cass., var. levior Robinson, Proc. Am. Acad. 
xxxvi. 468 (1901). 

LAGASCEA HELIANTHIFOLIA HBK., var. suaveolens Robinson, n. 
comb, L. suaveolens HBK. Nov. Gen. et Spee. iv. 25 (1820). Nocea 
helianthifolia Cass., var. suaveolens Robinson, 1. 6. 

Lagascea Palmeri Robinson, n. comb. Nocca Palmeri Robinson, 
]. Ὁ. 471 (1901). 

Lagascea Pringlei Robinson, n. comb. Nocca Pringlei Robinson, 
l. ο. 469 (1901). 

Guardiola Palmeri Robinson, n. sp., glaberrima atroviridis com- 
pacte ramosa foliosa 3.5 dm. alta basi lignescens; caulibus teretibus 
striatulis gracilibus, ramis oppositis ascendentibus ; foliis oppositis 
petiolatis ovatis vel subreniformibus integerrimis vel plus minusve 
repandis nec angulatis nec dentatis 1.5-3 em. longis 1.2—2.8 em. latis 
utrinque leviter reticulato-venosis subtus vix pallidioribus apice rotun- 
datis basi late cordatis, petiolo 5-7 mm. longo ; inflorescentiis in api- 
cibus ramorum folioso-bracteosis 1—-3-capitulatis ; pedicellis 3-7 mm. 
longis ; capitulis 12-14 mm. longis 6-8 mm. diametro ; involucri sub- 
cylindrati fusco-viridis 1 em. longi 4-5 mm. crassi squamis oblongis 
obtusiusculis striatulis leviter convexis nullo modo ecarinatis ; radiis 
ca. 3; corollae tubo gracili glaberrimo 5 mm. longo, ligula elliptica 
4mm. longa 2.2 mm. lata bidentata alba; achaeniis immaturis con- 
cayvo-convexis obovato-oblongis 4.6 mm. longis glabris ; floribus disci ea. 
10 gracillimis, tubo corollae ca. 9 mm. longo, faucibus brevissimis 
campanulatis, lobis limbi 5 lineari-oblongis obtusis recurvatis albis ; 
filamentis albis tomentosis quam antherae virides multo brevioribus. — 
Outer circle of mesas, Otinapa, Durango, Mexico, alt. about 2450 m., 
25 July—5 August, 1906, Dr. λ΄. Palmer, no. 377 (type, in hb. Gray), 
This species in its few scattered heads, broad clearly petiolate leaves, 
and unkeeled involucral scales, closely approaches G. Losei Robinson ; 


ROBINSON. — NEW SPERMATOPHYTES, CHIEFLY FROM MEXICO. 99 


but it differs from that species in its decidedly smaller untoothed 
leaves, which are rounded at the apex. 

Zinnia tenella Robinson, n. sp., erecta gracilis annua tenuiter pilis 
subappressis griseis in novellis copiose pubescens in parte inferiore 
simplex supra saepissime 3-5-ramea 1.5-2.7 dm. alta; foliis tenuibus 
lanceolatis integris utrinque viridibus appresso-puberulis et sparse 
atomiferis obtusiusculis 3-nerviis patentibus vel deflexis basi cuneatis 
brevissime petiolatis 1.5-3.5 cm. longis 4-10 mm. latis; capitulis sae- 
pissime 1-5 terminalibus graciliter pedunculatis erectis ca. 7 mm. diam- 
etro (ligulis exclusis) aequi-altis ; involucri campanulati squamis paucis 
(ca. 8) late oblongis obtusissimis subaequalibus appressis tenuiter 
appresso-puberulis ca. 5 mm. longis; ligulis ca. 5 patentibus late ob- 
longis aurantiacis extus prope apicem saepe viridi-striatulis vel reti- 
culatis minutissime puberulis et granuliferis 7.5 mm. longis ὅς Ὁ. mm. 
latis ; achaeniis florum liguliferorum obovatis concavo-convexis margine 
ciliatis in summa parte bidentatis 4 mm. longis (immaturis) ; corollis 
florum (ca. 15) disci 3 mm. longis sursum leviter ampliatis infra lim- 
bum brevissimum aurantiacnm plus minusve purpureo-lineatis ; paleis 
tenuibus ovato-oblongis acutis carinatis ciliolatis apice saepissime au- 
rantiacis ; achaeniis obovatis. — Very common on grassy plains and 
hills, Tejamén, Durango, Mexico, alt. about 2135 m., 21-27 August, 
1906, Dr. Μ΄. Palmer, no. 500 (type, in hb. Gray). This species resem- 
bles in many respects Z. linearis Benth. It differs, however, in having 
broader leaves and a more slender erect and simple habit. It is espe- 
cially to be distinguished from the related species by its fewer subequal 
involucral scales. 

Cymophora Robinson, n. gen., Compositarum T[Helianthiearum. 
Capitula homogama parva cymosa; disco parvo leviter convexo ; 
paleis lanceolato-oblongis acutis carinatis flosculos amplectentibus. 
Involucrum anguste campanulatum, squamis paucis ovato-oblongis 
obtusis saepe mucronulatis subherbaceis striatis subaequalibus. Co- 
rollae tubulosae, tubo proprio brevissimo, faucibus cylindratis, limbo 
vel aequaliter 5-dentato vel flosculorum exteriorum plus minusve 
irregulari sed vix radiatiformi. Antherae connatae basi obtusae vel 
obscure sagittato-auriculatae apice distincte appendiculatae. Styli 
rami breves recurvato-patentes filiformes graciliter et distincte appen- 
diculati, appendicibus capillaribus rectis ca. 0.1 mm. longis. Achae- 
nia anguste obconica pilis curvatis longiusculis albis villosa, pappo 
nullo. — Herba annua pubescens et glandulifera ; foliis oppositis late 
ovatis subintegris ; corollis albis ; antheris purpureis. 

C. Pringlei Robinson, n. sp., caulibus laxe oppositeque ramosis 
patente pilosis 3-4 dm. altis; ramis arcuato-curvatis vel flexuosis 


40 PROCEEDINGS OF THE AMERICAN ACADEMY. 


teretibus ; foliis tenuibus a basi 3-nerviis breviter petiolatis, limbo 
late ovato integerrimo vel obsolete repando obtusiusculo 2-6 cm. longo 
1.6-4 cm. lato utrinque sparse adpresseque pilosis supra viridi subtus 
pallidiore basi obtuso saepissime obliquo ; cymis compositis laxis glan- 
duloso-pubescentibus ; capitulis ca. 10-floris 7 mm. longis 3.5 mm. 
diametro ; pedicellis filiformibus rectis glanduloso-puberulis 6-10 mm. 
longis ; involucri squamis ca. 6 subaequalibus (una vel duabus extimis 
valde minoribus exceptis) pallide viridibus striatis convexis nec cari- 
natis ; achaeniis nigrescentibus 2.2 mm. longis 0.6 mm. diametro 
ubique villosis apice rotundatis plus minusve margine squamacea 
cupulata coronatis. —Iguala Cafion, Guerrero, Mexico, alt. 760 m., 
22 September, 1905, C. G. Pringle, no. 10,068 (type, in hb. Gray). 

This plant appears to stand near Lleutheranthera, with. which it 
shares many characters. It differs, however, markedly in its anthers, 
which are appendiculate and connate, in its non-accrescent involucre, 
and densely puberulent achenes. Furthermore in Hleutheranthera 
the achenes have a nipple-shaped contracted summit which is here 
lacking. 

Perymenium globosum Robinson, n. sp., caule quadrangulato 
griseo-brunneo angulis rotundatis faciebus sulcatis, internodiis 7-9 em. 
longis ; foliis oppositis petiolatis ovato-oblongis serratis rugosis acumi- 
natis basi rotundatis vel abrupte breveque cuneatis supra scabris 
strigillosis subtus vix pallidioribus scabriusculis in nervis venisque his- 
pidulo-pubescentibus 8-12 em. longis 4-5 cm. latis, petiolo 1.8 em. 
longo flexuoso supra canaliculato ; capitulis corymbosis, corymbis com- 
positis 8-18 em. latis ; bracteis inferioribus foliaceis, bracteolis lineari- 
subulatis 3-5 mm. longis, pedicellis filiformibus flexuosis 1-2 em. longis 
adpresse griseo-pubescentibus ; involucri squamis ovatis acutis viridi- 
bus ca. 3 mm. longis; disco valde convexo; flosculis liguliferis ca. 7, 
ligulis linearibus aureis patentibus 6-8 mm. longis; paleis oblongis 
conduplicatis apice vix acutiusculis flavidis ; capitulis fructiferis de- 
presso-globosis 8 mm. diametro ; achaeniis disci obovatis crassiusculis 
atrobrunneis plus minusve bullatis 2 mm. longis 1 mm. latis glabris a 
basi styli conica indurata coronatis ; pappi aristis ca. 15 flavidulis in- 
aequalibus plerisque 1 mm. longis. — Uruapan, Michoacan, Mexico, 
C.G. Pringle, no. 10,354. This species is nearly related to P. verbesi- 
noides DC., but differs in having broader and less attenuate pales, 
greener involucral scales, and leaves 3-nerved not from the base but 
from a point nearly 1 cm. above the base. 

VERBESINA MONTANOIFOLIA Rob. & Greenm., var. leptopoda Robin- 
son, n. var., pedicellis subaequalibus quam eis formae typicae longioribus 
(ca. 1 em. longis) et gracilioribus; capitulis paulo minoribus. — By 


ROBINSON. — NEW SPERMATOPHYTES, CHIEFLY FROM MEXICO. 41 


streams, Tarascon, Mexico, 28 October, 1905, C. G. Pringle, no. 10,118 
(type, inhb. Gray). According to note of Mr. Pringle this variety grows 

to a height of 3-4.5 m. 
΄ Verbesina pedunculosa Robinson, n. comb. <Actinomeris peduncu- 
losa DC. Prod. v. 576 (1836). Verbesina Capitaneja Nees, Linnaea, 
xix. 729 (1847); Rob. & Greenm. Proc. Am. Acad. xxxiv. 546 (1899). 
\ Verbesina pleistocephala Robinson, n. comb. Encelia pleistoce- 

phala J. D. Smith, Bot. Gaz. xii. 189 (1888), & Enum. Pl. Guat. i. 22 
(1889). Verbesina Donnell-Smithii Coult. Bot. Gaz. xx. 50 (1895) ; 
J. D. Smith, Enum. Pl. Guat. iv. 88 (1895); Rob. & Greenm. Proc. 
Am. Acad. xxxiv. 556 (1899). 

Coreopsis Pringlei Robinson, n. sp., fruticosa ramosa ; ramis tereti- 
bus a cortice ochraceo-griseo obtectis ; ramulis striatis viridibus plus 
minusve 6-angulatis foliosis ; foliis oppositis petiolatis bipinnatifidis 
pallide viridibus glaberrimis vel vix pilosiusculis 2-4 em. longis 1-3 em. 
latis, segmentis patentibus angustissime linearibus leviter acutatis in- 
tegris vel cum lobis secundariis paucis similibus instructis 4-16 mm. 
longis 0.6-0.8 mm. latis ; capitibus terminalibus solitariis vel ad 3-5 
corymbosis pedunculatis erectis vel nutantibus 3 cm. latis (ligulis pa- 
tentibus inclusis) ; pedunculis 1-4 cm. longis nudis vel in media parte 
cum bractea unica lineari instructis; involucri campanulati squamis 
exterioribus ca. 8 herbaceis lineari-oblongis 3-5 mm. longis 1 mm. 
latis apice rotundatis basi pilosiusculis, squamis interioribus ovato- 
oblongis subscariosis acutatis ca. 6 mm. longis striatis flavido-brunneis ; 
ligulis ca. 8 juventate supra aureis subtus flavidis maturitate laete 
flavis oblongis ca. 1.2 em. longis 4-6 mm. latis, nervis atrobrunneis ; 
paleis linearibus pallidis brunneo-lineolatis apice obtusis eroso-ciliatis ; 
achaentiis disci linearibus valde obcompressis in facie interiore et in 
marginibus valde villosis in facie exteriore subglabris 5 mm. longis 
(vix maturis); pappi aristis 2 pallidis villoso-plumosis attenuatis 3-4 
mm. longis. — Dry ledges, San Juan del Rio, Queretaro, Mexico, alt. 
1920 m., 8 September, 1905, C. G. Pringle, no. 10,050 (type, in hb. 
Gray). This species is related to C. rhyacophila Greenman, but differs 
in its linear-oblong round-tipped outer involucral scales and much 
narrower leaf-segments, as well as in its shorter petioles and more 
decidedly ligneous stem. 

Tridax platyphyila Robinson, ἢ. sp., herba, perennis laxe ramosa 
pubescens ; caulibus teretibus viridibus vel purpurascentibus striatulis 
pubescentibus ; foliis membranaceis oppositis petiolatis supra basin 3- 
nerviis, lamina late ovata 6.3-11.5 cm. longa 4.5-10 em. lata dentata vel 
leviter 3-lobata supra viridi sparse pubescenti cum pilis basi tuberculo- 
incrassatis subtus vix pallidiore in nervis appresso-pubescenti apice 


42 PROCEEDINGS OF THE AMERICAN ACADEMY. 


acuta vel obtusiuscula vel brevissime acuminata basi cuneato-attenuata ; 
capitibus laxe corymbosis longe pedicellatis radiatis, disco leviter con- 
vexo ; involucri squamis paucis subaequalibus ovatis vel late oblongis 
acutis herbaceis hirsutulis ca. 7 mm. longis ; flosculis disci numerosis, 


corollis anguste tubulosis aurantiacis 7 mm. longis externe glabris, | 
tubo proprio brevi basi ampliato ; faucibus multo longioribus paulo et . 
gradatim amplioribus 5-nerviis, limbi dentibus 4 brevibus ovato-lanceo- . 


latis. acutiusculis apice puberulis ; achaeniis turbinato-cylindricis 2.8 | 

mm. longis sericeis, pappi setis plumosis numerosis attenuatis plus 

minusve inaequalibus ca. 2.6 mm. longis; flosculis radiatis 5, ligulis 

albis late oblongis vel suborbicularibus patentibus apice 3-dentatis 

6-10 mm. longis. — River ledges, Balsas Station, alt. 600 m., 27 Sep- 

tember, 1905, Guerrero, Mexico, C. G. Pringle, no. 10,075 (type, in hb. 

Gray). ‘This species is habitally similar to 7. tenuifolia Rose, which, 

however, has smaller leaves and pappus decidedly longer than the 

achenes. 

ν Gatiysoga Fitirormis Hemsl., var. epapposa Robinson, n. var., 
habitu foliis inflorescentia, etc., formae typicae simillima; achaeniis 
omnino epapposis apice annulo albido inconspicuo coronatis ; foliis caul- 
inis quam eis formae typicae paululo minoribus. —San Ramdén, Du- 
rango, Mexico, 21 April-18 May, 1906, Dr. Μ΄. Palmer, no. 127 (type, 
in hb. Gray). This puzzling plant, which according to the notes of the 
collector was found in numbers, much dried, on stony ridges among 
trees and bushes, differs in its lack of pappus from any other Galinsoga. 
Its otherwise close correspondence with G. filiformis, however, would 
seem to show that it is merely a new instance of a calvous form of an 
ordinarily pappus-bearing species. Similar cases are familiar in sev- 
eral neighboring genera, e. g. Calea, Jaegeria, ete. The phenomenon 
seems to present an ecological problem of interest, and it is to be hoped 
that collectors who have an opportunity to study these plants in the 
field may bear the matter in mind and endeavor to learn the conditions 
which determine the presence and absence of pappus in these in other 
respects essentially identical forms. 

Y Flaveria bidentis Robinson, n. comb. Fthulia bidentis L. Mant. i. 
110 (1767). Flaveria chilensis Gmel. Syst. 1269 (1796); Johnston, 
Proc. Am. Acad. xxxix. 285 (1903). Milleria Contrayerba Cav. Ic. Pl. 
i. 2, τι 4 (1791). The author has examined the type of Hthulia bidentis 
in the Linnaean Herbarium and finds that, as given in the Index Kew- 
ensis, it is the plant which haslong passed as Mlaveria Contrayerba. 
The Vienna rules of nomenclature require the restoration of the earlier 
specific name. 

ν᾽ Pericome macrocephala Robinson, n. sp. griseo-pulverula vel 


ROBINSON. — NEW SPERMATOPHYTES, CHIEFLY FROM MEXICO. 43 


puberula oppositiramea ; -caulibus fragilibus subteretibus leviter 
angulato-striatis glabriusculis brunneis paulo lignescentibus ; foliis 
triangulari-hastatis 5-6 em. longis 4-5 cm. latis caudato-attenuatis sub- 
integris basi abrupte cuneatis, auriculis subacuminatis, petiolo gracili 
2-2.7 cm. longo ; inflorescentiis corymbosis terminalibus 6-8 cm. latis 
subplanis 9-15-capitulatis ; pedicellis gracilibus rectis vel leviter arcuatis 
sursum modice incrassatis pubescentibus 1-2 em. longis ; capitulis 1.7 
cm. longis 1.2 cm. diametro homogamis multiflosculosis; involucri cupula 
ovoideo-subcylindrata 1.2-1.4 cm. longa griseo-puberula multistriata 
dentibus brevissimis caudiformibus plus minusve patentibus ; corollis 
laete flavis 1 em. longis, tubo proprio gracillimo 3 mm. longo glandu- 
loso-puberulo, faucibus anguste tubulosis sursum paululum ampliatis, 
dentibus limbi 4 brevibus ovato-oblongis obtusis ; achaeniis nigrescen- 
tibus anguste oblongis valde compressis margine et apice fimbriato- 
ciliatis. — A showy plant growing in large masses on talus in moun- 
tains near San Ramén, Durango, Mexico, 21 April-18 May, 1906, Dr. 
1. Palmer, no. 69 (type, in hb. Gray). In habit and floral strue- 
ture this species closely approaches P. caudata Gray, but differs from 
it conspicuously in having heads nearly twice as large. ‘The form of 
the involucre also is different, being ovoid-subcylindrice in the species 
here described while it is considerably more campanulate in P. 
caudata. 

Loxothysanus Robinson, n. gen, Compositarwm Heleniearum. 
Capitula homogama. Involucrum campanulatum vel turbinatum, 
squamis paucis uniseriatis aequalibus plerumque obovatis vel oblance- 
olatis acutis vel saepissime obtusiusculis herbaceis puberulis. Recep- 
taculum parvum planiusculum onustum. Flosculi modice numerosi 
tubulosi hermaphroditi fertiles. Corollae albidae, tubo proprio gracili 
puberulo vel glandulifero fauces campanulatas subaequante, limbo 5- 
lobato. Styli rami breves recurvati filiformes vix infra apicem incras- 
sati brevissime et obtusiuscule appendiculati. Antherae basi breviter 
sagittato-auriculatae apice obtuse appendiculatae. Achaenia gracilia 5- 
angulata sursum hispidula deorsum longiuscule angustata. Pappi 
squamae 5-8 oblongae erosae eis In margine exteriore achaenii quam aliis 
valde brevioribus. — Frutices humiles vel suffrutices ramosi erecti vel 
procumbentes. Capitula pauca mediocra axillaria vel laxe corymbosa. 
Flosculi vel omnes regulariter 5-dentati vel exteriores obscure subbila- 
_ biati. Folia opposita petiolata, limbo ovato vel orbiculari paucilobato 
vel vix crenato. (Nomen a λοξός, obliquus, et θύσανος, fimbriae, pap- 
pum unilateraliter abbreviatum designat. ) 

L. sinuatus (Less.) Robinson, ἢ. comb., foliis ovatis sinuatis pler- 
umque 3-lobatis basi obtusis vel subtruncatis vel late cordatis ; capitulis 


44 PROCEEDINGS OF THE AMERICAN ACADEMY. 


corymbosis ; involucri squamis ca. 12 oblanceolatis acutis vel acutius- 
culis. — Bahia sinuata Less. Linnaea, v. 160 (1830). B. nepetaefolia 
Gray, Proc. Am. Acad. v. 184 (1861). — On rocky soil in Central and 
Southern Mexico. ‘The following specimens have been examined. On 
cliffs near Hacienda de la Laguna, Schiede, no. 358 (hb. Berlin, frag- 
ments in hb. Gray); between San Luis Potosi and Tampico, Palmer, 
no. 1090 (hb. Gray) ; bare mountain ledges, Tamasopo Cafion, San Luis 
Potosi, Pringle, no. 3096 (hb. Gray); Wartenburg near 'l'artoyuca, 
prov. Huasteca, Lrvenberg, no. 65 (hb. Gray) ; steep banks of barrancas, 
Zacuapan, Vera Cruz, Purpus, no. 1862, in part (hb. Gray). - 

L. filipes Robinson, n. sp., fruticulus gracillimus proctmbens ra- 
mosus; ramis curvato-ascendentibus foliatis breviter pubescentibus ; 
foliis graciliter petiolatis, limbo suborbiculari 1-1.8 cm. diametro cre- 
nato supra viridi obscure tomentello subtus incano-tomentello ; petiolo 
1-1.5 em. longo filiformi flexuoso puberulo ; capitulis ca. 30-floris ax- 
illaribus ; pedunculo 2-3.5 em. longo filiformi ; involucri subturbinato- 
campanulati squamis ca. 7 obovatis obtusiusculis anthesi ca. 3 mm. 
longis ; corollis 2.8 mm. longis, tubo proprio gracili glanduloso-puberulo 
ca. 1 mm. longo, faucibus campanulatis limbum fere aequantibus ; 
pappi squamis interioribus ca. 0.4 mm. longis exterioribus 0.2-0.3 mm. 
longis ; achaeniis 2.8 mm. longis deorsum valde angustatis. — Steep 
banks of barrancas, Zacuapan, Vera Cruz, Mexico, May, 1906, Purpus, 
no. 1862, in part (type, in hb. Gray). 

This plant, which was sent to the writer by Mr. T. δ. Brandegee, 
proves to be a near relative and evident congener of the problematic 
species originally decribed as Bahia sinuata by Lessing and later rede- 
scribed by Dr. Gray as B. nepetaefolia. Both plants differ from the 
more typical species of Bahia in general habit, in the broad leaf-blades, 
which are very shallowly if at all cleft or lobed, in the absence of rays, 
and in the strongly unsymmetrical pappus. ΤῸ judge from Dr. Gray’s 
description and notes relating to his B. nepetaefolia, he was much in- 
clined to regard the plant as belonging to a separate genus and only 
referred it to Bahia from a reluctance to increase the number of mono- 
typic genera. ‘I'he discovery by Mr. Purpus of a second plant main- 
taining perfectly the generic distinctions of the first seems now to 
warrant fully the recognition of the two as an independent genus. 

Tagetes stenophylla Robinson, n. sp., perennis erecta usque ad 
1 m. altitudine ramosa glaberrima basi suffrutescens ; caule tereti cos- 
tato folioso glaucescenti ; ramis ascendentibus gracilibus in pedunculos 
longos nudos apicem versus purpurascentes et modice incrassatos ter- 
minantibus ; foliis 2-4 em. longis pinnatifidis, rhachi anguste lineari, 
segmentis etiam linearibus angustissimis utrinque ca. 3 acutis vel setu- 


ROBINSON. — NEW SPERMATOPHYTES, CHIEFLY FROM MEXICO. 45 


liferis simplicibus vel semel lobatis, lobis similibus angustis ; pedun- 
culis 5-10 cm. longis apice saepe nutantibus ; involucri anguste ovoidei 
1.5 em. longi basi rotundati vel paulo turbinati pallidi vel purpureo- 
tincti squamis 5 alte connatis a lineis binis glandularum linearum no- 
tatis apice aureis obtusis tomentosis ; flosculis liguliferis 5 ; ligulis 
aureis obovato-oblongis 10-12 mm. longis 6-8 mm. latis apice obcor- 
datis saepe obliquis ; achaeniis disci compressis lineari-oblongis nigre- 
scentibus 3 mm. longis sursum strigillosis ; pappi aristis 5 connatis 
quarum 2 multo longioribus apice liberis attenuatis sursum barbellatis. 
—Dry soil of fields near Uruapan, Michoacan, Mexico, 25 January, 
1907, C. G. Pringle, no. 10,361 (type, in hb. Gray). ‘This species has 
much in common with P. linifolia Seaton, but differs from it in having 
more deeply colored rays and obtusish not at all caudate-acuminate 
teeth of the involucral cup. 

Cacalia Goldsmithii Robinson, n. sp., perennis herbacea erecta, cau- 
dice parvo ovoideo sursum fulvo-lanato ; caule subrecto vel leviter flex- 
uoso glabro simplici gracili 1-2-foliato 6-7 dm. alto ; foliis radicalibus 
longe petiolatis ovatis repando-dentatis vix lobatis 1 dm. longis 6-9 
cm. latis pinnatim nervatis firmiusculis utrinque glabris laxe reticulatis 
apice rotundatis basi late cordatis, dentibus cuspidatis, nervis venisque 
utrinque prominulis, petiolo gracili nudo 14-16 cm. longo basi vix 
dilatato ; folio caulino inferiore radicalibus simili sed minore basi obtuso 
nec cordato petiolo 12 cm. longo flexuoso nec appendiculato nec au- 
riculato ; folio caulino superiore multo minore oblongo dentato, petiolo 
2 cm. longo basin versus modice ampliato caulem amplectente ; corymbis 
compositis planis ca. 50-capitulatis ; bracteis linearibus ; capitulis ca. 
13-floris contiguis ; involucri simplicis haud calyculati campanulato- 
subcylindrici squamis ca. 8 oblongis 7 mm. longis 2-3 mm. latis dorso 
planiusculis apice obtusiusculis ciliatis ; corollis albido-ochroleucis 8 mm. 
longis fere ad mediam partem quinquifidis, lobis oblongis obtusis ; pappi 
setis sordidis tubum proprium vix superantibus ; achaeniis compressis 
breviter oblongis glabris. —On level pastures, Hacienda San Marcos, 
Jalisco, Mexico, alt. about 350 m., 12 July, 1905, Rev. P. Goldsmith, 
no. 8 (type, in hb. Gray). This species is probably nearest C. Palmeri 
Gray, but differs in its thinner smooth ovate rather than suborbicular 
leaves as well as in its larger more numerously flowered heads. 

Cacalia Holwayana Robinson, n. sp., herbacea erecta 1-2 m. alta ; 
caule tereti medulloso striato atropurpureo glanduloso-puberulo ; ra- 
dicibus carnosis ; foliis longipetiolatis orbicularibus subcentrali-peltatis 
9-13-sinuato-lobatis supra laete viridibus subtus vix pallidioribus 
utrinque sparse pubescentibus laxe reticulato-venosis 1.5-2 dm. diame- 
tro, lobis acutis 2-4 cm. longis 1.5-5 ecm. latis oblongis sinuato- 


46 PROCEEDINGS OF THE AMERICAN ACADEMY. 


dentatis (nec lobatis) et cuspidato-denticulatis ; petiolo 1.5-2 dm. longo 
atropurpureo griseo-piloso ; inflorescentia ampla pyramidata, bracteis 
inferioribus saepe petiolatis foliis similibus sed multo minoribus, brac- 
teis superioribus angustissime linearibus vel subfiliformibus atropurpu- 
reis glanduloso-pilosis ; capitulis numerosis in summis ramis ramulisque 
nutantibus ca, 10-floris 2 em. longis; involucri subcylindrici calyculo 
bracteolarum subfiliformium suffulti squamis lineari-lanceolatis ca. 10 
ca. 1.5 em. longis in carina atropurpurea griseo-puberulis margine albido 
subsearioso levibus ; corollis 13 mm. longis glabris, tubo proprio gracili 
8 mm. longo, faucibus vix ullis, limbo in lobis linearibus profunde par- 
tito; achaeniis 5 mm. longis adpresse tomentulosis ; pappi setis tenui- 
bus laete albis corollam aequantibus. — Uruapan, Michoacan, Mexico, 
11 October, 1899, Μ΄. W. D. Holway, no. 3617 (type, in hb. Gray); 12 
November, 1905, C. G. Pringle, no. 13,672; in granitic soil on the 
Sierra Madre of Michoacan or Guerrero, alt. 1100 m., 6 September, 18938, 
E. Langlassé, no. 576. This species is near C. peltata HBK., but is 
readily distinguished by its leaves, which are less deeply lobed, the 
lobes not again sinuately lobed, and by the smaller exceedingly narrow 
bractlets, those of C. peltata being foliaceous. 

CaCALIA LAEVIGATA Sch. Bip. ex Klatt, Leopoldina, xxiv. 125 (1888). 
Senecio heteroideus Klatt, 1. ο. 1888). Cacalia longipetiolata Robinson & 
Greenman, Am. Jour. Sci. 1. 157 (1895). When in 1895 the authors 
of C. longipetiolata characterized that species they knew C. laevigata 
only from Klatt’s description. A drawing and some fragments of the 
type of C. laevigata, subsequently received at the Gray Herbarium by 
the purchase of the Klatt Herbarium, prove beyond doubt the identity 
of ©. longipetiolata with C. laevigata, a correspondence which could 
scarcely have been inferred from the brief and in some respects mislead- 
ing characterization of C. laevigata given by Klatt. 

Cacalia michoacana Robinson, n. sp., herbacea perennis pilis crispis 
griseis puberula ca. 9 dm. alta ; caule simplici leviter flexuoso striato 
atropurpureo medio folioso basi et apice nudiusculo ; caudice crasso 
lanato ; foliis ca. 10 suborbicularibus palmato-lobatis 3-6 cm. longis 
5-8 cm. latis crassiusculis utrinque reticulato-venulosis et in venis pu- 
berulis supra laete viridibus subtus pallidioribus basi subtruncatis vel 
latissime cordatis, lobis 5-7 brevibus triangularibus margine cuspidato- 
denticulatis ; capitulis ca. 6 ramos ascendentes inflorescentiae termi- 
nantibus ca. 30-floris 1.5 em. longis 2 cm. diametro longe pedicellatis ; 
involucri atropurpurei campanulato-subcylindrici squamis principalibus 
ca. 15 lineari-lanceolatis dorso atropurpureis carinatis margine albis 
tenuibus subscariosis, involucro basi squamis minimis calyculato ; co- 
rollis 1 em. longis, tubo proprio viridescenti gracillimo 5 mm. longo, 


ROBINSON. — NEW SPERMATOPHYTES, CHIEFLY FROM MEXICO. 47 


faucibus cylindricis et limbo 5-lobato flavescentibus, lobis linearibus 
recurvatis ; pappi setis laete albis tenuibus aequalibus corollam fere 
aequantibus. — On pine-covered cratere cone, Uruapan, Michoacan, 
Mexico, alt. 1680 m., 31 October, 1905, C. G. Pringle, no. 10,117 
(type, in hb. Gray). Habitally near C. laevigata Sch. Bip., but differing 
conspicuously in its considerably smaller heads, narrower carinate dark 
purple involucral bracts, and less deeply lobed leaves. 

Perezia arachnolepis Robinson, n. sp., herbacea erecta a basi plus 
minusve decumbenti 1.5 m. alta; caule tereti striato purpureo glabro 
usque ad inflorescentiam perlaxam simplici ; caudice fulvo-lanato ; radi- 
cibus fibriformibus duris atrobrunneis ; foliis oblanceolato-oblongis vel 
oblongo-linearibus sessilibus sagittato-amplexicaulibus usque ad 1.6 
din. longis 1.7—-5.8 cm. latis firmis utrinque viridibus reticulatis supra 
glabris subtus vix pallidioribus sparse puberulis vel glabris argute den- 
ticulatis apice acutis vel breviter acuminatis ; inflorescentia perlaxa 
8-16-capitata ; capitibus ramos elongatos sursum valde squamosos ter- 
minantibus ca. 3 cm. diametro; involucro valde turbinato, bracteis 
pedunculi in squamas involucri gradatim transeuntibus anguste lanceo- 
latis vel linearibus apice subulatis margine arachnoideo-lanatis ; co- 
rollis purpureis 1.3 cm. longis glabris; antheris etiam purpureis ; 
achaeniis atrobrunneis sursum hispidulis 3 mm. longis. — Canons, 
Chapala Mountains near Guadalajara, Jalisco, Mexico, 13 December, 
1889, C. G. Pringle, no. 2935 (type, in hb. Gray), and in barranca of 
Rio Blanco near Guadalajara, 29 November, 1905, C. (ἡ. Pringle, no. 

13,668 (hb. Gray). 

Perezia lepidopoda Robinson, n. sp., meeedent valde affinis her- 
bacea erecta 7-8 dm. vel ultra alta glaberrima.; caule purpureo recto 
tereti striato foliosissimo in parte superiore ramos simplices valde 
patentes multi-bracteatos unicapitatos gerente ; foliis anguste oblongis 
vel oblongo-linearibus attenuatis acutissimis saepissime recurvatis vel 
reflexis conduplicatis subcartilagineis concoloribus sessilibus sagittato- 
vel hastato-amplexicaulibus argute et dupliciter sinuato-dentatis 6-13 
em. longis 8-22 mm. latis utrinque glabris viridibus reticulato-venosis, 
dentibus lanceolato-subulatis 2-4 mm. longis divaricatis acutissimis ; 
ramis pedunculiformibus ca. 12 cm. longis a bracteis numerosissimis 
fere a basi sed praesertim apicem versus tectis, bracteis inferioribus 
1-2 cm. longis anguste lanceolatis sagittatis denticulatis, superioribus 
anguste linearibus peracutis adpressis hinc inde contortis in squamas 
involucri gradatim transeuntibus ; capitibus (omnibus valde immaturis) 
usque ad 3 cm. diametro multifloris; involucri turbinati squamis 
lineari-lanceolatis acutissimis viridibus vel purpurascentibus striatulis 
obsolete puberulis. — Valley near Cuernavaca, Morelos, Mexico, alt. 


48 PROCEEDINGS OF THE AMERICAN ACADEMY. 


1220 m., 17 October, 1900, C. G. Pringle, no. 9253 (type, in hb. 
Gray). This species is clearly separated from the preceding by its 
much narrower leaves and merely puberulent more subulate involucral 
scales. It belongs to a gronp of several obviously diverse yet nearly 
related plants which have been provisionally referred to the merely in- 
ferential P. turbinata La Liav. & Lex. The latter, however, described 
as having ovate leaves and short-peduncled heads, must certainly have 
been a plant quite different from either here characterized. 


II. NEW PLANTS FROM GUATEMALA AND MEXICO, 
COLLECTED CHIEFLY BY C. C. DEAM. 


By B. L. RoBINSON AND H. H. BARTLETT. 


Polypodium (Goniophlebium) hispidulum Bartlett, n. sp., rhi- 
zomate crassitudine 3-5 mm. simplici vel furcato ad arborum truncos 
repenti longitudine usque ad 12 cm., aetate aperto foveolato-rugoso 
juventate paleis tecto, paleis deltoideo-linearibus secus lineam medi- 
anam ferrugineis margine straminellis; frondibus inter se propinquis 
6-12 em. longis 4-7.5 em. latis; stipitibus gracilibus 0.5-3.5 em. 
longis exigue pilosis supra canaliculatis subtus semiteretibus ; laminis 
fere usque ad costam pinnatipartitis utrinque hispidulis atroviridibus 
circumscriptione valde variabilibus ovatis semiovatis vel aequilater- 
aliter triangulis prout segmenta duo inferiora reducta aut haud reducta 
sunt; segmentis integerrimis approximatis lanceolatis 3-9-jugis basi- 
dilatatis confluentibus apice obtusis, maximis 6 mm. latis 3.5 cm. longis, 
terminale 1.5-6 cm. longo maxime variabili ; nervo mediano flexuoso, 
nervis lateralibus alternis utrinque 10-11 haud procul a basi furcatis, 
ramis anticis liberis in segmentis superioribus soriferis, ramis posticis 
arcuatis marginem nec attingentibus, aut simplicibus aut furcatis aut 
anastomosantibus areolarum seriem unam formantibus ; soris rotundis 
medio inter nervum medianum et marginem uniserialiter dispositis ca. 
1 mm. diametro ; sporangiis glabris ca. 20. — Los Amates, Department 
of Izabal, Guatemala, 11 February, 1905, C. C. Deam, no. 117 (type, in 
hb. Gray). The same fern, collected by Tuerckheim at Cubilquitz, 
Department of Alta Verapaz, December, 1900, was distributed as 
Polypodium pubescens Hook. et Grev., in John Donnell Smith’s “ Plants 
of Guatemala,” no. 8053. P. pubescens is, without doubt, the nearest 
related species to P. hispidulum. It has, however, a much larger frond, 
with irregularly laciniate segments, which at the base of the frond are 


ROBINSON AND BARTLETT. — PLANTS FROM GUATEMALA AND MEXICO. 49 


widely separated and not at all confluent. The segments are also 
prevailingly opposite in P. pubescens, whereas in P. hispidulum they 
vare alternate. , 

/ Paspalum guatemalense Bartlett, n. sp., perenne 6 dm. altum 
simplex vel ramosum ; internodus glabris lateraliter compressis, acie 
ad folii axillam versus canaliculatis ; foliorum vaginis equitativis pilo- 
sis (praecipue juxta margines et ad ligulae basin) quam internodiis aut 
brevioribus aut longioribus margine brunneo-scareosis ; ligula 2.5 mm. 
longa textura marginibus vaginarum simili; laminis lineari-lanceolatis 
10-15 mm. latis 6-15 cm. longis apice acutis basi rotundatis vel sub- 
cordatis utrinque dense pilosis; spicis 1-3 sessilibus inter se 2.5-3.5 
em. distantibus 3-6 em. longis ; rhachi angusta glabra vel scabriuscula ; 
pedicellis minute hispidulis ; spiculis geminatis altera breviter altera 
longius pedicellata, geminis secus rhachin in seriebus duabus alternis ; 
spiculis suborbicularibus 2.1 mm. longis 1.9 mm. latis glabris albican- 
tius viridibus antice planis postice valde convexis; gluma inferiore in 
spiculis geminorum superioribus suborbiculari apice rotundata quam 
spicula 6-plo breviore, in spiculis geminorum inferioribus longiore 
eccentrica late ovata obtusa vel acutiuscula ; gluma secunda membra- 
nacea quam spicula paulo breviore 5-nervata, nervis juxta marginem 
anastomosantibus ad apicem in mucronem perbrevem terminantibus ; 
gluma tertia membranacea quam secunda longiore 3 (—5)-nervata ; 
gluma quarta paleaque cartilagineis obscure nervatis ; staminibus sty- 
lisque ut in speciebus generis reliquis. — A swamp at Gualan, Depart- 
ment of Zacapa, Guatemala, January 20, 1905, C. C. Deam, no. 427 
(type, in hb. Gray). P. guatemalense is a member of Fournier’s genus 
Dimorphostachys. Following his arrangement of the group, the afiinity 
of the new species is with Dimorphostachys Schafineri Fourn., D. 
variabilis Fourn., and D. Ghiesbreghtii Fourn. Of these, only D. 
Schaffneri is represented in the Gray Herbarium. It may be at once 
distinguished. from P. guatemalense by its glabrous foliage and larger 

. ovate spikelets, acute at the apex. D. variabilis and D. Ghiesbreghtii 
both have pubescent spikelets, whereas those of P. guatemalense are 
perfectly glabrous. 

~  SrreprocuarTa Soprroana Hack. Noteworthy among the plants 
collected by Mr. C. C. Deam in Guatemala is a specimen of the anom- 
alous South American genus Streptochaeta. The genus consists of two 
species, and in its spirally arranged (not distichous) flower-scales forms 
a unique exception among the genera of grasses. When the generic 
afiimity of Mr. Deam’s plant was discovered, it became evident that the 
species might be identical with the Ecuadorian S. Sodireana Hack. A 


portion of the specimen was sent to Professor Hackel, who has kindly 
VOL, XLII. —4 


50 PROCEEDINGS OF THE AMERICAN ACADEMY. 


confirmed the apparent identity. ‘This is by no means an isolated case 
of the occurrence of identical species in Ecuador and Guatemala, but 
it has peculiar interest from the marked character and rarity of the 
plant concerned. Mr. Deam’s specimens were collected at Los Amates, 
Guatemala, 10 February, 1905, and distributed as no. 97 of his set. 
He writes that only a few plants were found, and that these were growing 
in rather wet situations deep in the virgin forest. An interesting 
morphological as well as systematic account of the species is given 
in Professor Hackel’s original characterization, Oest. Bot. Zeitschr. xl, 
111 (1890). 

Fuirena zacapana Bartlett, n. sp., rhizomate perpendiculari elon- 
gato modice incrassato ; culmis 9 dm. longis gracilibus ascendentibus 
hispidis vel ad basin glabriusculis ca. 8-foliis ; foliorum vaginis 1.5-3 
em. longis dense hispidis ; foliis linearibus utrinque hispidis usque ad 
5 mm. latis,in partibus culmi inferioribus 1 cm. longis superne 9 cm. 
longis ; capitulis 3-4, infimo solitario in axilla folii supremi peduncu- 
lato, reliquis plus minusve approximatis ; spiculis in capitulo quoque 
3-6 ovatis 4 mm. latis 8 mm. longis ; squamis brunneis pubescentibus 
in spiculae basi suborbiculatis in apice ovatis trinerviis, in dorso recti- 
aristatis ; sepalis 3 brunneis glabris duriusculis ovatis basi subcordatis 
longe unguiculatis apice rotundatis infra apicem in dorso breviaristatis, 
aristis retrorsum scabris; setulis 3 cum sepalis alternantibus superne 
retrorsum scabris quam achaenio multo brevioribus ; achaenio longe 
stipitato mucronato sepala paene aequante. — In swamps, Gualan, 
Department of Zacapa, Guatemala, 13 January, 1905, C. C. Deam, 
no. 423 (type, in hb. Gray). This very distinct species is nearest to 
F. simplex Vahl, from which it differs in its lax habit, in the extreme 
development of pubescence on the leaf-sheaths, in its short perianth- 
bristles, and long-stiped achene. 

Myriocarpa malacophylla Robinson ἃ Bartlett, n. sp., arborea 
4m. altitudine ; ramis curvatis crassiusculis molliter lignosis siccitate 
corrugato- ragulosis pallide griseis juventate tomentosis aetate glabra- 
tis, lenticellis paucis sparsis ; foliis membranaceis late ovatis cordatis 
breviter caudato-acuminatis serratis 17 em. longis 11 em. latis supra 
more generis sparse pilosis et cystolithis radiantibus instructis subtus 
molliter tomentosis griseis, apice candiformi ca. 1 em. longo, nervis 
lateralibus utrinque 4-5 ; petiolo 1.7-2 cm. vel ultra longo tomentoso ; 
inflorescentiis omnino sessilibus ca. 1 cm. supra basin furcatis ; ramis 

-2 dm. longis griseo-tomentosis unilateraliter floriferis; floribus 9 
arcte sessilibus ; calyculo 2-phyllo brevissimo villoso; ovario lenticu- 
lari-ovoideo 0.7-0.9 mm. longo villoso-hispidulo; floribus ἃ etiam 
sessilibus, sepalis 4 ovatis obtusis villosis, staminibus 4.— Gualan, 


ROBINSON AND BARTLETT. — PLANTS FROM GUATEMALA AND MEXICO. 51 


Department of Zacapa, Guatemala, 12 January, 1905, C. C. Deam, 
no. 361 (type, in hb. Gray) ; Maria Madre Island, Tres Marias Islands, 
May, 1897, μ΄. W. Nelson, no. 4275 (hb. Gray). This species appears 
to be either monoecious, as in Mr. Deam’s specimen, which has stami- 
nate flowers at the base of some of the pistillate inflorescences, or it 
may be dioecious, as in Mr. Nelson’s specimen, in which all the flowers 
are staminate. ‘The species appears to stand nearest J. cordifolia 
Liebm., but differs in its ovate rather than suborbicular less rugose 
leaves and wholly sessile inflorescences. 

Polygonum longiocreatum Bartlett, n. sp., caule simplici ca. 7 
dm. alto, ad nodos inferiores radicanti; internodiis 1.5-2 cm. longis 
glabris ; ocreis cylindricis eciliatis 1.5-1.7 cm. longis, in parte inferiore 
caulis quam internodiis brevioribus, plus minusye inflatis, in parte 
superiore imbricatis ; foliis lanceolatis 1.5-3 cm. latis 9-13 cm. longis 
perbreviter petiolatis, apice basique acutis, utrinque glabris pellucido- 
punctatis, margine nervisque subtus scabris; spicis ca. 9, paniculatis 
erectis 4—5 cm. longis ; pedunculis pedicellisque glabris ; ocreolis rubris 
2 mm. longis tri-vel quadrifloris ; calyce rubro 5-partito ; staminibus 7 
styloque (solum in extremo bifido) inclusis ; achenio lenticulari 2 mm. 
longo nigro, ad basin rotundato, ad apicem abrupte acuto, faciebus 
convexis. — In a swamp at Gualan, Department of Zacapa, Guatemala, 
January 14, 1905, C. C. Deam, no. 374 (type, in hb. Gray). The ob- 
vious affinity of P. longiocreatum is with Polygonum spectabile Mart., 
from which it differs in not having glandulose-scabrous peduncles. In 
his treatment of P. spectabile in De Candolle’s Prodromus, Meisner 
cites two earlier-published species of Weddell as possible synonyms. 
Dr. Small accepts, in his “ Monograph of the N. A. Species of Poly- 
gonum,” one of Weddell’s names, Polygonum ferrugineum, as an avail- 
able name for P. spectabile Mart. Whether he applies the name 
correctly or not, P. longiocreatum may be distinguished from the 
P. ferrugineum of Small’s monograph by the style, which in the former 
is bifid only at the end, and by the long pedicellate flowers, small 

achenes, and short-petioled leaves. 

_ Ruprechtia Deamii Robinson, n. sp., fruticosa (9 solum visa) ; 
ramis flexuosis glabris in specimine exsiccato sulcato-rugosis brunneis, 
internodiis 7-30 mm. longis, ocreis membranaceis griseo-castaneis vix 
0.6 mm. longis ; foliis magnis oblongis coriaceis penninerviis 10-18 cm. 
longis 5.5-8 em. latis integerrimis concoloribus utrinque prominulenter 
reticulato-venulosis subtus in nervis patenter fulvo-pubescentibus et in 
venulis puberulis, basi rotundatis vel modice angustatis, apice obtusis 
vel rotundatis, petiolo brevissimo crassiusculo supra leviter canaliculato 
ca. 3 mm. longo ; racemis numerosis fructiferis 2-6 em. longis solitariis 


52 PROCEEDINGS OF THE AMERICAN ACADEMY. 


vel usque ad 3 fasciculatim aggregatis patentibus vel deflexis sub- 
densifloris, tomentosis ; bracteis ovatis subacuminatis brunneis adpresse 
villosis ; pedicello fructifero filiformi 2-3 mm. longo tomentoso ; calyce 
fructifero ca. 3.5 cm. longo, tubo anguste ovoideo molliter subadpresse 
tomentoso ca. 6-7 mm. longo ca. 4 mm. diametro, alis 2.5 em. longis 5 
mm. latis spatulato-oblongis glabriusculis 3-nerviis reticulato-venosis 
apice rotundatis pallide viridibus subdiaphanis; sepalis interioribus 
subulatis glabris, parte libera ca. 4 mm. parte adnata ca. 1.5 mm. longa ; 
achaenio attenuato-ovoideo obtusissime trigono, angulis tumidis leviter 
suleatis in parte superiore sulci pubescentibus ; stylis liberis, stigma- 
tibus linearibus recurvatis.—Gualan, Department of Zacapa, Guate- 
mala, alt. 128 m., January 11, 1905, C. C. Deam, no. 231 (type, in hb. 
Gray). This species belongs to the ὃ Herasepalae of Meisner, and 
§ Pseudoruprechtia of Bentham and Hooker, these authors dividing 
the genus on different characters. It is nearly related to Rk. Cumingii 
Meisn., known to the author only from Meisner’s description (DC. Prod. 
xiv, 179). If the characters there given are correct, the plant here 
characterized is certainly distinct, as is shown by its larger leaves, 
longer calyx, the presence of pubescence on the lower surface of the 
leaves, decidedly rugose branches, spreading or deflexed racemes, ete. 
Aeschynomene Deamii Robinson & Bartlett, n. sp., fruticosa 
2m. alta laxe ramosa aspectu glabra; caulibus teretibus lignescenti- 
bus striatulis fusco-brunneis glabris ; foliis petiolatis oblongis 5-7 em. 
longis ; foliolis ca. 18-jugis lineari-oblongis glabris utrinque viridibus 
supra minutissime nigro-punctatis subtus pinnatim venosis basi obliquis 
apice rotundatis mucronatis 9-10 mm. longis 2 mm. latis ; rhachi supra 
sparse puberula subtus glabra; petiolo 1 em. longo; stipulis 1.5 mm. 
longis subulatis brunneis acutissimis; racemis axillaribus 2-7-floris ; 
pedunculis 10-17 mm. longis filiformibus glabris ; bracteis ovatis her- 
baceis margine scariosis apice acutis supra basin affixis basi rotundatis 
liberis ; pedicellis anthesi ca. 4 mm. longis fructiferis ca. 6 mm. longis ; 
calyce glabro 2-partito, labio dorsali ovato ca. 7 mm. longo ca. 5.5 mm. 
lato obtusiusculo, labio ventrali angustiore ca. 9 mm. longo acuto ; vex- 
illo obovato 12 mm. longo 10 mm. lato apice rotundato basi modice 
angustato ; alis semiobovatis basi a latere superiore obtuse auriculatis ; 
carinae petalis ca. 11 mm. longis; staminibus quinis connatis ; legu- 
mine ca. 13-seminato ca. 1 dm. longo 6.5 mm. lato fragili utrinque 
undulato, segmentis subquadratis margine crassiusculo faciebus glaber- 
rimis levibus modice nervosis nee rugosis ; seminibus atrobrunneis 
lunatis levissimis subnitidis 5 mm, longis 3 mm. latis. —San Felipe, 
Department of Izabal, Guatemala, 15 February, 1905, C. C. Deam, no. 
26 (type, in hb. Gray). In its numerous leaflets of oblong-linear shape 


— ea νὰ ἡ 


ROBINSON AND BARTLETT. — PLANTS FROM GUATEMALA AND MEXICO. 53 


this species somewhat resembles A. americana L., A. hispida Willd., 
and A. sensitiva Sw. It has, however, flowers which are much larger 
than those of A. sensitiva, and somewhat larger than those of the other 
species mentioned. It differs furthermore from A. Aispeda in its entire 
not dentate bracts, and from both A. americana and A. hispida in its 
essentially glabrous foliage and fruit. 

Cassta EMARGINATA L., var. subunijuga Robinson & Bartlett, 
n. var., foliolis saepissime 2 late oblongo-ellipticis 6-7 cm. longis 4-5 
em. latis supra molliter pubescentibus subtus flavido-tomentosis. — 
Gualan, Department of Zacapa, Guatemala, 15 January, 1905, C. C. 
Deam, no. 220 (type, in hb. Gray). This variety appears to agree in 
flowers and fruit with the typical form, but it is noteworthy in habit 
by reason of the striking reduction in the number of leaflets to two. 
Occasionally, however, leaves with four leaflets occur on individuals on 
which most of the leaves have but two leaflets; so there is reason to 
suppose that the plant is merely a varietal development from a form 
with more numerous leaflets, rather than a separate species. 


‘~ Mimosa (Habbasia) gualanensis Robinson & Bartlett, n. sp., 


ser. Leptostachyarum, caulibus gracilibus lignosis 4 m. longis aculeatis 
tomentellis, aculeis sparsis parvis valde recurvatis compressis Inaequal- 
ibus maximis vix 2 mm. longis brunneis ; foliis majusculis 27 cm. latis ; 
pinnis 3-jugis 9-14 em. longis; foliolis obovato-oblongis 2-4-jugis 4—5 
em. longis 2.4—-3 em. latis firmiusculis supra reticulatis utrinque glabris, 
petiolo 7 cm. vel ultra longo rhachique valde armatis aculeis sparsis 
numerosis recurvatis 0.7-2 mm. longis; rhacheolis etiam basin versus 
aculeolatis ; spicis gracilibus 5 cm. longis densifloris breviter peduncu- 
latis, pedunculis tomentellis ; floribus 2 mm. longis; calyce 1.2 mm. 
longo campanulato brevissime 5-dentato extus tomentello; petalis 5 
ealyce subduplo longioribus oblanceolato-oblongis ; staminibus 10 ma- 
turitate modice exsertis; legumine immaturo i0 cm. longo 1.3 cm. 
lato 15-seminato plano tenui glabriusculo leviter arcuato, stipite cras- 
siusculo tomentello tereti 5-6 mm. longo. — Gualan, Department of 
Zacapa, Guatemala, 19 January, 1905, C. C. Deam, no. 224 (type, in 
hb. Gray). This species, although clearly of the Leptostachyae, does 
not appear to be very closely related to any other. It should probably 
be placed near 2)7. guatemalensis Benth., and M. spirocarpa Rose. 


Y Tetrapteris emarginata Bartlett, n. sp., fruticosa procumbens 


3-5 m. longa; ramis oppositis glabris griseo-brunneis ; ramulis viridi- 
bus nigro-punctatis ; foliis oppositis, aetate utrinque glabris, juventate 
albo-sericeis pilis mox deciduis, forma valde variabilibus, in ramulo 
florifero sessilibus vel perbreviter petiolatis suborbiculatis 1-1.5 cm. 
diametro cordatis emarginatis saepe mucronulatis, in ramulo foliifero 


54 PROCEEDINGS OF THE AMERICAN ACADEMY. 


breviter petiolatis ovatis 4 cm. longis basi obtusis apice acutis ; ramulis 
floriferis in quasi-umbellas quadrifloras terminantibus ; pedunculis 7-8 
mm. longis cum pedicellis aequilongis articulatis ; bracteis pedunculo- 
rum bracteolisque pedicellorum lanceolatis minutis ; sepalis 5 albi- 
cantius viridibus 2 mm. longis, 4 basi biglandulosis glandulis magnis ; 
staminibus glabris calycem valde superantibus, omnibus basi coalitis ; 
ovariis in unum pyramidatum faciebus concavis coalitis ; fructu albo- 
lanuginoso dorso medio eristato crista integra glabra ; fructus alis 
glabris viridibus rubro-tinctis anguste oblongis, duobus exterioribus 
ca, 13 mm. longis, duobus interioribus ca. 9 mm. longis. Petala non 
visa, — Gualan, Department of Zacapa, Guatemala, January 19, 1905, 
C. (. Deam, no. 150 (type, in hb. Gray). Tetrapteris emarginata 
belongs among the glabrous-leaved species of Jussieu’s ὃ 7etrapteris 
* Anisopterae. It may be easily distinguished from any of the Mexican 
species by the leaves of the flowering branches. 

Euphorbia ephedromorpha Bartlett, n. sp., basi lignescenti ; ra- 
mis prostratis modice crassis longitudine usque ad 10 dm. saepe sim- 
plicibus viridibus flexuosis aphyllis juventate valde compressis, aciebus 
ambabus bialatis ; internodiis 2-4 cm. longis minute granulatis gla- 
bratis vel perexigue pilosis, in marginibus alarum minutissime scabratis ; 
nodis haud incrassatis corpore papillato (nonne cum folio aequivalenti ?) 
praeditis ; stipula una glanduliformi crateriformi pilosa recte super 
‘papillam (de qua vide supra) et quam eandem parviore ; cymis axil- 
laribus et terminalibus dichotomis 2-12-cyathiis valde glanduloso-pilosis 
bracteatis ; bracteis ad dichotomias oppositis 1.8 mm. longis linearispa- 
tulatis dense glanduloso-pilosis ; cyathiis anguste conicis 3 min. longis 
glanduloso-pilosis ; pedicellis gracilibus cyathiis aequilongis ; involucri 
segmentis propriis perbrevibus flabelliformibus ad mediam digitatim 
7-8-laciniatis; glandulis 5 planis transverse ovatis marginatis appen- 
diculatis ; appendicibus rectis quam glandulo 8-plo quam involucri seg- 
mentis triplo longioribus anguste spatulatis glabris ; stylo brevi usque 
ad basin bifido; ovario 2 mm. longo glabriusculo stipitato, stipite 
eyathio paulo longiore ; seminibus lilacinis ovoideis foveolatis. — Gua- 
lan, Department of Zacapa, Guatemala, 11 January, 1905, C. C. Deam, 
no. 232 (type, in hb. Gray). In regard to this species Mr. Deam 
writes: “I recall the place where it grew very vividly. There is a road 
leading from Gualan to the Motagua River, and as is the case with all 
travelled ways in Guatemala, it is washed into deep gullies. ‘This plant 
(no. 232) was found in the nude, rocky, dry soil at the side of the road, 
on an angle of about 75°. It grew prostrate in patches extending over 
an area perhaps six feet square. The soil was of a red type, similar to 
that around Chattanooga and Atlanta. I did not see it in any other 


ROBINSON AND BARTLETT. — PLANTS FROM GUATEMALA AND MEXICO. 50 
place.” Euphorbia ephedromorpha, a unique plant in both habital and 
technical characters, belongs to the ὃ Alectoroctonum. The only Hu- 
phorbia of the same aftimity which has been seen is in the Gray Her- 
barium from Cerro Quiengola, Oaxaca, Mexico, Caec. et Hil. Seler, no. 
1611. It represents a clearly distinct new species of very similar habit, 
but it cannot be described on account of the scantiness of the material. 

Acalypha euphrasiostachys Bartlett, n. sp., fruticosa ramosa 
1 m. altitudine; ramulis junioribus molliter pubescentibus ochraceis 
aetate glabriusculis rubentibus ; foliorum limbis ovatis 38-8 cm. longis 
2-4.5 em. latis dentatis utrinque molliter pubescentibus vel supra 
solum secus nervos pilosis, apice acutis vel caudato-acutis, basi max- 
ime variabilibus acutis rotundatis vel subcordatis; petiolis limbo ea. 
quintuplo brevioribus; spicis masculis axillaribus sessilibus ca. 1 em. 
longis nunquam ad basin bracteis femineis praeditis ; spicis femineis 
axillaribus 2.5-7 cm. longis 4-7-bracteatis, dispositione formaque brac- 
tearum speciebus alpinis generis Huphrasiae persimilibus ; bracteis 
femineis 8 mm. longis 10 mm. latis unifloris 13-dentatis, dentibus 
modice longis alternis brevioribus ; calycis masculi segmentis 4 ovatis 
0.5 mm. longis, feminei segmentis 3 ovatis ca. 1 mm. longis; ovario 
dense piloso; stylis viridibus bracteo exsertis 7 mm. longis multila- 
cinuligeris. — Zacapa, Department of Zacapa, Guatemala, 24 January, 
1905, C. C. Deam, no. 190 (type, in hb. Gray). A species near Watson’s 
Acalypha multispicata, which has very similar fertile spikes. 

Clusia quadrangula Bartlett, n. sp., arborea 5-6 m. alta ubique 
glabra ; ramis modice crassis subteretibus ; foliis coriaceis ovatis 3-4 
cm. latis 7-11 cm. longis, apice basique acutis, petiolo quam limbo 
quintuplo brevioribus ; nervis lateralibus numerosis parallelis utrinque 
prominulis inter se 1-2 mm. distantibus angulo ca. 45° a costa abeunti- 
bus; inflorescentia terminali quam foliis superis duplo breviore ramosa, 
ramulis angulosis plerumque in florem unum brevipedicellatum termi- 
nantibus ; bracteolis infimis semi-ovatis basi connatis, sequentibus (a 
sepalis non different) sepalisque 14-16 per paria decussatis coriaceis 
semi-ovatis cordatis dorso carinatis, collective obpyramidatis quadran- 
gulis (ex quo nomen specificum) ; petalis 4 coriaceis late ovatis quam 
sepalis duplo longioribus; staminibus pernumerosis in receptaculo 
elevato valde concavo pentagono dense aggregatis liberis, omnibus an- 
theriferis, filamentis perbrevibus paene nullis, antheris rimula longitu- 
dinali dehiscentibus, connectivis haud productis. Flores feminei ignoti. 
— Livingston, Department of Izabal, Guatemala, February 17, 1905, C. 
C. Deam, no. 56 (type, in hb. Gray). This Clusia has no obvious relation- 
ship with any heretofore described species. Until pistillate flowers are 
discovered it seems unwise to characterize a new section for its reception. 


ν 


τῶ 


J 


56 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Following Engler’s treatment of Clusia in Flora Brasiliensis, it is ex- 
cluded from all the sections of the genus except § Huclusia by the 
character of the receptacle. From subsections Oxrystemon and Chlamy- 
doclusia of ὃ Huclusia it is excluded by the muticous connective, and 
from Cochlanthera, the sole remaining subsection, by the four petals 
and very numerous stamens. 

Rinorea deflexiflora Bartlett, n. sp., fruticosa 2.5 m. alta dichotome 
ramosa glabra novellis inflorescentiisque puberulis exceptis ; ramis gra- 
cilibus juventate brunneolis aetate albobrunneolis glabris ; lenticellis 
numerosis albis; internodiis superioribus ca. 11 cm. longis; nodis 
modice incrassatis in gemmam floriferem terminantibus; foliis oppositis 
cuneato-ovatis 4-12 cm. latis 8-24 cm. longis remote serratis caudato- 
acuminatis basi angustatis subcordatis supra atroviridibus subtus palli- 
dioribus ; petiolis 2-4 mm. longis ; stipulis subulato-lanceolatis 7 mm. 
longis ; inflorescentiis ubique puberulis inter ramos dichotomiarum 
terminalibus simplicibus 6 em. longis ; floribus ca. 15 longipedicellatis 
nutantibus bracteatis; pedicellis gracilibus 6 mm. longis deflexis ; 
bracteis 3, una pedicellum subtendente, duabus infra pedicelli mediam 
suboppositis ; sepalis 5 aequalibus acutis extus puberulis margine cili- 
atis 2 mm. longis; petalis 5 aequalibus oblongis 5 mm. longis haud 
unguiculatis apice valde revolutis ; staminibus 5 glabris 3.5 mm. longis 
basi hand connatis; filamentis 1.3 mm. longis, anticis ad basin in dorso 
glandulae oblongae 0.8 mm. longae adnatis ; connectivis in squamam 
ovatam lacero-ciliatam antherae loculis dimidio longiorem productis ; 
stylo glabro stamina superante ; ovario dense piloso. — Livingston, De- 
partment of Izabal, Guatemala, February 18, 1905, C. C. Deam, no. 
61 (type, in hb. Gray). “ Four species of Rinorea or Alsodeia are now 
definitely known from north of Panama. One of them, the Mexican 
plant described by Watson as Alsodeia parvifolia, is of very doubtful 
generic affinity. ‘The other old species are Rinorea silvatica (Seem.) 
QO. K. and Rinorea guatémalensis ( Wats.) Bartlett, n. comb. (A /sodeia 
guatemalensis Wats., Proc. Am. Acad. xxi. 458). Points which distin- 
guish 7. deflexiflora from the former are that in 1), silvatica the 
spikes are nodding, the flowers are nearly sessile, and the sepals are 
almost as long as the petals. In &. guatemalensis the leaves are 
broadest at the middle and are acute at the base, as contrasted with 
the more cuneate, subcordate leaves of LR. defleviflora. 

Hybanthus cymosus Bartlett, n. sp., fruticosus 3 m. altus ; ramis 
gracilibus alato-angulatis glabratis supra straminellis subtus viridibus ; 
internodiis foliis brevioribus ; foliis alternis ovatis 2-4 em. latis 4.5-8 
em. longis serrato-crenatis glabratis basi acutis subsessilibus, apice 
rotundato-obtusis ; stipulis lineari-subulatis usque ad 2 mm. longis; 


a a 


ROBINSON AND BARTLETT. — PLANTS FROM GUATEMALA AND MEXICO. δ᾽ 


floribus in cymas racemosas 15-30-floras axillares terminalesve aggre- 
gatis ; cymarum bracteis perparvis ovato-deltoideis albidis ; pedunculis 
3-8 mm. longis ; pedicellis 5 mm. longis breviter supra basin articu- 
latis; sepalis ca. 1.6 mm. longis puberulis subaequalibus ; petalis 
glabris in fructu persistentibus, duobus posticis ovatis apice truncatis 
2.4 mm. longis, duobus intermediis aequilongis subquadratis breviter 
apiculatis ad basin antrorsum brevi-auriculatis, antico 1.9 mm. longo 
trinervio inter mediam apicemque constricto, parte inferiore (ungue) 
ampulliformi, parte superiore (limbo) multo parviore suborbiculari 
apice bilobata ; staminibus 2 mm. longis inter antheras connatis tubum 
formantibus, tribus posticis triangulo-appendiculatis, filamentis per- 
brevibus liberis, duobus anticis appendicibus connatis, filamentis extus 
ad basin glandulae late scutiformi adnatis, glandula gibbositati petali 
antici conformali, loculis duobus contiguis antherarum anticarum 
abortivis ; stylo corolla paululo longiore ; capsula glabra viridi 6 mm. 
diametro 9 mm. longa. —Gualan, Department of Zacapa, Guatemala, 
19 January, 1905, C. C. Deam, no. 385 (type, in hb. Gray). A species 
well marked by the combination of alternate leaves, numerous cymose 
axillary inflorescences, and short lower petal. In general structure it 
is most closely allied to such South American species as Lonidium 
atropurpureum St. Hil. and J. Spruce Eichl. 

Ipomoea anisomeres Robinson ἃ Bartlett, n. sp., volubilis ; caule 
gracili lignescenti glabro subtereti 3-6 m. longitudine a cortice brun- 
nescenti-griseo obtecto aetate papilloso-scabrato ; foliis ovatis integris 
profunde sinu patenti cordatis acutiusculis vel subattenuatis et in 
apice emarginato cum nervo excurrenti apiculatis penninervis 6-11 
cm. longis 4-7 em. latis utrinque glabris subtus pallidioribus ; petiolo 
gracili glabro 3-5 em. longo ; pedunculis axillaribus solitariis 3.5-6 em. 
longis in summa parte composite cymoso-ramosis ; pedicellis 1.5-2 cm. 
longis modice gracilibus sursum plus minusve incrassatis glabris ; sepalis 
glabris margine albis 2 exterioribus 1-3 mm. longis suborbicularibus 
obtusis vix herbaceis 3 interioribus 1 cm. longis ellipticis apice rotundatis ; 
corolla late infundibuliformi alba vel praesertim in faucibus purpuras- 
centi 6.5-7 em. longa, limbo 4-5 em. lato subintegro, faucibus 1 cm. 
diametro 3.5 cm. longis cylindratis deorsum in tubum brevem (ca. 1 
em. longum) proprium angustatis ; capsula ovoidea acuta 10-12 mm. 
longa glabra biloculari ; seminibus 4 griseo-fuscis breviter pubescenti- 
bus.—Gualan, Department of Zacapa, Guatemala, 12-14 January, 1905, 
C. C. Deam, nos. 318 and 319 (types, in hb. Gray). This species appears 
to fall into § Inaequisepalae, as defined by Peter in Engl. & Prantl, Nat. 
Pflanzenf. iv. Ab. 3, 29. The specific name alludes to the strikingly 
unequal sepals. 


58 PROCEEDINGS OF THE AMERICAN ACADEMY. 


“ Cerdia truncatifolia Bartlett, n. sp., arborea 5-7 τη. altitudine; 
ramulis 2-3 mm. crassis flexuosis juventate griseo-ferrugineis pubes- 
centibus aetate griseis glabris ad nodos incrassatis ; foliorum cica- 
tricibus reniformibus vel in ramulis vetustioribus lunatis, interdum 
gemma accessoria inter cornua infra gemmam normalem praeditis ; 
foliis late ovatis maximis infra mediam 5 cm. latis 7.5 cm. longis inte- 
gerrimis vel apicem versus crenato-dentatis basi obtusis truncatis apice 
plerumque abrupte acutis supra scabris atroviridibus subtus velutino- 
pubescentibus griseo-viridibus, petiolis quam 8 mm. brevioribus ; 
cyma dichotoma pauciflora foliis breviore omnino ferrugineo-pubes- 
centi; pedicellis gracilibus 2-7 mm. longis; calyce campanulato ca. 1 
em. longo juventate 5 mm. diametro ad fructus maturitatem plus 
minusve inflato 5-nervato 5-laciniato, laciniis irregulariter angusto- 
deltoideis ; corolla alba (?) infundibuliformi 15 mm. longa extus intus- 
que puberula usque ad mediam 5-lobata, tubo brevi, lobis rotundis 7 
mm. latis; staminibus 5 baseis loborum vix attingentibus, filamentis 
5 mm. longis ; stylo stamina aequante apice bis bifido ; drupa (imma- 
tura) ovoidea minute puberula mucronata calyce inclusa. — Zacapa, 
Department of Zacapa, Guatemala, January 23, 1905, C. C. Deam, 
no. 160 (type, in hb. Gray). In no. 160", collected at the same local- 
ity, the flowers and foliage are greatly reduced in size, a variation no 
doubt purely ecological. The shape of the leaves, which are remarkably 
like those of Polygonum cuspidatum Sieb. et Zucc., suffices to distin- 
guish Cordia truncatifolia from all other species of Sebestenoides. 

. Russelia rugosa Robinson, n. sp., fruticosa; ramis ramulisque 
6-angularibus tomentello-puberulis pallide griseis; internodiis 5-8 
em. longis; foliis oppositis vel ternis late ovatis obtusiusculis grosse 
crenato-serratis basi integerrimis cuneatis supra scabris valde rugosis 
atroviridibus subtus vix pallidioribus laxe reticulato-venosis breviter 
pubescentibus 5.5-8 em. longis 2.6-4.8 em. latis, petiolo crassiusculo 
5 mm. longo supra canaliculato pubescenti; cymulis subsessilibus 
axillaribus verticellastros parvifloros formantibus ; calycis lobis lanceo- 
lato-linearibus angustissimis caudato-attenuatis sordide pubescentibus 
nigrescentibus 5-6 mm. longis; corolla tubiformi verisimiliter coccinea 
11-12 mm. longa pubescenti; capsula ovoidea nigrescenti levi nitida 
4 mm. longa. —Gualan, Department of Zacapa, Guatemala, alt. 128 m., 
18 January, 1905, C. C. Deam, no. 183 (type, in hb. Gray). A species 
pretty well marked in the genus by its large and very rugose leaves. 

ν΄ Tetramerium gualanense Robinson & Bartlett, n. sp., suffrati- 
cosum 1 m. altum ramosum, novellis viscoso-pubescentibus ; caulibus 
subquadrangularibus lilacino-griseis minute albido-maculatis maturitate 
subglabratis ; foliis oppositis petiolatis membranaceis subconcoloribus 


ROBINSON AND BARTLETT. — PLANTS FROM GUATEMALA AND MEXICO. 59 


scabriusculis ovatis acute subcaudateque acuminatis integerrimis, 
limbo 6-8 cm. longo 3.5-6 cm. lato pinnatim nervatis basi acutis in 
nervis sparse puberulis aetate glabratis cystolithis conspicuis instructis, 
petiolo 1.5-2.5 em. longo gracili supra canaliculato puberulo subtus 
rotundato glabro; spicis subdensis 2.5-4.5 cm. longis 1.3 cm. crassis 
ramulos oppositos terminantibus ; bracteis obovatis cuneatis integer- 
rimis acutis 5-nerviis utrinque glanduloso-pubescentibus 1 cm. longis 
5 mm. latis, basi attenuatis ; bracteolis binis oblanceolatis acutis cym- 
biformibus 9-10 mm. longis basi attenuatis in latere altero usque ad 
mediam in altero vix supra basin connatis ; calyce 5-partito, lobis 
anguste lanceolatis acutissimis apice hispidulis ; corolla subaequaliter 
4-partita alba 1.5 cm. longa glabra, lobis anguste oblongis obtusis ca. 
9 mm. longis; staminibus 2 lobos corollae subaequantibus in sammo 
tubo insertis ; antherarum loculis 2 summo subaequi-altis basi loculo 
uno plus minusve calcarato ; stylo clavato ; stigmate bifido; capsula 
obovata acuminata glabra valde compressa ca. 2 mm. longa ca. 2 mm. 
lata, stipite obcompresso 2 mm. longo; seminibus 2 lenticularibus 
fulvis 2.6 mm. longis in latere interiore glabriusculis in latere exteriore 
crispo-pubescentibus. — Gualan, Department of Zacapa, Guatemala, 18 
January, 1905, C. C. Deam, no. 397 (type, in hb. Gray). In the form 
of its inflorescence and bracts this species approaches the members of 
the genus which have sometimes been separated as [enrya. 

 Isertia Deamii Bartlett, n. sp., arbor parva 5 m. alta; ramis ram- 
ulisque crassis inferne subteretibus superne obtuse quadrangulis sor- 
dide tomentosis ; internodiis 4-5 cm. longis; foliis 20-30 cm. longis 
8-11 em. latis utrinque acutis supra glabris subtus griseo-tomentosis, 
petiolo limbis 10-plo breviore ; stipulis 6-9 mm. longis triangulis per- 
sistentibus ; inflorescentia foliis multo breviore paniculata ca. 10 em. 
longa, ramulis tomentosis ascendentibus 7-20 mm. longis, pedicellis 
2-5 mm. longis, bracteis bracteolisque triangulis parvis ; calyce fuscato 
hemi-ellipsoidali truncato nec distincte dentato ; corolla ca. 30 mm. 
longa coccinea extus, lobis limbi exceptis, tomentosa, lobis 7 mm. 
longis obtusatis extus glabris intus lanugine flavo tectis ; staminibus 6 
inclusis tubo adnatis, antheris circum stigmata connatis ; stylo apice in 
ramulos sex ca. 6 mm. longos terminanti; bacca calyce coronata 6- 
pyrena. — Puerto Barrios, Department of Izabal, Guatemala, 24 
February, 1905, C. C. Deam, no. 48 (type, in hb. Gray). Jsertia 
Deamii, the third Middle-American species of the genus, is not similar 
enough to either of the old species to be confused with them. 

ν΄ Liabum caducifolium Robinson & Bartlett, ἢ. sp., fruticosum ; 
caulibus teretibus striatulis griseo-fuscis glabris delapsu foliorum nu- 
dis, internodiis 6-8 cm. longis; inflorescentiis laxe corymboso-pan- 


60 PROCEEDINGS OF THE AMERICAN ACADEMY. 


iculatis, ramis oppositis nudis patentibus vel arcuato-ascendentibus 
multicapitulatis, bracteis lanceolatis utrinque acutis integerrimis gra- 
ciliter petiolatis supra glabris subtus arachnoideo-tomentosis, petiolo 
planiusculo glanduloso-hispidulo ; pedicellis filiformibus 1-5 mm. 
longis ; capitulis discoideis 6-floris; involucri squamis 13 acutis cili- 
olatis exterioribus ovato-lanceolatis 1 mm. longis interioribus gradatim 
longioribus angustioribusque intimis linearibus vel lineari-lanceolatis 
5 mm. longis; flosculorum omnium corollis 6.5 mm. longis gracilibus 
sursum gradatim ampliatis sine faucibus distinctis, dentibus limbi line- 
aribus ad apicem obtusiusculum attenuatis; pappi setis biseriatis 
exterioribus brevibus paucis planiusculis interioribus ca. 40 capillari- 
bus fulvescentibus sursum scabriusculis. Achaenia immatura. — Near 
Acapulco, Guerrero, Mexico, between October, 1894, and March, 1895, 
Dr. E. Palmer, no. 245 (type, in hb. Gray). This species belongs to 
§ Andromachia, and is closely related to L. glabrum Hemsl., but it 
differs in its much looser corymbose-paniculate inflorescence, its shorter 
involuere, and much more attenuate involucral scales. 

Liabum Deamii Robinson & Bartlett, n. sp., scandens 3-5 m. 
longum ; caulibus anthesi delapsu foliorum ignotorum nudis subtereti- 
bus lanulosis albidis, internodiis 2-4 cm. longis, nodis crassiusculis ; 
inflorescentiis ovoideis thyrsoideis multicapitulatis albido-lanuginosis 
1-1.5 dm. longis 5-8 em. diametro; bracteis petiolatis ovatis integris 
discoloribus supra leviter griseo-pubescentibus subtus albo-lanatis ; 
ramulis 3—5-capituliferis; capitulis discoideis 6-floris subsessilibus 
vel brevissime pedicellatis ; involucri squamis ca. 13 obtusis exterio- 
ribus ovatis ca. 2 mm. longis externe pubescentibus interioribus 
gradatim majoribus 3-4 mm. longis ovato-oblongis apicem versus 
pubescentibus ; flosculis ¢ involucro longe exsertis, corollis glabris 
verisimiliter flavidulis 7 mm. longis, faucibus eylindratis tubum pro- 
prium graciliorem subaequantibus, dentibus limbi patentibus anguste 
lanceolatis acutissimis ; achaeniis 2.5 mm. longis deorsum angustatis 
griseo-olivaceis modice compressis striatulis breviter pubescentibus ; 
pappi setis 2-seriatis exterioribus paucis subpaleaceis 1-2 mm. longis 
interioribus ca. 50 capillaribus sursum minute scabratis ca. 6 mm. 
longis albidis.—Gualan, Department of Zacapa, Guatemala, C. C. 
Deam, no. 194 (type, in hb. Gray). This species clearly belongs to the 
ὃ Andromachia, and appears to be nearest L. glabrum Hemsl., from 
which it may be distinguished, however, by its pubescence and much 
shorter involucre, the latter scarcely exceeding the achenes. 


ΒΟ ἃ ὦ σ- - νς 


FERNALD. — NEW SPERMATOPHYTES FROM MEXICO. 61 


IV. DIAGNOSES OF NEW SPERMATOPHYTES FROM 
MEXICO. 


By M. L. FERNALD. 


Carex ciliaris Fernald, n. sp., laxe caespitosa, caudice duro; cul- 
mis duriusculis 4-5 dm. altis acute triquetris superne ciliatis ; foltis 
quam culmo brevioribus lineari-attenuatis 2.5-3.5 mm. latis, nervis 
marginibusque ciliatis marginibus revolutis ; spicis 3-5, terminali cla- 
vellata subsessili 1-1.5 em. longa vel omnino mascula vel apice foeminea ; 
squamis masculis lanceolato-attenuatis pallide brunneis ; spicis foemi- 
niis breviter oblongis 0.6-2 cm. longis 0.5 cm. crassis, superioribus 
approximatis, inferioribus remotis et a bractea inflorescentiam aequanti 
vel superanti subtentis ; squamis foemineis anguste ovatis acuminatis 
media parte viridibus 3-costatis levibus marginibus pallidis ; perigy- 
niis viridescentibus squamas aequantibus vel superantibus 4 mm. longis 
ellipsoideo-triquetris, faciebus planis 3-5-nerviis, rostro breviter conico- 
subulato hyalino bidentato. — Oak woods, Lena Station, Hidalgo, Mex- 
ico, alt. 2530 m., 26 August, 1905, C. G. Pringle, no. 10,039 (type, in 
hb. Gray). Nearest related, apparently, to C. anistostachys Liebm., 
which, according to the description, has scabrous culms, the staminate 
scales red-punctate, and the pistillate scales ciliolate. 

y Carex perlonga Fernald, n. sp., culmis 6 dm. altis laevissimis basi 
a vaginis ferrugineis tectis ; foliis quam culmo plerumque brevioribus 
4-5 mm. latis valde 1—-3-nerviis serrulatis basi ferrugineis ; bracteis in- 
ferioribus elongatis quam culmo longioribus, superioribus abbreviatis 
setaceis ; spicis 7 solitariis inferioribus remotis superioribus approxi- 
matis laxe ascendentibus vel pendulis lineari-cylindricis 5-10 cm. longis 
3-4 mmm. latis apice masculis ; squama mascula oblonga subacuminata 
fulva medio viridi, foeminea oblongo-lanceolata acuminata albo-fulva 
medio viridi; perigynio viridi trigono-fusiformi striato 4 mm. longo, 
ore obliquo subintegro. — Barranca below Trinidad Iron Works, Hi- 
dalgo, Mexico, alt. 1585 m., 2 June, 1904, C. G. Pringle, no. 8863 
(type, in hb. Gray). A species of the Polystachyae, unique in its soli- 
tary not clustered spikes, thus closely approaching the Debiles. 

ν΄ Alnus firmifolia Fernald, n. sp., arborea vel fruticosa 6-12 m. 
alta ; ramis ramulisque atrobrunneis glabris cum lenticellis numerosis 
munitis ; foliis elliptico-oblongis obtuse acuminatis vel apice rotundatis 
basi angustatis 5-17 cm. longis 2-5.5 em. latis firmis duriusculisque 
supra glabris sublucidis subtus pallidis piloso-hispidis in nerviis promi- 
nentibus ; petiolo crassiusculo glabro 0.7-1.2 em. longo ; inflorescentiis 


Vv 


ν 


62 PROCEEDINGS OF THE AMERICAN ACADEMY. 


fertilibus 6-9 em. longis, amentis maturis 3-5 oblongo-cylindricis atro- 
brunneis pedunculatis 7-14 mm. longis 5-7 mm. diametro; nuculis 
cuneato-obovatis vel suborbicularibus rufobrunneis lucidis 1.5-2 mm. 
longis. — Mountains about Cima Station, Mexico, alt. about 3000 m., 
30 August, 1905, C. G. Pringle, no. 10,040 (type, in hb. Gray). Re- 
sembling large-leaved A. jorullensis HBK., but quite lacking the close 
covering of waxy or granular atoms which characterizes the lower leaf- 
surface of that species. 

Alnus Pringlei Fernald, n. sp. arbor parva; ramis ramulisque 
angulatis, jJuventissimis cinereo-puberulis mox glabratis ; foliis late 
elliptico-ovatis 4.5-9 em. longis 3-7 em. latis apice breviter acuminatis 
basi rotundatis, marginibus regularibus vel paulo sinuatis crebre serru- 
latis, venis subtus prominentibus rufescentibus pilosis ; petiolis 0.5-1 
em. longis piloso-ciliatis ; ramis floriferis elongatis; amentis ¢ 4-7 
terminalibus anthesi 5-6 cm. longis ; pedunculis fructiferis 2 valde di- 
vergentibus crassis; amentis 9 3-4 sessilibus maturitate cylindricis 
2.2-2.7 em. longis 0.9-1.1 cm. diametro atrobrunneis ; nuculis crassis 
late cuneatis et angulatis 2.5-3 mm. longis obscuris pallide brunneis. — 
By streams, near Uruapan, Michoacan, Mexico, alt. about 1525 m., 13 
November, 1905, C. G. Pringle, no. 10,125 (type, in hb. Gray). Most 
nearly related to A. acuminata HBK., which has larger oblong-ovoid 
ashy-brown strobiles 1.5 em. thick, and larger thick-winged lustrous 
nutlets. 4 


ν Evenorsta arrensis HBK., var. villicaulis Fernald, n. var. Hume- 


canthus Benthamianus Kl. & Garcke, in Kl. Tricoce. 42 (1860), not 
Euphorbia Benthami Hiern, Cat. Welw. Afr. Pl. i. 943 (1900). Au- 
phorbia ariensis Benth., Pl. Hartw. 51, no. 387 (1840), not HBK. 
Nov. Gen. et Sp. ii. 57 (1817). Caulibus in parte inferiore valde vil- 
losis ; foliis quam eis formae typicae aliquid latioribus ; inflorescentia 
laxiore. — In pine forests at Coru Station, Michoacan, Mexico, alt. 
1970 m., 29 October, 1905, C. (αἰ. Pringle, no. 10,116 (type, in hb. 
Gray). This locality is only about 48 km. to the west of Patzcuaro, 
which was Hartweg’s original station. 

Heliotropium calcicola Fernald, n. sp., frutex gracilis 6-15 dm. 
altus; cortice brunneo exfolianti; ramulis albido-strigoso-puberulis ; 
foliis lanceolatis utroque attenuatis breviter petiolatis apice mucronatis 
cum pilis minutis et lucidis utrinque obtectis 2-4.5 cm. longis 
3-10 mm. latis margine revolutis ; spicis terminalibus et lateralibus 
geminis 0.5, maturitate usque ad 2, em. longis; pedunculis gracilibus 
1.3-2 em. longis canescentibus; calyce 1.5-2.5 em. longo cum pilis 
minutis adpressis canescenti, lobis lanceolatis ; corolla anguste “urceo- 
lata 3 mm. longa adpresse setulosa, lobis ovatis acuminatis ; stylo nullo ; 


FERNALD. — NEW SPERMATOPHYTES FROM MEXICO. 63 


nuculis subglobosis 1.3 mm. altis albidis adpresse setulosis. — Lime- 

stone cliffs, Iguala Cation, Guerrero, Mexico, alt. 760 m., 28 September, 

1905, C. G. Pringle, no. 10,062 (type, in hb. Gray). Not closely re- 

lated to other Mexican species, perhaps nearest H. coriaceum Lehm., 

which is much coarser, densely villous, with broader rugose villous 

leaves and larger flowers and fruits. 
y Satvia nispanica L., var. chionocalyx Fernald, n. var., foliis brac- 
teisque supra viridibus et minute pubescentibus subtus paulo pallidi- 
oribus et praesertim in nerviis breviter pilosis ; spicis pertenuibus ὅ-- 
10 cm. longis 1-1.5 em. crassis; floribus adpresse ascendentibus ; 
calycibus conspicue denseque albo-pubescentibus. — Fields, Uruapan, 
Michoacan, Mexico, 16 October, 1904, C. G. Pringle, no. 88374 (type, 
in hb. Gray). A striking extreme of S. hispanica, the typical form of 
which differs in its ordinarily thicker spikes of less appressed cinereous 
calyces. 

SALVIA HISPANTICA L., var. intonsa Fernald, ἢ. var., foliis et parti- 
bus superioribus caulis tomentosis; spicis brevibus crassis 1.5-5.5 cm. 
longis 1.5-2 cm. crassis ; calycibus tomentosis patentibus. — Buena 
Vista, Department of Santa Rosa, Guatemala, alt. 1680 m., December, 
1892, Heyde & Luz, no. 4401, in exsice. J. D. Smith. Differing from 
SS. hispanica in the dense tomentum of its leaves, stems, and calyces. 
ν΄. Salvia (Vulgares) mucidiflora Fernald, ἢ. sp., herbacea (7) alta ; 

caule cinereo-pulverulento obtuse angulato faciebus profunde suleato; 

foliis rhomboideo-ovatis 3.5-10 em. longis crenato-serratis subtus albidis 
et tomento brevi densoque obtectis supra griseo-viridibus cum pilis brevi- 
bus albis, basi cuneato integro in petiolum puberulum gradatim angus- 
tato ; ramis brevibus patentibus ; racemis laxis 3.5-10 em. longis ; rhachi 
et pedicellis et etiam calyce dense albovillosis paene lanatis ; verticellis 

3-6-floris subdistantibus; bracteis late ovatis mucronatis 4-7 mm. 

longis subpersistentibus laxe albo-villosis ; pedicellis 1-3 mm. longis ; 

calyce anguste campanulato anthesi 7 mm. fructifero 8-9 mm. longo, 

labio superiore acuminato ascendenti, inferiore rectiusculo cum lobis 2 

deltoideis aristatis ; corolla azurea et alba 13-14 mm. longa, labio su- 

periore villoso oblongo 6 mm. longo, inferiore violaceo patenti paulo 
longiore ; stylo villoso. —San Ramén, Durango, Mexico, 21 April-18 

May, 1906, Hdw. Palmer, no. 18% (type, in hb. Gray). Nearest related 

to S. longispicata Mart. & Gal. but differing in its crenate-serrate 

leaves and the long pubescence of the inflorescence. 

Salvia (Vulgares) arthrocoma Fernald, n. sp., caulibus superne 
pilosis, pilis pallidis nodulosis ; foliis rhomboideo-ovatis 4-8 cm. longis 
supra basin cuneatam crenato-serratis apice acuminatis supra pilis 
compressis adpresse setulosis et in venis pilis gracilibus nodulosis mu- 


XN 


64 PROCEEDINGS OF THE AMERICAN ACADEMY. 


nitis subtus in venis venulisque pilis gracilibus nodulosis pubescentibus ; 
petiolis gracilibus 1.5-4 em. longis ; racemo brevi, rhachi a pilis nodu- 
losis peculiaribus tecta; verticellis 3-6-floris demum 1-1.5 em. dis- 
tantibus ; bracteis late ovatis longe acuminatis et calycibus in nervis 
marginibusque pilis gracilibus nodulosis munitis ; pedicellis 3 vel usque 
ad 5 mm. longis; calyce campanulato anthesi 5 fructifero 8 mm. longo 
tubo valde costato, labiis deltoideo-acuminatis valde patentibus superi- 
ore ascendenti 2-3 mm. longo quam lobo recto inferioris breviore ; 
corolla 1 em. longa, tubo faucibusque albidis, labiis obtusis ringentibus 
apicem versus purpureo-tinctis, galea pilosa 4 mm. longa labium infe- 
rius latius paulo superante. — Barranca below Trinidad Iron Works, 
Hidalgo, Mexico, alt. 1620 m., 16 July, 1904, C. G. Pringle, no. 8940 
(type, in hb. Gray). Somewhat suggesting S. fluviatilis Fernald, but 
clearly characterized by its slender jointed hairs. 

Salvia (Vulgares) Lozani Fernald, n. sp., caulibus herbaceis gracil- 
ibus decumbentibus basi saepissime radicantibus aliquid ascendenti- 
bus demum 5-6 cm. longis minute glanduloso-setulosis, pilis patentibus ; 
foliis regulariter remotis, jugis 4-6 cm. distantibus, foliis infimis sub- 
orbicularibus 1.2-1.6 cm. longis superioribus ovatis vel oblongis 1.5- 
2.5 cm. longis integris margine paulo revolutis basi rotundatis vel 
subcordatis apice rotundatis supra viridibus glabris pallide nervatis 
subtus pallidioribus et glandulis atrorubris punctatis; pedunculo 4.5-7 
em. longo; verticellis 3 remotis 2-floris; bracteis.ovatis obtuse acu- 
minatis glanduloso-setulosis 2-3 mm. longis; pedicellis 1-2 mm. 
longis ; calyce anthesi campanulato glanduloso-setuloso rubropunctato ἡ 
4-5 mm. longo, labio superiore obtuso 2-dentato nigrescenti 2 mm. 
longo, inferiore pallidiore lato brevissimo; corolla 17-18 mm. longa, 
tubo infundibuliforme leviter ventricosa 8 mm. vel ultra longo, galea 
breviter pubescenti 3-4 mm. longa, labio inferiore cyaneo albo-maculato 
1 cm. longo, lobo medio 12 mm. lato. — Wet grassy places in pine for- 
ests near Trinidad Iron Works, Hidalgo, Mexico, alt. 1770 m., July- 
August, 1904, C. G. Pringle, no. 8928 (type, in hb. Gray). Named for 
Filemon L. Lozano, for several seasons Mr. Pringle’s able field com- 
panion. A unique species, nearest related perhaps to S. villosa 
Fernald. 

Salvia (Candicantes) chionophylla Fernald, n. sp., fruticosa de- 
pressa ; ramis laxis gracilibus prostratis 3-6 dm. longis; cortice pallide 
brunneo pilis brevissimis crebris stellatis canescenti ; foliis elliptico- 
ovatis vel breviter oblongis integris vel obscure crenatis utroque angus- 
tatis 0.5-1.5 em. longis cinereis dense stellato-puberulis juventate 
canescentibus ; petiolis gracilibus 2-4 mm. longis; racemis 0.5-1 dm. 
longis ; verticellis 3-6-floris demum 2-2.5 cm. distantibus ;.pedicellis 


FERNALD. — NEW SPERMATOPHYTES FROM MEXICO. 65 


2-4 mm. longis ; calyce tubuloso-campanulato anthesi 6-7 fructifero 8- 
9 mm. longo valde costato, tubo lobis latis obtusis breviter acuminatis 
duplo longiore; corolla 1.5 em. longa, tubo paulo exserto ; galea azurea 
et alba pilosa 6 mm. longa a labio inferiore cyaneo superata. — On shelv- 
ing rocks and gravelly slopes of the cafion-wall, Chojo Grande, Coa- 
huila, Mexico, 29 August, 1904, μάτιν. Palmer, no 368 (type, in hb. 
Gray). Nearest related to the upright narrow-leaved S. thymocdes 
Benth., which has a glandular calyx. 

Salvia (Scorodoniae) chalarothyrsa ['ernald, n. sp., ramis gra- 
cilibus retrorse molliterque pilosis ; foliis cordato-ovatis acuminatis 
dentatis superioribus 2.5-4.5 cm. longis 2-3.5 cm. latis vix rugosis 
utrinque adpresse pubescentibus, pilis planis ; petiolis 0.5-1.5 em. longis 
dense pilosis ; inflorescentia cylindrica laxe thyrsoidea 1.5-6 dm. longa ; 
rhachi necnon pedunculis pedicellisque cum pilis mollibus patentibus 
glanduloso-capitulatis tectis ; cymis 3-10-floris usque ad 3-4 em. dis- 
tantibus, pedunculis 0.5-2 cm. longis ; bracteis lanceolatis vel lineari- 
bus tarde deciduis; calyce pedicellos aequante anguste campanulato 
anthesi 4 fructifero 5-6 mm. longo glanduloso-hirsuto, lobis alte del- 
toideis subaequalibus apice subulatis ; corolla cyanea 12-13 mm. longa, 
tubo pallido glanduloso-punctato paulo exserto, galea brevissima bre- 
viter pilosa, labio inferiore multo longiore, lobo intermedio magno 
emarginato 7-9 mm. lato. — Hills about 'luxpan, Jalisco, Mexico, alt. 
1220 m., 27 October, 1904, C. G. Pringle, no. 8856 (type, in hb. Gray). 
A remarkable species in its thyrsiform inflorescence, related only to 
S. thyrsijlora Benth., a species also from the Jalisco mountains, from 
Tepic to western Michoacan. 
γ΄ Salvia (Inflatae) muralis lernald, ἢ. sp., fruticosa 1-2 τη. alta; 

ramis gracilibus firmis subteretibus cinereo-puberulis ; foliis anguste 
ovatis 6-9.5 cm. longis 2-4.7 cm. latis remote crenato-dentatis obtuse 
acuminatis basi subcuneatis vel rotundatis supra pallide viridibus ad- 
presse setulosis subtus pallidioribus et glanduloso-punctatis dense 
albo-pilosis in costa media et in nervis principalibus ; petiolo gracili 
cinereo-puberulo 2-3 cm. longo ; ramis floriferis gracilibus brevibus ex 
axillis superioribus inferne foliatis ; floribus saepissime geminis ; pedi- 
cellis gracilibus 3-5 cm: longis ; calyce anthesi curvato tubiformi 1.5-2 
em. longo inferne constricto viridique superne patente expanso et 
rubro-tincto sparse piloso, lobis deltoideis 5 mm. longis ; corolla cinna- 
barina 4.5-6 cm. longa valde exserta pilosa tubulari-infundibuliformi, 
faucibus paulo gibbosis, galea pilosa 1.5-1.7 cm. longa labium inferius 
subaequante ; staminibus styloque exsertis illo piloso. — Hanging 
from fissures in limestone-cliffs, Iguala Cafion, Guerrero, Mexico, alt. 
762 m., 28 September, 1905, C. G. Pringle, no. 10,072 (type, in hb. 


XLII. — 5 


a 


66 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Gray). Nearly related to S. pubescens Benth., which has a shorter, 
broader, and more colored calyx, shorter corolla, and nearly or quite 
glabrous style. 

Salvia (Cyaneae) atrocaulis Fernald, n. sp., caulibus nigrescen- 
tibus vel purpurascentibus 1.8-2.4 m. altis basi 2-3 cm. crassis in par- 
tibus inferioribus glabris inflorescentiam versus puberulis ; foliis late 
cordato-ovatis utrinque viridibus supra sparse adpresso-setulosis et in 
nerviis puberulis subtus glabris sed glanduloso-punctatis regulariter 
dentato-serratis, limbo 7.5-15 em. longo 5-12 cm. lato apice caudato- 
acuminato ; petiolo 4-14 cm. longo ; inflorescentia racemosa 1.5-3 cm. 
vel ultra longa, rhachi puberula, verticellis 5-12-floris inter se denique 
2-2.5 em. disjunctis ; pedicellis puberulis anthesi 7 mm. fructiferis 
12 mm. longis; calyce anthesi 14 mm. fructifero 22 mm. longo glan- 
duloso-punctato, in nervis cum pilis caducis moniliformibus pubescent, 
lobis subulato-mucronatis deltoideis tubo anguste campanulato triplo 
brevioribus ; corolla 5 cm. longa violacea fere vel omnino glabra, tubo 
aliquid ventricoso labiis paulo longiore ; stylo barbato. — Wet banks, 
barranca below Trinidad Iron Works, Hidalgo, Mexico, alt. 1650 m., 
22 August, 1904, C. G. Pringle, no. 8887 (type, in hb. Gray). Near- 
est related to S. vecurva Benth., but differing in its dark stems, broader 
firmer leaves, less pubescent calyx, and essentially glabrous corolla. 

Salvia (Cyaneae) flaccidifolia Fernald, n. sp., verisimiliter fruti- 
cosa; ramis gracilibus superne decussatim bifariam pilosis ; foliis 
graciliter petiolatis ; petiolis supra pilosis inferioribus limbum super- 
antibus ; laminis ovatis cordatis caudato-attenuatis tenuissimis 3.5-9 
cm. longis crenato-serratis supra atroviridibus adpresse setulosis subtus 
pallide viridibus fere glabris in venis adpresse setulosis ; racemis 6-8 
em. longis, verticellis 6-8 remotis 3-6-floris ; bracteis ovatis aristatis 
caducis ; pedicellis 2-5 mm. longis puberulis ; calyce anthesi 5-6 mm. 
longis, labio superiore ovato aristato inferiore bilobo biaristato ; corolla 
2-2.3 em. longa cyaneo-purpurea, tubo valde ventricoso, labio superiore 
recto 1 cm. longo, inferiore longiore pendulo valde dilatato. — Barranca 
below Trinidad Iron Works, Hidalgo, Mexico, 1906, C. G. Pringle, 
no. 10,298 (type, in hb. Gray). Nearly related to S. recurva Benth., 
which it resembles in its very thin long-petioled leaves, but with much 
smaller calyx and corolla. 

Salvia (Tubiflorae) simulans Fernald, n. sp., caulibus glabris ; 
ramis erectis brevibus ; foliis ovatis abrupte acuminatis basi rotundatis 
vel rotundato-cuneatis regulariter dentato-serratis 0.5-1 dm. longis 
3.2-6.5 em. latis supra adpresse setulosis et resinoso-punctatis subtus 
glabris ; petiolis paulo pilosis 4-- em. longis gracilibus ; racemo prin- 
cipali 1.5 dm. longo ; rhachi glanduloso-pulverula ; verticellis 5-15-floris 


FERNALD. — NEW SPERMATOPHYTES FROM MEXICO. 67 


demum 2 cm. distantibus ; pedicellis gracilibus glanduloso-pruinosis 
1.5 usque ad 7 mm. longis; calyce purpureo-tincto tubiformi anthesi 
7-8 mm. fructifero 1 cm. longo, tubo basi valde costato pruinoso, fau- 
cibus paulo dilatatis levius costatis glabratis, labiis aristato-acuminatis 
3-4 mm. longis inferiore bifido recto superiore sursum curvato ; corolla 
rubro-purpurea 2.22.6 em. longa, tubo et faucibus anguste cylindricis 
sursum curvatis 1.5-1.7 em. longis 2-3 mm. diametro, labiis approxi- 
matis, galea dense pilosa labium inferius aequanti; stylo barbato. — 
Wet barranca below Trinidad Iron Works, Hidalgo, Mexico, alt. 
1680 m., 22 August, 1904, C. G. Pringle, no. 8927 (type, in hb. Gray). 
Strongly suggesting S. Martensii Gal., which, however, has the ventri- 
eose corolla-tube of the Cyaneae. From that species, S. s¢mulans, 
which has the cylindric corolla-tube of the Tubiflorae, is further dis- 
tinguished by its rounded-cuneate leaf-bases, and especially by the 
elongate galea. 

ν΄ Castilleja Conzattii Fernald, n. sp., suffruticosa; caulibus sim- 
plicibus erectis glanduloso-puberulis ; foliis linearibus vel lineari-lance- 
olatis 3-5-nerviis 2-7 cm. longis dense puberulis, inferioribus integris, 
superioribus pectinatis, laciniis linearibus patentibus ; bracteis oblongis 
1.5-2.5 em. longis, summis coccineis trifidis, lobis lateralibus linearibus 
vel spatulatis, intermedio majore anguste obovato integro vel obsolete 
trilobo ; pedicellis 1 mm. longis ; calyce mediam tantum corollam pau- 
lulo superante 1.5-1.8 cm. longo viridi et albo, antice et postice aequa- 
liter fisso, lobis oblongis subtruncatis 5-6 mm. longis; corolla viridi 
et rubella 2.2-2.5 em. longa, tubo 1.2-1.3 em. longo, galea elongata, 
labii lobis obtusis 1 mm. longis. —Sta. Ines del Monte, Zimatlan, 
Oaxaca, Mexico, alt. 820 m., 8-9 December, 1905, C. Conzatti, no. 1360 
(type, in hb. Gray). Nearest related, apparently, to the variable C. an- 
gustifolia (Nutt.) Don, of the northwestern United States, from which 
At differs chiefly in the broad middle lobe of the bracts. 

V  Ruellia (Ophthalmacanthus) Pringlei Fernald, n. sp., fruticosa ; 
ramis gracilibus flexuosis subteretibus glanduloso-villosis cinereis ; 
foliis ovatis 3-10 em. longis 1.5-4.3 cm. latis tenuibus utrinque mol- 
liter pubescentibus basi cuneatis apice longe attenuatis ; petiolis gra- 
cilibus sublanatis 1.5-3.5 em. longis; pedunculis 1.5-3 cm. longis 
cinereo-pubescentibus unifloris ; bracteis lineari-spatulatis acutis 2.5—-5 
cm. longis ; calyce 3-4 cm. longo, laciniis lineari-lanceolatis 2.3-3 cm. 
longis ciliatis ; corolla alba 7-8 cm. longa anguste infundibuliformi 
valde exserta, limbi 5-6 em. lati lobis breviter oblongis vel suborbicu- 
laribus retusis; capsula immatura angusta 2.5-3 cm. longa 7 mm. 
crassa glabra. — Hillsides, Balsas Station, Guerrero, Mexico, alt. 610 m., 
27 September, 1905, C. G. Pringle, no. 10,071 (type, in hb. Gray). 


68 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Apparently nearest /?. rosea (Nees) Hemsl., which is said, however, to 
have the obtuse leaves short-petioled, the stem angled, and the rose- 
eolored corolla 2 inches long. 

ν΄ Brwens rosea Sch. Bip., var. aequisquama Fernald, n. var., invo- 
lucri squamis subaequalibus, eis seriei exterioris elongatis 5-8 mm. 
longis. —Thickets near Uruapan, Michoacan, Mexico, alt. 1525 m., 
1 November, 1905, C. G. Pringle, no. 10,109 (type, in hb. Gray). 
Differing from 7. rosea in the very elongate segments of the outer in- 
volucre, which in the original description of the species is said to be 


shorter than the inner, and which in herbarium specimens measures 
2-4 mm. long. 


20. 


22. 


28. 


29. 


VOLUME 42. 

Rosson, B. L.—Studies in the Eupatorieae : (I.) Revision of the Genus Pigueria; (IT.) 
Revision of the Genus Ophryosporus ; (III.) The Genus Helogyne and its Synonyms; (1V.) 
Diagnoses and Synonymy of Hupatorieae and of Certain Other Compositae which have been 
Glassed with them. pp. 1-48. May, 1906. 50c. 

Saping, W. C. — Architectural Acoustics: (1.9) Introduction; (II.) The Accuracy of Musical 
Taste in regard to Architectural Acoustics ; (III.) Variation in Reverberation with Varia- 
tion in Pitch. pp. 49-84. June, 1906. 4506. 

Pemce, B. Ο. — On the Permeability and the Retentiveness of a Mass of Fine Iron Particles. 
pp. 85-91. June, 1906. 15c. 

Perce, B, 0. — On the Length of the Time of Contact in the Case of a Quick Tap on a Tele- 
graph Key. pp. 93-100. June, 1906. 160. 

Marx, Εἰ. L., and CoretanD, M.—Some Stages in the Spermatogenesis of the Honey Bee. 

pp. 101-111. 1 pl. June, 1906. 20c. ἷ 

Hose, J. L. --- Friction and Force due to Transpiration as Dependent on Pressure in Gases. 
pp. 113-146. July, 1906. 450. 

Pzirce, B. 0. —On the Conditions to be Satisfied if the Sums of the Corresponding Members 
of Two Pairs of Orthogonal Functions of Two Variables are to be Themselves Orthogonal. 
pp. 147-157, July, 1906. 160. 

Pemce, B. O. — On the Correction for the Effect of the Counter Electromotive Force induced 
in a Moving Coil Galvanometer when the Instrument is used Ballistically. pp. 159-169. 
July, 1906. 156. 

Perrce, B. 0. — A Simple Device for Measuring the Deflections of a Mirror Galvanometer. 
pp. 171-174. 1pl. July, 1906, 15c. 

Rippie, L. W. —On the Cytology of the Entomophthoraceae. pp. 175-197. 3 pls. August, 
1906. 40c. 

Baxter, G. P. — A Revision of the Atomic Weight of Bromine. pp. 199-214. August, 1906. 
25¢. 3 

LARRABEE, A. P. —The Optic Chiasma οἵ Teleosts: A Study of Inkeritance. pp. 215-231. 
October, 1906. 25c. : 


- Woop, R. W. — Fluorescence and Magnetic Rotation Spectra of Sodium Vapor, and their Analy- 


sis. pp. 233-260. 5 pls. November, 1906. 65c. 

Roton, A. L. — Results of the Franco-American Expedition to Explore the Atmosphere in the 
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Kenneiiy, A. E. — An Approximate Law of Fatigue in the Speeds of Racing Animals. 
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Coxe, L. J. — An Experimental Study of the Image-Forming Powers of Various Types of Eyes. 
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ΒΜΊΤΗ, A. W. — Expansion and Compressibility of Ether and of Alcohol in the Neighborhood 
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Conepon, E. D.—The Hydroids of Bermuda. ‘pp. 461-485. January, 1907. 406. 

Buackman, M. W. — The Spermatogenesis of the Myriapods. (V.) On the Spermatocytes of 

. Lithobius. pp. 487-518. 2 pls. February, 1907.. 50c. 

Moors, A. H. — Revision of the Genus Spilanthes. pp. 519-569. March, 1907. 60c. 

RicHarps, T. W., and Messrs. HENDERSON and Freyert. — Concerning the Adiabatic Deter- 
mination of the Heats of Combustion of Organic Substances, especially Sugar and Benzol. 
pp. 571-593. March, 1907. 35c. ; 

Hatt, E. H., and Messrs. CAMPBELL, SERVISS, and CuurcHitn. — On the Thomson Effect and 
the Temperature Coefficient of Thermal Conductivity in Soft Iron between 115° and 204° C. 
pp. 595-626. March, 1907. 40c. 

Mark, E. L. — An Electric Wax-Cutter for Use in Reconstructions. pp. 627-636. March, 117. 
20c. 


Henverson, L. J.— Concerning Position Isomerism and Heats of Combustion. pp. 637-647. 


March, 1907. 206. 

Loweti, P. — Temperature of Mars. .A Determination of the Solar Heat Received. pp. 649- 
667. March, 1907. 250. 

Avams, J. M. — The Transmission of Rontgen Rays through. Metallic Sheets. pp. 669-697. 
April, 1907. 45c. 

Kenney, A. E.— The Process of Building up the Voltage and Current in a Long Alternating- 
Current Circuit. pp. 699-715. May, 1907. 25c. 

Sanger, C. R., and Gisson, J. A. — The Determination of Small Amounts of Antimony by the 
Berzelius-Marsh Process. pp. 717-733. 1 pl. May, 1907. 89. 

Records of Meetings; Biographical Notices; Officers and Committees; List of Fellows and 
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(Continued on page 2 of Cover.) 


» Vol. 11. Parr. Centennial Celebration. 1880, pp: 1-104 1882. $2.00, 
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— Memoir of Sir Benjamin Thompson, Count Rumford, with Notices of 4 


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Proceedings of the American Academy of Arts and Sciences. 


Vou. XLIII. No. 3.— June, 1907. 


CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE 
MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD COLLEGE, 
E. 1. MARK, DIRECTOR, — No. 190. 


MATURATION STAGES IN THE SPERMATOGENESIS 
OF VESPA MACULATA L1yy. 


By E, L. MARK AND MANTON COPELAND. 


Saal Sh. 5 

* ° he δὰ ᾿ - iP he) ἡ». ot. a, a, >~ ᾿ τἂν 
> ar! Veh Ἢ ee Ἴἢ oe i. ae a γ ᾿ ᾿ 
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: (Continued from page 3 of Cover.) peeaae 


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VOLUME 43. 


1. Morse, H. W. — Studies on Fluorite: (IV.) The Kathodo-Luminescence of Fluorite. pp. 1-16. 
1lpl. June, 1907. 850. x « 

2. Greenman, J.M. —(L) New Species of Senecio and Schoenocaulon from Mexico ; (II ) Ronrxson, 
B. L. — New or otherwise Noteworthy Spermatophytes, chiefly from Mexico; (III.) Roni- 


son, B. L., and Barrett, H. H — New Plants from Gautemala and Mexico collected | 


chiefly by C. C. Deam; (IV.) Fernatp, M L. — Diagnoses of New Spermatophytes from 
ἶ : New Mexico pp. 17-68. June, 1907. 50c. 
a ‘: 3. Marx, E. L, and CorreLanp, M. — Maturation Stages in the Spermatogenesis of Vespa Macu- 
ANS lata Linn. pp. 69-74. June, 1907. 1δο, 
“sy ~ 
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Proceedings of the American Academy of Arts and Sciences. 


VoL. XLIII. No. 3.— JUNE, 1907. 


CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE 
MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD COLLEGE, 
E. L. MARK, DIRECTOR. —No. 190. 


MATURATION STAGES IN THE SPERMATOGENESIS 
OF VESPA MACULATA Lyn. 


LIBRARY 
NEW York 
BOTA Nic Al 


By E. L. MARK AND MANTON COPELAND. GARDEN. 


CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE 
MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD COLLEGE, 
E. L. MARK, DIRECTOR. — No. 190. 


MATURATION STAGES IN THE SPERMATOGENESIS OF 
VESPA MACULATA Livy. 


By E. L. MARK AND MANTON COPELAND. 


Received May 27, 1907. 


In a brief account of spermatogenesis in the honey bee, published 
four years ago, Meves (:03) showed that, contrary to the condition thus 
far observed in the animal kingdom generally, the maturation divisions 
of the primary spermatocytes resulted in the production of two ‘“ Rich- 
tungskérper ” and a single functional cell, instead of four functional 
spermatozoa. ‘The first of these two bodies was composed exclusively 
of cytoplasm ; the second, however, was nucleated. Our observations 
on the germinal cells of the honey bee published last year (Mark and 
Copeland, :06) confirmed in a general way those of Meves, differing 
from his, however, in numerous details. 

Meves states in a very few words in the paper cited that in the 
spermatogenesis of Vespa germanica the first maturation division re- 
sults, as in the honey bee, in the formation of a non-nucleated bud 
of cytoplasm, but that the second gives rise to two cells of equal size, 
both of which are metamorphosed into spermatozoa. 

Having been able to collect, prepare, and examine the male germinal 
cells of Vespa maculata Linn., we will set forth briefly in this paper 
some of our observations. 

At the end of the growth period following the last spermatogonial 
division, the cells (compare Figure 1) closely resemble those of the 
honey bee. The nucleus is relatively large, and the chromatin is for 
the most part aggregated into a single, somewhat irregularly shaped 
body, Lying against the cell membrane are the remnants of the inter- 

ἘΞ sonal filaments of the preceding cell division, which have become 
2 metamorphosed into a rather homogeneous mass, to which we have 
! given the name interzonal body (Figure 1, 2’). 


JUL 5 


ΤΩ PROCEEDINGS OF THE AMERICAN ACADEMY. 


As the spermatocyte enters the prophase of the first maturation 
division the centrosome, lying in contact with the cell membrane, 
divides, and the two daughter centrosomes move apart (Figure 1) 


Ficures 1-4. Primary spermatocytes. XX 
2800. 

Ficure 1. The two centrosomes moving 
apart; zx, interzonal body. 

Figure 2. Centrosomes at opposite poles 
of cell ; nucleus showing chromosomes ; prz., 
proximal centrosome; dst., distal centrosome. 

Ficure 8. First spindle figure with intra- 
nuclear spindle fibres. 

Ficure 4. Interzonal body at proximal 
pole, immediately before its abstriction ; 
spindle figure disappearing, and extranuclear 
fibres prominent. 


until they arrive at opposite 
poles of the cell (Figure 2). 
Although the centrosomes dur- 
ing their migration seem to 
influence to some degree the 
form of the cell, this modifica- 
tion in outline is not so promi- 
nent asin the honey bee. The 
nucleus continues to lie close 
to that one of the centro- 
somes which in the cells ot 
the honey bee we have desig- 
nated as the distal centrosome 
(Figure 2, dst.). 

The stages,immediately fol- 
lowing this correspond strik- 
ingly to those of the honey bee. 
The chromatin, after passing 
through a spireme condition, 
gives rise to chromosomes 
which lie scattered irregularly 
through the nucleus (Figure 
2). We have not as yet suc- 
ceeded in determining the 
exact number of the chromo- 
somes, but believe that it is 
not less than sixteen. ‘The 
nucleus now elongates, finally 
becoming more or less spindle 
shaped, but apparently fails 
to reach the proximal pole of 
the cell. Intranuclear spindle 
fibres staining in iron haema- 


toxylin have meanwhile made their appearance, extending from the 
chromosomes first to the distal centrosome, and later in the opposite 
direction, to a region near the proximal end of the nucleus, it being 
now difficult to determine the exact extent of the nuclear membrane. 
Thus the proximal ends of the spindle fibres often appear to converge to 
a point at some distance from the, corresponding centrosome (igure 


MARK AND COPELAND. — SPERMATOGENESIS OF VESPA MACULATA. 73 


3); unlike the corresponding stage in the honey bee, there seems to be 
no evidence that these fibres connect with the proximal centrosome ; 
however, numerous eatranuclear fibres extend from the distal centro- 


some in the direction of the proximal 
one. 

At this stage the interzonal body 
already lies near the proximal cen- 
trosome. 

The proximal end of the cell now 
elongates (Figure 4), and there is 
formed a small bud of cytoplasm 
containing the interzonal body and 
the proximal centrosome. ‘This bud 
remains for a time connected with the 
cell by a neck-like process of cyto- 
plasm, through which may be traced 
extranuclear fibres. This connecting 
process of cytoplasm becomes more 
and more attenuated until a complete 
detachment of the protoplasmic glob- 
ule is effected. 

This ‘ Richtungskérper”’ consists 
chiefly of the interzonal body, but in 
most cases the interzonal body is 
surrounded by more of the unmodi- 
fied cell protoplasm than exists in 
the corresponding globule of the honey 
bee. Like the latter, it contains no 
chromatin. 

We have good evidence to show 
that the proximal centrosome divides, 
and that the two daughter centro- 
somes, in some cases, at least, move 
apart around the periphery of the 
globule. This migration may begin 
before the protoplasmic bud has be- 
come completely separated from the 
parent cell. 


Ficures 5-8. Spermatocytes af- 
ter the abstriction of the interzonal 
body (i.e.,secondary spermatocytes) 
Χ 2800. 

Ficure 5. Spindle figure of sec- 
ond maturation division in the 
beginning of the metaphase. 

Ficure 6. Anaphase of second 
maturation division. 

Figure 7. Early telophase. 

Ficure 8. Latetelophase. Sper- 
matocyte nearly divided into two 
spermatids. 


During the period of the abstriction of the interzonal body and 
accompanying cytoplasm, which closely resembles that of the honey 
bee, the development of the spindle figure is arrested, as in the bee, 


not being carried beyond the beginning of the metaphase. 


It is diffi- 


14 PROCEEDINGS OF THE AMERICAN ACADEMY. 


cult to determine the fate of the chromosomes and spindle fibres at 
this time. ‘The former appear to be aggregated to a greater or less 
extent, and their individuality seems thereby to be obscured. 

After the formation of the non-nucleated “ Richtungskérper ” the 
chromatin is found to occupy the equator of the spindle, where it has 
regained the appearance of more or less distinct chromosomes. ‘Thus 
is formed a fairly characteristic spindle figure in the metaphase 
(Figure 5). Division of the chromosomes now takes place, and the 
daughter chromosomes migrate toward the poles of the spindle, leav- 
ing stretched between them interzonal filaments (Figure 6). As the 
cell enters on the telophase it elongates, and a constriction is then 
formed at the equator (Figure 7). The constricting process is con- 
tinued until the daughter cells remain connected to each other by only 
an attenuated neck of cytoplasm, through which can be traced the 
interzonal filaments. There result two spermatids, both apparently 
destined to become functional spermatozoa, for these cells, unlike the 
corresponding cells of the honey bee, are equal in size ; they are imme- 
diately metamorphosed into spermatozoa. 


BIBLIOGRAPHY 


Mark, ἘΠ. L., and Copeland, M. 
:06. Some Stages in the Spermatogenesis of the honey bee. Proc. Amer. 
Acad. Arts and Sci., Vol. 42, No. 5, pp. 103-111, 1 pl. 


Meves, EF 
:03. Ueber “ Richtungskorperbildung ’’? im Hoden von Hymenopteren. 
Anat. Anz., Bd. 24, pp. 29-82, 8 Fig. 


a 


af 
BAY {ἢ a ἮΝ 
bie Hh 


fy 
= 


‘ 


VOLUME 42. 


1. Rostnson, B. L.— Studies in the Eupatorieae: (I.) Revision of the Genus Piqueria; (IT.) 


Ss 


> 


Sh 


a 


16. 


22. 


23. 


24. 


Revision of the Genus Ophryosporus ; (III.) The Genus Helogyne and its Synonyms ; (IV.) 
Diagnoses and Synonymy of Hupatorieae and of Certain Other Compositae which have been 
Classed with them. pp. 1-48. May, 1906. 50c. 

Sapine, W. C. — Architectural Acoustics: (I.) Introduction; (II.) The Accuracy of Musical 
Taste in regard to Architectural Acoustics; (III.) Variation in Reverberation with Varia- 
tion in Pitch. pp. 49-84. June, 1906. 45c. 

Perrce, B. O. — On the Permeability and the Retentiveness of a Mass of Fine Iron Particles. 
pp. 85-91. June, 1906. 156.. 

Perce, B. O. — On the Length of the Time of Contact in the Guns of a Quick Tap on a Tele- 
graph Key. pp. 93-100. June, 1906. 1δο. 

Mark, Εἰ. L., and Coretanp, M.—Some Stages in the Spermatogenesis of the Honey Bee. 
pp. 101-111. 1pl. June, 1906. 20c. : 

Hoae, J. L. — Friction and Force due to Transpiration as Dependent on Pressure in Gases. 
pp. 113-146. July, 1906. 45c. 

Perrce, B. O. — On the Conditions to be Satisfied if the Sums of the Corresponding Members 
of Two Pairs of Orthogonal Functions of Two Variables are to be Themselves Orthogonal. 
pp. 147-157. July, 1906. 15c. 

Petce, B. O. — On the Correction for the Effect of the Counter Electromotive Force induced 
in a Moving Coil Galvanometer when the Instrument is used Ballistically. pp. 159-169. 

_ July, 1906. 156. 

Perce, B. 0. —A Simple Device for Measuring the Defiections of a Mirror Galvanometer. 
pp. 171-174. 1lpl. July, 1906. 15c. 

RippiE, L. W. —On the Cytology of the Entomophthoraceae. pp. 175-197. 3 pls. August, 
1906. 40c. 

Baxter, G. P. — A Revision of the Atomic Weight of Bromine. pp. 199-214. August, 1906. 
25c. 

LARRABEE, A. P. —The Optic Chiasma of Teleosts: A Study of Inheritance. pp. 215-231. 
October, 1906. 25c. 

Woop, R. W. — Fluorescence and Magnetic Rotation Spectra of Sodium Vapor, and their Analy- 
sis. pp. 233-260. 5 pls. November, 1906. 65c. 

ΒΟΤΟΗ, A. L. — Results of the Franco-American Expedition to Explore the Atmosphere in the 
Tropics. pp. 261-272. December, 1906. 20c. 

ΚΈΝΝΕΙΥ, A. E.— An Approximate Law of Fatigue in the Speeds of Racing Animals. 
pp. 273-331. December, 1906. $1.15. : 

Coxe, L. J. — An Experimental Study of the Image-Forming Powers of Various Types of Eyes. 
pp. 333-417. January, 1907. $1.10. 

ΒΜΊΤΗ, A. W. — Expansion and Compressibility of Ether and of Alcohol in the Neighborhood 
of their Boiling Points. pp. 419-460. January, 1907. 60c. 

Conavon, E. D.—The Hydroids of Bermuda. pp. 461-485. January, 1907. 40c. 

BiackMAn, M. W. — The Spermatogenesis of the Myriapods. (V.) On the Spermatocytes of 
Lithobius. pp. 487-518. 2pls. February, 1907. 50c. 

Moorr, A. H. — Revision of the Genus Spilanthes. pp. 519-569. March, 1907. 60c. 

Ricuarbs, T. W., and Messrs. HENDERSON and FREeveRT. — Concerning the Adiabatic Deter- 
mination of the Heats of Combustion of Organic Substances, especially Sugar and Benzol. 
pp. 671-593. March, 1907. 35c. 

HAut, E. H., and Messrs. CAMPBELL, SeRviss, and CHURCHILL. — On the Thomson Effect and 
the Temperature Coefficient of Thermal Conductivity in Soft Iron between 115° and 204° C 
pp. 595-626. March, 1907. 40c. : 

Marg, E. L. — An Electric Wax-Cutter for Use in Reconstructions. pp. 627-636. March, 1907. 
20c. 

HENDERSON, L. J. — Concerning Position Isomerism and Heats of Combustion. pp. 637-647. 
March, 1907. 20c. 


Ἵ 25. Lowet1, Ρ. -- Temperature of Mars. A Determination of the Solar Heat Received. pp. 649- 


26. 


27. 


28. 


29. 


667. March, 1907. 25c. 

Avams, J. M. —The Transmission of Réntgen Rays through Metallic Sheets. pp. 669-697. 
April, 1907. 45c. 

KeEnnewiy, A. E.— The Process of Building up the Voltage and Current in a Long Alternating- 
Current Circuit. pp. 699-715. May, 1907. 2c. 

Sanoer, C. R., and Greson, J. A. — The Determination of Small Amounts of Antimony by the 
Berzelius-Marsh Process. pp. 717-733. 1 pl. May, 1907. 30. 

Records of Meetings; Biographical Notices; Officers and Committees; List of Fellows and 
Foreign Honorary Members ; Statutes and Standing Votes, etc. 


(Continued on page 2 of Cover.) 


“Oe “wa ee ee 


ΠΟ PUBLICATIO: 


OF THE 


“AMERICAN ACADEMY OF ARTS AND SCIENCES. — 


MEMOIRS. Otp Series, Vols. 1-4; New Series, Vols. 1-12. 


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Vol. 11. Parr. Centennial Celebration. 1880. . 1-104. 1882. $2.00. “ 

Parr 2. No.1. ,Agassiz, A.— The Tortugas and Florida Reefs. pp. 105-134. 
12 pls. June, 1885. (Author’s copies, June, 1883.) $3.00. 

Part 3. Nos. 2-3. Searle, A.—'The Apparent Position of the Zodiacal Light. 
pp. 135-157 and Chandler, S,C.— On the Square Bar Micrometer. pp. 158-178. 
October, 1885. $1.00. 

Part 4. No. 4. Pickering, Εἰ. C.— Stellar Photography. pp. 179-226. 2 pls. 
March, 1886. $1.00. . 

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THE PHYSIOLOGICAL BASIS OF ILLUMINATION. 


By Lovis BELL. 


Presented April 10, 1907. Received May 28, 1907. 


THE purpose of this paper is to point out that with the existing 
knowledge of physiological optics artificial illumination can be removed 
from the domain of empiricism and can be made to rest upon constants 
which have a definite physiological basis and which can be and have 
been predetermined with reasonable precision. For obvious reasons 
data which relate to the sensation of sight cannot rank with exact 
physical measurements, but they can nevertheless be evaluated closely 
enough to give a reliable basis of judgment in planning illumination 
to meet any given requirements. 

Except for the aid received from accommodation and in binocular 
vision from convergence, we see things in virtue of their differences of 
color and of luminosity. Of these two the latter is by far the more 
important, particularly in distant vision. Objects of similar luminosity 
but differing considerably in color blend into the general view in a most 
astonishing fashion when at any considerable distance. Objects of sim- 
ilar color butof different luminosity also fuse into the general field, and 
if color and luminosity are both similar, things disappear in a way that 
is positively amazing. Small colored areas of moderate luminosity blend 
even at relatively short range, —a fact which the impressionists have 
turned to extremely good use, albeit they often transfer to canvas the 
color vagaries of the tired eye and the effects of simultaneous contrast 
rather than the fleeting impressions which they hold so precious. One 
of Monet’s landscapes, however, is wonderfully interesting from the 
standpoint of physiological optics, and especially in the existence of a 
critical distance, within which the picture loses its magic. 

Practically, therefore, vision depends very largely upon the power of 
distinguishing differences of luminosity. And since objects in general 
are luminous only in virtue of light reflected from them, their visibility 
depends in turn upon their coefficients of reflection. So far at least as 
problems of artificial illumination are concerned, objects seen do not 


78 PROCEEDINGS OF THE AMERICAN ACADEMY. 


range over a long scale of values of luminosity. Whatever the absolute 
values of the light reflected, the relative values expressed by the coeffi- 
cients of reflection range from about 0.80 to about .01, very few sub- 
stances returning more than the former or less than the latter percentage 
of the incident light. 

The fundamental fact at the basis of vision is that the eye can per- 
ceive, within a very wide range of absolute intensity, a substantially 
constant fractional difference of luminosity. This is the purport of 
Fechner’s law, and the fractional difference mentioned is well known 
as Fechner’s fraction. Its numerical value for normal eyes and ordinary - 
intensities of illumination is from .02 to .0055. The importance of this 
law in practical seeing is enormous, for in a room well lighted by diffuse 
daylight the illumination may vary from 100 meter-candles down to 10 
or 20 in different parts of the room or at different times; and if power 
of discriminating difference of luminosity changed much with the illu- 
mination, one would be purblind most of the time. In some abnormal 
eyes Fechner’s fraction, with vision otherwise normal, is considerably 
increased, with serious results. A case is cited by Krenchel in which 
a patient was unable to get about in full daylight without stumbling 
over things. His condition was most puzzling until a test showed 
Fechner’s fraction at a value of 0.1. At this value one could not dis- 
tinguish between dark and light shades of brown and gray, having 
coefficients of diffuse reflection of say .15 and .25 respectively, and 
ordinary shadows on neutral surfaces would therefore disappear en- 
tirely. With Fechner’s fraction at 0.5 no contrast less than that be- 
tween white and very dark pigments would be easily distinguished. 

Now while Fechner’s fraction is fairly constant over a wide range of 
intensities, one easily realizes that as twilight deepens his power of dis- 
criminating shades is seriously impaired. It is this variation of Fech- - 
ner’s fraction with the illumination which determines the minimum 
amount of artificial (or natural) light which is effective in enabling one 
to see things en masse in their natural relations. For general vision 
any illumination above that required to bring Fechner’s fraction for 
the normal eye up to its steady value is needless, and, as we shall pres- 
ently see, may be injurious. 

Human vision, however, is frequently concerned with the observation 
of fine details both far and near, and the power of seeing these is within 
wide limits independent of the capacity of the eye for distinguishing 
small differences of luminosity. In the case mentioned by Krenchel 
this v/swal acuity was normal in spite of the extraordinary lack of sen- 
sitiveness to variations of light and shade. Acuity seems to depend on 
the structure of the retina and the quality of the eye as an optical in- 


Lar 


BELL. — THE PHYSIOLOGICAL BASIS OF ILLUMINATION. 19 


strument rather than on the direct or secondary sensitiveness of the 
nerve endings to stimulation by light. Great acuity is possibly com- 
moner among savage peoples than in civilized races. Konig} has noted 
it among the Zulus, whose color vision, by the way, was normal ; it has 
been found in unusual degree among the Kalmucks, and Johnson ? noted 
it in the Congo peoples, in every case associated with slight hyperme- 
tropia. Some observations of Johnson (loc. cit.) would suggest that the 
extremely dark hue of the fundus oculi and consequent diminution of 
choroidal reflection found among the dark-skinned races may improve 
the definition, although perhaps at the expense of sensitiveness. It is 
of course well known that in the last resort the ability to separate 
objects like neighboring points and lines depends on the minute struc- 
ture of the retina, and is greatest in the fovea centralis, where the cones 
are most closely packed. The fovea too is well known to be somewhat 
less light sensitive than the retina in general. Using a wedge photom- 
eter, I find for my own eye that there is a difference somewhat exceed- 
ing one stellar magnitude between the foveal visibility and that outside. 

Following out this line of investigation, it is not difficult to project 
the fovea as a dull spot in the field of view. Using a wedge photometer 
and fixing the eye at any point on a large sheet of white paper, one 
finds, on rather quickly cutting down the light by sliding the wedge, a 
roundish dark spot exactly in the axis and corresponding in diameter 
with the projection of the fovea. It is not easy to hold vision of this 
phenomenon since the axis of the eye inevitably tends to wander. 

By drawing five rather faint crosses at the centre and corners of a 
square, say a decimeter on a side, one can, by careful manipulation of 
the wedge, make the central cross disappear in the foveal blind spot 
while the corner crosses remain visible. The facts regarding the 
independence of acuity and sensitiveness lend weight to the theory of 
our confrére Professor Lowell regarding the bearing of this matter on 
astronomical observations. Extreme acuity and extreme sensitiveness 
being both rather rare, any considerable degree of independence must 
render the coexistence of both in the same individual unusual in a very 
much higher degree. 

The failure of acuity in a dim light is familiar, and its variation with 
intensity affords an independent criterion of the necessary requirements 
in artificial illumination. Enough light must be provided to bring the 
eye to its normal acuity as well as to its normal value of Fechner’s 
fraction. Fortunately the researches of Dr. Uhthoff? and of Drs. 


1 Nature, 31, 476. 2 Phil. Trans., 194, B. 61. 
3 Graefe’s Arch., 32,171; 36, 33. 


80 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Kénig and Brodhun* on acuity and Fechner’s fraction respectively 
give us safe ground on which to travel in these respects. 

In Figure 1 are shown the acuity curves and the shade-perception 
curves of the normal eye for intensities up to 100 meter-candles. 
Curves a and ὁ give the values of Fechner’s fraction for white light and 
deep crimson light (A = 670 uj) respectively, while ὁ and d give the acu- 
ity curves for light orange (A605 pu) and yellowish green (A=575pp) 
= and in the latter 
case are in arbitrary units. ‘lhe most important feature of these curves 
for the purpose in hand is that they are already becoming asymptotic 
at low values of the illumination, and except for strong colors at about 


respectively. ‘The ordinates in the first case are 


Meter-candles 
Figure 1. 


the same point. At about 10 meter-candles they have turned well 
toward the axis, and beyond 20 meter-candles the gain in shade-percep- 
tion and acuity is very slow with further increase. Hence, when the 
light reaching the eye has risen to 10 to 20 meter-candles, further in- 
crease does very little in the way of assisting practical vision. 

Artificial illumination can be safely based on this amount as a work- 
ing intensity. Visual acuity is the controlling factor in most indoor 
lighting. It varies noticeably with color, but for practical reasons, 
which will appear later, the actual visibility of colored objects depends 
not on the differences here shown so much as upon their general light- 
reflecting power, which for dark hues is always low. 

At great intensities both shade-perception and visual acuity consider- 
ably decrease, the former at roughly 25,000 to 50,000 meter-candles, the 
latter at much lower intensity. Neither function is likely to fail at any 


4. Sitz. Akad., Berlin, 1888. 


BELL. — THE PHYSIOLOGICAL BASIS OF ILLUMINATION. 81 


intensity reached in the ordinary course of artificial lighting, though 
acuity may be seriously interfered with by dazzling and consequent 
rapid retinal exhaustion at intensities of a few hundred meter-candles, 
and the same secondary cause also impairs shade-perception long before 
its final decline. 

It must be clearly understood that in specifying 10 or 20 meter- 
candles as the intensity physiologically necessary to bring the eye into 
its normal working condition, these intensities are those which become 
visible to the eye, and not merely those that reach the objects under 
observation. 

The light reflected from any object is 74 where 7 is the incident 
illumination and ὦ the coefficient of reflection. Then, if is the 
normal illumination just indicated, the required incident illumina- 
tion is 

“ α 
f= i 

Taking, for example, α ΞΞ 1ὅ meter-candles, and assuming that one is 
observing white or very light colored backgrounds for which / would 
have a mean value in the vicinity of 0.6, the value of Z should be about 
25 meter-candles. If the background is dark fabric for which 4 would 
not exceed 0.2, 7 would rise to 75 meter-candles, and for black fabrics 
one could hardly get too much light. A typical application of the 
principle may be taken in a draughting room where tracing has to be 
done, and the drawing must be well seen through the tracing cloth. & 
for tracing cloth is about .35, and the illumination which makes the 
drawing visible is reflected from the drawing paper behind and passed 
back through the tracing cloth. The drawing paper probably reflects, 
if slightly off white, as is common, about 60 per cent of the incident 
light, and the final coefficient of the combination falls to about 0.25. 
Taking the same value of a as before, /=60 meter-candles. Ordinary 
draughting rooms are found to be well lighted at this intensity. It 
should be noted that draughtsmen generally use hard pencils, which 
make marks contrasting rather weakly with the paper, so that strong 
illumination is needed at all times. 

In illumination out of doors, as upon the street, where no weak con- 
trasts or fine details need to be made out, a may be taken very much 
lower, but ἢ is also low, and the minimum of about .25 or .30 meter- 
candle often allowed between lamps is, as the curves show, consider- 
ably too small for good seeing. 

Hiject of Pupillary Aperture. The iris serves as an automatic stop 
behind the cornea, adjusting itself so as to protect the retina from 
too violent changes of brilliancy. It may vary in diameter of aperture 


VOL, XLII. — 4 


82 PROCEEDINGS OF THE AMERICAN ACADEMY. 


from less than 1 mm. up to the full diameter of the visible iris, which 
in the darkness may retreat even within the rim of the cornea, as 
‘Du Bois-Reymond® has shown. The eye therefore works over an 
aperture range varying from £20 or more down to /2.5 or f2. Inci- 
dentally the iris, acting as a stop behind the strongly refracting cornea, 
produces a certain amount of typical “ pincushion distortion” which is 
evident in some optical illusions. 


“ Meter-candles 


Ficure 2. 


Data on the actual relation between intensity of incident light and 
pupillary aperture are scarce and imperfect. So much depends on the 
state of adaptation of the eye, individual sensitiveness, and probably 
also upon the intrinsic brightness of the source, that reliable values of 
the relation are difficult to obtain. From a reduction of Lambert’s 
data, however, I have plotted the curve of Figure 2, giving as abscissae 
the illumination in meter-candles and as ordinates the area of the 
pupil in square millimeters. The striking fact is at once in evidence 
that this curve, like those of Figure 1, is rapidly becoming asymptotic in 
the neighborbood of 10 meter-candles. In other words, the contraction 
and expansion of the iris is less to protect the eye at high intensities 


5 Centralbl. f. prakt. Augenheilkunde, 1888. 


BELL. — THE PHYSIOLOGICAL BASIS OF ILLUMINATION. 83 


than to strengthen the retinal image at low intensities, even at the 
expense of considerably impaired definition. The human eye seems, 
however, to have become specialized for considerable acuity in a mod- 
erate light rather than for such extreme sensitiveness as is found in 
many nocturnal animals whose pupillary apertures vary over a much 
wider range than in man. 

The curves of Figure 1 show simple retinal sensitiveness, and in 
reckoning from them one must at low illuminations take account of 
the gain from increased aperture. At ordinary working values of the 
illumination the gain is small, but at 1 or 2 meter-candles it is very 
material and plays a most important part in practical vision. For 
example, by curve a, Figure 1, an illumination of 0.5 meter-candle would 
imply a value of Fechner’s fraction of about 0.2, which would in turn 
imply very much impaired shade-perception. In point of fact, one 
can see quite tolerably by a candle at the equivalent distance of 1.4 
meters. 

For if the pupil has adjusted itself to this situation the virtual 
illumination is that corresponding to about 2 meter-candles, the equiv- 
alent area of the pupil having increased to at least four times its ordi- 
nary value, which is that to which the curves of Figure 1 pertain. 
The result is a value of 0.1 or less for Fechner’s fraction, which is 
quite another matter. 

Were it not for this assistance, it would be quite impossible to get 
accurate photometric readings at the low intensities common upon the 
photometer screen. Similarly it would be exceeding difficult to get 
about at night, even by moonlight. In this latitude moonlight near 
full moon may fall to about 0.2 meter-candle, which would give Fech- 
ner’s fraction at nearly .5, barring aid from the iris. With this aid 
increasing the aperture perhaps 6 times, one can see to get about very 
easily and can even read very large print. ‘The same conditions have 
an important bearing on vision in presence of a strong radiant. For 
example, suppose that in a general illumination of 1 meter-candle one can 
make out objects having a contrast = = .15. Then let a light giving 
20 meter-candles come fairly into the field of vision without materially 
illuminating these objects. The pupil will close to about one third its 
former area, giving a virtual illumination of about 0.3 meter-candles 
and a shade-perception of about .30, in which, of course, the objects 
disappear. Hence one cannot see well across a bright light, and even 
objects illuminated by it lose in visibility unless the change in illumi- 
nation from them is greater than the concomitant change in aperture 
ratio. 


84 PROCEEDINGS OF THE AMERICAN ACADEMY. 


The loss in visibility by the presence of a brilliant radiant in the 
field of view is increased by the change in adaptation of the eye. It 
is also probable that the intrinsic brilliancy of the radiant, as well as 
the light received from it, has a bearing on the pupillary aperture. 
Certainly at equal illuminations a well-shaded lamp gives higher visi- 
bility than a bare one, both being assumed to be in the field of view. 
There is therefore every reason for keeping such things as bare gas 
lights and electric lamps entirely out of the visual field, only admitting 
them thereto when they are so shaded as to keep the intrinsic brilliancy 
to low limits. 

The eye has been evolved under conditions that imply rather 
moderate intrinsic brilliancy, admitting the general desire to keep the 
direct rays of the sun out of one’s eyes. Sky light, of course, varies 
very widely in apparent intensity, being most intense in the presence 
of white cloud of moderate density. An average all the year round 
mean for the northern part of the United States, giving the intrinsic 
brilliancy of an aperture fully exposed to the upper sky, would be from 
measurements by Dr. Basquin,® in the neighborhood of 0.4 candle power 
per square centimeter. ‘This is lower than the intrinsic brilliancy of any 
flame, and approximates that of a bright lamp behind a thin opal shade. 
The ordinary window, which is in a wall rather than the roof, and gets 
its light largely from low altitudes and somewhat reduced by trees or 
buildings, is much less brilliant. 

For instance, a window 1 m. wide and 2 m. high would be unusually 
effective if it gave 50 meter-candles at a point 5 m. within the room. 
This illumination would imply a virtual intensity of about 1250 candles 
at the window or an intrinsic brilliancy over the window area of 0.0625 
candle power per square centimeter. Natural intrinsic brilliancies are 
decidedly low, and the chief difference between natural and artificial 
illumination, from the standpoint of wear and tear upon the visual 
organs, is the high intrinsic brilliancy of artificial light. If radiants are 
to be within the field of vision, they should be screened by diffusing 
globes or shades down to a maximum intrinsic brilliancy of preferably 
not above 0.1 or 0.2 candle power per square centimeter, certainly 
not above double these figures. As I. have pointed out in a former 
paper,” if one plots the pupillary apertures as ordinates and the 


function — as abscissae, the result is nearly a straight line, so 


that if one measures the visual usefulness w of a certain illumination 


8 The Illuminating Engineer, Jan., 1907. 
7 Trans. Ill. Eng. Soc., July, 1906. 


BELL. — THE PHYSIOLOGICAL BASIS OF ILLUMINATION. 85 


1 in terms of what one may call the admittance of the pupil, then 
approximately 


w=c VI, 


assuming that J is within ordinary ranges of intensity ; that is, the eye 
works most efficiently at moderate illumination. The adverse factors in 
lowering the illumination are the optical errors introduced by increase 
of pupillary aperture and the general failure of shade-perception and 
acuity as the illumination falls below about 10 meter-candles. Spheri- 
cal aberration and astigmatism increase rapidly at large apertures, so 
that definition of objects is much impaired. This doubtless plays its 
part in the failure of acuity in very poor light, although a more promi- 
nent fact is the increase of acuity as the eye is stopped down at illu- 
minations considerably above the critical value at which the eye comes 
into normal working condition. 

This critical value to which shade-perception, acuity, and pupillary 
reaction all point relates, it must be remembered, to the illumination 
received from the objects viewed considered as secondary light-sources. 
In too strong light thus received the eye is as seriously dazzled as if 
the source were a primary one, and the usual effects of after images 
and other evidences of retinal exhaustion and irritation at once appear. 
In very insufficient illumination there is failure to see contrast and 
detail, and there is an instinctive effort to push the eye near to the 
object at the risk of straining the mechanism of accommodation se- 
riously. The familiar success of this expedient opens up some of the 
most curious questions of physiological optics. 

Suppose, for instance, that one is viewing white letters on a dark 
ground. Evidently the letter acts as a secondary source of illumina- 
tion, which proceeds from it, following the law of inverse squares. Now 
by halving the distance to the eye the intensity at the pupil is quad- 
rupled, and at first thought one would infer that inspection of the 
shade-perception and acuity curves would give ample reason for the 
gain in visibility. But at half the distance the object subtends double 
the visual angle, and the retinal image is therefore quadrupled in area, 
leaving the luminous energy per unit of area the same as before ; why, 
therefore, any gain in visibility? A similar question in a more aggra- 
vated form arises in accounting for improved vision through night 
glasses. 

The key to the situation is found in the fact, put on a sound experi- 
mental basis by Dr. Charpentier,® that for the visible brightness of 


8 “Ta Lumiere et les couleurs,” p. 188 et seq. 


86 PROCEEDINGS OF THE AMERICAN ACADEMY. 


objects giving images less than about 0.15 mm. in diameter the simple 
law of inverse squares holds. In other words, for weak stimuli at least, 
the visibility of small objects is determined by the total light emitted 
and by the distance and not by the surface brilliancy. It is as if 
a retinal area of about 0.15 mm. diameter acted as a visual unit, all 
stimuli acting upon this as a whole. As Charpentier (loc. cit.) puts 
the case with reference to distance, “In a word, the apparent brightness 
of a luminous object varies, other things being equal and within the 
limits indicated, in inverse ratio with the square of its distance from 
the eye.” 

As the eye then approaches a luminous object its apparent brightness _ 
increases, and it is distinguished more plainly so long as its image di- 
mension is anywhere within the limit mentioned. As this corresponds 
to an object 2 mm. long at a distance of about 20 cm., the rule holds 
for reading type and the observation of small objects generally. ‘The 
cause of this phenomenon is somewhat obscure. The natural suppo- 
sition that it might well be due to spherical aberration and faulty 
accommodation in an eye with its pupil expanded, fails, as Charpentier 
(loc. cit.) shows, in two ways. First, the circle of diffusion in the eye 
due to spherical aberration is much smaller than the critical diameter 
in this case, and second, the phenomenon occurs when the eye is stopped 
by a diaphragm. I have tried it with a wedge photometer provided 
with a pair of 2 mm. apertures in line and separated by 6 mm., so 
that the ray pencil was of very narrow aperture, and find it still very 
conspicuous and apparently unchanged. 

Charpentier and others are disposed to think its origin purely retinal, 
resulting from the spreading of the stimulus over retinal elements ad- 
jacent to those immediately concerned, and closely allied to the phe- 
nomenon of irradiation. 

This latter phenomenon, however, is charged by Helmholtz largely to 
aberrations and dioptric faults generally. One of the best sources for 
studying irradiation is an incandescent lamp filament. At a distance 
of say 2 meters the apparent diameter of the filament at full incandes- 
cence is 4 or 5 mm. Using the wedge photometer upon it, the diminu- 
tion of apparent diameter is at first rapid, until it falls to about 0.5 
mm., at which it remains nearly constant until it completely vanishes. 
Stopping down the pencil of rays to 1 mm. or so cuts off most of the 
irradiation, but this seems to act in the main merely as a reduction of 
intensity, since the same effect is produced by a similar reduction in 
intensity by the wedge retaining the full aperture of about 5mm. At 
a few hundredths of a meter-candle most of the irradiation has disap- 
peared. The apparent breadth of the filament decreases without any 


BELL. —- THE. PHYSIOLOGICAL BASIS OF ILLUMINATION. ST 


marked shading off at the edges, something as if a slit were being 
closed. The appearances indicate that beside the undoubted aberra- 
tions which come into play, there is considerable spreading of light in 
the retina at high intensities, reinforced very likely by reflection from 
the choroid, producing an effect quite analogous to the halation observed 
in a photographic plate. i 

The dimensions of the irradiation effect thus observed are inferior to 
‘the dimensions required by Charpentier, but it is quite probable that 
with a dark-adapted eye and feeble illumination, lessened contrast with 
the chief image would render the outlying portions more conspicuous. 

The increased visibility of rather large areas is a still more puzzling 
matter, for which no satisfactory explanation has been produced. Inas- 
much as all dealings like these with threshold sensibility have by this 
condition eliminated the cones of the retina from action, and depend 
upon rod vision entirely, it may be, since the rods are relatively more 
numerous away from the fovea, that mere size of image insures its 
falling on retinal areas relatively rich in active visual elements. 

Aside from questions of intensity in artificial illumination is the 
matter of steadiness. It is of course well known that violent transi- 
tions of light and darkness, whether by moving the person or the eye, 
or by changing the intensity of the light itself, are distressing and 
injurious. The retina has a certain amount of visual inertia, which 
furnishes protection against very rapid changes, else one could not use 
lights successfully with alternating current. Flicker, from a practical 
standpoint, is troublesome about in direct proportion to its magnitude 
and in inverse proportion to its frequency. A change of intensity, how- 
ever, covering some seconds, giving the iris plenty of time for readjust- 
ment, is hardly noticeable, while one of the same numerical magnitude, 
say 20 per cent each side of the mean, occurring once or a few times 
per second, is most painful. Ordinary incandescent lamps run on alter- 
nating current vary from 5 to 15 per cent on each side of the mean, 
according to the thermal inertia of the filament, and the frequency. 
With lamps of ordinary voltage and candle power the flickering is per- 
ceptible at between 20 and 30 cycles per second, the new high-efficiency 
lamps being worse than the older ones. Practically all lighting is 
done at above 80 ~, and troublesome flickering comes only from the 
irregular fluctuations of bad service. It must not be forgotten that one 
can impress serious fluctuations of light on the retina by compelling the 
eye to confront great variations of illumination when it moves. No 
artificial light should be arranged so that it forces the eye to make 
sudden transitions from blackness to brilliancy. Figure 3 is given here 
as a horrible example of what should never be permitted. I am sorry 


838 PROCEEDINGS OF THE AMERICAN ACADEMY. 


to say that it is from the catalogue of a maker of reflectors who should 
have known better. Note the blackness of the interior and the exces- 
sive brilliancy of the light on the work. 

In this connection should be mentioned the trouble that may come 
from the glare of light reflected from white paper, a risk to which book- 
keepers are especially subject. I havé been in counting rooms where 
I found every clerk with signs of bad eyes. 

Much paper is too highly calendered, and from this cause gives a 
combination of regular and diffuse reflection. Obviously a mirror 
placed on one’s desk would give at certain angles an image of the lamp 


FIGURE 3. 


of distressing brilliancy, and as the head might move this image would 
dodge into and out of the field of vision, giving an added cause of 
trouble. Glossy paper does somewhat the same thing. Figure 4 shows 
from Trotter’s data® the relative reflection at various angles of inci- 
dence from ordinary Bristol board (a) and from the nearly pure matte 
surface of freshly set plaster of Paris (4). The sharp peak corresponding 
to the angle of regular reflection is very striking. Light on a desk 
should therefore come from the side or rear rather than from the front, 
especially if the source is of high intrinsic brilliancy. For a similar 
reason the direction of illumination should be such as to free the eye 
from the effect of wavering shadows of the hand or head. The avoid- 
ance of shadow from the hand is the rationale of the sound old rule 


9 The Illuminating Engineer, 1, 488. 


BELL. — THE PHYSIOLOGICAL BASIS OF ILLUMINATION. 89 


that the light should come from the left (left-handed people were 
forgotten). Shadows from the head and shoulders are much more 
troublesome, as they may exist to an-annoying degree in rooms other- 


By 
: i 
a 
14 


12 


Kelative Intensities 


me ENS 
Rane 


10 20 30 40 50 60 70 80 90 


Angles of Incidence 


FIGuRE 4. 


wise well lighted, and they are in fact difficult to avoid in the general 
lighting of counting rooms and similar places. 

Finally, one is nowadays often confronted by questions of color. 
Until electric lighting in its more recent forms appeared there was a 
sufficient similarity in the colors of artificial illuminants to place them 
substantially on a parity. At present, strong colors are common, and 


90 PROCEEDINGS OF THE AMERICAN ACADEMY. 


are likely to be increasingly so, since, as I have noted in a previous 
paper (loc. cit.), selective radiation is necessary to high luminous effi- 
ciency. One has to deal with the yellow of the flaming arc, the yel- 
lowish green of the Welsbach, the blue green of the mercury tube, and 
the violet of the enclosed are, all of which may have to be compared 
with the deep orange of the Hefner lamp. 

Practically the question of suitable color resolves itself into two parts, 
— first, the effect of color on the proper functioning of the visual appa- 
ratus, and second, its relation to our observation of colored objects. I _ 
shall not take up here the theories of color vision, save to note that 
many of their difficulties may now be charged to the existence of at least 
two kinds of independent visual elements, the rods and cones, differently 
distributed in the retina, and possessing two radically different types of 
visual sensitiveness. ‘That the cones are highly evolved rods has been 
shown beyond much doubt by Cajal, and is in evidence in the simple rod 
structure found in the parietal eyes of some fishes and lizards and in 
lower organisms generally. Whether, as Mrs. Franklin 10 surmised, there 
are definite intermediate phases of sensitiveness between the achromatic 
vision of the rods and the full chromatic vision of the cones is an 
important topic for research. 

May I venture to suggest that there are some reasons for thinking 
that there may even be a difference in kind between a simple photo- 
chemical rod stimulation and the strongly selective stimulation of the 
highly specialized cones? Selective activity does not necessarily con- 
note chemical instability. 'They may coexist, as in some organic dye- 
stuffs, or may be entirely independent, as in the fluorescence of heavy 
paraffin oils. The presence of strong pigmentation at the rods and its 
absence at the cones, coupled with the absence of visual purple in some 
nocturnal creatures whose eyes are presumably specialized for very weak 
light, suggests that the evolution of the retinal elements may have pro- 
ceeded along more than one line. In fact, the Young-Helmholtz and 
Hering doctrines may find in a heterogeneous retina a certain amount 
of common ground. Be this as it may, mankind certainly has super- 
imposed a very sensitive but achromatic rod vision, and a much less 
sensitive but chromatic cone vision, the latter being mainly central 
and the former mainly peripheral. The passage from predominant rod 
vision to predominant cone vision is shown in the sharp flexure of 
the curves in Figure 1. The exact point at which the color sensitive 
cones begin to get into action undoubtedly varies greatly in different 
eyes, and in the same eye in different conditions of adaptation. As the 


10 Mind, N. S., 2, 473 et seq. 


BELL. — THE PHYSIOLOGICAL BASIS OF ILLUMINATION. 91 


illumination is progressively diminished, color vision gets more and more 
imperfect and uncertain, especially toward the red end of the spectrum. 
The effect is shown very clearly in the variation of Fechner’s fraction 


with color as the intensity changes. Figure 5 shows the change in = 


with A for intensities of 15 meter-candles (a) and 0.75 meter-candles 
(0) respectively from the data obtained by Konig and Brodhun (loc. 


Ficure 5 


cit.). Looking at the latter, it is evident that for the orange and red, 
vision must be very poor indeed, and in no part of the spectrum really 
good. In curve a color vision is pretty well established, although there 
are still traces of the point of inflection, which, as we shall presently see, 
falls near the point of maximum sensitiveness in very weak light, as if 
the superimposed rod vision were still helping out at this moderate 
intensity. 

The Purkinje phenomenon, now well known to depend on the pro- 
gressive failure of cone vision, also gives valuable evidence along the 
same line. It was noticed more than twenty years ago by Professor 


92 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Stokes11 that the phenomenon varied with the areas involved, and 
recently Dow 22 has found that for small areas (7. 6., nearly central and 
hence mainly pure cone vision) Purkinje’s phenomenon appears only 
below about 0.2 meter-candle. This figure would quite certainly have 
been somewhat higher had he used instead of red and signal-green 
glass the primary red and green, but it is clear from his results that 
the superposition of rod vision has a very considerable effect at moder- 
ate illuminations. 

Finally, one must consider the luminosity curves at various intensities. 
Figure 6 gives in curve a the relative luminosities of the spectrum 
colors at fairly high intensity. 'The maximum is in the yellow, and the 
falling off, especially on the red side, is very rapid. ‘This seems to be 
about the normal curve when the eye is fully in action. Curve ᾧ gives 
the luminosity curve for an intensity of about 0.0007 meter-candle. 
At this point color sensation is practically extinguished, and the maxi- 
mum luminosity is perceptible, in what would seem the pure green were 
the light brighter, very near the E line and at a point corresponding 
to the inflection in the curves of Figure 5. ‘This is practically the con- 
dition of pure rod vision. Curve ὁ, Figure 6, lends confirmatory evidence. 
It is the luminosity curve obtained by Abney 1% from a patient with pure 
monochromatic vision. He had apparently an absolute central scotoma 
(cones atrophied rather than replaced by rods ?), visual acuity greatly 
subnormal (central vision absent), and nyctalopia. This is a typical 
condition, nyctalopia being generally associated with central color sco- 
toma, leaving peripheral vision but slightly affected (Fick). The patient 
apparently had no color perception, and his luminosity curve was prac- 
tically identical with ὁ, the normal curve for very weak light. 

It would be most interesting to get proper tests for luminosity in one 
of the rare cases of congenital hemeralopia which would present the 
reverse condition of rods inactive and cones nearly normal. A com- 
parison of such a case with luminosity in the hemeralopia associated 
with retinitis pigmentosa, in which peripheral vision is progressively 
contracted, might give valuable evidence as to the existence of retinal 
elements intermediate in function between rods and cones. 

To sum up this phase of the matter, rod vision seems to be predomi- 
nant from the very threshold illumination up to several tenths of a 
meter-candle, and to continue in force to all ordinary intensities, although 
rather easily exhausted. It gives low visual acuity and shade-percep- 
tion perhaps of the order of a tenth normal, but, such as it is, it is our 


11 Nature, 32, 537. 12 Phil. Mag., Aug., 1906. 
18 Proc. Roy. Soc., 66, 179. 


ὅν... 


BELL. — THE PHYSIOLOGICAL BASIS OF ILLUMINATION. 


93 


Cone vision begins to come perceptibly into 
play at a few thousandths of a meter-candle, and at a few tenths is 


main nocturnal reliance. 


FicureE 6. 


pretty well established, but does not become normal over the visual area 


below five or ten meter-candles, and gains materially even beyond that, 
especially in acuity, which is weak at the lower intensities. 


94 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Acuity in practical degree is chiefly an attribute of cone vision. The 
general theory of optical resolution requires acuity inversely as the 
wave-length of the light concerned. In practice this difference is in 
great measure masked by other and larger causes of variation. Chief 
among these is the very low luminosity of the shorter wave-lengths on 
the one hand and of the very long ones on the other. For example, in 
comparing acuity at A= 500 μμ and A= 650 uy there is a proportional 
difference really due to color, but a ratio of 2.5: 1 in luminosity in fur- 
ther favor of the green. Violet light favors acuity, if one can get 
enough of it, but a luminosity of .02 of the maximum in the yellow 
stands in the way. 

Certain strongly colored lights, like the flaming calcium fluoride are 
and the mercury are, give apparently extremely sharp definition in black 
and white objects. In general this is not due to any advantage in color 
as such, but to improvement in the conditions of chromatic aberration 
in the eye. At rest for distant vision, the normal eye is in focus for the 
rays of maximum luminosity, and the focus for blue lies perhaps 0.4 mm. 
in front of the retina. That is, the eye is short-sighted for short rays. 
In near vision the rear conjugate focus moves backwards and the eye 
finds focus on the blue with less accommodation than usual. Thus 
Dow 14 finds that, while the mercury arc gives easy and sharp definition 
for near vision, at a distance of twenty feet or even less it becomes 
difficult to get focus. Lord Rayleigh 15 noticed some years ago that in 
very weak light he became myopic and required a glass of —1 diopter to 
restore normal vision. This effect is of the order of magnitude required 
by the shift of maximum luminosity into the green at very low intensi- 
ties. Another phase of chromatic aberration is even more important. 
Were it not for the existence of a very high maximum in the luminosity 
curve, distinct vision would be impossible, since the difference of focus 
between the red and violet in the eye is something like 0.6 mm. ; and 
were these extreme colors highly luminous, there would be no focal sur- 
face to which the eye could adjust itself. Only the great predominance 
of the central colors in luminosity gives the chance for a fairly sharp 
image. 

It is easy to show the difficulties into which equal luminosity 
throughout the spectrum would plunge us. If one forms a grid of cer- 
tain purples by cutting strips of tissue paper of the required color per- 
haps 5 mm. wide and 100 mm. long and pasting them upon a dark 
neutral background spaced about their width apart, one readily finds 


14 The Illuminating Engineer, 2, 26 et seq. 
15 Nature, 31, 340. 


BELL. —- THE PHYSIOLOGICAL BASIS OF ILLUMINATION. 95 


the practical effect of chromatic aberration. From a distance of a 
couple of meters sharp definition of the grid is quite impossible. The 
purple chosen should give considerable absorption of the green, yellow, 
and orange, leaving strong red and blue evenly balanced in luminosity, 
and the background should be of not greatly different luminosity, so 
that the eye must rely mainly upon color effects. The rays from the 
grid are then of two widely different colors, for which the focal length of 
the eye differs. There are therefore two image surfaces of about equal 
intensity perhaps half a millimeter apart, and the effect is a curious 
blur, the eye hunting in vain for something definite upon which to focus. 

Interposing now a deep red screen (concentrated saffronine is good), 
or a suitable blue screen, the image of the grid becomes nearly mono- 
chromatic and appears sharply defined. This is an extreme case, but 
any monochromatic light has an advantage in definition if other con- 
ditions are at all favorable. It seems highly probable that the well- 
known trouble found at twilight in trying to work by a mixture of 
natural and artificial light is due to a similar cause. The predominant 
hue of diffused sky light is strongly blue, while that of gas flames, incan- 
descent lamps, and like sources, is strongly yellowish. At a certain 
point in the fading of daylight the luminosities of these widely different 
colors should balance closely enough to produce something of the effect 
just described, although the usual difference of direction in the two su- 
Be iposed illuminations may play a part in the general unpleasant 
effect. 

There is, however, an inherent danger in using monochromatic or 
strongly colored light for general purposes. Whatever may be the 
nature of color vision, a strongly colored light utilizes only a part 
of the visual apparatus. If of high intensity to make up for inherently 
low luminosity, it rapidly exhausts that part, and produces, as is well 
known, a temporary color blindness. There is at least a serious chance 
that long continued use of colored light would produce persistent and 
perhaps permanent damage to color perception. A light nearly white, 
with its maximum luminosity near the normal wave-length, runs the 
least chance of imposing abnormal strains on the visual apparatus. 

In color discrimination the same rule holds good, for any considerable 
departure from white leads to entirely false color-values. In closing I 
may mention an interesting question which arises with reference to 
obtaining a light of high efficiency by building it up from the mono- 
chromatic primary components. Would the eye see clearly by such a 
light, and could it discriminate colors properly ?- The answer is prob- 
ably yes. The equation for white is roughly 


W = .20R + .20 G+ .50 8. 


96 PROCEEDINGS OF THE AMERICAN ACADEMY. 


These are quantities as determined by slit width in the spectrum or 
a like process. ‘here is sufficient predominance of luminosity in the 
green to avoid trouble from chromatic aberration, and the actual work- — 
ing of the combination in giving photographs in natural colors is such — 
as to indicate proper color vision. As yet, however, no means are avail- — 
able for producing all three primary colors efficiently, and for white arti- — 
ficial light we are compelled to rely on what is in effect building up a — 
nearly continuous spectrum from heterogeneous components, unless as 
usual we employ the continuous spectrum of an incandescent solid. 


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HARVARD UNIVERSITY. 


ON THE DETERMINATION OF THE MAGNETIC BEHAVIOR 
OF THE FINELY DIVIDED CORE OF AN ELECTRO- 
MAGNET WHILE A STEADY CURRENT IS BEING 
ESTABLISHED IN THE EXCITING COIL. 


By B. Oseoop PEIRCE. 


Presented December 12, 1906. Received June 22, 1907. 


More than fifty years ago Helmholtz established, on theoretical 
grounds, the now familiar equations for the manner of growth of a 
current in a circuit of constant inductance under a given electromotive 
force, and proved by a brilliant series of experiments! that the 
predictions of this theory were fulfilled in practice. It appeared, 
in particular, that if a circuit of resistance 7 containing a constant 
electromotive force, /, were closed at the origin of time, the current, 
I, would be given by the expression 


=¢ = eat) (1) 


if Z were the “potential of the circuit upon itself,” that is, the self- 
inductance. The “induced current” (1) would satisfy the equation 


Gar tapes) ORR 
= —- — = — - L, 2 
Sa eae (as (2) 
If, therefore, Z were plotted against the time, the resulting curve 
(OGQKC, Figure 1) would have as asymptote the straight line (ZC) 
parallel to the ¢ axis at a distance H/r above it; the current in 
the circuit at any time (OP) would be given by the corresponding 


1 F. E. Neumann, Abh. d. Berl. Akad. 1845 and 1847; Helmholtz, Die Erhalt- 
ung der Kraft, 1847; Pogg. Ann., 83, 1851; 91, 1854; Phil. Mag., 42, 1871. 


100 PROCEEDINGS OF THE AMERICAN ACADEMY. 


ordinate (PQ) of the curve and the instantaneous value of the induced 
current by the distance (VQ) at that time, of the curve from the 
asymptote. ‘The whole “amount” of the induced current up to 
the given time would be represented by the shaded area (A) shut 
in by the curve, the asymptote, and the ordinates, ὁ = 0, ¢= OP. If 
the electromotive force were suddenly shunted out of the circuit 
after the current had reached its final value, the “extra current” 
would have the value 


chy τ (3) 


Helmholtz also studied the “forms” of the currents induced in the 
secondary circuit of a small induction coil at the making and breaking 
of the primary circuit, and, by using in the apparatus iron cores, some of 
which were solid and some finely divided, he showed that the effect 
of eddy currents in the iron upon the apparent duration of the induced 
currents might be very appreciable. ‘The results of Helmholtz’s 
experiments were confirmed with the aid of other apparatus, during 
the next thirty years,? by a number of physicists. 

The mathematical treatment of the subject begun by Neumann and 
Helmholtz was in 1854 pushed somewhat farther by Koosen, and in 
1862 E. du Bois-Reymond 8 published an elaborate discussion of the 
equations laid down by Helmholtz for the determination of the cur- 
rents in two neighboring circuits of constant self-inductances (Z;, .1..) 
and constant mutual inductance (J/), and gave the solutions of the 
simultaneous equations 


Th: -- + M.— = 3 7 th Ξε δι, 
dl. al, ) 
M. a = Be PE ae + rel, = Fr, 


corresponding to a number of different sets of physical conditions, 
in nearly the forms in which they now appear in textbooks. Du 


2 Felici, Ann. de Chimie, 34, 1852; N. Cimento, 3, 1856; 9, 1859; 12, 1874; 
13, 1875. Cazin, Compt. Rend., 60, 1865; Ann. de Chimie, 17, 1869. Guillemin, 
Compt. Rend., 50, 1860. Bertin, Mem. de la Soc. des Se. Nat. Strasbourg, 6, 
1865. Bazzi and Corbianchi, N. Cimento, 4, 1878. Bartolli, Mem. ἃ. Acc. d. 
Lincei, 6, 1882. Bazzi, Att. ἃ. Acc. ἃ. Lincei, 6, 1882. Lemstrém, Pogg. Ann., 
147, 1872. V. Ettingshausen, Pogg. Ann., 159, 1876. 

3 Koosen, Pogg. Ann., 91, 1854. E. du Bois-Reymond, Monatsberichte d. Berl. 
Akad., 1861, 1862. Brillouin, These, 1880; Jour. de Phys., 10, 1881; Compt- 
Rend., 1882. 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 101 


Bois-Reymond showed that if the secondary circuit contained no 
battery, and if, after the primary current had been fully established, 
its circuit were suddenly broken, the current induced in the secondary 
circuit would have a form like that of the dotted curve (?) in Fig- 
ure 2; if after a few seconds the primary circuit were again closed, 
the secondary current when plotted against the time would yield 
a curve either like Q or like S in the same diagram. ‘The lines in 
this familiar figure have been drawn to scale for a certain pair of 
circuits the self-inductances of which are equal, fixed quantities 
and the resistances also fixed. @, Δὲ, S correspond to three different 
values of the mutual inductance (J/), which are respectively half 
as great, nine tenths as great, and equal to the self-imductance (1) 


WITT 
7; (a ω 
Ci el δὲ τὰ 


SSRs 
εο.:-" 


FIGURE 1. 


NWN 


WAY 


5 TIME 


If the current is expressed in absolute units (absamperes) and the time in 
seconds, the shaded area represents the change in the total flux of magnetic 
induction through the circuit, during the time OP. 


of either circuit. These curves show the currents induced in the 
secondary circuit when the primary is made; the crest of any such 
curve comes earlier the larger the value of JZ. The curve P, which 
represents a current induced in the secondary circuit when the 
primary circuit is broken, is drawn for the case 77 =4Z, and there- 
fore corresponds to the curve Q@; E. du Bois-Reymond called atten- 
tion to the fact that in such problems as this the areas V and W 
must be equal. The curves like P corresponding to # and S could 
be found merely by exaggerating all the ordinates of P in the ratio 
9/5 or the ratio 2. 

From the early days of induction coils, iron cores had been used 
to increase the mutual inductance of the circuits, and, soon after 
Helmholtz had given the equations for the currents in neighboring 


102 PROCEEDINGS OF THE AMERICAN ACADEMY 


circuits of constant inductances, coils containing iron were studied 
from the point of view of the principles which he had laid down. 
Helmholtz’s own experiments and those of others soon showed, 
however, that the introduction of masses of magnetic metal into the 
space within the coils complicated very much their action. It ap- 


CURRENT. 


Ficure 2. 


The curves Q, R, S represent for different relative values of the mutual in- 
ductance the current induced in the secondary circuit of a certain induction 
coil without iron, when the primary circuit is suddenly closed. 


peared that the existence of eddy currents in the iron, if the coil were 
solid, and the fact that the counter electromotive force in a circuit — 
as measured by the time rate of change of the flux of magnetic indue- 
tion through it—is by no means proportional to the rate of change 
of the intensity of the current if a circuit “contains iron,” made the 
simple theory of Helmholtz inapplicable, as he himself had foreseen 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 103 


that it would be. The subject interested many investigators,* who 
found it easy to exhibit the disturbing effects of eddy currents in 
hindering rapid magnetic changes in solid masses of iron and in 
thus modifying the characters of the induced currents ; but it was not 
until much work had been done by many persons on the phenomena 
attending magnetic induction in iron that the theory of the alternate 
current transformer which had meanwhile come to be of much 
practical importance was very well understood. With the general 
introduction of dynamo-electric machinery the magnetic behavior of 
the different kinds of iron used in its manufacture became of practical 
interest, and several different magnetometric and ballistic methods of 
studying permeability were invented and employed in making the 
necessary measurements upon relatively small pieces of the metal. 
Soon after the first hysteresis diagrams had been obtained as a 
result of experiments either on comparatively thin iron or steel rings, 
or on long, fine wires, it was found by engineers that, on account 
of the considerable time required to establish a steady current in 
the coil of a large electromagnet to which a given electromotive force 
had been applied, the ‘reversed current,” and even the “step- 
by-step ” ballistic methods which had proved effective in the cases 
of slender toroids, were, in their old forms at least, not well fitted 
for studying the magnetic properties of such massive closed iron 
circuits as frequently occurred in practice. When there was a 
gap in such a circuit, the problem, of course, offered no difficulty, 


* Faraday, Researches, 1831, 1832, 1846. Lenz, Pogg. Ann., 31, 1854. Henry, 
American Journal of Science, 1832; Phil. Mag., 16, 1840. Dove, Pogg. Ann., 43, 
1888; 54, 1841; 56, 1842. Beetz, Pogg. Ann., 102, 1857 ; 105, 1858. Pliicker, 
Pogg. Ann., 87, 52; 94, 1855. Rayleigh, Phil. Mag., 38, 1869; 39, 1870; 23, 
1887; 22, 1886. Bichat, Ann. de l’Ecole Norm., 10, 1873. Sinsteden, Pogg. 
Ann., 92, 1854. Magnus, Pogg. Ann., 38, 1836; 48, 1859. Schneebeli, Bull. de 
la Soc. des Se. Nat. de Neufchatel, 11, 1877. Blaserna, Giornn. di Sc. Nat., 6, 
1870. Maxwell, Electricity and Magnetism, 2,iv. Donati and Poloni, N. Cimento, 
13,1875. Stoletow, Phil. Mag., 45, 1873. Auerbach, Wied. Ann., 5, 1878. Row- 
land, Phil. Mag., 46, 1873; 48, 1874. Thomson, Phil. Trans., 165, 1875. J. 
Hopkinson, Phil. Trans., 176, 1885. Von Waltenhofen, Pogg. Ann., 120, 1863. 
Warburg, Wied. Ann.,13,1881. Wiedemann, Lehre von der Elektricitat. Ewing, 
Phil. Trans., 176, 1885; Proc. Roy. Soc., 1882, Magnetic Induction in Iron and 
other Metals. Du Bois, The Magnetic Circuit. Fleming, The Alternate Current 
Transformer. Ewing and Low, Proc. Royal Soc., 42, 1887; Phil. Trans., 180, 
1889. Du Bois, Phil. Mag., 1890. Oberbeck, Wied. Ann., 22, 1884. J. and E. 
Hopkinson, Phil. Trans.,177, 1886. Jouaust, Compt. Rend., 139, 1904. E. Hop- 
kinson, Brit. Assoc. Report, 1887. Tanakadaté, Phil. Mag., 1889. Wilson, Proc. 
Royal Soc., 62, 1898. Baily, Phil. Trans., 187, 1896. Many other references 
may be found in these sources. 


104 PROCEEDINGS OF THE AMERICAN ACADEMY. 


but when large iron frames were completely closed, it became the 
custom, in satisfying commercial contracts, to attempt to get informa- 
tion about the permeability of the metal as a whole from tests, under 
given conditions, upon small, thin specimen pieces made as nearly as 
possible of the same material as the original, or else cut from it. It 
was usually impossible, however, to be sure that the temper of the 
small piece was sufficiently like that of the mass to make it a fair 
representative of the whole, and the preparation of the specimens was 
often troublesome, so that some more practical method of procedure 
was seen to be desirable,5 and it seems to have occurred to a number 
of different persons independently that a good deal might be learned 
about the magnetic properties of the core of an electromagnet if 
one determined the manner of growth of a current in an exciting 
coil of a given number of turns wound closely about the core, when, 
under given initial conditions, a constant, known, electromotive force 
was applied to the coil circuit. 


THe DETERMINATION OF SOME OF THE MAGNETIC PROPERTIES OF 
THE CORE OF AN ELECTROMAGNET FROM THE MARCH OF A 
CURRENT IN THE ExcITING (ὉΠ. 


If, at any instant, the total flux of magnetic induction through the 
n turns of the exciting coil of an electromagnet is V (maxwells), if r 
is the resistance of the coil circuit (in ohms), 7 the current in it (in 
amperes), and / the applied electromotive force (in volts), then 


1 dN : 
if ae (5) 
or Ξ- =r (4 - ὴ ; (6) 


and if the final value (#/7r) of the current be denoted by 7,, and the 
change in V during the time interval ἐς to t. by Vi, 


fy 
Δι. = 7-108: 1 (ἢ — ὃ dt. (7) 
4 


If, now, 7 be plotted against the time in a curve s (Figure 3) in 
which ὦ centimeters parallel to the axis of abscissas represent one 
second, and an ordinate m centimeters long one ampere, the curve 


5 Drysdale, Jour. Inst. Elec. Engineers, 31, 1901. 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 105 


will have an asymptote, CY, parallel to the axis of abscissas, at a dis- 
tance, AC, from it corresponding to #/r amperes, and, if OA’ represents 
the time 4, and OL the time t:, the area PGDC, or Ai», expressed 
in square centimeters, is equal to 


to 
lin ᾿ (i,, — ὃ dt, (8) 
ty 


_ 7-108- Are 10°-H- 41. 


so that Ni ye, Tee (9) 


In practice NV usually differs from »¢, where ¢ is the induction flux 
through the iron core of the electromagnet alone, by only a small frac- 
tion of itself, and, if α is the area of the cross section of the core at 
any point, a certain average value of B, the induction, can be obtained 
from the expression V/na, though in such cores as are used in large 
transformers, 17, and therefore 2, would probably have very different 
values at different points of the section. Really J is greater than n@ 
by the amount of the magnetic flux, in the air about the core, through 
the turns of the exciting coil, caused by the current in the coil itself 
or by neighboring currents, if there are such. 

Using this theory, a good many persons have studied at various times 
the magnetic properties of different large masses of iron, and in 1893 
Professor Thomas Gray of Terre Haute published in the Philosophical 
Transactions of the Royal Society a long series of very beautiful 
current curves,® obtained, with simple apparatus handled with great 
skill, from a 40 K. W. transformer belonging to the Rose Polytechnic 
Institute. A number of diagrams? showing the manner of growth of 
currents in the exciting coils of large electromagnets with solid cores 
have been printed within the last dozen years; of these the curves 
given by Dr. W. M. Thornton are especially interesting. 


If to the coil of an electromagnet, in series with a rheostat of 
resistance 7, a given electromotive force be applied, and if r be then 
reduced by steps, at intervals so long that one is sure that the final 
current belonging to each stage has been practically attained, the 
curve which has elapsed times for abscissas and the corresponding 


6 T. Gray, Phil. Trans., 184, 1893. 

7 Hopkinson and Wilson, Journal of the Institute of Electrical Engincers, 24, 
1895. Thornton, Electrical Enginecr, 29, 1902; Phil. Mag., 8, 1904; Electrician, 
1903 Peirce, These Proceedings, 41, 1906. Several figures from this last paper 
are here reproduced. 


106 PROCEEDINGS OF THE AMERICAN ACADEMY. 


values of the strength of the current for ordinates, will have the 
general form of the line {7 in Figure 4, though, if the core be so large 
that the building up time at each stage is long, the diagram will be 
much drawn out horizontally. The curve which shows the march of 
the current when the electromotive force is applied directly to the coil 
without the intervention of the rheostat will resemble line V in the 
same figure. ‘The exact forms of these curves depend, of course, upon 


τις. 
ΝΕ ΠΝ 
GRE ΑΕ: Ἐς 
Ὄπ 


γα τὸ. 
i τ 


SECONDS. 


FIGure ὃ. 


If / centimeters parallel to the horizontal axis represent one second, and an 
ordinate m centimeters long one ampere, A-10°8-7//m (where A is the area, 
in square centimeters, of CDGF) represents the change in the magnetic flux 
through the circuit during the interval AL. 


the magnetic state of the core at the outset, and will be very different 
if the iron has been thoroughly demagnetized before the observation 
is made, or if it be strongly magnetized. Figure 5, which illustrates 
this fact for some V curves, records some measurements made upon a 
15 K.W. transformer (/) belonging to the Lawrence Scientific School. 
In the case represented by each line the core was previously magne- 
tized in one direction with the full strength of the current, and the 
circuit was then broken and left open for a few seconds. With the 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 107 


electromotive force in it unchanged in intensity, but in some instances 
changed in direction, the circuit was then closed again and a current 
curve obtained. If the electromotive force has its old direction, such a 
curve is said to be “direct” ; if the new direction is the opposite of the 
old, the curve is called “reverse.” In one case the magnetic journey 
of the core during the rise of the current is represented approximately 
by the portion P/M of the corresponding hysteresis diagram (Figure 6) ; 
in the other case the journey follows the are QUZM. Lines 1, 2, 
and 4 in Figure 5 are reverse lines, while 3 and 5 are direct. 

In Figure 4 the line OY corresponds to the final value (7,,) of the 
current, and if its length in centimeters is m ἦς and if A is the area in 
square centimeters shut in by OY, YX, and J, it is evident that in the 


F 


Ficure 4. 


Curves which represent the growth of the current in the exciting coil of an 
electromagnet when (77), the circuit which has the resistance r, is closed and 
left to itself; and when (U), the circuit, is closed when it has a comparatively 
large resistance, which is then reduced to r by steps. 


case represented by V the whole change in induction flux through the 
turns of the coil due to the current is 


105... Α 
ON aa 


In the case represented by the line 77, (10°. #/7) times the sum of the 
terms formed by dividing each of the small shaded areas by the ordi- 
nate, expressed in centimeters, of its upper straight boundary, gives 
the change in the induction flux through the turns of the coil due to 
the current when it grows in the manner indicated. Of course if the 


108 PROCEEDINGS OF THE AMERICAN ACADEMY. 


current is not allowed time to attain its final value at each stage, a 
serious error may be introduced. 


340 turns: 


Ficure 5. 


, and the applied electromotive force was adjusted so as to make 


es, 1.50 amperes, and 0.75 amperes. 


Oscillograph records of direct and reverse curves for the magnet R taken with an exciting coil of 


the resistance of the circuit was kept constant 
the final values of the current 3.00 amper 


‘S3yu3dWY ο 


The amount of flux which, in a given large mass of iron, in a given 
magnetic condition at the outset, corresponds to a current of given final 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 109 


strength in the exciting coil, usually depends in some slight degree upon 
the manner of growth of the current. If after a large core has been 
magnetized in one direction by the steady application of a given elec- 
tromotive force until the current has reached its full value, the excit- 
ing circuit be broken, and, after the direction of the electromotive force 
has been reversed, closed again, 
it sometimes happens that the 
magnetic flux after the new cur- 
rent has attained its maximum 
value is slightly less when the 
current follows the course of 
the curve V than when it grows 
by short stages in the manner 
indicated by the curve UV. If, 
however, there are but two or 
three steps, the difference is, as 
a rule, of no practical. impor- 
tance, and if one has a suitable 
oscillograph or other recording 
instrument, it is possible to get 
a set of current curves for any 
given maximum value of the 
current from which an extremely 
good statical hysteresis diagram 
may be obtained for the core. 
If while a steady current from 
a constant storage battery of 
voltage Μ΄ is passing through Ficure 6. 
the coil of an electromagnet, the When a direct current curve is taken, 
resistance of the coil circuit be the core of the electromagnet makes a 
suddenly increased to a new I aeiraaise ἀπε: at tate τ με Η 
value 71) so that the current (ὃ τὸς δὲ μας Πρ τὰ τς Ἰσὴ τὴ aha ae 
will ultimately fall to a lower gu zur. 
value represented by ON in 
Figure 7, the current curve, which has been a horizontal line, sinks in 
such a manner as to become asymptotic to the horizontal line VB. At 
any instant after the change, 


aN 
if} — ΤΠ ΞΞ γιῖ, (0) 


in absolute units, so that in volts, ohms, amperes, and maxwells, 


110 PROCEEDINGS OF THE AMERICAN ACADEMY. 
aft fy 
Nya = 10° { (B= ri) dt = 10%-ry: (ἡ — ὃ dt. (11) 
ty 5 


If an abscissa 7 centimeters long corresponds to one second, and an 
ordinate m centimeters represents one ampere, and if Ao, stands for 
the area in square centimeters bounded by the current curve, the 
asymptote, and ordinates corresponding to the times fo, #1, the change 
in the flux of magnetic induction through the circuit during this time- 
interval is (in maxwells) 


108 - 7, “Agr 
lm 


(12) 


If, after a current has been built up by stages in the coil of an 
electromagnet, in the manner indicated by curve {7 of Figure 4, the 


Ficure 7. 


The shaded area represents on a certain scale the change in the flux of mag- 
netic induction through a circuit when the resistance of the circuit is suddenly 
increased and then kept constant. 


process be reversed, and the resistance of the circuit be increased by 
steps, the current curve will look very much as the curve {7 would if 
looked at from the wrong side of the paper when upside down. 

As has already been stated, it is possible to get slightly different 
hysteresis diagrams for a massive core originally demagnetized, when 
the current is made to change from a given positive limit to the 
negative limit in different ways ; and it is important, in predicting the 
behavior of a magnet which is to be used for a given purpose, to 
employ in computation the hysteresis diagram which corresponds to 
the particular magnetic journey which the core will take in practice. 
A single carefully made curve of the U type with a dozen steps will, 
however, give a result good enough for any commercial purpose, though 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 111 


my own experience shows that it is not always easy to measure all the 
small areas, especially the lower ones, with the desirable accuracy, 
when the width (OY) of the whole diagram is only 12 or 14 
centimeters. 

If in the U diagram there is only one intermediate stage, and if the 
core is in a given magnetic condition at the outset, the change in the 
magnetic flux, due to a current of given final value, ought not to differ 
by more than perhaps a fraction of one per cent from the correspond- 
ing change when there is no intermediate step and the case is rep- 
resented by V. Sometimes a series of U diagrams, each with but one 


N 
S SOIT 


S6LL, 


Ficure 8. 


The areas between the asymptote and the curves Z and P are proportional to 
the changes of magnetic flux through the circuit caused by direct and reverse 
currents of the same final strength. 


intermediate step, at a place determined by a proper choice of 7, may 
be made to yield very accurate information about the permeability of 
the large mass of metal which will suit some special use of the magnet. 

Figure 8, which resembles in general design some diagrams given by 
Dr. Thornton, shows a “ direct curve” (7) and a “reverse curve ” (P) 
for a certain magnet. The area ΟΖ. Y represents the change of 
magnetic induction when the core covers the are P/M (Figure 6) on 
the hysteresis diagram belonging to the journey ; the area OPQ.XY Y 
represents the change of magnetic flux when the core takes the 
journey corresponding to the are QUZM on the hysteresis diagram. 
The doubly shaded area represents the flux change corresponding to 
the line QUZMKP. 


112 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Tue Uses or Exptortnc Comms wouND UPON THE CORE OF AN 
ELECTROMAGNET. 


If an electromagnet, in addition to its exciting coil, has another 
wound about its core, and if the observer has means of obtaining the 
intensity (7’) of the current induced in this secondary coil, for given 
current changes in the exciting coil, as a function of the time, it is 
easy to study the magnetic properties of the core under the circum- 
stances of the experiment. Let there be z’ turns in the secondary coil, 
let the resistance of its circuit be 7’ ohms, and let WV’ be the total in- 
duction flux, in maxwells, through the turns of the coil at the time ¢, 
then if 7’ is measured in amperes 


dN’ 
dt 


= — 10°-7/- 7’, (13) 


If 7’ be plotted against the time in a curve in which 1} centimeters 
parallel to the axis of abscissas represent one second and an ordinate 
m' centimeters long one ampere, and if A‘; represents the area 
between the curve, the axis of abscissas and the ordinates correspond- 
ing to the time 4, and ¢., we have in absolute value, 


to 8 / / 

ῃ τ * 10 : = A 3 
Ni -- NY Ξ 108! [αι = mre = 7: A's,» (14) 
4 


where 7 is a known constant. 

When the primary current (7) in the exciting coil is growing, the 
current in the secondary coil has a direction opposite to that of 7, and 
it is often desirable to emphasize this fact in a diagram by drawing 
the 7, ¢ and 7’, ¢ curves on opposite sides of the axis of abscissas ; but if 
the relative values of 7 and 7 are alone to be considered, it is some- 
times more convenient to disregard their relative directions. If in any 
case the current in the exciting coil of an electromagnet be made to 
grow in the manner indicated by curve {7 in Figure 4, the 7’, ¢ diagram 
will consist (Figure 9) of a set of detached areas on the ¢ axis. The 
sum of any number of these areas when multiplied by 105 γ᾽ 1} m' n! 
gives approximately the whole change in the induction flux through 
the core up to the corresponding time, from the outset. In the “step- 
by-step” ballistic method of determining the permeability of a closed 
ring of rather small cross section the areas represented by the shaded 
portions of Figure 9 are determined by discharging the induced | 
current through a calibrated ballistic galvanometer of long period, and 
assuming that the first elongations of the suspended system measure 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 113 


these areas directly. As will appear in the sequel, it is possible, 
though not very easy, to get good results in this way, even if the 
cross-section of the laminated core is as great as, say, 800 square 
centimeters ; for this, however, a properly constructed galvanometer is 
required. 

The “time constant” of a circuit in which a current of given final 
intensity is to be established is shorter the higher the electromotive 
force used to generate the current ; it is desirable, therefore, to employ 
a battery of rather high voltage and to reduce the current by non- 
inductively wound resistance in series with the exciting coil of the 
electromagnet. Ifa moving coil galvanometer is used, it is often neces- 
sary to correct for the effect of the counter electromotive force induced 
in the coil as it swings in the field of its own permanent magnet, and 


©, CURRENT, 


_TIME. 


FIcure 9. 


A portion of the record of an oscillograph in the circuit of a secondary coil 
wound on the core of an electromagnet when the current in the exciting coil is 
made to change by sudden steps in the determination of a hysteresis cycle. 


it is always necessary to use steps so short and to make the period of 
the galvanometer so long (perhaps 300 or 500 seconds) that the practical 
duration of the induced current may be small in comparison. It is usual 
to send the current to the exciting coil by means of a commutator and 
a long series of manganine resistance coils capable of carrying the de- 
sired currents ; these coils are often mounted in a frame furnished 
with some device by which any or all of them can be shunted out of the 
circuit at pleasure. ‘T'wo rheostats, made for this purpose some years 
ago by the Simplex Electric Company, have been found by the staff of 
the Jefferson Physical Laboratory very satisfactory in practice. By 
means of such a set of coils as those just described, one may easily get 
either a progressive, step-by-step increase or decrease in the current, 
or a reiteration of any particular step. One convenient way of arrang- 
ing the apparatus for the repetition at pleasure of any desired step 
has been recently described by A. H. Taylor.8 The method of rever- 


8 A. Hoyt Taylor, Phys. Rev., 23, 1906. Mordey and Hansard, Elect. En- 
gineer, 34, 1904. Searle and Bedford, Phil. Trans., 198, 1902. Drysdale, Jour. 
Inst. Elect. Engineers, 31,1901. Lamb and Walker, Electrical Review, 48, 1901. 


VOL. XLill. — 8 


114 PROCEEDINGS OF THE AMERICAN ACADEMY. 


sals is usually unsatisfactory with large cores. A set of adjustable 
electrolytic resistances fitted for carrying heavy currents is often 
useful. 

In the case of a very large closed electromagnet, even if the core be 
laminated, it is extremely difficult to get very useful results by aid of 
a ballistic galvanometer of short period, but if one has a suitable oscil- 
lograph or other recording instrument at hand, it is easy to obtain a 
diagram something like that shown in part in Figure 9, though it is 
necessary to make sure that the intervals between the steps, unlike 
those in this figure, are long enough to record the whole of each in- 
duced current. 

If the primary current (7, ¢) curves are to be used in studying the 
magnetic changes in the core of an electromagnet, the sensitiveness of 
the oscillograph must be so adjusted that the deflection due to the 
largest value of the current ({7, Figure 4) will make a record on the 
paper ; if the (’’, ¢) curves are to be used, the steps may be as numer- 
ous as one likes, and the sensitiveness of the recording instrument may 
be so great that, starting from the base line, the record of the highest 
induced current shall just fall on the drum. In this latter case the 
areas to be measured may be made so large that any uncertainty as to 
the exact time when any induced current may be considered to end is 
unimportant. When many records are taken on the same paper, the 
drum has an opportunity to revolve a good many times during the 
operation, and it is not always easy to decipher the complicated maze 
of curves. Of course the fact that an electromagnet has a closed secon- 
dary circuit modifies somewhat the form of the building-up curve in the 
primary, but, theoretically at least, this should not affect the value of 
the magnetic flux due to the primary current if its final intensity is 
given, and the difference is inappreciable if there are only a few turns 
in the secondary coil. 

Instead of changing the resistance in the primary circuit suddenly, 
at each step, Dr. Thornton, in dealing with the frames of some very 
large dynamos, made each step gradually, by moving an electrode 
slowly in a trough of acidulated water from one stopping place to 
another. Figure 10 is a close copy of one of his records published in 
the “ Philosophical Magazine” for 1904. 


FLUXMETERS AND QUANTOMETERS. 


Given an amperemeter of the ordinary d’Arsonval type, in which an 
open-frame, low resistance, unshunted coil swings in the strong mag- 
netic field between an interior soft iron core and the hollowed-out jaws 
of a powerful magnet, it is often possible to make the controlling 


Veg 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 115 


springs so weak that if the coil circuit be suddenly closed on itself 
while the coil is in motion, the damping effects of the induced currents 
will bring the coil almost instantly to rest wherever it may happen to 
be, and, until the circuit is broken, the coil will keep its position fairly 
well. Several years ago Dr. R. Beattie 9 showed that if the ends of a 
low resistance exploring coil (A) be electrically connected with an in- 
strument of this kind, and if the flux of magnetic induction through A 
be changed during the time interval 7 by an amount JN, the coil will 
move from its initial position to a new position through an angle pro- 
portional to V and, apart from pivot friction, practically independent, 
within wide limits, of 7’ 


Ficure 10. 


Typical record for half a hysteresis loop, given by Dr. Thornton. 


The “ quantometer’”’ first made by Dr. Beattie had a coil of twenty- 
four and a half turns wound on a metal frame and suspended on a single 
needle point between the poles of an electromagnet ; the ends of the coil 
dipped into mercury cups fixed to the case of the instrument. In the 
kind of fluxmeter now common, the coil is hung by a silk fibre (or a 
quartz thread) from a spring, so as to avoid pivot friction ; a permanent 
magnet is used, and the current is led into and out of the coil through 
helices of very fine silver or copper gimp ; the resistance of this gimp 
is sometimes much greater than that of the coil itself, and for laboratory 
use it is often well to employ mercury cups, as Dr. Beattie did, so ar- 
ranged as to minimize the disturbing effects of capillarity. The original 
quantometer had a resistance of only one ohm. 

Many persons who have attempted to use very strong electromagnetic 
fields in d’Arsonval galvanometers have found that it is very difficult 


9 R. Beattie, Electrician, Dec., 1902. 


116 PROCEEDINGS OF THE AMERICAN ACADEMY. 


to procure insulated copper or silver wire for the suspended coil so free 
from paramagnetic properties that the coil shall not have a permanent 
“set” in the field, too strong to be conveniently controlled by the tor- 
sion of the gimp through which the current enters the coil. In the 
case of a quantometer where there is practically no controlling moment 
from the suspending fibre, the paramagnetic properties of the coil may 
be very troublesome ; and in some of the most recent instruments the 
angular movements of the coils, due to given changes of induction 
through the turns of the exploring coils, are somewhat different ac- 
cording as the movement is towards the left or towards the right. If 
a telescope and scale be set up in such a position that the behavior of 
the coil can be watched after it has moved through a considerable angle, 
urged by a sudden, definite change of flux in the exploring coil, it will 
often be found that the coil does not remain even approximately at 
rest, but moves steadily and so rapidly that a considerable error is 
introduced if the given change of flux through the exploring coil is 
made slowly. It is desirable, therefore, to test an instrument of this 
kind carefully before using it. 

If great accuracy is not required, a good fiuxmeter, of some standard 
make, and of sensitiveness suited to the work to be done, is, in experi- 
enced hands, a most useful instrument ; the time needed to establish a 
current of given strength in the coil of a large electromagnet with a 
solid core may be several minutes, but a very good fluxmeter will, 
nevertheless, show directly, with an error of not more than 2 per 
cent, the change of magnetic flux through the core. 

If the fluxmeter coil is not wound on a closed metal frame, the 
mutual damping effect of currents in the coil and in the core which 
it surrounds are not always effective unless the resistance of the ex- 
ternal circuit, made up of the exploring coil and its leads, is fairly small 
compared with the resistance of the suspended coil itself. An instru- 
ment, therefore, which works very well with an exploring coil of a small 
number of turns often becomes quite useless when, in order to get the 
required sensitiveness, the observer tries to employ an exploring coil 
made of many turns of fine wire. On the other hand, if a fluxmeter of 
this kind is too sensitive for a given piece of work, it is not always easy 
to reduce the sensitiveness quickly. 

If the flux changes to be measured are large, it is often convenient 
to have a fluxmeter the coil of which consists of a few turns either 
wound on a copper frame or else accompanied by several turns of stout 
wire closed on themselves. It is possible to use such an instrument 
with many different exploring coils and to change its sensitiveness 
within wide limits by varying the resistance of the external circuit. 


ὶ 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 117 


In doing a small part of the work described below, I was able to use 
either a Grassot Portable Fluxmeter, or a certain fixed laboratory 
fluxmeter (/”) furnished with a tall chimney to hold the 140 centi- 
meter long fibre by which the coil was suspended. ‘The cast-iron 
magnet of this last mentioned instru- 
ment had, when finished, the form 
shown in plan in Figure 11 and was 
45 mms. thick, The casting was 
made with a web connecting the 
poles, and this was removed after the 
hole for the coil had been cut out 
and finally reamed to a diameter of 
exactly 5 cms. on a Browne and 
Sharpe milling machine. The mag- 
net was hardened and treated by Mr. 
G. W. Thompson, the mechanician of 
the Jefferson Physical Laboratory, 
who has had much experience in 
this kind of work. During the proc- 
ess the poles were held in position 
by an iron yoke. The core (shaded 
in the diagram) within the coil is 
41.3 mms. in outer diameter, and is 
about 7 mms. thick. The instru- 
ment was constructed and set up eis oe he ee 
by Mr. John Coulson, who has shaded area represents the cross-sec- 
helped me in countless ways during tion of the soft iron core. 
the progress of the work. It was 
comparatively easy to substitute one of the set of coils belonging to 
this fluxmeter for another. For certain purposes it was convenient to 
have a coil of 200 turns of stout insulated wire which was wound about 
the magnet, though the latter had a large permanent moment. 


FicureE 11. 


THe COEFFICIENTS OF SELF-INDUCTION OF A CIRCUIT WHICH 
HAS AN [RON Core. 


When many years ago it was found that the induction B at a given 
point in a piece of iron exposed to a given magnetic field 7 is not only 
not in general proportional to the intensity of the exciting force, but is 
not even determined when // is given, it became evident that no such 
constant can exist in the case of an inductive circuit which ‘“‘contains” 
a magnetic metal as was assumed in the conception of Neumann’s 


118 PROCEEDINGS OF THE AMERICAN ACADEMY. 


“Electrodynamisches Potential,” 2° and that the different common defi- 
nitions of self-induction, when applied to an electromagnet of the 
usual form, really describe physical quantities which are widely 
different from one another. The ambiguity in the use of the term 
“ self-induction ” still exists, and it will be convenient in this paper to 
adopt the notation used by Sumpner 11 in his article on “ The Varia- 
tions of the Coefficients of Induction.” If, in absolute value, J is the 
strength of a current growing in the coil of an electromagnet with 
laminated core, if NV is the total flux of magnetic induction through 
the turns of the coil, and ὁ the counter electromotive force of induc- 
tion, we may call the ratio of e to the time rate of change of the 
current, 1.4, the ratio of NV to the current, Z., and the ratio, to J°, of 
twice the contribution (7’) made by the current to the energy when 
there are no other currents in the neighborhood, Zs, so that 

e= In, Neo ἢ L=o 

(15) 
dL, 


uy αἀ(14- ἢ 
ἮΝ 


7; 


’ T=t1,-L, L,=1,+ I- 


If then for a particular magnetic journey, taken at a given speed, V is 
given as a function of J in the form of a curve like OPQ in Figure 12, 
the value, at any point P on the curve, of JZ, is the slope of the 
curve or the tangent of the angle YAP; the value of L. at P is the 
slope of the line OP or the tangent of the angle YOP;; the value of 1.5 is 
the ratio of twice the curvilinear area OP to the area of the square 
erected on OJ. Similar definitions are sometimes given for such a 
magnetic journey as is represented by the line WG PQ of Figure 13. 

In the paper just cited Sumpner gives a very interesting graphical 
method of constructing a curve which shall show the manner of growth 
of the current in the coil of the electromagnet when the curve which 
connects V and J is given. 


Tue ELECTROMAGNETS USED IN DOING THE WoRK 
DESCRIBED BELOW. 


A number of electromagnets were used in carrying on the experi- 
mental work described in this paper. 

Though the investigation had to do primarily with magnets the 
cores of which were laminated or otherwise finely divided so as to get 


10 Neumann, Abh. d. Berl. Akad., 1846. 
11. Sumpner, Phil. Mag., 25, 1888. 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 119 


rid in great measure of the disturbing effects of eddy currents, one or 
two large magnets with massive cores were useful for purposes of com- 
parison. One of these (P), which weighs about 1500 kilograms, has 
the general shape shown in Figure 14. The outside dimensions of the 
frame proper are about 101 cms. Χ 80 cms. X 40 cms. The base is 
of cast iron and of rectangular cross-section (20 ems. X 40 cms.), the 
cylindrical arms are of soft steel 25 cms. in diameter, the rectangular 
pole pieces are 4.5 cms. thick, and the area of each of the opposed 


Figure 12. Woueerist 


This illustrates different meanings 
of the word inductance. 


faces is about 580 square centimeters. The four coils have together 
2823 turns, and a resistance at 20° C. of about 12.4 ohms. 

Figure 15 shows in outline the electromagnet Q, which weighs about 
300 kilograms : the core has a square cross-section of about 156 square 
centimeters area, and is built up, cobhouse-fashion, of soft iron plates 
about one third of a millimeter thick, each of which was immersed in 
thin shellac and then thoroughly baked in an electric oven before it 
was used. Each of the spools, which are practically alike, weighs about 
30 kilograms and has four coils, an inner one forming a single layer, 
the next forming three layers, and the two outer ones wound together 
side by side from two supply spools, and each equivalent to five layers ; 
in all, both spools together have 3883 turns. The whole core frame is 
about 74 cms. long and 62 cms. broad. One stratum 2.5 ems. high 


120 PROCEEDINGS OF THE AMERICAN ACADEMY. 


and reaching across the middle of the core (Figure 16 @) within one of 
the spools, is made up of five portions insulated from one another, and 
each of these is surrounded by an exploring coil of insulated wire. 

Figure 164 shows the form of the cross-section of the rectangular 
core frame of a 15 kilowatt transformer (/?) constructed for experi- 
mental purposes and belonging to the Lawrence Scientific School. 
Besides a low-resistance primary coil, this transformer has 19 similar 
coils each of about 85 turns, any number of which may be connected 
to form a secondary circuit. The outside dimensions of the core frame 
are about 78 cms. and 34 cms.; the area of the cross-section of the 
finely divided core is about 108 square centimeters. 


Fieure 14. 


The electromagnet P. This magnet has a solid core which weighs about 1500 
kilograms. 


Magnet S has a core consisting of two round solid pieces 76 ems. 
long and 7.4 cms. in diameter with axes 24 cms. apart, connected 
together at the ends (so as to form a rectangular frame) by two massive 
iron blocks. ‘This magnet has two spools; each of which has two coils 
formed by winding two strands side by side; the whole number of 
turns is 1724. 

The core of magnet 7’ forms a square 58 cms. long on the outside 
and 53.5 ems. wide. Its cross-section is a rectangle 7.5 cms. by 6.7 
ems. ‘The core is built up of sheet metal 0.38 of a millimeter thick. 

Through the kindness of Dr. George Ashley Campbell I have been 
allowed to use also seven toroidal coils (of inductances between 0.3 and 
13 henries) wound on cores made of very fine (No. 38 B. & 8.) iron wire. 
Such cores are, of course, extremely expensive, but the disturbing 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 121 


effects of eddy currents in them are practically negligible for the 
purposes of this paper. 


THe DEMAGNETIZING OF THE CorE OF A LARGE ELECTROMAGNET. 


In order to be able to study satisfactorily the magnetic properties of 
a given piece of iron or steel, it is usually necessary that one should 
know with some accuracy the magnetic state of the specimen at the 
outset, and, especially when the metal has the form of a closed ring or 
frame, the previous history of which is unknown, the only safe pro- 


Ficure 18. 


The electromagnet Q, which has a laminated core made of sheet iron one 
third of a millimeter thick and weighs about 300 kilograms. 


cedure is to demagnetize the iron as completely as possible before one 
makes any experiments upon it. If the metal has the form of a long 
rod in a solenoid, or of a slender ring wound about uniformly with 
insulated wire and magnetized in the direction of its circumference, it 
is easy to send through the coil which surrrounds the iron a long 
series of currents alternately in opposite directions, which, starting with 
a value that shall subject the core to a magnetic field at least as 
strong as any to which it has been previously exposed, gradually de- 


122 PROCEEDINGS OF THE AMERICAN ACADEMY. 


crease in intensity to zero. One common way of doing this is to 
attach. the coil to the secondary of a sufficiently powerful alternate 
current transformer so arranged that the primary coil may be slowly 
withdrawn to a long distance from the secondary. In the case of the 
soft iron wire the demagnetization is sometimes accomplished by 
heating the wire red hot. 

It is often a matter of considerable difficulty to remove entirely the 
effects of previous magnetization from the completely closed massive 
core of a large transformer: even if the source of a current in the 
exciting coil has a high voltage, several seconds may be required to 
established the current, and the use of an alternating demagnetizing 
current in the coil, with any commercial frequency, is barred out. If 
a powerful storage battery be connected to the exciting coil through a 
commutator and a suitable “liquid rheostat,” one may begin with a 
sufficiently strong current (10) and, after reversing this several times 


1095. 


Figure 10, 


Forms of ,the cross-sections of the laminated cores of the electromagnets 
Q and R. 


by hand, increase a little the rheostat resistance so as to decrease the 
current slightly, then reverse this weaker current a number of times, 
and thus proceed until the current is reduced to a very small value ; 
but if the core is very large, the operation may take a couple of hours 
even if the number of steps is not excessive, and after all, it is not 
easy to tell whether the work has been successful. If the initial 
current was strong enough, if the stages were sufficiently numerous 
and properly spaced, and if the number of reversals at each step was 
great, one may, of course, expect to find the core pretty thoroughly 
demagnetized, but to test the matter it is usually necessary to undo 
what has been accomplished by determining the amount of magnetic 
flux sent through the core when a current of given intensity (7) is sent 
through the exciting coil. This amount ought to be the same whether 
this testing current has the same direction as that of the last applica- 
tion of the large current (/,) or the opposite direction, and unless one 


‘ 
: 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 128 


has a hysteresis diagram for the core obtained by using currents which 
range exactly between +/, and —/, the whole work must be done twice. 
The determination of the flux changes may be made very conveniently 
with the help of a fluxmeter, but if the highest accuracy is required, 
it is better to take an oscillogram of the building-up curves of the 
current when the core starts from its state of supposed neutrality. 
If the core of a large electromagnet is not quite closed, it is compara- 
tively easy to demagnetize the iron almost completely and to prove 
that this has been done; indeed, if the gap has the proper width, the 


Figure 17. 


iron practically demagnetizes itself in a wonderful manner. An in- 
stance of this was given by Professor Thomas Gray in the case of a 
40 K. W. transformer, and I found that the hysteresis diagram for a 
certain electromagnet which has a solid core the area of which in its 
slenderest part is more than 450 square centimeters, consists prac- 
tically of a single straight line when the air gap has a width of 35 
millimeters. With this magnet, using an excitation of either 7800 
ampere-turns or 15,800 ampere-turns, I obtained current-time curves 
which were wholly indistinguishable even when much enlarged and 


124 PROCEEDINGS OF THE AMERICAN ACADEMY. 


superposed on a screen, whether the current had the same direction as 
its predecessor or the opposite direction. 

If the core of an electromagnet happens to be a straight bar, or a 
straight bundle of wire, it may be demagnetized by a long series of 
currents which have alternately one direction and the other, and which 
slowly decrease in intensity from an initial value which may be con- 
siderably smaller than the current which magnetized the iron. Figure 
17 shows the results of experiments upon a rod of soft steel 80 diame- 
ters long in a long solenoid. The arrangement of the apparatus is 
shown in Figure 18. ‘The extreme value of the magnetizing field was 
27 gausses, and the average moment per cubic centimeter which the 


W ( © 
{1} 


Figure 18. 


field caused was 246. At the outset the core was thoroughly demag- 
netized, then a series of steady currents, each a little stronger than the 
last, was sent through the coil, and the moment of the rod was deter- 
mined for each direction of the current. This gave the curve WYOQV. 
Then the hysteresis diagram VGA WMZV was obtained, and after the 
core had returned to the condition indicated by the point V, the 
current was somewhat decreased until the core “reached” the point B, 
and then this current was reversed in direction one hundred times, 
after which (when the current had the positive direction) the iron had 
exactly arrived at the point on the curve O/JQV beneath B. The core 
was then brought to V again, the current was decreased,—this time 
until the core reached the point ?,—this current was reversed one 
hundred times, and it was then found that when it ran in positive 


a 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 125 


direction the core had arrived at the point @. This process, repeated 
for many points on the line GPV, yielded the curve VQACG. If 
after being at V the core was brought to a point between P and J, 
and if after it had been many times reversed the current was decreased 
by short steps with many reversals at each stage, the core traversed 
the curve U, whereas if the first drop carried the core no farther than 
P, the procedure led the core to the origin along the curve /. ‘The 
lowest point of the curve VQAG lies, of course, nearly over the point 
Z. The shaded diagram in the upper part of the figure shows a 
similar curve obtained at another time and drawn strictly to scale. 
If after many reversals of a comparatively small current the core which 
started at Z reached the point /, and if the current was then slowly 
increased, the core made the journey indicated by the line “ZL. The 
shaded diagram in the lower part of the figure is a reduction of a curve 
obtained with a large induction coil the core of which is a compact 
round bundle of fine wire 7.5 cms. in diameter and about 85 cms. long. 
The curves vec, cak, cek, in this diagram correspond to O1QV, VPG, 
VQAG in the larger figure. The retentiveness of a core of these 
dimensions is, of course, very small. 

Even if much time has been spent in demagnetizing a large closed 
core by sending through the exciting coil currents alternately in one 
direction and in the other, of intensities gradually decreasing to a very 
small final value, it frequently happens that after a much larger 
current has been put for, say, twenty times through the coil alternately 
in one direction and the other, the hysteresis cycle does not “close,” 
for the change of flux caused by applying the given current in one 
direction is not equal to the flux change caused by applying the same 
current in the other. This fact often makes the accurate determina- 
tion of a hysteresis diagram for such a core a long and trying piece of 
work. Some toroidal cores I have never succeeded in demagnetizing 
completely. The demagnetizing apparatus which I have usually 
employed in the course of the work here described consists first of a 
storage battery of forty large cells, a set of rheostats made up of 
metallic and liquid resistances intended for heavy currents, and a 
commutator run from the main shaft of the laboratory machine shop, 
and so arranged as to reverse the direction of the current from the cells 
every ten seconds. Starting with no resistance in the rheostats, 
resistance was gradually introduced into the circuit until the current 
had become very small. After this procedure, the secondary circuit 
of a specially constructed transformer was attached to the exciting coil 
of the magnet, and from an initial voltage of about 660, at 60 cycles 
per second, the electromotive force was gradually decreased until the 


126 PROCEEDINGS OF THE AMERICAN ACADEMY. 


current became too small to measure. In some cases it seemed better 
to omit the second part of the process. 


Tre EstaABLISHMENT OF A STEADY CURRENT IN THE COIL OF AN 
ELECTROMAGNET. 


If the circuit of the exciting coil of an electromagnet contains a 
battery of storage cells of constant voltage Μ΄, and if this circuit be 
suddenly closed, the strength of the current will rise more or less 
gradually from its initial zero value to 4/r amperes, where 7 is the 
whole resistance of the circuit in ohms. In the case of a given magnet, 
with a given electromotive force in the coil circuit, the manner of 
growth of the current depends very largely, as we have seen, upon the 


np OE gO σας 


: 777 etre ere 
wu SNS ΩΡ 
5 LEZ 
v Co 
ὍΣ 


ο 


Ficure 19. 


Currents from a battery of 20 storage cells in the circuit of a coil of 2788 
turns belonging to the magnet Q. Before the middle curve was taken, the core 
was carefully demagnetized. The upper and lower curves represent direct and 
reverse currents, respectively. The areas V and W are equal. 


magnetic state of the core when the circuit was closed. ‘The three 
curves of Figure 19, which are carefully made reproductions of the 
photographed records of an oscillograph, show the march of the current 
from a battery of 20 storage cells in the circuit of a coil of 2788 turns 
belonging to the magnet @ under three different sets of conditions. If 
after the core had been demagnetized as thoroughly as possible, by the 
method already described, the circuit was suddenly closed, the current 
followed the middle curve of the three. If the current was allowed 
practically to attain its maximum value, and if then a commutator in 
the circuit was reversed and, at intervals of a few seconds, reversed 
again and again, and if finally the circuit was broken, it was possible 
by closing the commutator again in the proper direction, to make the 
new current follow either the upper or the lower curve of the diagram. 
If this current coincided in direction with the last current through the 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGMET, 127 


coil, the current was “direct,” and its rise was represented by the upper 
curve. If the new current had a direction opposite to that of the last 
current through the coil, the current was “reverse,” and followed the 
lower curve. The areas V and W are practically equal. 


It is evident that, other things being equal, the rapidity of rise of 
the current in a circuit which contains a coil wound around the core of 
an electromagnet will depend very much upon the number of turns in 
the coil. Figure 20 shows reverse curves from the magnet &. The 
actual strengths of the currents were 6, 3, and 1.5 amperes respectively, 
and the numbers of turns in the exciting coils were 85, 170, and 340. 


CURRENT. _ 


Ficure 20. 


Curves showing the growth of currents in coils of 540 turns, 170 turns, and 85 
turns belonging to the magnet &. The same electromotive force was used for 
all the cases, and the final values of the currents were 6 amperes, 3 amperes, and 
1.5 amperes. 


The electromotive force was the same in all three cases. The horizon- 
tal units are tenths of seconds. 

Although the typical current curve for the coil of an electromagnet 
wound in many turns about the core has two points of inflexion if the 
core is laminated, both of these disappear if the change of the magnetic 
flux through the circuit due to the current is small enough, and 
occasionally one finds an oscillogram which seems to have only one 
point of inflexion. Some of the direct curves shown in Figures 5, 23, 
and 28 are everywhere convex upward. Among the nearly three 
thousand photographed oscillograph records taken for use in this paper 
No one is concave upward at the very start, but a curve of this kind, with 
one point of inflexion, has been shown by Dr. Thornton, and I have 


128 PROCEEDINGS OF THE AMERICAN ACADEMY. 


many curves which become concave upward very near the origin. In 
current curves belonging to the coil of an electromagnet which has a large 
closed, solid core, there are often two points of inflexion, but many of 
even the reverse curves are everywhere convex upward. Figure 21 
shows curves taken for the coil of the large magnet P in the circuit of 
which was a storage battery of voltage 84. When each current started, 
the core was nearly neutral. 


SECONDS. 


Ficure 21. 


Curves showing the manner of growth of currents of various final strengths 
in the coil of 2823 turns belonging to the magnet P., The gap was closed and 
the core was nearly neutral at the beginning of each current. The applied vol- 
tage was the same (84) for ail the curves. 


When the coil of a transformer, the core of which is built up of such 
thin plates of soft iron as are used in the best practice, is subjected to 
an alternating electromotive force of extremely high frequency, the 
disturbing effect of eddy currents in the iron are, of course, very ap- 
parent, but the manner of growth of a current under a constant electro- 
motive force is usually not very greatly affected by such currents. 

The fact that the susceptibility of the iron is by no means constant, 
materially alters the shape of a current curve when iron is introduced 
into a circuit ; nevertheless, it is instructive to compare the manner of 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 129 


growth of a current in the coil of an electromagnet which has such a 
core, with that of a current in a circuit of fixed inductance, without 
attempting at the outset to account mathematically for the differences, 
though it will be easy to do so later on. 

In the case of a simple circuit, without iron, of resistance 7 ohms 
and constant inductance, LZ henries, which contains a constant electro- 
motive force of # volts, the rise of the current J when the circuit is 
suddenly closed follows the law 


EB ἘΠ 
T==(1-e, (16) 
and attains the fractional part / of its final value (#/r) in the time 
t= —" loge (1 — 4), (17) 


which is independent of the ultimate current strength and involves 
only the time constant (Z/r) of the circuit. If the circuit is made 


CURRENT. 


FiGureE 22. 


Curves which show the manner of growth of currents in a coil of 1394 turns 
belonging to the magnet Q, to a given final value, when the applied voltages 
were 82, 41, and 20.5, nearly. In each case the core was neutral at the outset. 


up partly of non-inductively wound resistance wire, and partly of 
helices, 7 may be kept constant, while LZ is changed, by changing the 
relative proportions of the two parts; or 7 may be altered while Z is 
constant, by increasing or decreasing the non-inductive portion of the 


circuit. 
VOL. XLII. — 9 


130 PROCEEDINGS OF THE AMERICAN ACADEMY. 


If E/r and L are given, different values of # may be used by giving 
properly corresponding values to the non-inductive resistance, and if 
the “building-up time” of the current under given initial conditions 
in the core be defined as the number of seconds required for the current 
to attain any arbitrarily chosen fractional part of its final value, this 
time will be inversely proportional to # In the case of a circuit 
which has one or more iron cores the phenomenon is much less simple, 
and if the cores be of solid metal, the effects of eddy currents may 
complicate the problem seriously ; but although under these circum- 
stances the law of proportionality no longer holds, it is almost univer- 
sally true that the establishment of a current of given final intensity 


ΓΤ. ee 
ft fi ft 
i 7 7 
(oe 
Micha) 


Figure 23. 
Direct and reverse current curves for the magnet Q with a given final excita- 
tion of 2650 ampere turns, under applied voltages of 82, 41, and 20.4, nearly. 


CURRENT. 


Se 


in the coil of a given electromagnet can be accelerated by increasing 
very much the applied electromotive force and then introducing a 
sufficient amount of non-inductive resistance to make #/r the same as 
before. 

Figure 22 shows current curves for the magnet Q under a fixed final 
excitation of 2650 ampere-turns. In curves A, B, C, the currents 
were caused by 40 cells, 20 cells, and 10 cells, respectively, and these 
currents were made equal by adding to the circuit in each case a 
suitable non-inductive resistance. Before each of these curves was 
taken, the core of the magnet was carefully demagnetized by the 
elaborate process described above. After the magnet @ had been put 
a good many times through a cycle with a given maximum excitation 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 131 


of 2650 ampere turns, under one of the voltages just named, direct and 
reverse curves were taken with the help of the oscillograph. Careful 
reproductions of these curves are given in Figure 23: to avoid con- 
fusion the reverse curves are drawn from a separate time origin. 

If in a circuit which contains no iron, # and r be kept constant, 
while Z is changed, the building-up time as defined by equation (17) 
will be proportional to Z. Of course no such simple relation holds 
when the circuit includes the magnet Q; Figure 24 shows current 
curves for the same final value of 2.60 amperes, under an applied elec- 


ΠΡ 
z 
μι 
c 
c 
=) 
Oo 


Figure 24. 


The manner of establishment of a current of final strength 2.60 amperes, in the 
coil circuit of the magnet Q, under a voltage of 82, when the number of active 
turns was 407, 823, 13894, or 2788. 


tromotive force of about 82 volts, for exciting coils of 407 turns, 823 
turns, 1394 turns, and 2788 turns. For convenience, the curves are 
drawn from different time origins. The dotted line which crosses curve 
Q calls attention to the fact that if curves P and @ were drawn from 
the same origin, the former would cross the latter. 

If in a circuit without iron # and Z were kept constant while 7 was 
varied, the building-up time (Z/r) would be inversely proportional to 
the resistance of the circuit, or, since the electromotive force is fixed, 
directly proportional to the current strength. ‘There is no approxima- 
tion to this in a circuit which contains iron. The current curves 
shown in Figure 25 were obtained from the electromagnet @ when 


182 PROCEEDINGS OF THE AMERICAN ACADEMY. 


2788 turns were used in the exciting coil and a battery of 40 storage 
cells with a voltage of about 82 furnished the electromotive force. 
Curve C evidently corresponds to a case where the total resistance 
in the circuit is about twice as great as in the case represented by A, 
but for every value of ᾧ the building-up time is greater for C than 
for A, though the difference becomes very small at the end. A com- 
parison between A and 7) shows the same fact. Before each of the 
curves A, B, C, D, was taken the core of the magnet was carefully de- 
magnetized. Figure 26 exhibits current curves taken for different 
values of 7 with the same coil of the magnet Q and with the same elec- 
tromotive force as the curves just mentioned. In each of the cases 


CURRENT. 


Figure 26. 


Currents in the coil of the electromagnet Q for four different values of r when 
E and the number of magnetizing turns were fixed. At the starting of each 
current the core was magnetically neutral. 


shown in Figure 26 the core was put several times through a cycle 
before the direct and reverse oscillograms were taken. The records are 
reproduced as accurately as possible; B, C, and 2) run together in a 
complicated manner, and the same tendency is shown in the reverse 
curves (ἡ, H, J, but in general the longer building-up times belong to 
the lower currents. 

If in an inductive circuit without iron 7 and Z are fixed, the build- 
ing-up time will be independent of the value of #, but this is not the 
fact if the circuit contains an electromagnet. Figures 27 and 28 show 
current curves obtained from the coil of 2788 turns belonging to the 
magnet @. In all the curves of each diagram the value of 7 was the 
same, but the voltage of the battery in the coil circuit had three differ- 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 133 


CURRENT. 


FIGURE 26. 


Direct and reverse current curves in the coil of the electromagnet Q for five 
different values of r when # and the number of active turns were kept fixed. 


CURRENT. 


FIGURE 27. 


Currents in the coil of 2788 turns belonging to the magnet Q for three differ- 
ent values of the applied voltage with the same value of r. At the starting of 
each current the core was magnetically neutral. 


CURRENT. 


134 PROCEEDINGS OF THE AMERICAN ACADEMY. 


ent values the largest of which (belonging to the curves C, M, NV) was 
about 82: in this case the current was almost exactly 2.50 amperes. 
Before each of the curves A, &, C was taken the core was thoroughly 


Figure 28. 
Direct and reverse currents in a coil of 2788 turns belonging to the magnet 
Q for three different values of the applied voltage, but the same value of r. 


demagnetized: #, P, M are direct curves, but S, Q, NV are reverse 
curves. It is evident that the building-up times are not even approxi- 
mately independent of /. 


Figure 29 shows the records of an oscillograph in a secondary circuit 
in which were a few turns of wire wound around the core of the magnet 
@. The primary circuit contained, besides the storage battery, a rheo- 
stat and an exciting coil of 1394 turns. When the primary circuit 


c 
= 
oO 


: 


\ 


ο 


WNiiititiinee 
TIME. 


was suddenly closed with such a resistance in the rheostat that the final 
strength of the current was 1.1 amperes, the induced current had the 
value indicated by the curve Q; when the rheostat resistance was 
suddenly removed so as to bring the final strength of the current up to 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 135 


2.3 amperes, the induced current curve was #. The sum of the areas 
under the curves @ and # was 74.3 square centimeters. Thecurve P 


shows the current record in the secondary 
circuit when the primary circuit was sud- 
denly closed with no resistance in the rheo- 
stat: the area under this oscillogram was 
74.6 square centimeters. All the currents 
were reverse currents. Most of the area 
determinations of this paper were made 
with a Coradi “Grand pianimétre roulant 
et ἃ sphére.” 

Figure 30 shows a careful reproduction 
of the record of an oscillograph in the 
primary circuit of the arrangement just 
described. ‘These curves were taken on 
the same day as those of the last figure. 
In this case the flux change due to the 
current which gave the curve 7’ was 
to the sum of the flux changes caused 
by the partial currents as 1130 to 1126. 
These numbers do not show any real dif- 
ference between the corresponding physi- 
cal quantities, but point to difficulties of 
measurement. 


Tue Errect or THE Maanetic CHaRac- 
TERISTICS OF THE CORE UPON THE Man- 
NER OF GROWTH OF A CURRENT IN THE 
Com or A Larce ELEecrRoMAGNET. 


If under the application of a constant 
electromotive force to the coil circuit of 
an electromagnet a current grows grad- 
ually in the coil to its full value, the 
magnetic flux in the core at any moment 
depends, as we have seen, not only upon 
the instantaneous strength of the current, 
but also upon the magnetic state of the 
core at the beginning. Moreover, if the 
core is solid, it is clear that the magne- 


Ficure 90. 


tizing field to which the interior of the iron mass is exposed may be 
quite different at any instant from what it would be if eddy currents 
were nonexistent. If, however, the core is built up of such thin sheets 


136 PROCEEDINGS OF THE AMERICAN ACADEMY. 


of iron as are used in good transformers, a fair approximation to the 
form which the current curve will have under any given circumstances 
can be made if one has an accurate statical hysteresis diagram of the 
core for the range required, and if the core is made of very fine var- 
nished wire, as in the case of loading coils for long telephone circuits, 
a hysteresis diagram obtained either from a long “step-by-step series” 
of measurements or from one or more oscillograms, enables one to pre- 
dict with accuracy what the form of a current curve will be for any 
practical case. ‘These last statements are based on experiments such 
as those recorded below. 

As a result of a long series of measurements, it appears that when 
the core of the magnet @ has been well demagnetized and a series of 
steady currents each a little stronger than the preceding one are estab- 
lished in the exciting coil, the magnetic flux through the core in 
thousands of maxwells follows fairly accurately the course indicated 
in the following table : 


TABLE I. 


Ampere Turns. Magnetic Flux. 


100 


Figure 31 reproduces the table graphically in the full curve: the 
vertical unit is a thousand maxwells, and the horizontal unit is 139.4 
ampere-turns, to suit the case when the particular exciting coil used 
has 1394 turns. ‘The ordinates of the dotted curve represent twice the 
corresponding values of the slope (A) of the other. A template of the 
curve & was made as accurately as possible from a large piece of sheet 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 137 


zinc ; this was fastened down on a table over a number of sheets of co- 
ordinate paper, and the value of A was determined by measuring on the 
paper the position of a straight edge which touched the template at 


any desired point. 
TABLE II. 


ti Current i 
pees Log [(13.94)A]. ἐπ πέτα Log [(13.94)A]. 


0.00 0.445 0.55 
0.05 0.860 0.60 
0.10 1.248 0.65 
0.15 1.602 0.70 
0.20 715 0.75 


0.25 67! 0.80 
0.30 : 0.90 
0.35 1.00 
0.40 1.10 
0.45 
0.50 


If after the core of Q had been demagnetized, a steady electromotive 
force of / volts were applied to the exciting circuit of resistance 
r ohms, containing the coil of 1394 turns, and if eddy currents were 
nonexistent so that the core followed the statical magnetizing curve, 
the march of the current (in amperes) would be given by the equation 


di 


Ξ- 4 = 13.942A- τ, ζε 
E TL 9 dt (18) 
515 94 ἃ 
h 1 - dt. 9 
whence hon 2 (19) 


If from an actual current curve obtained from Q for a given journey 
of the core we were to determine the corresponding magnetizing curve 
for the metal (flux versus coil current), we should find that the values 
of the flux, for small values of the current, at least, would fall short of 
the flux values which the same currents would cause if they were to act 


138 PROCEEDINGS OF THE AMERICAN ACADEMY. 


for some time because the magnetizing field is less than that due to 
the coil current by that due to the eddy currents. If, therefore, from 
the numbers of ables I and II we were to determine the form of a 
current curve for Q, corresponding to any journey of the core, this 
would fall somewhat below the actual curve at the beginning. The 
core of @ has, however, a typical magnetizing diagram, and the theo- 
retical curves are instructive as showing what the actual curves would 
be if the same core were more finely divided. The effect of eddy cur- 
rents can be seen in the curves for this magnet given above. 


INDUCTION FLUX 


\ 
5 


Ficure 31. 


Magnetization curve for the core of the magnet Q which at the outset is ina 
neutral state. The ordinates of the dotted curve represent twice the slopes of 
the other curve. 


The boundary of the shaded area in Figure 32 shows twice the value 
of the integrand 


w= (20) 


for the case H = 26, + = 20: the horizontal unit is one tenth of an 
ampere. ‘The vertical line corresponding to 7 = 1.3 is evidently an 
asymptote. The area under the curve from the beginning to the ordi- 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 139 


nate representing any given value of the current shows, in twentieths of 
a second, the time required, under the given conditions, after the cir- 
cuit is closed for the current to attain this value. It is easy to deter- 
mine a series of such areas with the help of a good planimeter, and the 
full curve of Figure 32 actually represents the growth of the current in 
the case mentioned according to my measurements of the large dia- 
gram of which Fig. 32 is a very much reduced copy : for this curve the 
horizontal ‘unit is one tenth of a second and the vertical unit is one 
fifth of an ampere. This curve has the general form of most of the 


eee ae eae EN 
yt te ee 
ΠΕ ΕΠ 


NS 


Ἐν 
Ze es 


Figure 92. 


The ordinates of the boundary of the shaded area represent 2(dt/di) for 
E=26, r=20. P shows the theoretical form of the corresponding current 
curve. 


current curves which one obtains with a transformer the core of which 
is at the outset neutral, but it is evident that in any case where the 
final value of the current is small enough the asymptote will be moved 
so far to the left that the integrand curve will rise continually from 
the beginning, without the maximum and minimum values, and the 
current curve will have the everywhere convex shape that we find in 
practice when we cause the current to grow by short steps in the man- 
ner indicated by the curve {7 in Figure 4. 

Figure 33 shows building-up current curves (A, ὁ, c) for HE = 26, 
and r = 20, 40, and 60, respectively. The dotted curves B and ( are 
copies of ὁ and ὁ with ordinates so magnified that the curves have the 


140 PROCEEDINGS OF THE AMERICAN ACADEMY. 


same asymptote as A. According to this diagram the current attains 
75 per cent of its own final value more quickly when r is 40 than when 
ris 20, but B crosses A at the point 2 and the current seems to reach 
practically its full strength sooner in the latter case. The curve C first 
crosses the curve A and then B. It would be easy to show from a 
series of oscillograph records for similar cases that the characteristics 
of the theoretical curves correspond in general to fact. 


Figure 33. 


Forms of current curves for Q deduced from theoretical considerations. The 
coil has 1394 turns and contains a storage battery of voltage 26. C is everywhere 
convex upward: A and B have two points of inflexion. 


If with the core of the magnet Ὁ initially neutral a steady current 
of given strength be established in the coil of 1394 turns, by use of a 
storage battery of voltage /, the integrand will be for every value of 
the current inversely proportional to # (since #/r is given), and the 
building-up time will be inversely proportional to the applied electro- 
motive force, as it would be if the inductance were fixed. For a given 
exciting coil, the general shape of the curve for a given current is ~ 
independent of the applied voltage. Curves A, C, and D of Figure 34 
are the current curves computed for 7 = 26, 52, 104, and 7 = 20, 40, and 
80: the maximum value of the current is the same in every case. G@ 
and ’ are the current curves computed for 4 = 26, r= 80, and for 
E= 104A, r = 320. 

As has been explained already, it is difficult to obtain an accurate 
hysteresis diagram for a very large core by the ordinary ballistic 
methods with such galvanometers as are usually to be found in the 


TENTHS OF SECONDS. 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 141 


testing room, but it is fairly easy to attach extra weights to the 
suspended system (Figure 35) of a good d’Arsonval or Thomson Mirror 
galvanometer which shall so increase the moment of inertia that the 
time of swing shall be lengthened to five or ten or twenty minutes. 
With an instrument thus modified it is usually possible, by changing 
the intensity of the current in the exciting coil by small steps, to deal 
satisfactorily with very large masses of iron. It is of course desirable 
to use a rather high electromotive force in the exciting coil in order 


TABLE III. 


Flux in Thousands 
of Maxwells. 


Flux in Thousands 


Ampere Turns. of Maxwells. 


Ampere Turns. 


1812 1371 —151 


—148 


to make the building-up time short, and to reduce the current to the 
desired strength by introducing extra non-inductively wound resistance 
into the external circuit. In order to test this matter thoroughly, I 
measured with great care, by aid of a modified Rubens-du Bois 
“Panzer Galvanometer,” the flux changes in the core of the magnet Q 
(the area of the cross-section of which is more than 150 square centi- 
meters), corresponding to a hysteresis cycle for an excitation of 1812 
ampere turns. I then determined the same total flux change by 
means of planimeter measurements of the areas under a long series of 


142 PROCEEDINGS OF THE AMERICAN ACADEMY. 


oscillograph records; all the testing instruments were different in the 
two cases, and no comparison was possible until the final results were 


Ε..,71.ἃ}2. ae ae 


TENTHS OF SECONDS. 


Figure 84. 


Theoretical forms of current curves in a coil of 1394 turns belonging to the 
magnet Q. In practice these would be somewhat modified by eddy currents. 


obtained and were found to differ 
from each other by only one part 
in about fourteen hundred. ‘The 
labor of reducing the oscillograms 
was very great, and this extremely 
close agreement must be consid- 
ered accidental, since it is not 
easy to make a large mass of iron 
go over exactly the same magnetic 
journey twice. 

Hysteresis diagrams for the 
magnet @ and corresponding to 
maximum excitations of 1812, 
5370, and 10,880 ampere turns 
are given in Figure 36. Some 
results of measurements of the 

. flux changes in the core for the 
and the brass masses C, can bescrewed ,, = : 5 
on the rod as far as is necessary. The Urst of these cycles are given in 
system must be accurately balanced. Table ΠῚ. 


Ficure 88. 


The horizontal rod ABP is threaded 


148 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 


1,500,000 


1,0 00,000 ] 


tte 


Figure 36. 
Hysteresis diagrams for the core of the magnet Q. 


YK 
of 
Q 
fa 
p 
o 
μι 
FY 


144 PROCEEDINGS OF THE AMERICAN ACADEMY. 


After a curve had been drawn on a very large scale to represent the 
numbers of Table III, a zinc template was made from it, by aid of 
which and a long “‘straight-edge” the slopes of the curve could be 
determined with some accuracy. The next diagram (Figure 37) shows 
the slope as a function of the strength of the current. 

When the slope for any point of the curve is multiplied by 
(13.94) / (#—~ri), where / and ¢ are given, the result is the value of 
dt/di for the reverse current curve when the applied voltage is # 
and the resistance 7, for the given value of 7. Figure 38 exhibits 
dt/di for H = 19.5, and r = 15. 

The actual curve was drawn on a large scale, and the area A from 
x = 0 to 2 =?, fora number of different values of 7 were measured by a 
planimeter in terms of the unit square of the figure; this area ex- 
pressed in tenths of seconds the time required for the reverse current 
to attain the strength 7. A few values of XY are shown in the next 
table. 


TABLE IV. 


Every form of current curve which I have met in practice can be 
closely imitated by a theoretical curve ; but all these curves have at 
the outset a direction differing widely from the horizontal. Dr. 
Thornton, however, shows a beautiful curve which at the beginning is 
convex downward and has at the start a direction not very different 
from that of the axis of abscissas. 

Before one uses an oscillograph for purposes of accurate measure- 
ment, one must make sure that the instrument has been properly set 
up. When the drum which carries the sensitive film or paper is at 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 145 


lS ee ΒΕ. δ. 
eas 


at 


TENTHS OF AMPERES. 


Figure 38. 


The value of dt/di for a reverse current in a coil of the magnet Q when 
Ἢ =19.5 and r = 15. 


INDUCTION. gs00,000 


600,000 


SECONDS. 


Figure 39. 


The full curve shows the rate of increase of the flux of magnetic induction 
through the core of the magnet Q while a reverse current of 1.3 > amperes is being 
established in the exciting coil of 1894 turns. The current curve is shown on ar 
arbitrary scale by the dotted line. 


VOL. XLII. — 10 


ἘΞ 
Ζ 
WW 
[τα 
c 
=) 
Oo 


146 PROCEEDINGS OF THE AMERICAN ACADEMY. 


rest, a current sent through the conductor should give a perfectly 
straight record accurately perpendicular to the base line, and the 
length of this record should be proportional to the strength of the 
current. It sometimes happens that an oscillograph which records 
accurately the march of a moderate current lags in its indications a 
very little behind the strength of a comparatively feeble current owing 
to the viscosity of the oil used for damping, which only then becomes 
troublesome. I have myself had sad experience in drawing from the 
records of an instrument of this sort, which I thought I had carefully 
calibrated, elaborate inferences which were contrary to fact. If, however, 


Ficure 40. 


Theoretical forms of direct and reverse current curves for a coil of 1804 
turns belonging to the magnet Q when the resistance of the circuit is 8 ohms 
and the applied voltage is 10.4. 


one has at hand, first, a well-constructed and mounted ballistic gal- 
vanometer with a period of from eight to ten minutes, and means of 
damping the swings of the suspended system (electromagnetically or 
otherwise) without touching it, and secondly, some kind of chrono- 
graph designed to close and after a given interval to open again any 
circuit to which it may be attached, it is easy to test almost any 
supposed fact about the growth of the flux through the core of an 
electromagnet. 

The toroids I used had cores made of extremely fine, varnished iron 
wire, costing about four dollars per kilogram. For some of these I deter- 
mined by ballistic methods, as carefully as I well could, the hysteresis 
diagrams for several excitations, and then compared with these other 
diagrams obtained from the oscillograph records of current curves for 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 147 


the same magnetic journeys of the cores, but I could not detect any 
differences which did not lie far within the small uncertainty which 
the viscosity of the oil in the oscillograph may be supposed to cause. 
It does not seem worth while to print a long series of numbers to 
illustrate this kind of comparison though the labor was great. 


If, then, the core of an electromagnet is made of iron wire not more 
than one tenth of a millimeter in diameter and carefully varnished, it 
seems to be true within the limits of accuracy of my measurements 
and for the comparatively moderate excitations used, that if the core 


ae es (ee [a 
es ea A 
ste | ale] 

|_| 


Sa See 
[Ξ 
ΠΕΡΊ 
ἘΠῚ 


FIGureE 41. 


Theoretical forms of direct and reverse current curves fora coil of 1394 turns 
belonging to the magnet Q when the resistance of the circuit is 15 ohms and the 
applied voltage is 19.5. 


is in a given magnetic state at the start, the change of the flux of 
magnetic induction caused by a current which grows from zero with- 
out decreasing to a given final intensity, is quite independent of the 
manner of growth of this current. It may grow continuously or by 
steps, and if eddy currents are not appreciable, the condition of the 
core at the end is the same. According to this, one would get exactly 
the same hysteresis diagram from an accurately drawn current curve 
of the form V (Figure 4) corresponding to any change of current in the 
exciting coil as from the corresponding {7 diagram or from any slow 
step-by-step ballistic method. Nothing of the nature of time lag, if it 
exists at all, affects the growth of the induction in the iron appreci- 
ably. Even in the case of an ordinary transformer, where the effects 


148 PROCEEDINGS OF THE AMERICAN ACADEMY, 


of eddy currents are very noticeable at the early portions of most cur- 
rent curves, the whole change of flux due to a given current in the coil is 
the same apparently whether the current grows steadily or by steps; in 
this case an accurate diagram of the 77 form and a step-by-step ballis- 
tic method with a proper galvanometer may be expected to yield 


CURRENT. 


0.3. SECONDS 


Ficure 42. 


Theoretical form of reverse current curve for a coil of 1394 turns belonging 
to the magnet Q, under an electromotive force of 208 volts. The resistance of 
the circuit is 160 ohms. 


identical results within the limits of the measurements. This state- 
ment seems to be justified by such comparisons of the two as that 
recorded on page 142, which required many days in the making. From 
a current curve we may expect to get a hysteresis diagram good enough 
for any commercial purpose, but differing slightly at the beginning 
from the statical diagram found ballistically. Of course, it would 
not be easy to get any very accurate information, as some of the curves 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 149 


given in this paper show clearly, from a current curve taken in the 
exciting coil of a magnet which has a large solid core. 

It will be evident from what precedes that it is possible to predict 
accurately the building-up curve of a current in the coil of an electro- 
magnet with fine wire core, from 
a corresponding hysteresis dia- 
gram obtained by aid of a ballis- 
tic galvanometer of long period, 
and one of the old methods of 
procedure. 

Figure 43 shows two reverse 
current curves for ἃ toroidal 
magnet of about one third of a 
henry inductance belonging to 
the American '‘T'elephone and 
Telegraph Company. The final ee aree43) 
strength of the current was the 
same (1.42 amperes) in both cases, but the applied electromotive 
force was 10.9 for the left-hand curve and 21.5 for the other. The 
disturbing effects of eddy currents were here (as will be shown in the 
sequel) wholly inappreciable. We should be justified in expecting 
that each of these current curves would yield by aid of a good plani- 
meter a hysteresis diagram substantially the same as any ballistic 
step-by-step method would furnish for the same magnetic journey of 
the core. 


THe INFLUENCE OF Eppy CURRENTS UPON THE APPARENT MAGNETIC 
BEHAVIOR OF THE CORE OF A LARGE ELECTROMAGNET IN THE 
CoIL OF WHICH A CURRENT IS GROWING. 


If after the solid core of a large electromagnet had been demagnetized 
we were to establish a steady current in the exciting coil by applying 
to its circuit a constant electromotive force, eddy currents would, of 
course, be set up in the core, and at any instant during the growth of 
the current in the coil the iron at the centre of the core would be sub- 
jected to a magnetic field weaker than the field belonging to a steady 
current of intensity equal to the instantaneous strength of the coil 
current. If, therefore, we were to attempt to determine the magnetic 
properties of the core from the record of an oscillograph in the coil cir- 
cuit, we should find that the induction through the core corresponding 
to a given instantaneous current intensity in the coil was less than 
the flux belonging to a steady current of the same intensity as deter- 


150 PROCEEDINGS OF THE AMERICAN ACADEMY. 


mined from a statical hysteresis diagram. The same phenomenon 
appears when an electromagnet with finely laminated core has a sec- 
ondary coil. ‘The closing on itself of a secondary coil wound on the core 
of an electromagnet when a current is being established in the primary 
will, therefore, expedite at first the rise of this current, but the area over 
the current curves ought to be the same in the two cases, and we must 
expect, therefore, the building-up time to be somewhat longer when the 
secondary coil is closed than when its circuit is broken. 

It is to be expected, of course, that the curves which show the march 
of the current in the primary circuit will be noticeably different in form 
when the secondary circuit is closed and when it is open ; for this is 
often the fact in the case of two neighboring circuits which have fired 
self and mutual inductances (Z,, Z,, 27) if one of them containing an 
electromotive force # be suddenly closed at the time ¢=0, while the 
other, which contains no electromotive force, is closed. Here 


Ly: = + M: = +n-L= fs, 
(21) 
1] dT, 
M. apt ee? ai + r.:I,=0, 


where 7}, 75 are the resistances of the circuits and ἢ, 7, the currents in 
them. 


on UG) we Ee) 
i. — ΤΟΥ το and KS τ τοιοῦ 


where = LT ‘Ly Me Q = γα" Ln ar r1: Ln, ἘΞ 3 -- 4 γι. 72: 5; 


E 

h=; : Le $eM(re-Li— Lot 10) +heH'(re-Lys—71-Lo—R)], (22) 
1M 

ΤῸΞΞ = [ext — e™], (23) 
"Πρ ne Gee i,)\¢= 24) Gm 
Jo 7 7.4 0 71 


Figure 44 illustrates a typical case where S is positive : the heavy 
line shows the current in the primary circuit when 7; = 3 ohms, 72 = 
2 ohms, Z, = 3 henries, Z, = 2 henries, J/ = 4/6/3 henries, H, = 12 
volts, when the secondary is closed ; the lighter curve shows the rise of 
the current in the same circuit when the secondary circuit is open. 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 151 


3t 3t 


L,=4a—te #—+te 2), (25) 
and h=40-—e4. (26) 


The slope of the first curve is at the outset somewhat greater than 
that of the secondary curve, but eventually becomes less, the curves 
intersecting at a pomt Y. The area between the curve and the asymp- 
tote drawn parallel to the axis of abscissas is the same for both cases. 

If the circuits just described had in common a large closed iron core, 
the current curves for open and closed secondary circuit would be 


CURRENT. 


TIME. 
Figure 44. 


Currents in the primary circuit of an induction coil with air core, when the 
secondary circuit is closed (full curve) and when the secondary is open. 


much less like each other than the curves of Figure 44 are, even if the 
core were not solid. We may illustrate this fact by some oscillograms 
from a transformer which has a laminated core. 

Figure 45 shows two typical reverse current curves for the exciting 
coil of the magnet ᾧ which has 2788 turns, when the circuit of a 
secondary coil of 1095 turns is (2) open and (C) closed. Both curves 
rise very rapidly at the start, and then bend suddenly, so as to become 
almost horizontal for a time, but in the first fifth of a second the curve 
taken when the secondary is closed attains 40 per cent of its final 
value, and the other curve only 18 per cent; yet the second curve 
reaches half its height about two fifths of a second sooner than the 
‘first does ; and when the secondary 15 open the current in the primary 


152 PROCEEDINGS OF THE AMERICAN ACADEMY. 


circuit reaches 98 per cent of its maximum strength in about ths of 
a second less time than when the secondary is closed. In this case the 
final current was 2.80 amperes. Of course the degree of divergence of 
the current curve for the primary circuit when the secondary is closed, 
from the corresponding curve when the secondary is open, depends 
very much upon the number of turns of the secondary and upon its 
resistance. 


- Figure 45. 


Reverse current curves for the coil of 2788 turns belonging to the magnet Q, 
when the circuit of a secondary coil of 1095 turns was closed (C) and open (J). 
The resistance of the primary circuit, which contained a battery of 40 storage 
cells, was 30 ohms. 


Figure 46 shows both reverse and direct curves for the magnet Q 
when the primary and secondary coils were geometrically alike and 
each had 1394 turns. The resistance of the primary circuit was about 
16.7 ohms. 

The curves of Figure 47 belong to a primary coil of 823 turns of the 
magnet ᾧ. The lines which have O as origin represent currents of 
about 2.05 amperes due to astorage battery of 10 cells ; the lines which 
start at .V were caused by currents of 7.55 amperes from a battery of 
40 cells. 

Figure 48 shows direct and reverse curves for a current of 3.30 am- 
peres (due to a storage battery of 40 cells) in a coil of 1394 turns 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 153 


belonging to ὦ. The curves 77, N were taken with a secondary coil 
of 16 turns and comparatively high resistance closed ; the boundaries 


0 U SECONDS. 
FIGURE 46. 


Direct and reverse current curves for a coil of 1394 turns belonging to the 
magnet @ when a secondary circuit of 1394 turns was closed and open. 


of the shaded areas m, n show the forms of the currents induced in 
this secondary as obtained from an oscillograph in the circuit. Since 


Figure 47. 


Direct and reverse curves representing currents in a primary coil of 823 turns 
belonging to the magnet Q, for open and closed secondary circuit. The second- 
ary coil had 2788 turns. For the curves which start at O the voltage was about 


20.6; for the curves which begin at X the voltage was about 82 and the maximum 
current 7.55 amperes. 


154 PROCEEDINGS OF THE AMERICAN ACADEMY. 


the number of turns in this secondary was so small and the resistance 
large, the forms of the curves J/, NV are not very different from what 
they would have been if the secondary circuit had been open. The 
curves V’, W were taken with another secondary circuit of 1095 turns 
closed on itself: the boundary of the area v shows on an arbitrary 
scale the form of the induced current in this last mentioned secondary 
circuit. 

It is not to be expected, of course, that a current curve for the ex- 
citing coil of an electromagnet which has a large solid core will be so 
much altered in general appearance by the closing of a secondary coil 


FIGURE 48. 


as it would be if the core were divided so as to prevent in large measure 
the effects of powerful eddy currents which are present when the iron is 
in one piece. 

Even in the case of an electromagnet the core of which is built up of 
broad varnished pieces of sheet iron, eddy currents in this iron may 
radically change the form of a current curve unless the sheets are very 
thin. Figure 49 illustrates this fact by an actual example drawn to 
scale. 

Figure 50 shows curves belonging to a certain transformer. J/ is a 
piece of a statical hysteresis curve ; V is a similar curve obtained from 
a reverse current oscillogram. Although the core of this magnet is 
made up of varnished pieces of sheet iron, the effects of eddy currents, 
as will be shown more clearly in the sequel, are here very noticeable. 

Some instances of the phenomenon just mentioned suggest a possible 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 155 


pure time-lag}? of magnetization, like that observed by Ewing and Lord 
Rayleigh, large enough in the case of a very large core to affect some- 
what the forms of the current curves ; in fact, I have spent a very long 
time and have made many measurements upon a great number of oscil- 
lograph records in order to see whether any such lag could be shown ; 
but after all allowances have been made for the effects of eddy currents, 
nothing tangible, if anything at all, remains, for such moderate excita- 
tions as I have used with closed, finely divided cores. 


ΡΠ ΞΡ ee 
“ΘΓ ΠΡ ΚΡ ν ναῷ 1. Ἰ 


& AMPERES. 


ο 
oa 


3 SECONDS. 
Ficure 49. 

The full line represents the actual form of a reverse current curve in the coil 
of a certain transformer the core of which is laminated; the curve sketched out 
by dashes represents the theoretical form as obtained from the statical hysteresis 
diagram. The dotted curve represents on an arbitrary scale the areas between 


the real curve and the asymptote ; the flux change being nearly proportional to 
the time. 


If to a circuit — without iron and unaffected by any neighboring 
currents — which has a fixed inductance Z, and resistance 7, be applied 
a fixed electromotive force, /, the current-time curve will follow the 
equation 


rt 
ae, 


and the current will attain the intensity 4, = H#/(r+h) at the time fy 
such that 


12 G. Wiedemann, Galvanismus, 3, 738. Ewing, Magnetic Induction, ὃ 84. 
Gumlich und Schmidt, Electrotechnische Zeitschrift, 21, 1900. Riicker, In- 
augural Dissertation, Halle- Wittenberg, 1905. 


156 PROCEEDINGS OF THE AMERICAN ACADEMY. 


If, however, the resistance of the circuit at the outset had been 
(r + /) and if after the final value of the current 70 for this resistance 


1,500,000 


1,000,000 


500,000 


LV, 


M is a portion of a statical hysteresis dia- 
gram for a certain transformer under an excita- 
tion of 1812 ampere turns. Nisa similar curve 
obtained from a reverse current oscillogram. 


AMPERES. 


Figure 650. 


had been established, the 
extra resistance had been 
suddenly removed from the 
circuit, the current curve 
from that instant on would 


have followed the equation 


rl’ γί" 


L=lhe™ bese 7), 


or, since 
rly 


1, = Ἐν 1), 


we +to) 


τ ἃ τὴν 


It is clear, therefore, that 
in the case of a circuit of 
this kind the last (upper) 
portion of a step curve of 
the form U (Figure 4) will 
have exactly the same shape 
as the corresponding part of 
the V curve, although the 
lower portions may be very — 
different. 

If in the case also of a 
circuit which has one or 
more finely divided iron 
cores the flux of induction 
through the cireuit can be 
considered as a single val- 
ued (given) function of the 
current strength when the 


magnetic state of the iron at the outset is given, the upper portion of a 
curve of the {7 type (Figure 4) belonging to the circuit will be identical 
with the corresponding part of a curve of the V type. We need con- 
sider only a U curve with one intermediate step. If the induction (17) 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 157 


through the circuit corresponding to a current of intensity / is ¢ (J), 
and if the resistance of the circuit is 7, the differential equation which 
determines the growth of the current is 


nN pp κα PO gy 


dt 5-- 1 
Since ¢ is known, the coefficient of 7/7 is known after values have been 
assigned to the constants # and #. If with a given Δ᾽, & has the 
value 7, the curve obtained by plotting the coefficient of α΄} against 7 
will have a shape something like that of the line ACDP of Figure 51, 
which has the line 7 = #/r for an asymptote. If with the same value 
of the electromotive force 2 has the value (7 +h), the curve will havea 
shape something like that of the line ADA, which has the vertical 
asymptote [= #/(r-+h) 
which passes through Q. If Τ 
with the core in the state for Cc 
which the diagram is drawn, 
the circuit be closed at the 
time ¢ = 0, and if the resis- 
tance be (r+ A), the time 
required for the current to 
attain any value /’ less than ΙΝ 
E/(r +h) is proportional to | LAL ΤΙ, 
curve ABDA from the ordi- 6 
nate axis up to the vertical Ficure 51. 
lnez=/J'. If, however, the 
resistance of the circuit had been 7, the time required for the current 
to grow to the intensity Z’ would be represented on the same scale by 
the area under the curve ACDP from x=0, tow= TJ’. If the circuit 
were closed when its resistance was (7 + Δ), and if the current were 
allowed practically to reach its final value for this resistance, as repre- 
sented by the line OZ, and if then the resistance ὦ were suddenly 
shunted out, the current would grow to its new final value at a rate 
determined by the fact that the time required to reach the current OH 
must be equal, on the scale of the diagram, to the area HF’ PH. If the 
circuit had been closed first when its resistance was 7, the time required 
for the current to grow from the intensity OZ to the intensity O/T 
would still be equal, on the scale used, to the area HF'PH, and the 
shape of the current curve, from //(r - 1) on, would be the same as 
before. Of course the WV of this theory need not be the same as the 
NV of the statical hysteresis diagram for the given magnet; it might 


Ss 


SSS 


= 
ὡς 
Ss 


SS 


= 
= 


S 
SSS 


᾿ς 
ὡς 
> 


SS 


= 
ὡς 
SS 


SS SS 
= 
ὡς 


SS 
os 
SSS 


3 


= 


SS 


SS 


158 PROCEEDINGS OF THE AMERICAN ACADEMY. 


have for any value of Ja value which in the case of the statical curve 
belonged to a current weaker by any given constant or otherwise deter- 
mined amount. The curve 4} must, however, have the same form 
for a continuously growing current and for one which suddenly begins 
to increase from the value OF. 

As a matter of fact, experiment seems to show that if the core of an 
electromagnet is made of varnished wire so fine that eddy currents are 
practically shut out, the upper portion of a {7 curve with a single inter- 
mediate step is exactly like the corresponding portion of the V curve. 
Figure 52 represents a set of current curves obtained from a number 


5. ὼ Ww 


\ 
) 


CURRENT. 


δ 


σι 


᾿ 


τ 


| 


SECONDS. 


Ficure 62. 


Current curves for a coil with fine wire core. The second part of a two-stage 
current is exactly the same as if the current were allowed to grow at once to its 
final value. 


of toroidal coils (with very fine wire cores) connected up in series ; the 
current came from a storage battery of ten cells.) When the circuit had 
its normal resistance, the final value of the current was represented by 
OA ; it was possible, however, to close the circuit with such an extra 
amount of resistance that the final value of the current should be repre- 
sentable on the same scale as before, by the line OA. The extra resist- 
ance could then be suddenly shunted out of the circuit by closing a 
switch at any time after the lower current had practically attained its 
maximum strength. When the core had been previously demagnetized, 
a diagram of this kind had the form OH DU ; but if the circuit had 
from first to last its normal resistance, the current curve had a shape 
accurately represented — when the starting point was shifted tothe proper 


PEIRCE, — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 159 


point (P) on the time axis—by PDYU. The upper part of the curve 
was in no way distinguishable from the corresponding portion of the {7 
diagram. Mr. John Coulson and I have taken many records of this 
kind and have not been able to detect any difference between the 
upper parts of the different kinds of curves. The second part of the 
{7 diagram starts off at exactly the same angle with the horizontal that 
| the other curve has when the line XG is crossed. The area OKDHO 
when divided by the length OX should be the same as the area PST’DP 
divided by the length OA. 

If eddy currents are present, the upper portions of a {7 diagram and 
ofa V diagram do not entirely agree. Figure 53 represents diagrams 


— NN / \ 
ΠΝ YM MAY KY} Wi 
WAY yi MY Ρ 
AMAT ἡ γὴ } 1A) 
/ i / 
MVM 
᾿ YY AVY 
ANIMA LAY 
ΝΥ ALYY 
/ 
Wi 
᾿ ΝΥ 
/ i 
VYH/ 
ὺ 


ὁ 1: | a 


Figure 53. 


ὴ 
Ni ) 
IXY XK) 
RR ἮΝ 


SECONDS. 


Growth from an originally neutral core of a current in a transformer with 
a laminated core. The effects of eddy currents are here noticeable. 


for the magnet @ which has a laminated core, although eddy currents 
are not entirely shut out. If the upper part of the {7 diagram (GDQ) 
be shifted to the left, it will be found to agree with the curve PCO from 
P to C, but beyond C the two are quite different, as the dotted line 
indicates. When the V current, the growth’ of which is represented 
by the line OCP, has reached the strength OA, the induction flux 
through the core is only a small fraction of the flux when a steady 
current of final strength OA is established in the coil in the manner 
represented by OAKG. The existence of eddy currents is indicated 
clearly by the fact that the first portion of the curve GDQ is nearly 
vertical. These diagrams were obtained when the core had been well 
demagnetized. Figure 54 shows similar diagrams for direct curves 
(dotted) and for reverse curves (full). 


160 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Tue GrowtH or THE [NDUCTION FLUX IN THE CoRE OF AN ELEC- 
TROMAGNET WHILE THE EXCITING CURRENT 1s ‘TEMPORARILY 
CONSTANT. 


It sometimes happens that if a number of secondary coils of low 
resistance, wound upon the core of an electromagnet, are closed on 
themselves, the building-up curve of a current in the exciting coil is 
for a comparatively long time almost exactly parallel to the time axis. 
During this time it is difficult to detect any change in the intensity 
of the current, and yet the, flux of magnetic induction through the 
core is increasing at a very nearly constant rate. This fact, which 
has a certain pedagogic interest, is easily illustrated. The curve 


K a 
Vi) yy HN Ste a 


Aah piney 


iM iy i ᾿ i iv 
᾿ 


Figure 84. 


Direct and reverse current curves for a transformer with a laminated core. 
The existence of eddy currents is clearly shown. 


OPQU (Figure 55) shows a nearly typical case, and the line OA LG 
represents on a different scale the induced current in one of the second- 
ary circuits. ΤῸ a person watching an amperemeter in the primary 
circuit, the current seems to have attained its final value in less than 
a second, and if he leaves the instrument at the end of, say, five sec- 
onds, he feels sure that the current has become steady. Meanwhile the 
induction flux, as measured on the scale of the diagram by the area 
between the curve and the line YU (or, on a different scale, by the 
area under the curve OALG), is constantly growing. Of course if the 
core is very large, the whole building-up time may be a minute or 
more, and the phenomenon may then become very striking. 

The magnet 7’ has three coils. The first (A) has 750 turns, the 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 161 


second (2) 250 turns, and the third (C), which is made of wire of very 
large cross-section, has a small unknown number. Figure 56 reproduces 
accurately the records of two oscillographs, one in the coil A, the other 
in B, when C was closed. O.JW/QZL is a part of the building-up curve 
for the main circuit (4), and Ochs is a corresponding portion of the 
record of the induced current in &. In the case represented by the 
full line OMQTV W, the coil C was suddenly opened at about 1.05 
seconds after the start: Ocbznda shows the record of the induced 
current in B under these circumstances. The scales of the two oscillo- 
graphs were, of course, not the same. ‘The sudden jumps in the 
oscillograms might have been predicted, in amount as well as in direc- 
tion, by the principle of the “Conservation of Electromagnetic Mo- 


U 


pr] MLL LLL UMA A YYW, 


"ἢ ἯΙ 
ἀν RAP 
ἮΝ ἌΝ, ἮΝ Νὰ NE 
Mi Nth RNIN RDN AR OOK SI SI WNUK EL G 
SECONDS. 


FIGURE 59d. 


menta.” We shall return to the subject of the sudden changes brought 
about in the currents in inductively connected circuits when the 
inductances of the system are impulsively changed. 


Tue EFFECTIVENESS OF ΕἾΝΕ SUBDIVISION IN THE CorE OF AN ELEcTRO- 
MAGNET FOR THE PREVENTION OF ELECTROMAGNETIC DISTURBANCES 
DUE To Eppy CURRENTS, WHEN A STEADY ELECTROMOTIVE FORCE Is 
APPLIED TO THE CIRCUIT OF THE ΕΧΟΙΤΙΝα Colt. 


In order to determine approximately the magnitude of the effect of 
eddy currents upon the growth of a current 15 in the coil of an electro- 
magnet the core of which is made of fine iron wire, we may consider 
the case of a very long solenoid consisting of VV turns of wire per cen- 
timeter of its length, wound closely about a long prism of square cross- 


13 The influence of eddy currents in the formation of a regularly fluctuating 
current in the exciting coil of a transformer under a given, alternating electro- 
motive force has been studied by J. J. Thomson for cores of square cross-suc- 
tion built up of iron sheets, and by Heaviside for round cylindrical cores cut 
radially. See the Electrician for April, 1892, and Heaviside’s Electrical Papers, 
1, xxviii. 

VOL, xLi.— 11 


162 PROCEEDINGS OF THE AMERICAN ACADEMY. 


section (2a X 2a) built up uniformly (Figures 59 and 60) of a large 
number of varnished filaments of square cross-section (ὁ Χ 6), or else 
consisting of a bundle of infinitely long straight wires. ‘he axis of 
the prism shall be the z axis, and the « and y axes shall be parallel 
to faces of the prism. ‘The electric resistance of the solenoid per centi- 
meter of its length shall be w, the constant applied electromotive force 
per centimeter of the length of the prism shall be Μ᾽, and the intensity 
of the current in the coil shall be C. Within the core, the magnetic 
field (/7) will have the direction of the z axis, and if gis the current 
flux at any place 


4 7q = Curl H, (27) 
oH CH 
or Ang, = ay? 4Anq,=— δε’ 4 xq, = 0. 


Within any filament of iron in the core, H satisfies the equation 


oH __p (@H | Ὁ: 
δὲ ἀπμιδι OP 


(28) 


where p is the specific resistance of the iron and μ is its permeability, 
which for the present purpose shall be regarded as having a fixed 
value. 

When there are no Foucault currents in the core, the intensity (/7 ) of 
the magnetic field within has at every point the boundary value //, 
or 47 NC, but if positively directed eddy currents exist, H may be 
greater at inside points than at the surface. We need not distinguish 
between the flux p through the turns of the coil per centimeter of its 


length, and N times the induction flux 4 Ae dxdy through the 


core, so that we may write 


"-- ae — un [{ ‘dedy=w:-C= ΞῈ os 29) 
dt 


or by virtue of (28), 


a c+ J (Gat τὸ oi dy, (30) 


where the integration extends over a cross-section of the core. 
The vector 17 is always perpendicular to its curl, and the intensity 
of the component of the current at any point in the iron, in any direc- 


ὃ 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 163 


tion, s, parallel to the zy plane at any instant, is equal to 1/4 7 times 
the value at that point, at that instant, of the derivative of H in a 
direction parallel to the wy plane, and 90° in counter clockwise rota- 
tion ahead of s. 

Along any curve in the iron parallel to the zy plane, H must be 
constant if there is no flow of electricity across the curve. At every 
instant, therefore, the value of 7 at the boundary common to any two 
filaments must be everywhere equal to Hy. If the coil circuit is 
broken, 7 must be constantly zero at the surface of every filament. 


Two or three general theorems concerning solutions of differential 
equations of the form 
Ow rm Ow Ow 
q An ED “πο 
I\ δι oy? dz’ 
will be helpful to us. 


If v and w represent any analytic functions of 2, ἡ, z, and if L (w), 
M (0) represent the adjoint differential expressions 


Cw Cur Ow 
. { eee .... -ε Ἠθβ 


9 
9 δ 5 oy” dz’ (31) 
83 ὃν ὃυ 
. . e 2 
ae Tg Cy” a dz’ (32) 


the corresponding form of the generalized Green’s Theorem may be ex- 
pressed by the equation, 


ff. [v-L(w)—w-M(v)] - (ἡ ἂν ας = 
au : 
if {oF = Ἔ we): cos (7,2) -dS+ 
- Ow Ov ᾿ 
aff (ese; ἫΝ cos (y, n)- dS =f for ες, n)-dS; (33) 


and it is easy to prove that 


Ef pe) ae π᾿ Γ᾿ cos (a, n) Ὁ ἘΣ 7 C08 (Ys n) as 
Ow oF > Ow 
-[{{{ τ ἘΦ’ ἢ re: «ἄν ἂν ἄς. (34) 


164 PROCEEDINGS OF THE AMERICAN ACADEMY. 


If w and v are identically equal, the last equation becomes 


: ν ow Vas 

[fife L (w)-dadydz= of | w (ξ ἐ008 (2,2) + ay - COS (yn) Jas 
dw \? ow \? ὙΠ ᾿ 

-- ὙΠ οἷς ({) | vayas τας iff w - cos (2, "ae 


(1) If, is a closed cylindrical surface the generating lines of which 
are parallel to the z axis, and if 2, 2/— two functions which within 
Np satisfy the equations Z (Ω) Ξξ 0, Z(Q’) = 0 — (1) vanish at all points 


TIME. 


Figure 656. 


of So and at all points within S, for which z is positively infinite, and 
(2) have the given constant value ©) at all points in the zy plane 
within S,; then if we apply (35) to the difference between 2 and /, 
using as a field of volume integration the space inside S, on the positive 
side of the ay plane (Figure 57), we shall learn that in this space 2 and 0! 
must be identically equal. The value of 2 within 4 is in no way 
affected by conditions which a physical extension of the function 
might be required to satisfy outside Sp. 


(Il) If S is a closed cylindrical surface, the generating lines of 
which are parallel to the z axis, if Wis a function which within 4, 
satisfies the equation ZL (W)=0, and if 

(1) Wand ¢W/éz vanish at all points within and on S for which 
2 18 positively infinite, 

(2) W has a given constant value (JV,) at all points on the zy 
plane within 4}. 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 165 


(3) Won, is a function (W) of z only, such that if n indicates 
the direction of the external normal to S, 


Wet kf (τ a= (36) 


where / is a given positive constant, and the line integral is to be 
taken around the perimeter of a right section of δὴ made by the plane 
z=z; and, hence, if 


(4) i } (Ξ dS, taken over so much of the zy plane as lies within 


S), is given, then JV is uniquely determined. 
If we assume that two different functions (W, W’) may satisfy all 
these conditions, and denote their difference by w, 


L (u) =0, within Ὁ, ¥ 


w and δι ὃ: vanish at all points 
within S,, for which z is positively 
infinite, 

w vanishes at all points on the zy 
plane within Δ᾽, 

u on & satisfies the equation 


Cu τῷ O 
us tk oe asi 0. (37) Figure 57. 


If we use the space bounded by S,, the zy plane, and the plane 
z=, asa field of volume integration, and denote the whole bound- 
ary by S, then, since cos(z, 2) vanishes on S, and τ, 605 (ὦ, 7), 
cos (y, 2), vanish on the portions of the planes z=0,7= » used as 
boundaries, (35) yields the equation 


Cu Cu 2 pee Ay : 7 
Sle + (5) |e dy dz =f fuss as (38) 


Now w has the same value at all points on the perimeter (s) of any 
right section of S,, so that 


hae -dSo = fv dz dee ds = — — εν τος (39) 


>| 


a 


166 PROCEEDINGS OF THE AMERICAN ACADEMY. 


and (38) becomes 


SIS (a) + + (#) “Jawayas + tf [. 2.dz2=0, (40) 


where Δ is intrinsically positive; but each of these last integrals has 
an integrand that must be either zero or positive at every point in its 
domain, so that w must be independent of 2 and ἡ, and must vanish 
on S, at every point. It follows that wis everywhere zero and that 
W=W'. 

It is evident that the condition (3) might have been stated in the 
form of the equation 


a2 ΠΤ’ 2 
γι ἘΠ Sf (Ge LE +5) ad =0, (41) 


where the integration is to be extended over so much of the plane 
¢ =z as lies within S,. 

If the space within S) were cut up into portions (filaments) by the 

cylindrical surfaces δι, S2, S3,- τ -, the generating lines of which were 

parallel to the z axis, and if within each filament 

1, (W) vanished, while, in addition to the other 

ee requirements enumerated above, W were constrained 

to have at every point of the surface of every filament 

&S JID the value (IV), which points with the same z co- 

O ava Ὁ ordinate on the surface S) had, — though the normal 

derivative of W at the common surface of two fila- 

Figure 58. ments were not expected to be continuous, — we 

might assume as before that two different functions 

could satisfy all these conditions and denote their difference by uw. 

We could then apply (35) to every filament separately (Figures 57 
and 58) and obtain from each an equation of the form 


[ΑΓ εν {ΠῚ Ὁ #(@) ana 


(42) 


where B denotes a cross-section of the filament. If, then, all these 
equations were added together, the resulting equation would be 


Jose τ +- LPI UC) (6) eens 


which is (35). In this case also, therefore, W is determined: 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 167 


(III) If S% is a closed cylindrical surface the generating lines of 
which are parallel to the z axis, if V is a function which within Sj 
satisfies the equation LZ (V) = 0, and if 

(1) V and @V/éz vanish at all points within and on S, for which z 
is positively infinite, 

(2) V has a given constant value (V,) at all points on the zy plane 
within S;, 

(3) Von &% is a function (V;) of = only, such that, if 2 indicates 
the direction of the external normal to S, 


Vet 


V's eV 23 
or pes ΠΣ +o ») de dy = 0, (44) 


where ὦ and / are given positive constants, the line integral is to be 
taken around the perimeter (s) of a right section of Sy made by the 
plane z=, and the double integral over the section; then V is 
uniquely determined. 


dV s 


ds = 0, 


(IV) Let δὺ bea closed cylindrical surface which completely surrounds 
(Figure 58) several other mutually exclusive, closed cylindrical surfaces 
(ϑι, S2, Ss,- τ τ) the generating lines of which are parallel to those of Sp 
and to the z axis; and let the intersections of these surfaces with the 
plane z = z be denoted by 80» 81» s2, ss,- +--+. Let the portions of the 
plane z = z within S,, S., S;, - - -, be denoted by Ai, A, As, - - -, and 
the portion within 8, but outside δὲ, S., S;,---, be denoted by A,. 
Let 7 τι, T 7s, " "5, represent the volumes of the prisms (bounded 
by the planes z = 0, 7 = ~) of which the cross-sections made by the 
planes 2 =z are A,, A, As, As, ---. 

In the regions τι», 71, 72, Το, ° +; let the scalar function U satisfy 
the equations 


au eu, PL 

oe = 90 ( Fs Ἢ =) 

au 8517  eU 

eam Geet ae (5) 


ane wonie, οἱ ἴοι πο; .04- 0 (e) (δ᾽. ἴοι, \6) τοῦ 6 


168 PROCEEDINGS OF THE AMERICAN ACADEMY. 


where 4%, 91, J2, Js are given positive constants, and let the value ( 17.) 
of 7 on the cylindrical surfaces be a function of 2 only (the same for 
all the surfaces), such that 


2377 ii 2 
U,+ hf { (So+ + ap iat τα vo) 
27 
τὰ [{{{τ Ὁ Ὅτ) 14: Sis 5 sau, (46) 


where ἦν» ἦι, 42, ks are given positive constants. Then if {7 has the 
constant value U, at all points in so much of the ay plane as lies 
within S, and the value zero at all points on and within S, for which z 
is positively infinite, {7 is determined in the positive space within S,. 
For if we assume that there could be two such functions and apply 
(35) to their difference (w) in each of the regions 7,, 71, Τα, Ts, "" 
multiply the resultant equations by /,, ἦ:, fe, ΓΒ -++, and add tha 
together, it will be easy — to show in the way indicated under (II) 
—that w is zero everywhere inside S, on the positive side of the 
vy plane. 
It is to be pecans that 


PU te, 
On" τ ey” (47) 


is an invariant of a transformation of orthogonal Cartesian co-ordinates 
in the ay plane. 


(V) In an important special case similar to that stated in (IV), 
ἦι, ἦς, ks, + +, ave all equal, σι, Js, gs, + - +, are all equal, and all the 
n> areas A,, Ao, Ἂς, τ τ τ, are alike in form, however they may be 
oriented. In the region το, {7 is everywhere equal to ls, which is, as 
before, a function of z only, and the surface condition becomes 


τ 


Us 


oN at tA G8) 


ae 


where / and ἢ are given positive constants. 
If in this case we find for every one (7,,) of the regions 71, Τῷ», 73° + *; 
the function (w,,), which within (r,,) satisfies the equation 


ΕΠ (ue 5. Fee), (49) 


Ox" oy” 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 169 


and at the boundary the surface condition 


ee πὸ + atk [{{Π Wm Sat tn = 0, (50) 


and which has the given constant value U7, on so much of the zy plane 
as lies within S, and the value zero when z is infinite, and if we assign 
to the function without S,, where it is not defined, the value zero, then, 
apart from differences of orientation, all these functions will be alike. 
If after this we define a function within S, by assigning to it within 
every one of the regions τι, Τῷ, Τῷ, "τ, the same value as the zw func- 
tion belonging to this region, and give to it in 7, the common value wz, 
the function thus determined will be the unique function {7 described 
above. 


If after a steady current of intensity //w has been running for some 
time in the coil of the solenoid under consideration, so that the mag- 
netic field within the core (which in this case 
shall be built up, in the manner shown in 
Figure 59, of filaments of square cross- 
sections) has everywhere the given constant 
value H,, the coil circuit be very suddenly 
broken, the value of H falls instantly, not 
only at the outer surface of the prism, but 
also at the surface of every filament, to zero. 
Inside every filament 


| 
Soe SeE Sse 
8] as] | | 
CH _ p OOH ‘ OH (51) Figure 59. 

ot 4πμ ΜΡ 


When ¢ = 0, H = H, everywhere within the iron, and when ¢ is in- 
finite, the field intensity is everywhere zero. According to (1), there- 
fore, we may consider every filament by itself. 

If we seek a solution of the equation (51) which shall be of the form 
AX: Y-T, where X involves z alone, Y involves y alone, and T isa 
function of ¢ alone, we shall obtain the expressions 


X=A,-coser+ A,-sinaz, Y=B,-cosGy+ B.-sinBy, T=e—*, 
(52) 

where 

p(a + B*) 


ΔΩ ΞΞ 
4πμ 


170 PROCEEDINGS OF THE AMERICAN ACADEMY. 


If we use as normal function the product 


. ne .. Or 
Amn se7 2 sin + oi (54) 
c c 


where A* = zp(m? + n*) (4 με) and m and n are positive integers, 


and write 
mM—O N—c 


mre nr 
H= bs dsm et. sin aie a ἐξ αὶ 


(55) 
m—1 n=1 
this expression will satisfy all conditions if A,,,, be so taken that when 


¢ =, the second number of the equation shall be equal to //, for all 
values of 2 and y within the filament. We have, therefore, the 


equation 14 
Am = 2 [ [sin 2X. sin ay (56) 
( 0 0 ce c 
and yee Be Ay 
= mn 
when m and 7 are both odd ; 
Amn ΞΞ 0, 


when either m or 2) is even, so that 


/ 
j= 


_ 16H, ee _ (2k + πα (29 + Ἰὴ)ὴπν 
ἜΣ Ἐπ Σ ἘΠ το. (51) 


pV eA 2 δ 2], 
δ τρία τ D+ ΟΊ Ὲ 1)}} (58) 


From (58) it appears that the whole flux of Se ys induction 
through the core at the time ¢ is 


j= k= - 
64-u-H,- εἰ Tee ᾿ 
oy π' Σ Ἔ1) Δ + 1)” (59) 


71 


or, if g = πρὶ] uc’, 


14 Byerly, Treatise on Fourier’s Series, ete., § 71. Riemann-Weber, Die par- 
tiellen Differential-gleichungen der mathematischen Physik, Bd. II, § 99. 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 171 


64-u- ja bp : Cr e—9(25-+1)% Rae eH 2k+1)% 
re at (27+ 1)* “κα (2 ὁ Ὁ 1)? 
= ’ 


= k= 


(60) 


In these equations absolute electromagnetic units are to be used, and 
for good soft iron we may assume that zp/4 is very approximately equa! 
to 8000. It is evident that for different values of ¢ when μ is given, 
e—* will have the same numerical value for values of ¢ proportional to 
e?; for instance, if ὁ = 20, ὁ = 10, e—** will have the same value as it 
would if ¢ were 1 and ¢, 1/40. If ¢ is fixed, e—*” will have the same 
value for values of ¢ proportional to μ. 

It is possible to show that if ὁ = 1 and » = 200, — to take a special 
case, — the series 

k=0 


eo 2 +14 


Y_— 


= FT Law (61) 
hea (2 1) 

k=0 
has at different times the approximate values given in the following 
table : 

TABLE V. 


0 238 0.01000 0.6734 


0.00025 14 0.02000 0.4494 
0.00050 : 0.02500 

0.00100 056! 0.05000 

0.00200 : 0.07500 0.04979 
0.00250 0.10000 0.01852 
0.00500 0.8374 0.20000 0.00054 


From the numbers in this table it is easy to compute, for cores of 
square cross-section, the fractional part of the original induction flux 
through the core which remains after the circuit of the exciting coil has 
been broken for a given time. For a solid core, the area of the square 
section of which is 100 square centimeters, the results are given in the 
next table, when μ is 200. 

If the core were built up compactly of varnished square rods of one 
square centimeter in cross-section, the times in the table should be 


172 PROCEEDINGS OF THE AMERICAN ACADEMY. 


divided by 100, and if the core were made up of 10,000 slender fila- 
ments, the flux would sensibly disappear during the first thousandth of 
a second. It is easy to get similar results for any other value of μ. 


TABLE VI. 


Time in Seconds Fractional Part Time in Seconds Fractional Part 
after the Breaking of Original Flux after the Breaking of Original Flux 
of the Circuit. still remaining. of the Circuit. still remaining. 


0.000 1.000 1 0.298 
0.025 0.861 4 0.199 


0.050 0.807 . 0.089 
0.100 0.75: 5. 0.012 
0.200 0.635 ; 0:0016 
0.250 0.597 1 0.0002 
0.500 0.461 


If the cross-section of the core were acircle of radius a, and if, after 
a uniform magnetic field of strength Hy) had been established in the 
core the exciting circuit were suddenly broken, the intensity of the 
field at any time, at any point distant 7 centimeters from the axis 
would be given by the expression 15 


ἫΞ 2 Hy > J (nk 7) o-Ps (62) 


a ne Jy(ne- a) 


where β3 = pn?/4 7p and the whole flux through the core would be 
8 


Bot 
yen ile Hier ἢ SS Ba (63 


In these equations »,a is the Ath root in order of magnitude of the 
Bessel’s Equation 
J, (na) = 0. (64) 


15 Heaviside, Electrical Papers, 1, xxviii. Peirce, These Proceedings, 41, 1906. 
Byerly, Treatise on Fourier’s Series, ete., p. 229. 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 173 


The first ten roots are as follows: 
TABLE VII. 


18.071064 


21.211637 
24.852472 
11.791554 27.493479 


14.930918 30.634606 


From these numbers the β᾽5 can be found, and then from (63) the flux 
in the core after any interval. When the time is short, the series con- 
verges very slowly, and the computation is long and troublesome, but 
for relatively large values of ὁ the work is not difficult. 

The next table shows the fractional part (Q) of the original flux re- 
maining in a core, the cross-section of which is a circle of 20 centi- 
meters diameter, and in which w is 200; 1 second, 4 seconds, and 8 
seconds after the breaking of the exciting circuit: the corresponding 
fraction for a core of square cross-section (20 cms. X 20 cms.) is given 
for comparison. The actual value of the original flux is of course a 
little larger in the second case because the area of the cross-section is 


greater. 
TABLE VIII. 


Qforthe — © for the 
Round Core. Square Core. 


0.588 0.597 


0.270 0.298 


0.106 0.183 


After 16 seconds © for the round core would be 0.016. In the case 
of a round core of exactly the same cross-section area as the square 
solid core, and the same original flux, the fractional part remaining 
after one second would be 0.630. 


If the square core of the solenoid — the area of the cross-section of 
which is A square centimeters — be made of a bundle of infinitely long, 


174 PROCEEDINGS OF THE AMERICAN ACADEMY. 


straight iron wires, placed close together (Figure 60), and if, after a 
steady current of intensity #/w has been running for some time through 
the solenoid, so that there is a magnetic field of 
uniform intensity 17) = 47N£/w in the core, the 
applied electromotive force be suddenly shunted 
out of the solenoid circuit, the current (C) in the 
coil will gradually die out. At any instant the 
field, in so much of the space A as is occupied by 
air, is 4 VC, for eddy currents in the wires act 
ee τ like solenoid sheets and do not affect the field 
without the wires. Within each wire there are 
eddy currents, of course, and at every point in the wire, at every 
instant, the field intensity, HW, must satisfy the equation 


2 2 
gH aa ee eH (et 


ἐπ πὶ Ec eee 


The induction flux through the turns of the solenoid per centimeter 
of its length shall be p, so that 


dp Ἔν: dp _ 
" -- ee C, or, in this case, a oe wl, 


If there are x? wires in the core and the area of the cross-section of 
each of them is B, 


p=47rN°O(A — n*B) + pv { Hae dy (66) 


where the double integral is to be extended over the cross-sections of all 
the wires ; hence . 


CO τ é 7 
wl + (A —n*B)4 ww. oh uv ff oT de dy=0; (67) 
and if the wires fill the square space as full as possible, 


A — n°B = 0.2146 A, nearly. 


If 77, represents the strength of the magnetic field in the air space 
within the solenoid, 


oT 72 
Hs +" τα -- ἀπ τὰ ὅτε : | γ OF εάν =0. (68) 


dt 


a 
ἃ 
a 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 175 


The function H thus defined falls under theorem (V) above, and it is 
evident that we ought to seek, for a single wire, a function τ which 
within the wire shall satisfy (65), at the surface shall fulfil the 
condition 


2 
π΄ (A—n poe 4 s. ἄς ἄγ τ, (69) 


and which when ¢ = 0 shall have the value H, and when ¢ is infinite, 
the value zero. When we have to deal with a single wire of radius 
b(=a/n) alone, it is obviously convenient to use polar co-ordinates 
with origin at the point where the axis of the wire cuts the zy plane, 
and if we do this (65) and (67) take the forms 


ΠΕ 2 Tes 7 
δὲ Amps =| =|, (10) 
2 Bey, “ 2N ol Oa 
os + 5, (A — n2B)= tie =0, (71) 
Ww ΟΥ̓ ὃ 
Ss 5 
or ws + 1-25 + dnt =) (72) 
rab 


where J, ᾧ, ἢ, and ὦ are given, positive constants. 

If we attempt to find a solution of (70) in the form of the product 
of a function of ¢, and a function of 7, we arrive, of course, at the nor- 
mal form 

eF*(L- J,(mr) + W- K,(mr)), (73) 


but Bessel’s Functions of the second kind will not be needed here, 
and we may write, 27 = 0, 


w= > Lae J,(mr) (74) 


where either m or 8 may be assumed at pleasure and the other com- 
puted from the equation 


mp = 4 πμβ. (75) 
If for m in the equation (74) we use the successive roots of the trans- 
cendental equation 


- mb 


J,(mb) = ae 


- J; (mb) (76) 


176 PROCEEDINGS OF THE AMERICAN ACADEMY. 


the series will satisfy (70) and (72), and if the coefficients can be so 
chosen as to make 


> L.-J, (mr) = H, (77) 
0 


equation (74) will give the function sought. 

Although the development (77) is not one of those for which the 
coefficients can be found by the usual devices, it is easy to solve the 
problem, for such cases as are of practical interest, to any desirable 
approximation. 


We shall find it instructive, however, to inquire first what the soln- 
tion would be if the second term of (72) were lacking, for, in view of the 
fact that the permeability of the iron is relatively large compared with 
that of the air, it seems likely that in some instances, where the series 
is very convergent, this modified problem and the real one will have 
nearly equal numerical answers. 

We have, then, so to choose Z,,, 8, and m, subject to (75) that the 
value of the series (77) shall be 7, when ¢ = 0, for all values of 7 up 
to ὁ ; and that at every instant 


2 2N? tf da 
oer an*N *; (= ὴ _= 0. (78) 


Ww 


It is necessary, therefore, that m shall be a root of the transcenden- 
tal equation 


2 ΠΕ 


J, (mb) = -mb-+ J, (mb), (79) 


which may be written in other forms by virtue of the relations 


TI (2) _ J, (2), af “e > (2) dx = a- J,(a). (80) 


da Υ 


It will be convenient to illustrate the effect of making ἢ small (and 
therefore » large) while a is kept constant, by a numerical example. 
Let us assume that the cross-section of the solenoid is a square of 10 
centimeters side-length, so that a = 5; let the solenoid have 10. turns 
of insulated wire per centimeter of its length, and let the resistance of 
these 10 turns be 7;th of an ohm, so that in absolute units w = 10°/16. 
If, then, we take the specific resistance of the core to be (10°/327) 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 177 


absohms at the room temperature (Fleming and Dewar), 27V7p/w 
will be equal to 75, and the equation for m takes the form 


J, (mb) = “(mb) ‘Ji (mb) = τ - J, (mb). (81) 
2r-J, (mr) ᾿ 

16 = ὡς 
ἘΠ: a > (A? + m*b*) J, (mb)’ 2) 
mar (CLs) oe 
and hence mw = ΔΗ͂, LO i) Jed + wb) F(mb) (83) 


The whole flux of magnetic induction through the iron of the core is 
then pn” times the integral of a taken over the circle of radius ὦ in 
which a is defined ; that is 


ἃ eS —B. J, (mb) 
ἡ τὸ ee m(A* + mb") J,(mb)’ (84) 
> ΟΡ 
—= 2 2 A fad 
or φ = ἀπμλ" Π,ἢ m0! + mb?) mB) (85) 


Since A = 10/n?, the coefficient of the series may be written 400 πμ /7,/n", 
and we may assume that μ = 100. 

The time rate of change of the total induction flux through the turns 
of the solenoid, per centimeter of its length, is 


9950-104 ἢ 10H, e-P a 
>See V+m ΠΝ (80) 


If the square core is built up of 100 circular rods, each 1 centi- 
meter in diameter, x? = 100, ἃ = 1/10, and the m’s are defined by the 
equation 

J, (mb) = 10 mb- J; (mb) (87) 
in which ὦ = 1/2. 

It is not difficult to show by trial and error from Meissel’s tables 17 
that the first five roots of this equation have values approximately 
equal to those given in the following table: 


16 Byerly, Treatise on Fourier’s Series, etc., p. 229. 

17 Meissel, Tafel der Bessels’schen Functionen, Berliner Abhandlungen, 1888 ; 
Gray and Mathews, Treatise on Bessel’s Functions, pp. 247-266; Peirce and 
Willson, Bulletin of the American Mathematical Society, 1897. 


VOL. XLIII. —12 


178 PROCEEDINGS OF THE AMERICAN ACADEMY. 
TABLE IX. 


mb = 0.44168 log B,? = 0.79077 m2 — 0.78032 
mob = 8.858 log B.? = 2.6733 mg? = 69.527 
mgb = 7.030 log B,* = 3.1946 m3” = 197.672 


mb = 10.188 log By? = 3.5164 m4? = 414.798 
msb = 13.331 log B;? = 3.7504 πὶ: = 710.884 


A mere inspection of these values shows that the value of ¢ can be 
computed with an accuracy much more than sufficient for any practical 
purpose from the first two terms of the series (85), if ¢ is as great as 
roth of a second, and from the first term alone if ¢ is as great as z45th 
of a second. Let ¢» represent the first term of (85), then 


an 400 7 H, οὔ 1τ08ι 
τ (0.78032)(0.20508)’ 


400 
(0.78032)(0.20508) 


φ 


but = 2499.55, (88) 


which differs from 2500 by about th of one per cent only. 


If there were no eddy currents in the iron, the total induction flux — 


through the rods which make up the core would be 
φ' = mua*H' s, (89) 


and if (Οὐ were the strength of the current in the exciting coil at the 
time ¢, we should have 


dH! —w-H!' 

DAT na Δ ἘΞ DN ee eee 
πμα δΝ di w-C 1a (90) | 
and Mo =A (91) 
where = w/47°N’a*p = 6.332573 + 
and φ' = πμα Ἢ, ἢ, (92) 


In the case under consideration we should have very nearly 


φ' = 2500 rH, e—6:382578t (93). 


Δπ. 0! -- ἡ’, -- Η, e—6-332573¢, (94). 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 179 


When there are eddy currents the value of H is given with suff- 
cient accuracy by the first term of (83) very soon after the electromo- 
tive force has been shunted out of the circuit, that is by the equation, 


2000 
a pee py £ —6.1768¢ 5 
Hs=3 the (95) 


and the ratio of ¢ to zb?n*uHs is practically equal to the constant 
2051/2000, for it is easy to find a very convergent geometrical series 
every term of which is greater than the corresponding term of the 
series which begins with the second term of (85), and the sum of this 
geometrical series is extremely small except for very small values of ¢. 

According to this analysis, the current in the solenoid will have 
fallen in the first second to the fraction 0.002025 or to the fraction 
0.001777 of its original value according as there are or are not eddy 
currents in the iron. 

If the ten centimeter square iron core of the solenoid were built up of 
straight rods only one millimeter in diameter, we should have ὦ = 1/20, 
n= 100, and A= 1/1000; the m’s would need to be roots of the 
equation 

J, (mb) = 1000 mb - J; (mb). (96) 


By using differences of the third order it is possible to show from 
Meissel’s table that the first root is approximately equal to 0.044715 + 
and the second to 3.83. For the first, then, A? + mb? = 0.002000, 
and 8? = 6.33077. For the second root, 8? = 46500, and the second 
terms of the series (83) and (85) become negligible almost immedi- 
ately after the electromotive force has been removed from the circuit. 

In this case 


by = 2500 rH,» e-8:98077t (97) 
very nearly ; and 
τς = H, = H,- e830 , (98) 


so that the disturbing effects of the eddy currents are comparatively 
slight. At the end of one second, the current will have fallen to the 
fraction 0.001777 of its original value or to the fraction 0.001781, 
according as eddy currents were absent or existent. These differ by 
only about one two hundred and fifty thousandth part of the original 
current strength. We may note in passing that a very approximate 
value (correct to four significant figures) of the first root of the equa- 
tion might be found by equating to unity the coefficient of the first 
term of the series (83). 


180 PROCEEDINGS OF THE AMERICAN ACADEMY. 


If the core of the solenoid were made of wire one tenth of a milli- 
meter in diameter, such as is now in common use in coils intended for 
loading long telephone circuits, we should have / = 1/200, πὶ = 1000, 
A = 1/100000, and m would need to satisfy the equation 


J, (mb) = 100000 mb- J, (mb). (99) 


It is easy to see that the first root of this has a value very nearly — 
equal to 0.0044721, and that the effects of eddy currents would be 
quite inappreciable. 


Having considered somewhat at length—on the supposition that 
the induction flux in the air spaces of the core might be neglected — 
the manner in which a current in the solenoid would decay if the — 
electromotive force were suddenly removed from the circuit without 
changing the resistance, we may now return to the more general case 
to which the equations (74) and (76) belong, and remark that in the 
ideal case where eddy currents are supposed to be absent (68) takes 
the form 


4x? dH', | 4apN*n*xb*? dH, 
il cs eat Sf oS ne Re OE — 
H's + i (21.46) di a 5 aia 0, (100) 
whence Wg ee (101) 


It is clear at the outset that the larger roots, at least, of the two 
equations (76) and (79) will be very different, since the second mem- 
ber of (76) soon has a negative coefficient. If then the coefficients of — 
the series (77) could be found, the series (74) and (83) would not re-— 
semble each other in appearance for large values of ὁ and small values 
of the time. If, however, is fairly small, as it usually is in practice, — 
we may dismiss all thought of the infinite series, since it is easy ἴθ 
choose the coefficients of two or three terms of the form (73) so that — 
the initial condition shall be satisfied very approximately. In many — 
cases one term suffices. 

Let us consider first the case — already treated in another way — of 
a square core of 100 square centimeters cross-section, built up of long © 
straight wires 1 millimeter in diameter; so that ὁ = 1/20, n = 100, ὴ 
18? = 1.36620 mL", kn? = 1000, and the equation for mb has the form 


a ey 


10002 3 
J, (2) = T— 1.366202 J; (x). (102). 


PEIRCE. — BEHAVIOR OF THE CORE OF AN ELECTROMAGNET. 181 


It is possible to show by a rather long application of the method of 
trial and error, using third differences in Meissel’s table, that the value 
of the first root is 0.044654+ and this corresponds to m = 0.89308, 
B® = 6.31351, J,(mb) = 0.9994891+4. 

Tf, then, we consider the single term 


Q = A, e315". J, (0.89308 r), (103) 


@ will satisfy (70) and will vanish when ¢ is infinite. When ¢ is zero, 
Q will be equal to H, for r = 0, and will differ from H, by about one 
twentieth of one per cent when 7 =. The second root of (102) is 
roughly equal to 3.8 and the corresponding value of 6? is about 45,000, 
so that the exponential factor would soon be very small. An inspection 
of the graph of J, (2) shows that if we were to use several terms of the 
form L- e—**. J,(mr), we could easily form a function which should 
differ very little from 170 for any value of r up to ὁ, when ¢ was zero ; 
but it is clear that after the lapse of about 1/5000th of a second, all 
the terms beyond the first would be negligible, and there is no practi- 
cal advantage in using more than one term. 

We may assume then that the value of H in any one of the iron rods 
is given fairly accurately, except at the very beginning, by (103). Since 
47NC = H, the current in the solenoid falls in the first second to 
0.001808 of its original value, or to 0.001812 times that value accord- 
ing as eddy currents are absent or present. These fractions differ 
from each other by about one two hundred and fifty thousandth part of 
the original current strength. Another close approximation to the 
value of H may be made by dividing (103) by J, (mb) and another by 
multiplying the second member of (103) by 


1+ J, (mb) 

2 JS, (mb) {τ 
These changes would not affect the relative rate of decay of the 
current. 

The nearness of the approximation to the value of the field attain- 
able by a single term is evidently much increased as the diameter of 
the iron wire of which the core is built up is decreased. If as before 
a= 5, but if ὃ = 1/200, n = 1000, the value of the first root of the 
equation for mb will be 0.00446616, nearly, and the value of J, (mr) 
will not change by so much as 1/100000th part of itself as 7 changes 
from 0 to b. A single term, therefore, will represent H with great 
accuracy. In this case the effect of eddy currents is wholly inappre- 


182 PROCEEDINGS OF THE AMERICAN ACADEMY. 


ciable. Of course this statement does not apply to the case of an 
alternate current of very great frequency. 
‘ 


In the problem just considered the electromotive force was suddenly 
shunted out of the solenoid circuit after a steady current had been τὸ 
established in it, and, on the assumption that the permeability of the — 
iron was fixed, the value of the magnetic field within the core was 
determined as a function [H)/(¢, 7)] of the time and the space co- — 
ordinates. The function / satisfies (65) and (68), vanishes when ¢ — 
is infinite, and is initially equal to unity. If the solenoid circuit 
containing an applied electromotive force # be suddenly closed at the 
time ὁ = 0, and if the ultimate value (4 Z/vw) of the magnetic field 
in the core be denoted by H,,, the value of the field at any time will — 
be given by the equation f 


H = ΗςΤὶ —f(t7)]. (105) 


The function defined by this equation vanishes, when ¢t = 0, for all 
values of 7, and when ¢ is infinite is equal to H,,. It satisfies at all 
times the equation (65) and the surface equation 


47rN? ΕΣ er (FZ =i a 
Hy s+ a (A = Ba 7 aD τι “Ὁ ἀν = -E, (106) ὦ 


and such a function is evidently unique. 


Although in practice the permeability is not fixed, the analysis of — 
this section enables us to shut in between narrow limits the effects οὗ 
eddy currents in many cases, and to assert, when this is the truth, that 
in a given instance the effects of such currents will be negligible, if the — 
pieces of which the core is built are properly varnished. 


It is sometimes possible to get interesting information about the — 
magnetic properties of the core of a transformer which has several coils, 
and about the excellence of the insulation of the sheets of which it is 
made, by observing the sudden changes in the currents in the coils when — 
the inductances of the system are impulsively changed, or by studying — 
the rate of propagation of the induction flux into the core, but these 
subjects must be left for the next instalment of this paper. Ἧ 


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' HARVARD UNIVERSITY. 


THE DEMA GNETIZING FACTORS FOR 
CYLINDRICAL IRON RODS. 


ΒΥ ΟΣ ΙΝ ἘΠΕ σόν 


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= 


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δ᾿. Vou. XLIII. No. 6.—SEPTEMBER, 1907. 


HARVARD UNIVERSITY. 


THE DEMAGNETIZING FACTORS FOR 
CYLINDRICAL IRON RODS. 


LIBRARY 
By C. L. B. SHUDDEMAGEN. NEW YORK 
BOTANICAL 
GUAKDEN. 
ἊΜ A 
ἐν reas 
eats 
es 
A, hy, % ᾽ 
ΩΣ ΝΥ Χο, oY uf Me 


7 - 1907 


UL! 


————E————=—  —“—i—s 


THE DEMAGNETIZING FACTORS FOR CYLINDRICAL 
IRON RODS. 


By C. L. B. SHUDDEMAGEN. 


Presented by B. O. Peirce, April 10, 1907. Received June 25, 1907. 


OUTLINE OF THE SUBJECT. 


Ir has long been known that when an unmagnetized iron bar is 
placed in a fixed magnetic field H’ and thereby becomes magnetized, 
the actual force H within the iron is not so great as the original per- 

‘manent magnetic force at the same point before the iron was introduced. 

The vector difference H;, between the original force and the actual 
force resulting after the iron is brought in, is called the “ demagnetizing 
force” due to the magnetism which has been induced in the iron. An 
original uniform field does not in general induce a uniform demagneti- 
zing field within a piece of iron ; in fact, it is commonly accepted that 
there is only one practical exceptional case: an iron ellipsoid placed 
so that a given one of its axes is parallel to the direction of the original 
uniform field. In this case the demagnetizing force for a given ellipsoid 
with a given axis parallel to the field is simply proportional to the 
resulting uniform intensity of magnetization 7; and the proportionality- 
factor V is found by theory to depend only on the dimensions of the 
ellipsoid, that is on the semi-axes a, ὁ, and c. Moreover, when the 
ellipsoid is a body of revolution, so that b = 6, then we have a simple 
formula expressing NV as depending solely on the value of the ratio a/b. 
This NV is commonly called the ‘demagnetizing factor” for the 
ellipsoid. 

Lord Rayleigh?! first pointed out how from a knowledge of V a 
hysteresis curve obtained for an iron ellipsoid of revolution and plotted 
on the B vs. H’ plane, could be “sheared back”’ into the limiting hys- 
teresis curve for an ellipsoid of the same cross-section, which would be 
approached as the length of the axis which lies parallel to the field 
grows longer and longer. ‘The same process is evidently applicable to 
a simple magnetization curve obtained by letting the applied field //’ 


1 Phil. Mag., 22, 175-183 (1886). 


186 PROCEEDINGS OF THE AMERICAN ACADEMY. 


range from 0 to its maximum value, increasing continuously, and the 
iron being initially unmagnetized. The curve obtained by back- 
shearing is called the “normal” curve of iaagnetization for the kind 
of iron used. As the applied field H’ is now the same as the resulting 
field H, the demagnetizing field having disappeared, this normal curve 
gives us the true permeability » and susceptibility « for every H, and 
is therefore the characteristic curve of the iron which we must use 
in order to get correct values for the physical quantities mentioned. 
Ewing and other investigators have made much use of this back- 
shearing process in working out hysteresis curves obtained for long 
iron wires, it being assumed, while experimental determinations were 
still lacking, that cylindrical iron wires could be regarded as behaving 
magnetically like ellipsoids of the same length and cross-section, pro- 
vided the ratio of length to diameter was not too small. 

The first attempt to find numerical values for the demagnetizing 
effect in cylindrical iron rods was made in 1894 by Du Bois? in dis- 
cussing the only magnetization curves with varying length of rods 
which had up to that time been published: six by Ewing, obtained 
ballistically,? and a few by T'anakadaté, taken by a magnetometric 
method. From these results Du Bois constructed a table of values 
for .V for values of πὶ ranging from 10 to 1000, where m = ratio ot 
length Z to the diameter D, of the rod. He evidently considered that 
.V remains practically constant for the whole range of magnetic in- 
tensity. Du Bois’s values of JV for cylinders are from 10 per cent to 
20 per cent smaller than for the corresponding ellipsoids, that is ellip- 
soids having the same ratio of length to maximum cross-section. 

In 1895 C. R. Mann published® an extended series of results, 
obtained magnetometrically, for the demagnetizing factors of iron © 
cylinders. The leading points brought out by this investigator, for 
the rods experimented on, most of which were of small diameter, are: 
(1) The ’s for cylinders are very nearly constant for all intensities 
of magnetization below J = 800; after this point they increase rapidly 
as 7 increases. (2) For the range in which the 4’s are practically 
constant, they vary but’a very few per cent from the values of the V’s 
for the corresponding ellipsoids. Mann does not believe that ballistic 
and magnetometric determinations of V will give comparable results. 

The most recent work on the demagnetizing factor which I have 
seen, is embodied in a short but extremely suggestive paper published 


2 Magnetische Kreise, Berlin, 1894, pp. 36-45; Wied. Ann., 46, 485-499 (1892). 
3 Phil. Trans., 176, II, 535 (1886). 

4 Phil. Mag., 26, 450 (1888). 

> Dissert., Berlin, 1895; Phys. Rev., 3, 359-869 (1896). 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 187 


in 1901 by Carl Benedicks.6 This investigator, while working on the 
subject of pole-distances in cylindrical rods, interested himself in a 
few careful experiments on the demagnetizing factors. He gets fora 
hard steel rod of diameter 0.8 cm. and a length equal to 25 diameters, 
hysteresis curves by means of both the magnetometric and the ballistic 
methods. ‘hen by turning it down on the lathe, he transforms the 
same specimen of iron into an ellipsoid of revolution of length equal to 
30 diameters, and gets a hysteresis curve magnetometrically. This 
last curve is, by means of the known ellipsoid N for m = 30, back- 
sheared into the “normal” curve, which, according to Benedicks, can 
then be used to determine the JV for any point on either the ballistic 
or the magnetometric curve for the cylinder. The result is that the 
magnetometric VV behaves qualitatively exactly like that of Mann, but 
the ballistic WV, after likewise remaining practically constant up to 
I = 800, decreases rapidly as J is further increased. 

The present paper is an attempt to contribute to the subject a 
discussion of the demagnetizing factor for cylinders as determined 
ballistically. It will appear later that the curve on the B vs. H’ plane 
(or the 7 vs. H' plane) which determines the back-shearing from a 
magnetization curve of a finite cylinder to the limiting normal curve, 
is quite different from the straight line which obtains in the case of 
the ellipsoid of revolution. It has, in fact, two opposite curvatures : 
one near the origin, and the other soon after the maximum value of 
the susceptibility has been passed. The first curvature is not very 
marked, and it turns out, as has been found before for the magneto- 
metric JV, that up to values of B = 10,000 (or J = 800) the ballistic V 
is not far from constant. The upper part of the curve, however, has a 
violent turn toward the B-axis (or /-axis) just as has been observed 
by Benedicks for his short steel cylinder. Theoretical reasons can be 
given to account in a general qualitative way for these experimental 
results. 

Hitherto it has been the common custom, for lack of experimental 
evidence on the subject, to regard the Δ for iron cylinders, leaving 
out of consideration the variation of this coefficient with the J, as de- 
pending only on the ratio m = L/D, and not on the absolute dimen- 
sions of the rod. As practically all the previous results have been 
obtained from experiments on iron cylinders having a diameter of less 
than 1 mm., that is, mere iron wires, the question has naturally not 
received any attention. In the present work the writer had at his 


§ Bih. Svenska Vet.-Akad. Handlingar, 27, (1), No. 4, 14 pp. (1902) ; Wied. Ann., 
6, 726-761 (1901). 


188 PROCEEDINGS OF THE AMERICAN ACADEMY. 


disposal two magnetizing solenoids very much longer than any which 
have ever been used before, as far as he knows. Thus it was made 
possible to obtain complete series of magnetization curves, yielding 
tables of values for N, for a large number of iron rods, ranging in 
diameter from 0.2381 cm. to 1.905 ems. The results disclose quite a 
marked dependence of V on the 7), the L/D and J being considered 
constant. In fact the general rule may be stated that the value of V 
decreases as the diameter of the iron rod increases. 

In the work both the “reversal” and the “step-by-step” methods 
have been used, and the results obtained may be interesting to some 
who have had occasion to observe the peculiar disagreements in the 
results given by these two methods. As a rule the .V’s calculated 
from reversal curves will be smaller than those obtained from the 
“step-by-step” method under the same conditions. 


INTRODUCTION. 


When a piece of homogeneous isotropic soft iron of any shape is 
placed in a magnetic field, it will always become magnetized, and the 
induced magnetism will in general show its existence by changing the 
original field outside the iron. The only exceptional cases are those 
in which the iron is “endless,” that is, it is in the form of an anchor 
ring or a rod of infinite length, with the magnetizing solenoid wound 
directly over the iron. Whenever an apparent magnetic distribution 
of superficial charge o and volume charge p is induced by polarization 
on or in any body of iron, the magnetic field /7, due to it combines 
with the magnetizing field H’ to give a resultant field H7, so that the 
actual field which determines the intensity of magnetization J is given 
at every point by the vector equation 


H= HH + &;; 


and J = «H, where «x = susceptibility of the iron. Outside the iron 
H will usually be less than #7’ in some portions of space, and in others 
it will be greater than Μ΄. But inside the iron H will in general, 
perhaps always, be less than H’. Thus in the case of a sphere of soft 
iron placed in a uniform field 27’, we shall have, from the theory given 
in most of the text-books on electricity and magnetism,7 a uniform field 


of intensity 7 = 17 --- = J within the sphere at any point A, while the 


7 Maxwell, II, §§ 457-438; Webster's Electricity and Magnetism, p. 371; 
Peirce’s Newtonian Potential Function, p. 205. 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 189 


aot 4π : : : 
intensity is H’ — —/+ 4π7 at the point B just outside the sphere on 
0 


that line of H’ which passes through the centre of the sphere, while at 
all points C’ just outside the sphere and lying ina plane passing through 
the centre of the sphere and perpendicular to the //’-line mentioned, 


: 5 : poe 5 : 
the intensity will be H’— — J. Figure 1, reproduced from Figure 
o 


76 on page 373 of Webster’s “Theory of Electricity and Magnetism,” 
shows the resultant lines of force in this case. For a ring or an 
infinite rod of constant cross-section with the magnetizing solenoids 
properly arranged, we should get H, = 0, and H = Π'. 


a 
ΞΞΞ-----. - --- --- ---Ξ-- 


ae - 353 
[EE ASHEN 
(SET ee τι 
Gs 
is ey, 
eae cee 

»--------: 


ΕΞΞΞΞ--- ----  - -- ---- Ξ Ξ 
ee Le -  ΞΞ ΞΞ 


FIGURE 1. 


A sphere of permeability 3 in a uniform magnetic field. 


At any point in an iron body subjected to a magnetizing field H’, 
the strength of the field H; can be regarded as a function of 1 If in 
particular we write the scalar equation 


H,= NT 


and remember that in practical cases the H/, is a field opposed to H’, 
or tending to demagnetize the iron, then we may speak of the factor 
N as the “demagnetizing factor” of the particular body of iron at the 
point considered, with reference to the permanent magnetizing field 
used, which in all practical cases will be a uniform one. Since 97; is 
in general an unknown function of J, therefore Δ is also some function 
of. As the H; in the cases to be considered will be directed exactly 
oppositely to H’ in that part of the iron which we shall be interested 


190 PROCEEDINGS OF THE AMERICAN ACADEMY. 


in, we shall hereafter use the scalar values for H’, 7, and J, so that 
our first equation will become 


H=H —H,=H—NI. 


The only case of a magnetized body not endless, in which we can 
always calculate what the H; will be, is where an iron ellipsoid is 
placed with one of its axes parallel to a uniform magnetizing field H’. 
If the equation of the ellipsoid is 


then it is shown in text-books on the mathematical theory of electric- 
ity and magnetism,® that if there exists on the ellipsoid a surface dis- 
tribution of magnetic matter everywhere equal to 


o = I-cos (a, n) 


where / is a constant, and (2, 2) is the angle between the positive 
direction of the z-axis and the exterior normal to the ellipsoid, the 
volume density p being zero throughout the ellipsoid, then the mag- 
netic field due to this distribution is constant at every point within 
the ellipsoid and equal to 


H, = 2xabelK,, 


που ds 
} =i Ὶ 
where Ky >» Stas + b)3(s +c) 


This field 7; is directed parallel to the negative direction of the z-axis, 
and tends to demagnetize the iron; we see furthermore that it is di- 
rectly proportional to /. The constant J is simply the intensity of 
magnetization, uniform within the ellipsoid. ‘T’o keep this magnetic dis- 
tribution in equilibrium it is sufficient if we apply a uniform magnetic 
field parallel to the positive z-axis, of such a strength H’, that when 
diminished by the demagnetizing field /7,, there will remain in the 
ellipsoid the uniform resultant field /7=J//x, where x is the suscepti- 
bility corresponding to the magnetization J, for the kind of iron under 
consideration. Of course if the o has initially been chosen greater 
than the maximum value of magnetic intensity attainable, it will be 


8 Maxwell, 11, §§ 437 and 438; Webster, Elec. and Mag., §§ 192, 196; Peirce, 
Newtonian Potential Function, ὃ 69, 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON Rops. 191 


impossible to realize such a distribution. If we have a possible case, 
then 
Ἢ =H’ — H,= H' —2nabe-K,-I. 


Now the factor 27abc- K, is constant for a given ellipsoid, and is called 
its “demagnetizing factor” V. When the iron is an ellipsoid of revo- 
lution (b,=c), we can integrate A, and get a simple formula for V as 
a function of a/b, the ratio of the length of the ellipsoid to its greatest 
diameter.2 It is, when written in terms of ΠῚ, 


4π 
m?— 1 


2 πὶ f rT ETT 
ΠΤ ΞΞ at — pile (2 mo/m? — 1+ 2m? — 1) — 


When 1 is negligible in comparison with m* the formula assumes the 
simple form 


>, An 
Ve τῷ log 3 πὶ — ΠῚ): 


This V does not depend, therefore, on the softness of the iron nor on 
the magnetizing field, provided the iron ellipsoid was initially demag- 
netized and our magnetizing field has been continuously increased from 
zero to its final value. 

If the iron is perfectly “soft,” or incapable of retaining magnetism 
when the magnetizing force H’ is withdrawn, then any field H’ will 
produce a unique magnetization. The uniform H’ along the major 
axis of the ellipsoid of revolution will therefore produce such a magnet- 
ization as we found would be kept in equilibrium by the same //’. 
As the iron we deal with in practice is not “soft,” but shows hyster- 
esis, we find it necessary to define susceptibility as the ratio of //H 
when the iron is s/ow/y carried from zero magnetization to the value J, 
the magnetizing field to increase slowly and continuously up to the 
proper value H/’. Under these conditions it is reasonable to suppose 
that any magnetizing field will give a unique magnetic distribution, 
and our results hold true. 

Suppose we desire to measure the susceptibility of a specimen of ~ 
iron in accordance with our ideal definition, so that it may be free 
from ambiguity ; let us consider the suitability for this purpose of the 
various experimental methods now in use. The fluxmeter is an instru- 
ment recently invented, which attempts to give permanent deflections 
which are proportional to the changes of magnetic induction through 
a secondary circuit, and these deflections are independent of the time- 


® Maxwell, II, 88 437-438. 


192 PROCEEDINGS OF THE AMERICAN ACADEMY. 


intervals in which these changes complete themselves. The perform- 
ance of this instrument is as yet far from satisfactory. If it could be 
made perfect, we should have an ideal method for permeability deter- 
minations, for we could then increase the magnetizing field as slowly 
as we please, reading off the corresponding magnetic inductions for 
any desired values of the field. It is probable that the oscillograph 
methods are at present much more to be preferred, as they can be 
made to record accurately the slow and long-continued changes of 
magnetic induction through large masses of iron. 

A very good method to use is the “step-by-step” magnetization, 
where ballistic throws are produced in a Thomson galvanometer, or in 
a D’Arsonval galvanometer when we use proper precautions to secure 
the proportionality of throws to the flux changes. These changes in 
magnetic induction through a secondary coil wound around the iron 
specimen to be tested are most conveniently obtained by sudden de- 
creases (or increases) in the resistance of the primary circuit, consisting 
usually of a storage battery and the magnetizing solenoid. By this 
arrangement it is not difficult to obtain cyclic hysteresis curves. It 
has been shown1° that the maximal induction B (or J) which is 
reached varies with the number of steps taken, the difference being 
most marked in the region of greatest permeability. As the num- 
ber of steps is increased continually in different experiments, the B 
vs. H curves move nearer the ///-axis, but soon approach the limiting 
curve for a slow continuous change of H/’, which, as we saw before, 
is the one curve that, after the proper back-shearing, will give values 
for the permeability (and susceptibility) conformable to the ideal 
definition. Lastly in order of accordance with the ideal definition of 
susceptibility comes the “reversal” method of measuring ballistic in- 
duction throws, which is entirely contrary to a slow magnetization, 
but which is often the most convenient of all the methods to use, and 
which gives the most self-consistent determinations ; that is, repeated 
magnetizations will give almost identical results. Both the “ step-by- 
step” and the “reversal” methods of measuring magnetic induction 
may give results depending on the particular experimental conditions 
employed, unless one takes proper precautions. Thus the time-constant 
L/R of the primary circuit should be only one or two per cent of the 
time it takes the galvanometer-needle to reach its greatest deflection, 
which time will be the quarter-period of the needle suspension system. 
It should be noted that when there is a great bulk of iron in the mag- 


10 F, Riicker, Diss. Halle, 1905, 106 pp. 20 plates; Elektr. ZS. 26, 904-905, 979 
(1905). 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 193 


netizing solenoid, the 1) may be enormously large. There are two ways 
of realizing the condition of the smallness of the time-constant as com- 
pared with the quarter-period: (1) We may use a storage battery of 
high E.M.F. in the primary circuit, which will necessitate large 15 in 
the circuit in order to give magnetizing fields of the desired intensity ; 
(2) It is quite possible to increase the moment of inertia of the needle- 
suspension so as to give a complete period of several minutes. Several 
of the experimental series obtained in this investigation by means of 
the reversal and step methods illustrate very forcibly how these two 
different methods may lead to various determinations of the suscepti- 
bility. Finally, the magnetometric methods are often very useful, 
especially in accurate determinations of magnetic moment of short iron 
magnets. With none of these magnetometric methods can we measure 
the J at any particular part of the iron bar, but get instead a mean 
value of 7 (moment/volume of bar) for the whole rod. Plotting 7 vs. 
H' curves for various lengths of soft iron cylinders, we can find mean 
demagnetizing factors V, by means of which a “normal” curve can be 
constructed. But it will be seen, after a little reflection, that the curve 
Mean / vs. Mean H which we get here is not necessarily the same, or 
even approximately the same, as the “normal” curve of J vs. H, which 
gives corresponding values of 7 and H/ in the middle of the bar imme- 
diately surrounded by the secondary coil, and which may be regarded 
as an extremely close approximation to the 7 ἂπ H ata single point 
in the iron. It is this fact which accounts for the wide difference which 
has been found between the Vas determined ballistically and the V as 
determined magnetometrically. It is hardly likely that the process of 
back-shearing a magnetometric magnetization curve will yield a curve 
from which anything like the true susceptibilty can be found. 

Returning now to our iron ellipsoids of revolution, we see that if we 
know the ratio of the length to the diameter of one of them, we can 
calculate exactly what the demagnetizing factor V will be. Ewing and 
Du Bois, in their texts on magnetism, give tables of values of NV (see 
page 204) for various ratios a/b. It follows from a paper by Lord 
Rayleigh,11 that if we magnetize any iron ellipsoid of revolution 
having a known ratio a/b, from zero magnetism to full saturation, 
measuring the 7 ballistically by means of a small secondary coil around 
the middle part of the rod, and plot out the curve J vs. H’, we can 
“back-shear ” this curve parallel to the H'-axis by the amount 
H, = SH = NJ, and thus construct the “normal magnetization ” 
curve, for which H = H’, and from which alone the true susceptibility 
can be found for every ἢ 


11 Phil. Mag., 22, 175-183 (1886). 
VOL. XLII. — 13 


194 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Suppose now that we have any elongated piece of iron with a secon- 
dary coil wound around it near the middle and connecting with the 
terminals of a ballistic galvanometer. Suppose also that the normal 
magnetization curve for the kind of iron used were known, say, by 
taking measurements ballistically on an anchor-ring made of the same 
material. (As a matter of fact this method does not apply, for by 
welding the ends of a rod together to form a ring, we change the mag- 
netic behavior of the iron unavoidably, to say nothing of differences 
which exist in two different specimens of iron made from the same 
kind of iron.) If we now find experimentally the actual magnetization 
curve, and plot it together with the normal curve on the / vs. 17 plane, 
and plot on a similar plane, which we shall call the 7 vs. (H’—/Z) or the 
I vs. H;plane, the differences of the abscissae (which are AH = H,= NJ) 
of the two curves for each /, against this same J, we shall call this last 
curve the “ -curve” for the particular piece of iron and the particular 
position of the secondary coil, it being understood that we have placed 
the iron in a definite position in a given magnetic field, or distribution 
of lines. ‘The 7 of the actual magnetization curve is the average J ex- 
isting in the volume of iron immediately surrounded by the windings of 
the coil. In general we do not know what the form of the V-curve may 
turn out to be, until we obtain it experimentally ; in the ellipsoid of 
revolution placed with its major axis parallel to the uniform field, this 
N-curve will, according to theory, obviously be a straight line through 
the origin and making with the /-axis the angle whose tangent is equal 
to .V+(ratio of H’ scale unit to J scale unit). 

Now since ellipsoids of revolution are not very easily constructed, 
the case most important for magnetic measurements in laboratory 
practice is that of the cylindrical iron rod with ends squared off, and 
the secondary coil wound around just in the middle part of the rod, a 
uniform magnetizing field, such as can be secured inside a long solenoid, 
being used to produce the H#’. Here we do not obtain a uniform J by 
placing the rod in a uniform field, and although the problem is de- 
terminate mathematically, no one has as yet succeeded in obtaining 
the solution. ‘The great difficulty lies in the fact that the susceptibility 


is not constant throughout the rod for any given H’. The lines of © 


magnetization run parallel only through the middle cross-section of 
the rod, where the secondary coil is wound. If, then, we wish to know 
the .V-curves for some kind of iron in the form of cylindrical rods, our 
only resource is to find experimentally a series of J vs. H’ curves for 
greater and greater values of πὶ = L/D, where ἢ = length, and D= 


diameter of the rod. Then we must find, by some extrapolation 


method, or otherwise, the limiting curve as m becomes larger and 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON Rops. 195 


larger. We may then plot out the abscissa-differences between this 
normal curve and all the others, and thus actually construct the /V- 
curves. 

The only experimental magnetization curves for a number of varying 
m’s which had been published before 1895 are those obtained by 


ΦΠΠΠΠΠΉΠΗΠΙΠΗ 
PPT eee 

PCCP TTT TLL 

εἰ 7, 5.25 Γ τ] 

SAMME ιν. ἢ 

ΠΡ. ΠΕ] 


ΝΕ 
ΠῚ 111 
εἰ} ΠῚ ΠΠΤ ΠῚ 
PMY DPE EEE EEE 
BAA 
PWC eee 
Sec ee 
ecco 


Seg URE 2. 


Ewing’s magnetization curves for a soft iron wire of diameter 0.158 cm. 


Ewing 12 for m = 50, 75, 100, 150, 200, and 300 (see Figure 2), and 
some i Tanakadaté for rather small values of m, his highest being 
about m = 39. Ewing’s iron cylinder was a wire of diameter = 0.158 
cm. and original length = 47.5 cms., the other i’s being obtained by 
cutting off pieces from each end. The maximum permeability for this 
iron was found to be » = 3500. Tanakadaté’s iron wires were of 


12 Phil. Trans., 176, II, 535 (1885). 


ΝΠ: 


196 PROCEEDINGS OF THE AMERICAN ACADEMY. 


diameter = 0.153 cm., the length varying from 2 to 6 cms., also of 
diameter = 0.115 cm. anda length originally 33.4cms. For the shorter 
specimens he used Gauss’s A position, that is, the rod is placed east 
and west and the magnetometer is placed in the prolongation of the 
rod’s axis; for the longer wires Ewing’s method was used, in which 
the solenoid and wire are placed vertically, with an extra solenoid to 
compensate for the earth’s field, and the magnetometer being placed east 
or west of one end of the wire. 

Du Bois subjected these data to a very extensive discussion. He 
developed the proposition that, provided the length of the rod is 
sufficiently great compared with its diameter, then Vm? = constant. 
This constant he finds from Ewing’s curves to be equal to 45, provided 
m = 100. The reason why this formula cannot possibly hold for 
short rods is that the theory of Du Bois assumes that the average 
magnetization intensity Jin the whole rod differs but very little from 
the 7 within the secondary coil in the middle of the rod; in other 
words, that the magnetization is practically uniform. Of course this 
is never realized for finite rods and ordinary fields 7’, but it seems at 
first sight as if the magnetization in a rod of large m should be fairly 
uniform. If we follow Du Bois’s method, which gave him the necessary 
data to construct his table of values for V in case of cylinders, we may 
measure abscissa-differences, which are proportional to Δ΄, for the 
curves for rods of large in’s, and form three or four simultaneous 
equations, each of which linearly contains 2, the abscissa-difference of 
the normal curve and the 7) vs. 47’ curve for the largest πὶ used in the 
equations. Any two of these equations give z, and we can thus con- 
struct the normal curve, which gives us immediately all the -curves 
by plotting abscissa-differences as before. Du Bois, from the meagre 
data at his command, found values for V for various m’s and: has col- 
lected the results in tabular form (see table, page 204) in his book “ Die 
Magnetischen Kreise in Theorie und Praxis” (“The Magnetic Circuit 
in Theory and Practice,” translated by Atkinson). He apparently con- 
siders the V-curves to straight lines, as far as practical purposes are 
concerned, that is V is not a function of H (or J); at any rate he 
does not mention any such variation of VV. And as to the question 
whether or not the Δ᾽ for a given m and 7 varies with the diameter 
of the rod, no data were at hand. 

Now there is no reason to believe the -curves for cylindrical rods 


of the same diameter to be straight lines ; and since we know that the 


building up of magnetization, and perhaps even the final result, is very 
decidedly modified by the bulk of iron magnetized, it is quite likely 
that thick massive rods of iron really give different values for VV from 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 197 


those calculated by Du Bois for the “iron wires” used by Ewing and 
Tanakadaté. And, lastly, it is quite possible that the V may vary with 
the degree of softness and other physical characteristics of the iron 
magnetized. The present investigation was therefore undertaken to 
test as accurately as possible the true nature of the N-curves, whether 
they are really straight lines or not, and their possible variation with 
the diameter of the rod. Moreover, a table of values of NV determined 
carefully by the ballistic method for thicker rods than has been done 
so far, would be quite useful in the practice of electrical engineering 
as, for instance, in the designing of dynamo machinery. 

Before discussing the experimental results let us consider theoreti- 
cally the N-curves for a given kind of iron and a given diameter, the 
length alone being varied. We shall attempt to show that this back- 
shearing curve has two opposite curvatures. Let us suppose that we 
know the normal magnetization curve of our iron. We want to learn 
something about the nature of the -curve for a cylindrical rod of 
homogeneous isotropic iron whose length is finite but otherwise arbi- 
trary. All the facts which we need are these: (1) The / has a maxi- 
mum value /,,, which is reached asymptotically by increasing the 
magnetizing force H’ indefinitely. (2) In any finite cylindrical iron 
rod, no matter how short, the lines of magnetization can apparently be 
made straight, or J made uniform, by applying an infinite 7’. And 
whenever ///, the susceptibility, has rather small values, then the con- 
dition of uniform / is with some approximation realized. (3) Although 
the normal curve and all other / vs. H’ curves for rods of finite length 
do not run into the origin tangential to the 7’-axis, they do make a 
very small angle with it. In other words, the susceptibility approaches 
a small value x = 15, or thereabouts, as the 7’ decreases indefinitely.1% 
(4) The normal curve has one, and only one, point of inflection. 

With regard to the second part of (2) it might be noted that the non- 
‘uniformity of Zin an iron cylinder placed parallel to the lines in a uni- 
form magnetic field is measured in a rough way by the largeness of 
the ratio H,/H, the demagnetizing force divided by the resulting force, 
at the point considered. Now H; = NJ = NkH, so that this ratio is 
merely Nx. Therefore, if we suppose for the moment that N for a 
given finite rod is nearly constant for a considerable range of J, it follows 
that the magnetization will be the nearer to uniformity the smaller 
the susceptibility is. 

Let us then consider the N-curve for a rod for which mm = mh, say. 


13 C. Baur, Wied. Ann., 11, 399 (1880). Lord Rayleigh, Phil. Mag., (5), 23, 
225-245 (1837). 


198 PROCEEDINGS OF THE AMERICAN ACADEMY. 


In Figure 3 let P and Q be two points on the J vs. 1’ curve for m, 
where @ has the ordinate of the point of inflection (0, and P is any 
other point of the magnetization curve. Now suppose the rod were 
magnetized by an infinite Μ΄ to the maximum /J,,, so that all the 
πα", lines are straight and enter and leave the rod at the squared-off 
ends (a being the radius of the rod). In this case the distribution of 
magnetism which we may consider the cause of the demagnetizing force 
H,, or AH, is wholly superficial, and as far away from the secondary 
coil, where 7 is measured, as possible, and it has a perfectly definite 
value ΔΙ, say, which we lay off on the J vs. (7΄-- 1) plane, getting 
the point Α΄, and we draw the line OX. We see now that if, as we in- 


Ficure 3. 


Diagram illustrating magnetization and back-shearing curves. 


crease J from zero to J,, by continually increasing /7’, the lines of mag- 
netization were always straight, then the demagnetizing force would 
always be proportional to J, no matter what the susceptibility might be, 
and the V-curve would be the straight line OX. Another case where 
the V-curve would be a straight line OA, would be realized if the sus- 
ceptibility were a constant for all values of 7 from O to Z,. In this 
case no volume density would appear by magnetization, and any two 
fields 7,’ and H,’, giving separately the surface densities of magnetism 
σι and oy, could be superposed, so that a magnetizing field AM,’ + Hy’ 
would give the superficial distribution σι + 72. This last supposition 
would result in there being no limit to the intensity of magnetization. 
As a matter of fact the 7 is uniform only for an infinite 7’. At the 
point P, if P is not the origin, more or less lines of induction willleave 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 199 


the iron rod along the curved surface, as is well known. Now from the 
mathematical theory we know that in the case of “soft” iron B, or μἢ, 
is a solenoidal vector, continuous throughout all space, whether iron 
or air, not containing any fixed magnetic charges. Wherever lines of 
induction eave the surface of the iron we must therefore have positive c ; 
for the vectors H and J, although not solenoidal in the iron, have always 
the same distribution as the vector 4, J is zero outside the iron, and 
σ =T-cos(n,/). This means that a part of the surface distribution 
o of the magnetism is closer to the middle of the rod than it would be 
if J were uniform. ‘There is also some magnetic matter in the form of 
volume distribution p. ‘This, however, does not materially influence the 
argument, although it complicates matters somewhat. We shall come 
back to the volume charge later. Therefore, as far as the surface mag- 
netism is concerned, the demagnetizing force AH; is for every point P 
actually greater than it would be if 7 were uniform. We thus reach 
the result that the V-curve has the end-points O and K, but lies every- 
where else to the right of the straight line OX. Indeed for the most 
part the N-curve will be very decidedly to the right, for a very large 
number of the lines of induction will leave the iron rod before reaching 
the ends of the rod. ‘The demagnetizing factor V,, is the minimum 
value of NV, although A//,, is by no means vanishingly small. Near the 
origin the ratio of H to J is comparatively large, although of course 
still a fraction, so that according to (2) the 715. more nearly uniform 
than for higher points on the curve, so long as we do not pass the 
point of maximum susceptibility, which is the point of tangency of a 
line drawn from the origin to the normal magnetization curve ; therefore 
the V-curve is more nearly tangent to the line OX at the origin than for 
points a little more removed. As we increase /7’ from O to some point 
@ whose J is of the order of J at Q,, the lines of magnetization increase 
continually, but a larger and larger fraction of lines leave the rod be- 
fore reaching the ends, and JN increases continually. Again, as we 
follow the magnetization curve from any very large but finite value of 
H’ down toward Q, the lines spread out in greater and greater pro- 
portion, and the NV increases for quite a long interval. This shows 
that the curvature of the V-curve changes sign at some point Q,, which 
is a point of inflection for the N-curve, and probably the only one. 
We should expect, therefore, that the curve drawn in the second part of 
Figure 3 on the J vs. NJ plane represents roughly the qualitative be- 
havior of an V-curve for a finite rod. 

It remains to be shown that the volume distribution does not invali- 
date the argument just given. From the theory of magnetism we know 
that this can be expressed in the form 


200 PROCEEDINGS OF THE AMERICAN ACADEMY. 


—_ Iqhy+ C08 (he hy) 
p= ΤΣ τ δ Ν᾿ 


where «= the permeability, 4. and ἦν the gradients of the suscepti- 
bility and resultant magnetic potential function, respectively, and 
(Ax, hy) is the angle made by the directions in which « and V increase 
most rapidly. For we have by Poisson’s Equation, j 


V3V =—Anp, 


and from the fundamental equation of magnetic polarization, 


; Bose | eee 
p = — Divergence / = — Eas + ae Ἔξω] 


= ( i) = ( ay) = («ae) 

=F; | Ka += | «> +— | «Kk 

Ox \ Ox Gy \ ey Cz Oz 
Ox OV . Ox OV . Ox OV 


Se VOT era oe ee eae 


Eliminating the y?V we get the equation above. Now /,, ἦν, and μ 
are all intrinsically positive. ‘The 4, becomes zero under special con- 
ditions, and is vanishingly smail when the iron becomes fully satur- 
ated. Therefore the sine of o is governed by the cos (/,, ἢ αὐ alone. 
Considering only the half of the iron cylinder on which the positive σ 
appears, we see that 17 always increases from the end of the rod 
toward the centre, while p does so as long as the magnetization at the 
centre of the rod has not been pushed beyond the maximum suscepti- 


bility point. Under these conditions (ἦ,, ἀν) is an acute angle, and 


therefore p is positive. Therefore the argument regarding the curva- 
ture of the V-curve in the neighborhood of the origin is even strength- 
ened all the more on account of the positive p intensifying the 
demagnetizing force. Thus the lower curvature is proved (although 


not quite rigorously, mathematically speaking), and since the V-curve 


must end in the point A, there must be a curvature in the upper part 
of the V-curve directed oppositely to the first one. 

An interesting fact perhaps worth noticing in regard to the volume 
distribution p of the magnetism is that as soon as the point of maxi- 
mum susceptibility has been passed over, which will first occur at the 
centre of the rod, there will appear some negative p near the centre of 
the rod in that half of the rod which always carries the positive sur- 


= 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 201 


face distribution. This is due to the fact that (h,, Δ») now has become 
an angle of 180° at points in the axis of the rod and near the centre 
of the rod, while further away from the centre but still along the axis, 
where the « has not yet reached its maximum, the angle (/,, /,) is still 
zero. Somewhere between the two regions will be a curved surface 
for all points, of which «x has its maximum susceptibility, and /, is 
zero, and the angle (/,, Ay) is discontinuous by =, so that p is every- 
where zero on the curved surface, which separates the regions of posi- 
tive and negative p. As the iron is subjected to higher and higher 
fields H’, this curved surface moves further and further away from the 
centre, until finally there is only negative p left in that half of the iron 
rod which has the positive surface magnetism. ‘This occurs just as soon 
as every point in the iron has been magnetized past the point of maxi- 
mum «. ‘The presence of this negative p may perhaps account very 
largely for the fact that V is not far from constant for quite a long 
range οὗ" When saturation of the iron with magnetism is approached 
more and more, the « becomes nearly constant throughout the rod and 
continuously approaches zero, so that 4,, and therefore the negative p, 
are both becoming vanishingly small. Οὐ. G. Lamb!* gives a set of 
curves, reproduced in Figure 4, showing the variation of « along an 
iron rod from centre to end for various applied fields, which illus- 
trate the matter with perfect clearness. Of course the u, when found, 
as Lamb did, by ballistic methods. with a search coil placed at varying 
distances from the centre, is the mean value of w for the iron sur- 
rounded by the search coil, but it shows the variations along the rod 
very well indeed. 

All the \-curves found in the experimental series of the present 
paper do not deviate to a very great extent from straight lines for 
values of B less than 10,000 or thereabouts. They show quite defin- 
itely the two curvatures which we were led to expect by theoretical 
considerations. Above this point, however, the N-curves have an 
ever-increasing tendency to turn to the left, and at last actually do 
move from right to left, so that finally we have not only the 7,/I (= Δ) 
merely decreasing, but even the 7/7; decreasing. At first this was very 
puzzling, for it would seem natural to suppose that, although V must 
really decrease when the iron bar shows saturation, just as we were 
expecting from the theory, as long as more and more lines of magnetic 
induction are thrown into the rod when as yet unsaturated with mag- 
netism, there is more and more magnetism induced, which ought to 
increase the demagnetizing field 17, continuously. 


14 Phil. Mag., (5), 48, 262-271 (1899). 


202 PROCEEDINGS OF THE AMERICAN ACADEMY. 


This, however, is not at all the case, and the actual facts emphasize 
the fallacy of considering the magnetization in long iron rods, when 
not completely saturated, as even approximately uniform. As will ap- 
pear from the results obtained in this investigation, the values of V 
are not far from being constant below 2 = 10,000, and they are of the 
order of magnitude as those found by Du Bois from Ewing’s curves, 
although always somewhat smaller. But let us now find what these 
N-yalues would be if our various rods were really uniformly magne- 
tized. In other words, let us find the position of A’ of the straight line 


-- 
΄ι 
S 
oO 


Values of μ. 
5 
Θ 


Centre 22 20 18 16 14 12 10 8 
Ficure 4. 


Lamb’s curves showing the change in permeability along an iron rod. The 
distances along bar are given in inches. 


OK in Figure 8. Our rod has the length Z and diameter D, so that 
uniform magnetization would mean z(//2)?/ units of free positive 
magnetism on one end of the rod and the same number of negative 
units on the other end. If Z is large compared to 7), we may regard 
the demagnetizing field-intensity 7, (or NJ) at the centre of the rod 


, : \? 2 
as caused by a single point-pole of strength ax(2) T at a distance 
of L/2 units of length from it. Then 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON Robs. 203 


Therefore, for uniform magnetization, 
Nut = 27 = 6- 28+. 


This value for im’, it will be noticed, is considerably less than the 
constant 45 as found by Du Bois from experimental data, and which 
constant led him to construct a table of values for WV which, as we 
shall see later, is probably quite accurate for the iron wires of small 
diameter used by Ewing and T'anakadaté. Yet the conditions which 
Du Bois assumed in order that his theory might be applicable are pre- 
cisely those which we have here assumed. For the shorter rods Nin? 
would be smaller yet, for the two reasons that the magnetism o (or /) 
on the squared-off ends of the cylinder must now be considered further 
off than the distance 1/2, and much of it acts at a small angle; of 
course the resultant /7;, which is now really given by a double integral, 
is directed along the axis of the rod. It is now clear that Figure 3 
does not begin to show the tremendous sweep to the left, of the upper 
portion of the N-curve, which has been found by Benedicks 15. for 
his rod of steel where m was 25, and which really occurs in every one 
of the V-curves obtained ballistically. 

Let us now compare the values of NV for various ellipsoids of revolu- 
tion, and those obtained by Du Bois for cylindrical rods, with the 
limiting values of VV for uniform magnetization. ‘The values for the 
shorter rods are calculated from the same formula as the longer ones. 

The explanation of the great difference between the actual demagne- 
tizing force under non-saturating fields and the demagnetizing force in 
case of uniform 7 is of course found in the fact that in the former case 
quite a large part of the lines of force leave the curved surface of the 
iron rod very near the middle of the rod, so that the contributions 
AM/r* to the demagnetizing force count up very heavily in com- 
parison with the magnetism nearer the end of the rod. An ideal 
uniformly magnetized rod of the same diameter, and having the same 
number of lines through its middle section as one which is actually 
magnetized in practice to less than saturation, must be only about 
V/ 27/45, or 0.374 times as long, if it is to produce as much demagne- 


15 Bih. Svenska Vet.-Akad. Handlingar., 27, 1, No. 4, 14 pp. (1902); Wied. 
Ann., 6, 726-751 (1901). 


204 PROCEEDINGS OF THE AMERICAN ACADEMY. 


TABLE I. 


DeEMAGNETIZING Factors. (N.) 


Cylindrical Rods. 
Ellipsoid. 
Uniform I. 


0.2549 0.063 


0.1350 0.028 


0.0848 0.016 
0.0579 0,010 
0.0452 0.0070 
0.0266 0.0089 
0.0181 0.0025 
0.0182 0.0018 
0.0101 0.0013 
0.0080 0.00098 
0.0065 0.00078 
0.0054 0.00063 
0.0026 0.00028 
0.0016 0.000157 
0.00075 0.000070 
0.00045 0.000039 


tizing force at the middle point of the rod as the other suffers. This 
induced magnetism (both o and p) near the centre of a rod of iron 
magnetized to a value of B somewhat below 10,000, can be readily 
recognized by its effect on a small compass needle, which will be de- 
flected the moment it is moved a few centimeters from the middle 
part of the rod toward either end. 

It might be of interest to note that the highest possible demagne- 
tizing force would be obtained by placing a very large slab of iron, with 
plane parallel faces, perpendicular to the lines of an infinite magnetizing 
field //’; the value of /7, would be 47/,,, when the slab is infinite in 
extent, but has any finite thickness. This 7, would, moreover, have 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 205 


the same value at any point whatever in the iron slab. The value of 
N, the demagnetizing factor, is 47 throughout the slab. As in soft 
iron a negative force of H’ less than 10 c.g.s. units of field intensity is 
sufficient to demagnetize the remanent magnetization which exists in 
the iron after the original magnetizing field is withdrawn, and the 
value of 47/,, is about 200,000 of c.g.s. units, it is easily seen that on 
removing the infinite field the demagnetizing field H, would instantly 
demagnetize the slab completely. 

A diagram of the apparatus and its arrangement, as used prac- 
tically throughout the present investigation, is shown in Figure 5. 


Fictre 5. 


Diagram of apparatus used in the Jefferson Physical Laboratory in obtaining 
magnetization curves for the present investigation. 


EXPERIMENTAL METHODS AND APPARATUS. 


G is a Thomson four-coil ballistic galvanometer with astaticised mag- 
netic suspension, controlled by a permanent magnet S—N, and not 
shielded at all magnetically, for it was found that when shielded with 
three large cylindrical iron shells and heavy iron plate tops and 
bottom, certain unknown magnetic disturbances were caused in these 
shields, and effectually prevented the needle, which was then non- 
astatic, from coming to rest. / is the storage battery of from 5 to 20 
cells, giving about 2 volts each, for furnishing the current in the 
primary coil. Sis a large solenoid of the following dimensions: 


206 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Length = 207.7 ems. 
Outside diameter = 5.97 cms. 
Inside diameter = 3.63 cms. 


This solenoid was wound on a tube of pasteboard with two wire coils 
of 3386 turns each, —of No. 18 wire, in six layers, — which were used 
in parallel, so that 


H' = 47nC/10 = 20.5-(No. of amperes used). 


Later on in the work a still longer solenoid was built, in order to ex- 
periment on very thick iron rods. A is a “ P-3” amperemeter, that 
is, one of the type so successfully used in the laboratory of the course 
Physics 3 in Harvard University ; it reads with great accuracy up to Γ 
1.5 amperes. A is a double reversing knife switch, connected to the 
solenoid S, and also to a demagnetizing solenoid 7), with an iron core ἢ 
in the small coil, which could be connected to the light cireuit Z. R 

is a rheostat in series with a system of variable resistance coils, to ὦ 
regulate the current. [0 is a reversing key to change direction of 
ballistic throw in the galvanometer. 7715 a tapping key arrangement 
with small battery, for bringing the galvanometer magnet needle to : 
rest. Its circuit contains a very high resistance W. Z is the ραῖνα- 
nometer scale with telescope, at 116 cms. distance from magnet 
system. 10 is a resistance box in the secondary circuit; by varying | 
this resistance the throws were kept under control, so as to give good 
accuracy in the readings. 

The “ P-3” galvanometer was frequently compared with a Weston 
milliamperemeter with shunt, and the sensitiveness of the galvano- 
meter was often determined during the course of the work by charging 
a condenser of one microfarad capacity from a battery of four Samson 
(wet) cells whose voltage was read off on a voltmeter. ‘The sensitive- 
ness, given in centimeter divisions of throw per coulomb, ranged from 
1.24 to 1.60. In the latter part of the work the condenser was — 
charged by connecting across a standard resistance of 10 ohms, say, — 
through which about 1 ampere was flowing, thus getting about 10 
volts. ; 

In the earlier half of the experiments the “reversal” method was — 
used with great convenience and accuracy in the readings. The 
magnet suspension does not hold its zero very closely, but is slowly 
tossed about by magnetic disturbances over a range of 1 mm. scale — 
reading, and sometimes more. Moreover, the zero position, which ἴδ. 
quite definite at any one time, often changes slowly during the course — 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODs. . 207 


of the day. With the reversal method no attempt to read the zero 
was made, but instead a number of throws were taken alternately in 
the plus and minus directions, and then averaged. These throws often 
agreed regularly to about 1 part in 1000, when taken with a little 
care. ‘The reversal method, however, has a possible error due to the 
time-constant of the primary circuit being comparatively large when 
there is much iron in the solenoid S, and also to the slow establish- 
ment of the magnetism in a thick iron rod. This was counterbalanced 
by making the complete period of the astatic system about 25 seconds, 
and finally 31 seconds. 

The step-by-step method was used only in one series of experiments 
with the first solenoid S. This method is much harder to carry 
through successfully, especially since the battery “ must maintain its 
voltage without appreciable drop while furnishing an increasing cur- 
rent for about half an hour, and the zero reading must be taken care- 
fully every little while. Usually several curves were obtained for each 
length of the iron rod used, so that a good average curve could be 
constructed. As is well known, the two methods do not give the same 
magnetization curve, the one by the step method usually, but not 
always, lying below the reversal method curve. 

The iron rods tested in the first solenoid were all of soft Bessemer 
steel, six feet long and of diameters ranging from 0.2381 cm. (= 35 
inch) to 1.270 ems. (ΞΞ inch). The secondary coils consisted’ of 
from 30 to 400 turns of fine insulated wire wound directly over the 
middle of the rod. It was found necessary to reverse the magnetism 
about six times before reading the actual throws, otherwise the read- 
ings come out too low. After sufficient data had been collected to 
construct a curve, equal lengths of the rod were cut off from each end, 
so as to reduce ΠῚ from one value to the next. ‘The ends of the rod 
were then filed smooth and plane. Then a curve was obtained for the 

shortened length of the rod. 

After proper reduction of the observations, the magnetization curves 
B vs. H’ were carefully constructed for all the m’s used, on a large 
sheet of millimeter paper of the dimensions 43 x 53 ems. 

The next problem was to devise some means of getting at the normal 
curve (πὶ ΞΞ- «). In the earlier part of the investigation frequent use 
was made of the principle which leads to Du Bois’s experimental formula 
Ni? = 45, when m 2 100. It was found that so long as B did 
not exceed the value 8000, the formula was fairly well satisfied for 
m 2 150, provided only one system of simultaneous equations was 
used. That is, supposing we had plotted out the actual magnetization 
curves for πὶ = 300, 250, 200, and 150. If we take all these into 


208 PROCEEDINGS OF THE AMERICAN ACADEMY. 


account, reckoning therefore the distance in any units of length, say 
millimeters, from the normal curve to the one for πὶ = 300 as our un- 
known 2, we shall find the whole set of equations giving a good average 
value for 2, and thus we may construct what might be called “the 
normal curve based on it = 300.” Now if we use only the curves for 
250 to 150, so that our next 2 is the unknown distance from normal 


PPC eee 
ten tara 5 


204) A pad BS 
Se 
PLL MAO TA eet 

AV ae 


ene ri [TABLE el 


Reversal magnetization curves for a Bessemer soft steel rod of diameter 
0.6350 cm. 


curve to the curve of 250, we shall again find values for 2 which satisfy 
all the equations moderately well. But the normal curve thus deter- 
mined, which is the normal curve based on m = 250, will lie slightly 
to the right of the first one constructed, — at least every case tried gave 


this result. Similarly, the normal curve based on m= 200 will lie to _ 


the right of the one based on im = 250, and so for the one based on 


175. For higher values of B than 8000 the formula fails to hold at 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 209 


all. It should be noticed that as the iron rods become nearly saturated 
with magnetism, the magnetization curves bend around and become 
more and more parallel to the H’-axis, so that a very slight displace- 
ment of the curves up or down may result in proportionately large 
errors in the construction of the V-curves. The only thing to do is 


ΠΕ Ὲ ΕἸ 


Reversal magnetization curves for a Bessemer soft steel rod of diameter 
1.270 cms. 


GE 
B22 CEE 
5 


FIGURE 7 [TaBLe ah 


to construct by “trial and error” methods a normal curve which will 
give the best possible results for the whole body of V-curves. 

To be absolutely consistent the V-curves should be constructed from 
magnetization curves on the J vs. H’ plane, for N is defined by 
H = H’— NI. Substituting in this the value for 7 from the funda- 
mental equation B = H + 4π|, we get 

Hee iene 


VOL. XLIII. — 14 


210 PROCEEDINGS OF THE AMERICAN ACADEMY. 


But as even for the high value 7 = 30, B is somewhere near 15,000, 
we see that the error introduced by neglecting the H in the brackets is 
but 1 part in 500, which is much less than the experimental errors. 
Therefore, since the ballistic throw is proportional to B, it is very 


SNe 
CATT 
ΒΕΒΕΒΕΒΡ 202 
rebel || Ze 
᾿ τ 
ΒΕ ΠΕ sed 
WI 


INI 
ἘΞ =< 
AS ENO 
\ a A AA 
NST ale Noe NTE 
ἌΝ 
ΞΕ τος ΨΕΙΝ ἘΝῚ 


IN 


MY 
ge 


ie 
fe 
a 
Ze 
rr 
{πὶ 

1 


ENS 
Lae a ae eee 
eo Bet 


aaa eS 


= 
ae ee RY 


a Se ee τσ 


/ 
2 
- 
ἘΠ 
ΜΈ 
fa 
Ὁ 


Figure 8. [Tasve IV.] 
Reversal magnetization curves for a Bessemer soft steel rod of diameter 
0.4763 cm. 
much more convenient to construct the V-curves from the formula 
H = H' — NB/Az. 


EXPERIMENTAL Resutts ror DemMaGnetizina Factors. 


Let us now tabulate the actual values obtained for the end correc- 
tions, or demagnetizing factors VV, of a number of rods of Bessemer 
steel (copper coated), which is a very homogeneous soft iron. Later on 
we shall see just how these values were determined, and give the 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON Rops. 211 


necessary data from which the most important table was constructed. 
It might be noted here that the results for the extremes of magnetiza- 
tion B = 1000, and δ᾽ = 12,000 are somewhat less reliable, for reasons 
which will appear. ‘The numbers 10 to 150 are the values of m used. 
TABLE II. [Ficure 6.] 
October 2, 1906. 
Diam. = 0.63850 em. = 1/4 in. 


REVERSALS. 


Values of V x 104. 


50 60 


1990 | 1010 


1028 


Below each value of m is given the series of values of NV - 10* obtained, 
one for each interval of 1000 c. g. 5. units of B, or gausses. Of course 
in all these experiments the column under the highest number m gives 
values for the first curve obtained, for m is always decreased by each 
sawing off of the ends of the iron rod. 

See Figure 6 for the magnetization curves of October 2, 1906. 


212 PROCEEDINGS OF THE AMERICAN ACADEMY. 


The normal curve as determined is indicated in all these figures by 
the dots spaced every 1000 units οἵ, 

Figure 7 exhibits the curves taken on October 4, 1906, and shown 
in Table III. It will be seen that these curves are very much flatter 
than those of the 1 in. rod and the τὸς in. rod which follows this one. 


Ficure 9. [Taste IV.] 


Curves showing variation of magnetic induction with different lengths of a 
Bessemer soft steel rod of diameter 0.4763 cm. The numbers affixed to the 
curves give the constant currents in amperes through the solenoid. 


Figure 8 shows the original curves of October 9, 1906, and presented 
in Table IV. 

From the data of these curves Figure 9 was also drawn. This shows 
the curves of constant current as the rod is increased in length. The 
numbers affixed to the curves give the current in amperes, so that the 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 213 


applied field #/’ in the solenoid can be found by multiplying by 
the factor 20.5. It is seen that at first the induction increases very 
rapidly and nearly linearly. ‘Then after a sharp bend the curve ap- 
proaches a maximum induction asymptotically. It is interesting to 
see how for higher currents this maximum is reached very much sooner 

TABLE III. [Ficure 7.] 

October 4, 1906. 
Diam: —-27/0lems: = 1/2: 


REVERSALS. 


Values of V x 104, 


60 


95] 


97 | 


than for lower currents. As regards curvatures, the sharp bend, and 
approach to a maximum value, these curves bear a close resemblance 
to the magnetization curves, when plotted on the 7 vs. H’ plane. 

See Figure 10 for the magnetization curves accompanying Table V, 
October 20, 1906. These are also quite steep. 


214 PROCEEDINGS OF THE AMERICAN ACADEMY. 


No figure is given for the results obtained on November 6, 1906, an 
collected in Table VI. ‘The curves are very steep. 
See Figure 11 for the magnetization curves corresponding to Tables 
VII and VIII, of November 16, 1906. The curves passing through 
crosses are the ones obtained by using the method of steps, while 


TABLE IV. [Fievre 8.] 
October 9, 1906. 
Diam. = 0.4763 cm. = 3/16 in. 
REVERSALS. 


Values of V Χ 104. 


1000 | 2001 | 1028 038 
1049 | 659 
665 


2000 
3000 
4000 
5000 
6000 
7000 
8000 
9000 
10000 
11000 
12000 
113000 
14000 


15000 


The vertical arrow-points indicate the probable position of the normal 
curve by steps, and the oblique arrows give the reversal one. Severa 
series of step curves were taken for each m so that a good average 
curve could be constructed. It will be noticed that the step curve 
all lie below the others, except the one for m= 400. ' 


A ὧς ll te" 


.Ν 


τ τ th al ate ti 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 218 


No figure was made for the curves, which are exhibited statistically 
in Table IX, of December 1, 1906. 
The work up to this point indicates that the thicker rods have 
smaller demagnetizing factors than the thin rods. ΤῸ test this matter 
TABLE V. [Ficure 10.] 
October 20, 1906. 
Diam. = 0.8969 cm. = 5/382 in. 


REVERSALS. 


Values of V x 104. 


Oe eS sO) τ oo Ow Ὁ Ὁ Owe δι 


more carefully, a very long solenoid was built, probably the only one 
of its size ever constructed. The wire was wound in a double coil 

- over a thick brass tube, making in all eight layers. The wire used 
was the Annunciator No.18, of diameter = 1 mm., with red insulation. 
The dimensions of the solenoid are: 


bS 
fad 
σὺ 


PROCEEDINGS OF THE AMERICAN ACADEMY. 


Length of windings = 485.3 cms. = 15 ft. 11 ὃ; in. 
Outside diameter = 5.96 cms. 

Inside diameter = 2.86 cms. 

Number of turns = 10452 for each of the two coils. 


TABLE VI. [No Ficure.] 
November 6, 1906. 
Diam. = 0.2881 cm. = 3/82 in. 


REVERSALS. 


Values of NV x 104. 


The two coils were used in parallel, so that the magnetizing field is 
Π' = 27.064 ¢.g.s. units for each ampere. 

The first rod tried in this solenoid was one of 0.9525 em. diameter 
(= % inch), and was a complete failure, although it gave some very 
interesting results. No two consecutive step method magnetization 
curves would agree. The rod was 15 feet long, so that m= 480. 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 217 


The rod was carefully demagnetized and magnetized, apparently under 
similar conditions each time. Parts of eight different magnetization 
curves are shown in Figure 12 and illustrate the wide divergence at 
the higher inductions. The reason for this peculiar behavior of the 
tron was made clear when the rod was demagnetized and taken out of 


πο. 


"αὶ 


iil 

bint 

[esd 

en 

bel 

ΞΕ 

-π 

5 

ἊΝ ἢ} 

NIN 

Nae 

τ 
AXE 
See 
— Af 


SSS E 
PRN AAA 
Ν 


aun Segue 

τ τς 

ἑ 2 ee 
“ Ξ 

te Peer 


Re 


Figure 10. ee V.] 


Reversal magnetization curves for a Bessemer soft steel rod of diameter 
0.8969 cm. 


the solenoid, and then tested with a small pocket compass for con- 
sequent poles. It was found that the rod was quite strongly magne- 
tized, and had polarity in the order V—S-N-S, the two middle poles 
being both near the middle of the rod. Evidently this rod had once 
been lifted around a warehouse by means of an electric crane with an 
electromagnet lifting device, so that it had been subjected to quite 


218 PROCEEDINGS OF THE AMERICAN ACADEMY. 


a high magnetizing field. Besides, it is probable that the iron of this 
particular rod, which was not of the usual Bessemer steel, is not very 
homogeneous. In such cases it has been the experience of men who 
have had much to do with magnetization of iron in a practical way— 
as, for instance, Mr. Thompson, the mechanic of the Jefferson Physical 


BE ep eee 
Bee Eee 
ΒΒ 29725 5 
ΕΠ. ΠΡ 
oo! | || | | LWA et 4 
He fe BEPZAGREDEZ 
Ht A a ΒΒ, 4 
ΕΠ] OA 91 a 
τ,» er 
“οι ff me art | | | 
HA A a Toe 
LLL WZ aa eet | 
COA eC 
eer ἹἙ 
Peer {111 {ΠῚ TT 


Figure 11. [Tasres VIL ann VIIL] 


Sot 


AAA A 


' 
awe 5 
See oe κι 


ie 
Ζ 
Ζ 


- ἢ 
1 
᾿ 
; 
i 


a 


\ 


AY 


res SE Sa —— ὡς —— 


Step and reversal magnetization curves for a Bessemer soft steel rod of diam- 
eter 0.5175 cm. 


- CL eile mee a TE: ES PT 


Laboratory —that heating the iron specimen white hot and then 
allowing it to cool slowly will not get rid of the consequent poles. — 
Nor will subjecting the iron to higher magnetizing fields, and then 
decreasing the field while reversing constantly, so as to demagnetize, 
help the matter, for the poles come back straightway in their old 
positions. 
After this the iron rods used in the long solenoid were carefully tested 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 219 


for consequent poles before they were bought for the work. Even then 
some peculiarities were noted in the results, which are due to some 
irregularity in the polarity which was not apparent in the test with a 
small compass needle. It should be noticed that such irregularities as 


TABLE VII. [Ficvre 11.] 
November 16, 1906. 
Diam. = 0.5175 cm. = 1/8 in. 


Step MErHop. 


Values of V x 104. 


shown in Figure 12 are very much more pronounced when the step 
method is used. In fact, with the reversals it would probably turn out 
_that a very smooth curve would be obtained, but which would lead to 
erroneous results in the demagnetizing factor. 

No figure is given for the series whose results are tabulated in 
Table X, of January 16, 1907. This table should be compared with 


220 PROCEEDINGS OF THE, AMERICAN ACADEMY. 


that for the rod of same diameter worked out beginning on October 9. 
It will be noticed that these values for .V are considerably larger than 
those of the earlier series. ‘This again shows very clearly the difference 
between the reversal and the step method. 
TABLE VIII. [Ficvre 11.] 
November 16, 1906. 
Diam. = 0.8175 em. = 1/8 in. 


REVERSALS. 


Values of NV x 10+, 


4 
4 
4 
4 
4 
9000 ae 228 142 66 43 19 11 4 
10000 Aas 226 140 63 41 17 10 4 
11000 ks 222 184 59 38 15 9 4 
4 


12000 


15000 
14000 
15000 


January 18, 1907. They were taken by the step method, and ea 
curve was based on three or four separate magnetizations from zero to the 
highest value of Π', so that good average results might be obtained. 
It will be noticed that the curve for m= 200 passes very nearly 
through two sets of observations, but that on either side of it lie 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODs. 221 


observation-points at quite a distance off. Most of the other curves 
are in much better agreement with their points. There were also 
taken a number of magnetization curves for the initial length of the 
rod, 15 feet, which made πὶ = 329; these curves resembled the ones 
TABLE IX. [No Ficvre.] 
December 1, 1906. 
Diam. = 0.6350 cm. = 1/4 in. 


REVERSALS. 


Values of V Χ 104. 


80 


1000 
2000 
3000 
4000 
5000 


6000 


7000 
8000 
9000 
10000 
11000 
12000 
13000 
14000 


15000 


for the rod with pronounced consequent poles. It thus appears that 
there must have been some irregularity in the demagnetized rod near 
one or perhaps both ends of the rod. As the rod was cut down from 
m = 829 to m = 200, most of these irregularities were cut off. ‘Then at 
the next shortening practically all the rest was eliminated. For m= 30 
a reversal curve, represented in the figure by crosses, was also taken. 


222 PROCEEDINGS OF THE AMERICAN ACADEMY. 


See Figure 14 for the original curves, from m= 15 to m= 240, from 
which Table XII, of January 22, 1907, was constructed. It will be seen 
that on the figure there appear a number of crosses. These represent 
magnetization curves, not actually drawn, which were taken with the 


TABLE X. [No Ficvre.] 
January 15, 1907. 
Diam. = 0.4763 cm. = 3/16 in. 


Stee Metuop. Lone Coit. 


Values of V Χ 104. 


9000 
10000 
11000 
12000 
13000 


14000 


to 


15000 


reversal method. This brings out a most interesting point. The thick 
brass tube opposes a sudden change in the magnetizing field, by virtue 
of eddy currents, and thus the establishment of the field is somewhat 
delayed and the magnetization of the iron takes place more slowly. 
The step method magnetization also is slower than the step method 
when used in a plain solenoid wound on a tube of pasteboard, as is the 


il 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 223 


first solenoid. But as the reversal method has now almost overtaken 
the step method, we may conclude that both are very nearly at their 
limiting positions, reached for very slow establishment of the magnet- 
izing field, which are probably very nearly the same. 
TABLE XI. [Ficure 13.] 
January 18, 1907. 


Diamy—= lit icms: ΞΞ 7//1GAn: 


Stee Metuop. Lone Cott. 


Values of V x 10+. 


Figure 15 gives the original curves of Table XIII, taken on February 
21, 1907, and following. As it was found that in the long solenoid 
the reversal method gives us practically the same results as the steps 
method, it was now used throughout because of its convenience and 
accuracy. Compared with the results of the rod of “cold rolled shaft- 
ing” these values are somewhat smaller, but not more perhaps than is 


224 PROCEEDINGS OF THE AMERICAN ACADEMY. 


due to the slight difference between the step and reversal methods which — 
still remains. It is thus probable that the material of these two rods is 
not of very great importance. he curve for m = 240 was also taken, 
but was very nearly coincident with that for m = 200. 

When this rod, which we will call Rod No. I, was tested for conse- 
quent poles, there was also selected another one of the same diameter 


ἢ ΤΠ ΕῚ ἘΠ ΩΣ ἊΣ 

11 rte TTL 
EORE a iss 
oR RRR - 


2 
2 
μ [1.2  «Ἴ. 
“πω... 
ΒΒ ΕΣ ς 
ERE) 1 στὰ 
RGF 4" 1 ΟΕ ΕΣΕ 
ee 

ERA ERR ΒΑΕ ἢ" 
VLE, ESSE 
BER 1] ΓΙ ΤΕ RAE 
SARE RE {1 ΤΕ ΕΝ 
»} elt τ Se 


ΤῈ URE 12. 


5 
Ze 
aC 


NC 
NAS 


CAR 
- 
a 
Bi 
᾿ 
fe 


rs es aS 

ἘΞ ea ee ΣΡ aE ἢ 

πο τω. 
ΞΕ Seem | 
ἘΞ ΞΈΡΕΙΣ ee 


ο 


Effect of consequent poles in an ironrod. The magnetization curves shown 
were taken under apparently the same conditions. 


from the same lot of iron. Both were 20 feet long, and pieces of 1 
foot and 4 feet were cut off from the ends. Rod No. II was magnetized 
at m= 240, and gave the higher curve marked by the crosses. The 
‘pieces of 4 feet length had been mixed up so that it was impossible to | 
say which belonged to Rod No. I and which to the other one. Test 
pieces of 1 = 60 were now prepared from both of these pieces, all of 
these rods of diameter 1.905 ems. being wound with 50 secondary turns | 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 225 


in the centre. The short rods now gave the magnetization curves which 
are merely indicated by crosses near the curves for m= 80 and m= 60 
of Rod No. 1. It is now evident which rod each of the small pieces came 
from. Ofcourse the magnetic induction was now measured at a distance 


TABLE XII. [Ficvre 14.] 


January 22, 1907. 


Diam. = 1.905 ems. = 3/4 in. Cold Rolled Shafting. 


Steer Metuop. Lone Cort. 


Values of V x 104. 


of about 9.5 feet in the original 20 feet rods, but still the normal curves 
would probably not differ much. On the other hand, the normal curve 
for Rod No. I is quite different from that for Rod No. IL. 

With the help of the tracing cloth scale to be described below, Figure 


16 was constructed, it being assumed that the maximum 7 is practi- 
VOL. XLIIt.—15 


226 PROCEEDINGS OF THE AMERICAN ACADEMY. 


cally reached when 2 = 17,000. This body of .V-curves shows the 
curvatures which we were led to expect, and also the tremendous turn to 
the left as the curves get near the point of complete saturation. ‘This 
curve might be said to embody the most important results obtained 
about the V-curves. The one corresponding to m = 20, after going 


ed ee eee 

_ COREE RERERRE Σ Be 
BEBE 

ΑΒΕ 

| SKY 

al 


Hn 

Me 

AY 
4 
avn 
eee 
ie 
ig 
rez 


| 


—s 


NW 


ΣΡ, 
eS he ΜΒ. τα ΒΡ δον ΠΠῸ] ἘΠ 181] 
FRR τ νιν ἈΝ ΜΠ 

Aaa nwa we See See 


WW 


ὦ 
"» 
ξ 


Ne 


SA ARAS 


x 


= 
geet 
Γ 
μ᾽ 
"ἢ 


-- 
SS 


ΖΓ Π 
ΓΕ BBC 


Figure 13. ΓΕ ΧΙ] 


J 


Ρ 


ἘΣ ἘΠ Εν 
ca 


H 


ttt} ΒΕ ΒΕΒΕΒΗΕ ΕΒ 


TEA EEA ee 
SE) PN PE PA PT 7 (A DP S| 


δ 


Step magnetization curves in long coil for a Bessemer soft steel rod of diam- 
eter 1.111 cms. 


out nearly straight far beyond the limits of the figure, sweeps back to 
the left and just shows in the upper left-hand corner. It will be noticed 
that the points of observation for all the curves become uncertain after 
B = 12,000; this is to be expected because the magnetization curves 
there become almost horizontal and run into one another, and the find- _ 
ing of the abscissa-differences is a very difficult matter. 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 227 


MetHop oF REDUCING OBSERVATIONS. 


As a typical illustration of the whole work, let us consider the reduc- 
tion of the observations taken on the largest iron rod used in the long 


TABLE XIII. [Ficure 16.] 
February 21, 1907. 


Diam. = 1.905 ems. = 3/4 in. Bessemer Steel. 


REVERSALS IN LONG COIL. 


Values of NV x 


m=15)| 2 i 50 5 i 150 


1009 02 | 139 
1019 Be y 141 
1032 


1052 


1042 


1045 
1040 


solenoid. This is the series on Rod No. I, begun on February 21. It 
usually takes about two days to take a series of observations, and the 
reductions and plotting of curves take about two or three days 
more. 

When using the reversal method, the observations were taken under 


V\ μην WG μα ΣΉ aT 
Me A Tk | ON EA OEE τ ἢ 
baat 


LON ol Co Aa 


Ficure 14. [Tanre XII] 
Step magnetization curves in long coil for a rod of “cold rolled shafting” of diameter 1.905 cms. 


ΩΣ ὯΝ j 
ΠΤ SS Εὐρτ ον να ΝΝΝ 
RAN SOA AE 


Se a SSM 
a a a ΠΡ SST 
A 1 οὐδεν τεσ ον 
ἘΠ ΤΟ πὸ συ 
ΠΡΟΜ | ae Bopp 
a tat) Se ei en τ 


the headings : current in solenoid, resistance in the box /?’, and bal- 
listic throws observed. In the case of the step-by-step method the 
zero reading of the galvanometer was also necessary. 

We start from the fundamental equation of a current through whose 
circuit the magnetic flux varies : 


Hl 4 
(oa OS ae ΞΕ ΞΕ 
PRE 
SRR Sa i= se | al σαι 
Pe Ge Ξ GR ef oe a 
A A} Sf } το] 
[oct ΟΣ: a 


‘CAEL a ES ΕΞ a ee 
[{π ΠΕ ΕΞ ee ee a ΓΞ ΕΞ τ 
JS ean ΞΕ ΞΕ See 
ita hit ἘΞΊΞΞΗ 
aH Vee γώ 


a aE) [ΞΕ ΈΙΕΞΙΡΕΙ 

παρα ee ἘΞ ΒΕ ἘΒΙ ΒΕΊΝΗΙΞ 
πα πεν thee πὸ τ πὰ ie ees 
eae, eS See \ 
th A, 


ἘΞ. 1 ΒΕ ΡΝ 
ae SEEN eee ime 
ΞΕ a AK ΕΞ ΕΞ ἘΞ ἘΞ ΕΞ ΞΕ ΜΞ ΡΞ Ὁ 
SSN ee ee eee 
TESS tin Sahn Bim 
hy SEN SNS = | 


(EO BN GO CE ΑΘ ΕΞ ΓΞ ΠΕΣ ΞΕ ΠΕΡΙ Ε 
ΒΕ ἘΞ ΕΠ A) 
-ν ἘΞΠΙΕΞΙ Sas 


ΓΝ 
jae Ne 
ae {5 GEG oe 
Bae QL 


Gwe 
STANTS ete 
ΝΣ ΩΝ ΑΓ Ὑ 


ἘΠΕ ΓΠΠΠΠΠΠ 
ΕΞ ΒΕ ΠῚ PEE 
“ 


wool | || | tT 0 
ἘΠΕ ΒΕ aaa 
GA 


[Taste XIIT.] 
Reversal magnetization curves in long coil for rods of Bessemer soft steel of diameter 1.905 cms, 


Figure 15. 


o* 


230 PROCEEDINGS OF THE AMERICAN ACADEMY. 
dN 
E— —=CR 
dt ‘ 


where /’ = electromotive force in the circuit, not due to changes in 


flux, 


[33] 


Se 


Oe A a aS 
BAe ae ee 
ΞΙΝ 
Sa Nf 


eS [ΕΠΕ ΜΡ Ὁ:5Ὁ ΚΒΕ ΚΠ κὸ; ἄπο κά Π ΚΒ. ΓΒ σεὰ [δε ἢ 


a 
Fa BO ee τ AR PS i WE Fa GCS 


ERZEREES! 
0 


Ficure 16. [TABLE te 


Back-shearing curves for Bessemer soft steel rod of diameter 1.905 cms. 


N = total magnetic flux of induction through the circuit in the 
direction of the magnetic lines due to the current C, times the number 
of turns of wire in the circuit, 

ἐ = time variable, 

C= actual current at time ¢ flowing in the direction in which # 
acts, : 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 291 


1 = total resistance of the circuit. 


If we apply this equation to our secondary coil circuit, which includes 
the ballistic galvanometer, we have, since / = 0, 


t 
AN = nf (1: ΞΞ ΝΟ; 
ΟΥ O=ANSR, 


where Q = total charge through galvanometer, 

AN = number of flux-turns of change in the magnetic induction 
through the circuit. 

This equation is expressed in ¢.g.s. units. If we use as our units 


the ampere, ohm, microcoulomb, and gauss, as we have done, then we 
must use the equation, 


Q@ = AN/(100R). 
We have also ΟΥ̓ΞΞ 77,8: 


where 7’= actual throw in centimeters of scale reading produced by 

the discharge of Q microcoulombs through the galvanometer, and S = 

sensitiveness of galvanometer, expressed in centimeters of deflection 

obtained by discharging 1 microcoulomb through the galvanometer. 
Now in the reversal method as used in these experiments, 


AN =2 BAn = 2 Br(D/2)?n, 


where 4 = the magnetic induction in gausses, or number of lines of 


induction per square centimeter passing through the middle of the iron 
rod, 


A = cross-section of rod in square centimeters, 


nm = number of turns of secondary coil wound around the middle of 
the rod, 


PD = diameter of the rod, as before. 
This gives us 


2. Br(D/2)’n  T 
100-R Gis 


« ΟῚ . 100-8 
T  2Sx(D/2)?-n 


This formula is the most convenient for our purposes. As in our series 


_ we had the data 


bo 


32 PROCEEDINGS OF THE AMERICAN ACADEMY. 


S = 1.489 
D = 1.905 ems. 
= 50 turns 
B 100-R 


we get 


T  2(1-489) = (0.9525)?- 50 


The right-hand member is a constant for any given ?. In the work on 
the series of curves the # had values ranging from 117 to 7117 ohms; 
the galvanometer and secondary coil circuit having itself 117 ohms, of 
which the galvanometer had about 99 ohms, and the coil 18 ohms, 
the other resistance being added, when convenient, from the resistance 
box #’. ‘The constants for these various /?’s were found and written 
down. ‘Then all we have to do to find the B for any observation is 
multiply the observed throw in centimeters by the proper constan 
This was done either by means of logarithms or a very good slide rule. 

If we use the step-by-step method, the formula simply drops the 
factor 2 and becomes, 


SB_ 100k 
T ~ Sw(D/2)?n 
For the long solenoid we have simply 
= 4 TL y 


ra od (es 
= 27.064 (No. of amperes). 


: (No. of amperes used) 


Having found the values of Band //’, they were multiplied by 3 
and 2 respectively, in order to facilitate the plotting of the points of 
observation. ‘Then the magnetization curves were drawn by free-han¢ 
so as to fit the points as closely as possible. 

This gives us the curves from m= 15 to 200 in Figure 15. To fine 
the corresponding normal curve (111= «) a graphical device was foun¢ 
to be of the very greatest utility. Not only was an enormous amour 
of time saved, which otherwise it would have been necessary to spent 
in almost endless computations, but the device was a positive aid in~ 
determining the position of the normal curve. On a large sheet of 
tracing cloth were drawn about seventeen horizontal lines, so that whe 
properly placed over the sheet of millimeter paper on which the mag- | 
netization curves had been drawn, they coincided with the lines B=0, | 
1000, 2000, ete., up to 16,000. By means of lines radiating out from 
a point on the lowest of these horizontal lines, each one of the line 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 283 


above was divided into a large number of equal intercepts, each of 
which represented exactly 0.0010 of V, the demagnetizing factor, for 
the particular B corresponding to the line. The larger of these inter- 
cepts were further subdivided into tenths by means of short dashes, and 
each horizontal line was numbered for every 0.0010, beginning from 
zero on the left. Thus the tracing cloth was simply a large transparent 
scale through which the V corresponding to every 7; could be imme- 
diately read off. ‘The error in the inaccurate spacing of the divisions 
of the scale was about 1 part in 200. 

Now suppose we arbitrarily say for the moment that the WV for the 
curve m = 200, all along the curve, shall be 0.0016, or the value of V 
for the corresponding ellipsoid of revolution. By placing the tracing 
cloth so that any desired line coincides with its corresponding P below, 
and the magnetization curve for 11 = 200 crosses at V = 16 units, we 
ean read off the number of units for each of the other curves. After 
doing this for all of the horizontal lines of our scale, we have a table of 
values similar to that given for the rod of February 21, only the column 
for m = 200 will consist wholly of numbers 16. 

This table is thus our first approximation. We may now put away 
our magnetization curve sheet with the scale, and proceed to get a 
better approximation by merely studying the table. [Ὁ will be noticed 
that all the other columns will have values less than for the corres- 
ponding ellipsoids. The only logical thing to do is to decrease the 16’s 
somewhat, at the same time decreasing every other number in the same 
row by the same amount, so as to give a table consistent as a whole 
when compared with the table for ellipsoids ; and this gives us something 
similar to the table given. At the best approximation, the values for 
πὶ = 200 will still be a unit or two in doubt, but this will make but a 
small error in the rods 30 to 50 diameters long. Of course individual 
values of V in the table are subject to errors in the drawing of the 
curve as well as observational errors, but when all the values of V 
for a certain length of rod are considered, a smooth curve could easily 
be drawn throughout the range of # in the experiment. We have, 
however, preferred to leave the tables as given directly from the last 
approximation. 

Should any one not be quite satisfied with the values as tabulated 
for any one series of experiments, he may easily change the whole table 
to suit himself, but he must do this subject to the condition of adding 
or subtracting the same number for any one row as it is given here. 


234 PROCEEDINGS OF THE AMERICAN ACADEMY. 


TABLE XIV. 
Method. 


Ewing, 1885) Ball. 0.158 et ae 
7. 


Tanaka- Magn. 100 9 
daté, 1888 | Gauss A |(-153 | 2-6 
Ewing’s | .115 | 33.4 38.4 


C.R.Mann,| Magn. | 2.370 | 11.850; 30 {20-1300 
1895 Gauss A —.237 


22-660 


“e 


“ 


Benedicks, | Magn. 
QO? SS 
ve Ball. 
Steps 


Jetferson 
Physical 
Laboratory, 
1907 


1.270 


Steps | 0.4768 


ἐπ ai 


Stepsand | 1.905 


Rev.’s 1.06 


288-10 
100-50 
144-10 


384-80 | 


329.5 
—30 


.7| 240-10 


240-15 


Made in Japan. 
Made in England 


L constant, D 
turned down. 


L constant, D 
turned down. 


D constant, 7} 
cut down. ᾿ 


All-observations 
made on hyste-} 
resis cycles. } 
Normal curve 
obtained by el-]} 
lipsoid results. 


397 sec. turns. 


230 « “ae 


50 
50 


50 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 235 


Discussion OF INVESTIGATIONS ON THE DEMAGNETIZING Factors. 


It was considered worth while to collate briefly the leading experi- 
mental conditions which have been used in the determinations of V for 
iron cylinders. ‘Table XIV on the preceding page has therefore been 
constructed from available data. 

It will be noticed that Mann used some very thick iron bars in the 
first two of his experimental series. However, a given diameter re- 
mained constant only throughout a single magnetization curve, say for 
m= 5; after this the bar was turned down to a smaller diameter on 
the lathe, so that mm was thereby increased. If now the ballistically 


INTENSITY OF MAGNETIZATION J 


000. 1100 


100 200 300 400 500 600 700 800 
MAGNETIZING FORCE 30 


FiGureE 17. 


Mann’s magnetization curves obtained magnetometrically. The bars vary in 
diameter from 2.370 cms, to 0.237 cm., while the length remains constant. 


obtained results of the present paper can be at all related to magneto- 
metric experiments on similar iron rods, they would lead us to expect 
that had Mann cut down his longest rod of 25.08 ems. from im = 50 to 
m = 5, the values of NV thereby obtained would not have agreed with 
those which he did get by turning down the bar from m = 5 to m = 
50. In fact the two sets of values for .V, belonging to the two methods 
“sawing off” and “turning down” respectively, would probably have 
diverged more and more as m was decreased, the “‘ turning down ” 
values for V being always less because the diameters of the bars of 


τ this method are the greater, as carried out. 


As noted in the outline at the head of this paper, Mann found that 


236 PROCEEDINGS OF THE AMERICAN ACADEMY. ‘ 


the values of V as determined magnetometrically are nearly constant 
up to 7 = 800, but after this they increase enormously. ‘his behavior 


ἕ 


ENSREE 7 
BERNESE ERAR ee 
aN e eae eeeee 
ΠΡ ΠΝ A tL 


Ficure 18. 


RL 
ΒΕΩΡ 
ὃς SS 
ἘΠΕ ΣΕ 
aN 
isa 


Benedicks’s magnetization curves. 


/ 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 237 


of the -curves is undoubtedly closely related to the change in the 
pole-distance ratio //L, which probably approaches the value unity for 
complete saturation. The magnetization curves taken magnetometric- 
ally tend to diverge, or spread apart, for high magnetizations, whereas 
those taken ballistically all converge rapidly to the maximum ordinate 
1... Figure 17 is reproduced from Mann’s paper,?§ and shows the curves 
from 11 = 5 to πὶ = 50 obtained from his first cylinder. The method 
by which Mann gets at the position of the “normal ” magnetization 
curve for an infinite rod is to assume that the magnetometric JN for a 
cylindrical rod of πὶ = 300 is the same as for an ellipsoid of the same 
length and central cross-section, namely NV = 0.00075. 

In his investigation Benedicks obtained the value of Δ for only one 
rod of hard steel (im = 25), but did this very thoroughly, using both 
the ballistic step and magnetometric methods. His normal curve is 
determined by transforming the steel cylinder into an ellipsoid of 
it = 30, obtaining magnetometrically the magnetization curve for this 
ellipsoid, and back-shearing this curve into the normal curve by means 
of the known demagnetizing factor for this ellipsoid, which is 
N = 0.0432. Theoretically the method is perfect, but we rather doubt 
whether it can be depended upon to give uniformly agreeing results in 
practice. The magnetization curves obtained by Benedicks are shown 
in Figure 18, which has been reproduced from his article!7. The figure 
shows the two types of V-curves, — the magnetometric and the ballis- 
tic, — and their opposite behavior for high magnetizations. Benedicks 
also publishes the N-curves as he derives them from Ewing’s original 
six curves, all showing a behavior similar to that of his own curve 
NV. These N-curves are practically identical with those shown in 
Figure 19 of this paper; these were determined by our methods 
directly from Ewing’s curves shown in Figure 2, which were recon- 
structed from the original figure!% in order to have both figures on 
exactly the same scale as our own curves, for purposes of comparison. 
See Figure 16, which shows the N-curves for our Bessemer steel rod of 
diameter 1.905 cms. 

We might note that Benedicks gets no curvature in the N-curve 
near the origin, because he takes his observations from hysteresis 
cycles of magnetization, the maximum applied field being about 
H’ = 206 units. 

Benedicks criticizes Mann’s assumption that V = 0.00075 for an 


16 Phys. Rev., 3, 359-369 (1896). 
17 Bihang Svenska, Vet.-Akad. Handlingar, 27 (1), No. 4, 14 pages (1902). 
18 Phil. Trans., 176 (1885), Plate 57, Figure 3. 


238 PROCEEDINGS OF THE AMERICAN ACADEMY. 


iron cylinder of m= 300, as being unwarranted. He determines Δ΄ by 
both the ballistic and magnetometric methods for a rod of τὶ = 300 
by back-shearing the ballistic curve into the normal curve, using 
N41 = 0.0005, according to Du Bois, thus finding the V to be 0.0028 
for the magnetometric method. He would, therefore, correct Mann’s 


MEE 15 | EL TT TV ΠΝ 
11} Se 
| 


“.-.-.---- 

ZOE RRR 
eee 
"ΤΠ ΟΝ 


Ficvure 19. 


Back-shearing curves for Ewing’s soft iron wire of diameter 0.158 cm. Deter- 
mined from results found in the present paper. 


values of Δ by adding 0.0020 to each Δ throughout. Now it seems 
to us quite clear, as remarked somewhere in the earlier part of this 
paper, that we have no right to assume that the normal J vs. 17 curve, 
as obtained ballistically, should be even approximately the same as the 
Mean J vs. Mean // curve of the magnetometric method. This as- 
sumption is rendered particularly doubtful when we see the very wide 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 239 


difference between the magnetization curves for m = 300 by the 
ballistic and magnetometric methods as observed by Benedicks and 
published in the “ Bihang,” and when we consider at the same time 
that both these curves cannot possibly be very far away from their 


0.7015 
0.2549 
0.1850 
0.0848 
0.0579 
0.0432 
0.0266 
0.0181 
0.0182 
0.0101 
0.0080 
0.0065 
0.0054 
0.0086 
0.0026 
0.0016 
0.00075 


Du Bois. 


0.2160 


0.0238 
0.0162 
0.0118 
0.0089 
0.0069 
0.0055 
0.0045 


TABLE XV. 


VaALuEs or WN. 


Ballistic. 


CYLINDER. 


Magnetometric. 


Benedicks. 


Jeff. Phys. Lab. 


0.1820-0.2001 
0.1000-0.1075 
0.0635-0.0671 
0.0445-0.0465 
0.0331-0.0388 
0.0204-0 0284 
0.0139-0 0160 
0.0100-0.0116 
0.0076-0.0088 
0.0060-0.0069 
0.0050-0.0056 
0.0041-0 0040 
0.0028-0.0052 
0.0019-0.0028 
0 0011-0.00125 


0.0004-0.0007 


Mann. Benedicks. 


0.68000 
0.25500 
0.14000 
0.08975 
0.06278 
0.04604 
0.02744 
0.01825 
0.01311 
0.00988 
0.00776 
0.00628 
0.00518 


0.00251 
0.00152 
0.00075 


limiting positions for the infinite rod. On the other hand it is quite 
reasonable to suppose that the 4 for any iron ellipsoid is always 
greater than the WV for the corresponding cylinder, obtained by either 
of the two methods; because by adding the extra mass of iron to an 


240 PROCEEDINGS OF THE AMERICAN ACADEMY. 


TABLE XVI. 
Tue DEMAGNETIZING Factors IN THE RANGE OF PRacTICAL CONSTANCY. 


Reversals in Short Coil: 


D = 0.2381. | 0.3175. 0.4763. 0.6350, 


2001 1990 
1049 | 1028 
665 5 

461 


TABLE. XVII. 
Principle of Step Method : 


| 
1.905 Percentage 
Du Bois. | ἥ (Revy.’s Difference 
: ἢ ; in Long between 0.3175 
Coil). and 1.905. 


1045 
662 


The figures in parentheses are interpolated; all others have been obtained ex- 
perimentally. For purposes of comparison, the values of Du Bois are given im 
Table XVII. The numbers given in these tables represent .V - 104, as in the ear 
lier tables. 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON ROps. 241 


ellipsoid in order to form the corresponding cylinder, the surface mag- 
netism σ᾽ is shifted nearer to the ends of the rod and should exert less 
demagnetizing force. ΤῸ be sure, we now have some volume magne- 
tism, p = — Divergence J, in the cylinder, which does not exist in the 
ellipsoid, but the effect of this 
is probably always extremely 
small. On the whole we feel 930 
certain that Mann’s value is y 
quite near the truth, and is 
probably even a trifle too 935 
large. 

Table XV, on page 239, 
gives briefly all the results 080 


obtained on demagnetizing 
factors for the region in which 
they are practically constant, , fe 
that is, for the iron cylin- ΠΕΒΘΘΒΒ 
ders up to about J = 800, or SES 
B = 10,000 +H +H 
000. . fat ala ΠῚ ΕἸ 
The values of NV as obtained ° ΕΠ ΕΙΓΞΙ ΕΒ ΕΙΕΞΙΞ 
for the various diameters of ΓΕ ΤῊ 
rods in the present investi- BRRaE 
gation are given in Tables : tH 
XVI and XVII on the pre- A a 
ceding page. They were ta- ΒΕΒΕΒΕΝ 
ken from the tables given for | Tee etc lta 
each separate rod, and are a a tH 
fairly constant over the range ann HT 
es δι Ae | 180 | ie : 

ΕΞ reef ΕΞ ΞΞΙ ἘΠ ΕΞ OO lee [se] |e 
The values of NV of these na | ΒΗ 
tables have been plotted in Es 
Fi 1 Ξ GAAS 
igure 20 against the corre 5 + δ τε πὸ 


sponding diameters of the 
rods. The points connected 
by straight lines are the re- Curves showing the variation in N for 


. diff i i : - 
versal method values, while ὃ erent diameters of iron rods. The num 
bers near curves give the corresponding 


those left unconnected are SEG pont 
the ones taken by the prin- 
ciple of steps. It seems to be shown that the values of Δ΄ experience 
a rapid drop from D = 0.238 to about D = 0.50, and then remain 
nearly constant as the diameter is further increased. 

For practical use in finding permeabilities Table XVIII has been 


VOL. XLIII.— 16 


Ficure 20. 


242 PROCEEDINGS OF THE AMERICAN ACADEMY. 


constructed. ‘The induction is assumed to be observed experimentally 
by the step method, and the X of the table is used in the equation 


H = H’ — KB. 


TABLE XVIII. 


Vauves or K. 


; 
: 


D = 1.1 to 2.0 cms. 


0.00852 
0.00533 
0.00366 
0.00309 0.00273 


0.00186 0.00166 
0.00127 0.00116 
0.000925 0.000845 
0.00055 0.000505 
0.000366 0.000326 
0.000183 0.000167 


PROBLEM. 


Suppose the magnetic susceptibility in a soft iron rod similar to 
Bessemer steel is to be tested ballistically. Suppose the rod is neither 
very thick nor long, and the ballistic galvanometer (‘lhomson) is not very 
sensitive. In order to get the greatest possible throw we may wind a 
large number of turns of wire of secondary coil around the middle of 
the rod, being careful not to exceed the point of maximum sensitive- 
ness. ‘This is reached when an additional turn of wire adds propor- 
tionately more resistance to that already in the galvanometer circuit 
than it adds turns to the total number of turns. Of course as long as” 
the secondary coil is wound on in a single layer, and the resistance of 
the galvanometer is not negligible, this condition can never be reached 
but where the coil is built up in several layers the resistance finally — 
predominates. Suppose we have : 

Galvanometer resistance = 12 ohms. 

Sensitiveness = 0.0695 mm. throw per microcoulomb. 


SHUDDEMAGEN,. — DEMAGNETIZING FACTORS FOR IRON RODs. 243 


Dimensions of Iron Rod: Diameter =5 mms. Length = 20 ems., so 
that m = 40. 

Secondary Coil: 480 turns of fine wire. Length = 3 cms. Resist- 
ance = 19.42 ohms. 

We therefore neglect the leakage of induction through the secondary 
coil. If we have no extra resistance in the galvanometer circuit the 
formula gives for the method of reversals : 

Bee 100-R 42-31 


7 S-27(0.25)7480 ~~ 0.00695 =z - 0.60 


= 2400. 


This shows that we need no extra resistance for the secondary circuit. 
Suppose we magnetize in a solenoid 31 ems. long and wound with 
5 layers of wire, 113 turns in each layer. Then we have 
47565 : : 
a “iran (No. of amperes) = 22.9 (amperes). 
ie). 


We get the following observations: 


Current in Solenoid. Ballistic Throw. 


0.498 ampere 1.82 centimeters. 


0.664 
0.837 
0.975 


1.120 


244 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Now taking V = 0.0217 for m = 40, we have 


H = H' — NI=H'— KB 


and K = N/47, since we may neglect 7 in comparison with B. We 
get, therefore, 


K = 0.00173, 


and may now calculate 7 and the other quantities from the δ of the 
above table. ‘T'his gives us: 


We chose the value of V as would correspond to the ballistic step 
method. Had we, however, used the method of reversals with ¢ 
solenoid wound on a pasteboard tube, or a split brass tube, then 
ballistic throws observed would have been a little more than twice as 
great as those we found. If we take them as exactly twice as great, 
and if we assume that the time-constant of the solenoid is the same as 
for the short solenoid used in the earlier half of this work, then y 
should have 


N = 0.0206 K = 0.00164 


and the calculated values of the demagnetizing fields, the resultant 
fields, and the permeabilities would be : 


ho 
σι 


4 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 


This shows again how greatly different results obtained by step and 
reversal methods can be, if the observations are not properly corrected 
by using the appropriate JV. 


DISTRIBUTION OF MaGNetic INDUCTION. 


In our theoretical discussion of the shape of the .V-curves we found, 
page 197, that we might expect that the magnetization is much nearer 
uniformity when the applied field H/’ is quite small, than it is in the 
region of large susceptibility. Now several articles have been published 
on the distribution of magnetic induction in iron rods,!® but the mag- 
netizing fields which these writers used were of much greater strength 
than are necessary in order to investigate this particular question. 
However, Benedicks 2° found a very neat inverse relation between the 
susceptibility « and the pole-distance in a short bar magnet. ‘This is 
very clearly shown by Figure 21, which has been reproduced from his 
article. The curve called ‘‘ Distance des Poles” has the ordinates //L, 
where Z = actual length of the bar magnet, and / = distance between 
poles, the method of determining / being based on the formula 


19 Phil. Mag., (5), 46, 478-494 (1898), “On the Distribution of Magnetic Induc- 
tion in Straight Iron Rods,” J. W. L. Gill; Phil. Mag., (5), 48, 262-271 (1889), 
“On the Distribution of Magnetic Induction in a Long Iron Bar,” C. G. Lamb. 

20 Journ. de Physique, (4), 1, 302-307 (1902), “Etudes sur la Distance des 
Poles des Aimants”; Bihang Svenska Vet.-Akad. Handlingar, 27, (1) No. 5, 
23 pp. (1902), “ Untersuchungen iiber den Polabstand Magnetischer Zylinder.” 


246 PROCEEDINGS OF THE AMERICAN ACADEMY. 


in which the J... 15. the magnetization as determined magnetometri- 
cally, and the /,,.x is found from the B as determined ballistically 
at the centre of the rod in the usual way. For this rod πὶ = 300, 
The abscissae represent //’, the magnetic field applied from without. 
Similar curves had also been previously published by Dr. L. Holborn,21 
only the susceptibilities were taken directly from the unsheared mag- 
netization curve of a short cylinder. 

Although these experiments of Holborn and Benedicks practically 
prove the increased uniformity of magnetization for low fields, it is 
perhaps a better plan to settle this point by a more direct method. It 
was therefore thought that it might be of interest to compare the 


a a ΓΕ ΕΙΣ : 
1} 010 1. Sie πετπεσιτοτ 
Ἢ [|| Lael Ῥεμι ΤῈ 5 ΤΠ ΤΠ ΘΝ 
BCE CEE a ᾿ 
Fs ol ὉΠ ΕΝ Be 


10 20 30 40 50 60 70 @0 90 100 110 120 130 140 150 160 170 180 190 200 
Figure 21. 


Benedicks’s curves, showing variation of the pole-distance ratio and the suscep 
tibility in an iron rod. The abscissae give the field H’ in c. g. s. units. 


actual magnetic induction which passes through various cross-sectior 
of some of our iron rods, for practically the whole range of magnetiza 
tion from zero to saturation. ΤῸ do this one might use a secondary 
search-coil, fitting loosely around the ‘iron rod, which can be suddenh 
displaced along the rod by any desired distance. This would requit 
two observers; but it could not be used conveniently in this work 
since the rods in which the magnetic induction was tested were 1.904 
cms. in diameter, and the inner diameter of the brass tube aroun¢ 
which the solenoid coils were wound was not much larger. Anothel 
method would be to wind coils around different parts of the rod an¢ 
get the actual induction passing through each coil. This would de 


21 Sitzber. Akad. ἃ, Wiss., Berlin, 1, 159-162 (1898). 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 247 


well enough for the lower intensities of 7’ but would be an exceedingly 
insensitive method to use when the field H’ is very high, since then 
the induction is nearly constant along the bar except at the very ends, 
so that the experimental error might easily be even greater than the 
actual difference in the magnetic induction between the central part 
of the rod and any other part. The best method seems to be to read 
the reversal method ballistic throw from a coil wound directly over the 
middle of the rod, and then, connecting any other coil, wound around 
the rod nearer the end, in series with the central coil but in opposition 
to it, observe the ballistic throw due to the difference in the flux 


Figure 22. 


Diagram showing arrangement of secondary coil and switch-board used in the 
work on the distribution of magnetic induction along an iron rod. 


through the two coils. This was the idea adopted. Figure 22 shows 
diagrammatically the arrangement of the coils in one of the four different 
cases which were tried ; the others were similarly arranged. The po- 
sitions of all the secondary coils are shown in the diagrams drawn to 
scale and marked with the distances between the centres of the coils. 
All the ends of the coils were led into small mercury cups in a small 
switchboard. The extremities 255, C2, D2, 12, and one terminal of the 
ballistic galvanometer were all dipped into cup Δ᾽ If now the copper 
connector is placed in the position A C as shown, then the ballistic 
throw observed on reversing the current in the primary solenoid is that 


248 PROCEEDINGS OF THE AMERICAN ACADEMY. 


due to those lines of magnetic induction which thread through the 
centrally placed coil A, A, and do not also pass through the coil ΟἹ C,, 
provided we neglect the lengths A, A, and (ἡ C, of the secondary coils 
in comparison with the distance A, C; between the two coils. In 
other words, the ballistic throw measures the magnetic leakage be- 
tween the coils which are connected in opposition. When the con- 
nector is placed across from A to F, then we get simply the throw 


100 5 


20000 
Figure 29. 
Curves showing variations in the distribution of magnetic induction in rod 


No. Il Τὸ = 1.905 cms. and m= 240. The ordinate-axis represents percentage 
of magnetic induction. 


due to the whole magnetic flux of induction through the central coil 
‘A, Ay in precisely the manner which was used in all of the preceding 
work on magnetization curves for different 1’s. 

In this work on the distribution of the magnetic induction the extra 
resistance which had to be thrown into the galvanometer circuit by 
means of the resistance box Κ΄ in order to regulate the throw, varied 
greatly. For a connection like that shown in the figure usually no 
extra resistance was needed ; in fact for low as well as for high magne- 
tizing fields the magnetic induction approaches uniformity, so that in 
either case the ballistic throw is very low. Thus while in a certain 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 249 


case m = 25, and B = 21120, the extra resistance 1 had to be made 
as high as 10,000 ohms in order to keep the throw for the central coil 
alone from exceeding the length of the scale, yet when the coil nearest 
to the central one was connected in opposition to it, only a weak de- 
flection was obtained with no extra resistance in the galvanometer 
circuit. 

The curves which are shown represent four different rods, all having 
the largest diameter used, 1.905 cms., but two of these had the same 
length, the m being = 60, so that for these rods the results are com- 
bined in one figure. The data for these four rods are as follows: 


TABLE XIX. 


Bessemer Turns | Length | Maximum 
per of each Range of H’. Range of B. Battery 
Coil. | Coil. Voltage. 


240 1 3.7 cms. | 0.77- 63.0 1620-16800 


| 0.50- 66.8 84-16980 


|. 026. 67.7 25-16800 


| 3.7 -4400 | 550-21120 


Bessemer Rod. Length of Solenoid. Distances between Coils m Cms. 


50, 50, 50, 50; 29 to end. 
14, 14, 14, 14; 1.1 to end. 
25, 25; 7.1 to end. 


7.5, 7.4, 8.0; 0.4 to end. 


The coils are designated as follows, beginning with the central one: 


No. 11. 5-6-7-8-9. No. B. A—B—C-D-E. 
No. A. CD-MN-XY. (No. I) 1-2-3-4. 


The results are given graphically by Figures 23, 24, and 25 in this 
way: The induction δ᾽ in the middle part of the rod, as found from 
reversing the current in the solenoid while only the central coil is in- 
cluded in the galvanometer circuit, is plotted horizontally ; while the 
ordinates give the ratio of the corresponding inductions in the parts of 


250 PROCEEDINGS OF THE AMERICAN ACADEMY. 


the rod surrounded by the other coils, to the induction at the centre. 
Thus, suppose for a given constant 7’ we had obtained throws corre- 
sponding to the central coil alone, and also for this coil when connected 
in opposition to every one of the other coils in turn. In an actual case 
we had for Rod #: H’ = 59.5, the induction for the central coil was 
B = 16,560, leakage between CD and JN was 630, and between 
CD and X Y 7910, lines of induction per unit cross-section. From 
these results we get for the actual magnetic induction through JJ V 


Figure 24. 


Curves showing variations in the distribution of magnetic induction in rods 
No. A and No. B. D= 1.905 cms. and m = 60. 


15,920 lines, and through Y Y 8650 lines. Now, denoting the B 
through the central coil at any time by 100 per cent, we shall have 
96.3 per cent of this induction passing also through the coil MN, 
and 52.3 per cent through ΟΥ̓. These two numbers are therefore 
plotted against B= 16,560. Figures 23, 24, and 25 exhibit all the 
observations taken. The slight zigzag arrangement of the points is 
due to the fact that the current did not stay quite constant during the 
time of observing the throws from all the coils on a rod. All the rods 
have been referred to previously by the same designations, except 
(No. I), which is merely one of the end-pieces cut from the long rod 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 251 


No. I mentioned before. The crossing of the curves for coils 77 Δ 
and C at a high induction is merely another instance of the great 
difference in magnetic quality of Rods A and B (or Rods I and II) 
which was already noticed in the magnetization curves of Figure 15. 
From the curves in Figures 24 and 25 we see that for low fields 
there is quite an increase in the induction for coils not at the middle 
of the rod as compared with the induction through the central coil. 
This means that for these low fields the magnetization is more nearly 


Figure 25. 


Curves showing variations in the distribution of magnetic induction in rod 
(No. 1). D=1.905 cms. and πὶ = 25. 


uniform. The range in H’ for which the sharp upward bend of these 
curves occurs is precisely the same range for which the susceptibility 
changes most rapidly and is from H’ = 0 to about H’ = 5. After this 
we have quite a long interval for which the susceptibility is high, and 
the magnetization furthest removed from uniformity ; here the curves 
showing percentage of induction as compared to that through the 
middle coils have their minimum and run along very nearly parallel to 
the B-axis. However, as the induction through the middle of the rod 
increases past B = 10,000, all the curves begin to rise, slowly at first, 
then more rapidly. his indicates that the susceptibility is again 


252 PROCEEDINGS OF THE AMERICAN ACADEMY. 


decreasing, and that the magnetization is becoming gradually more 
and more uniform. At about # = 17,000 the curves rise the fastest, 
showing that the middle portions of the rod are very nearly saturated 
and take up more magnetization only very slowly, while for the coils 
nearer the end the magnetization is still rapidly increasing. Figure 
25, for the short rod (in = 25), shows that after B is about 20,000 
under the middle coil, the curves all have points of inflection and now 
approach the ordinate 100 per cent asymptotically. If we now con- 
sider Figure 23, for the very long rod (in = 240), we see that here we 
have a case of the magnetization being always very much nearer uni- 
formity, so that the curves for coils 6, 7, and 8 are already in the 
asymptotic stage for B = 15,000 under the coil 5, and the points of 
inflection are near B = 10,000. When B = 15,000, the curve for the 
coil 9, nearest the end of the rod, shows a tremendous upward shoot 
from a long horizontal course near the ordinate 50 per cent. Since the 
figure only gives the observations in the range of percentages from 80 
to 100, it might be well to give the missing values here : 


7 
B in Coil 5. Percentage : >. 


B in Coil 5. Percentage : Bo 
5 B; 


2720 : 11180 65.30 
3420 ; 12030 65.67 
4720 : Be 67.00 
6420 2 68.70 
71.90 
76.66 


In the case of the long rod the lowest fields used were still too high to 
show a rise in the curves, corresponding to increased uniformity of 
magnetization, as is seen in the other two figures. 

The results show that near the middle of a rod the induction is 
practically the same for quite a little range, especially if the rod is fairly 
long. Thus the curve 6 in Figure 23 shows that in the rod of length 
about 458 cms. and m= 240, the induction for a distance 50 cms. 
from the middle of the rod is always within about 2 per cent of the 
induction at the middle portion. And curve B in Figure 24 proves 
the induction at 14 cms. from the middle of the rod of length about 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON Rops. 2563 


114 cms. and it = 60 to be always within about 4 per cent of the 
central induction. ‘These facts justify the use of a secondary coil 
several cms. in length, provided the m of the rod is not too small. 
The conclusion to be reached from the work on the induction dis- 
tribution is that for low field-intensities, as well as for high ones, the 
magnetization of the iron rod is much more nearly uniform than it is 
in a long interval corresponding to rather high susceptibilities. 


Discussion OF RESULTS OBTAINED. 


When we look over the tables we readily see a number of interest- 
ing things. It is apparent that in general different methods or even 
different experimental conditions will give differént normal curves, 
and hence different susceptibility curves. A striking result, and one 
which was obtained entirely unexpectedly, is that in the long solenoid, 
which was wound on a thick brass tube, the method of reversals agrees 
very closely indeed with the step-by-step method. This may in fact 
.turn out to be quite a useful observation, for it points to the proba- 
bility of getting values for the susceptibility of some kind of iron in 
the form of a short rod, which conform very closely to the ideal defini- 
tion of susceptibility, which requires slow, continuous increase of the 
magnetizing field. hus by winding our solenoid on very thick brass 
tubes, a large E. M. F. from a storage battery may be suddenly turned 
on, without giving almost instantaneously the full value of the magne- 
tizing field within, on account of the eddy currents in the brass tube 
acting as a sort of “ brake.” 

The most important results described in this paper about the de- 
magnetizing factor N for cylindrical iron rods are the following: 

(1) The demagnetizing factor is not a constant, but shows two 
opposite curvatures, when plotted as abscissa-differences (H, = NJ) on 
the 7 vs. H; plane; while for the highest values of 7 it falls to about 
+ or } of its value for unsaturated /’s. 

(2) For values of B less than 10,000 the J is practically constant. 

(3) Using a solenoid made of wire wound on a non-metallic tube, or 
a split brass tube, the reversal method gives values for V considerably 
lower than the step-by-step method. 

(4) If the magnetizing solenoid is wound on a thick brass tube, the 
reversal and step methods practically agree, and values of NV derived 
from curves taken in this way are regarded as the most desirable for 
scientific purposes, as they will give most accurate values for the 
susceptibility or the permeability of the iron. 

(5) The demagnetizing factors are largest for thin rods. The differ- 


254 PROCEEDINGS OF THE AMERICAN ACADEMY. 


ences between the corresponding Δ᾽ 5 for a rod of 0.3175 cm. diameter 
and one of 1.905 cms. diameter range from 10 to 16 per cent, both sets 
of values being taken to conform to the conditions stated in (4). 

(6) Most of the rods used in this work have their Δ᾽ 5 in the range 
of practical constancy considerably smaller than the values given by 
Du Bois, but as the diameters of the rods decrease, a very close 
approach to Du Bois’s values is obtained. 

(7) ‘he magnetization is furthest away from uniformity in the 
region of highest susceptibilities, and becomes more uniform for very 
low as well as for very high applied fields. 


In conclusion it is my pleasant duty and privilege to thank Professor 
B. O. Peirce for suggesting this research and for his constant interest 
in the work throughout the year. 1 also desire to state that the 
astaticised galvanometer system is due to the skill of Mr. John Coulson, 
Professor Peirce’s assistant; and that the construction of the magnetiz- 
ing solenoid was most successfully carried out by Mr. Thompson, the 
mechanic of the Jefferson Physical Laboratory. 


LITERATURE ON THE DEMAGNETIZING Factor. 


J. A. Ewing: “Experimental Researches in Magnetism,” Phil. 
Trans., 176, 523-640 (1885). (Plate 57, Fig. 3.) 

A. Tanakadaté: ‘‘ Mean Intensity of Magnetization of Soft Iron 
Bars of Various Lengths in a Uniform Magnetic Field,” Phil. Mag., 
(5), 26, 450-456 (1888). 

H. E. J. G. Du Bois: “Zur mathematischen Theorie des Ferromag- 
netismus,” Wied. Ann., 46, 485-499 (1892) (also in “ Magnetisaig 
Kreise in Theorie und Praxis,” Berlin, 1894, p. 37). 

C. R. Mann: “ Ueber Entmagnetisirungsfaktoren kreiscylindrischer 
Stiibe,” Dissertation Berlin, 1895; ‘‘ Demagnetization Factors for 
Cylindrical Rods,” Phys. Rev., 3, 35 9-369 (1896). 

Ascoli e Lori: “Sopra il fattore smagnetizzante nei cilindri di ferro,” 
Rendic. R. Acad. d. Lincei, 3:2, 190 (1894); Ascoli: “Sul fattore 
smagnetizzante nei fasci e nei cilindri di ferro,” Rendic. R. Acad. d. 
Lincei, 6 : 2, 129 (1897). 

Carl Benedicks: ‘ Ueber die Entmagnetisirungsfaktoren kreiscylin- — 
drischer Stibe,” Wied. Ann., 6, 726-761 (1901); “Sur les facteurs 
démagnetisants des cylindres,” Bihang Svenska Vet.-Akad. Handlingar, 
27, (1), No. 4, 14 pp. (1902). 

E. J. G. Du Bois: “ Entmagnetisirungsfaktoren kreiscylindrischer 
Stiibe,” Wied. Ann., (4), 7, 942-943 (1902). 


SHUDDEMAGEN. — DEMAGNETIZING FACTORS FOR IRON RODS. 255 


LITERATURE ON RELATED SUBJECTS. 


Eduard Riecke: “Zur Lehre von den Polen eines Stabmagnetes,” 
Wied. Ann., 8, 299-325 (1879). 

C. Baur: “Neue Untersuchungen iiber den Magnetismus,” Wied. 
Ann., 11, 394-413 (1880). 

F. Kohlrausch: ‘Ueber den Polabstand, den Inductions- und 
Temperatur-coéfiicient eines Magnetes und iiber die Bestimmung von 
Trigheitsmomenten durch Bifilarsuspension,” Wied. Ann., 22, 411-424 
(1884). 

Lord Rayleigh : “I. On the Energy of Magnetized Iron,” Phil. Mag., 
(5), 22, 175-183 (1886) ; ‘‘ Notes on Electricity and Magnetism. — III. 
Qn the Behavior of Iron and Steel under the Operation of Feeble 
Magnetic Forces,” Phil. Mag., (5), 23, 225-245 (1887). 

H. E. J. G. Du Bois: “On Magnetization in Strong Fields at 
Different T'emperatures,” Phil. Mag., (5), 29, 293-306 (1890). 

0. Grotrian: “ Der Magnetismus eiserner Hohl- und Voll-cylinder,” 
Wied. Ann., 50, 705-741 (1893); “Zur Magnetisirung von eisernen 
Cylindern,” Wied. Ann., 52, 735-748 (1894) ; also, 54, 452-475 (1894). 

Gustav Réssler: “Untersuchungen iiber die Magnetisirung des 
Eisens durch sehr kleine und durch sehr grosse Kriifte,” Elekt. ZS, 14, 
97-99, 114-116, 133-134, 149-151, 161-163 (1893). 

H. E. J. G. Du Bois: Note on Réssler’s article, Elekt. ZS, 14, 208 
(1893). 

P. Culmann : Note on Rissler’s work, Elekt. ZS., 14, 345 (1893) ; 
“Ueber die Giiltigkeit eines von Kirchhoff in der Theorie des Electro- 
magnetismus aufgestellten Satzes,” Wied. Ann., 48, 380-383 (1893). 

J. L. W. Gill: “On the Distribution of Magnetic Induction in 
Straight Iron Rods,” Phil. Mag., (5), 46, 478-494 (1898). 

Dr. L. Holborn: “ Ueber die Vertheilung des inducirten Magnetis- 
mus in Cylindern,” Sitzungsberichte d. Akad. d. Wiss. zu Berlin, 1; 
159-168 (1898). 

F. Kirstaedter: “Zur Magnetisirung eiserner Hohl- und Voll- 

ringe,” Wied. Ann., 65, 72-85 (1898). 
| ©. 6. Lamb: “On the Distribution of Magnetic Induction in a 
Long Iron Bar,” Phil. Mag., (5), 48, 262-271 (1899). 

Carl Benedicks: “Untersuchungen iiber den Polabstand magne- 
tischer Zylinder,” Bihang Svensk Vet.-Akad. Handlingar, 27, io) 
No. 5, 23 pp. (1902); “ Etudes sur la distance des pdéles des aimants.” 
Team. de Phys., (4) 1, 302-307 (1902). 

G. T. C. Searle and T. G. Bedford : “The Measurement of Magnetic 
Hysteresis, ” Phil. Trans., A 198, 33-104 (1902) ; Abstract of this paper 
in Proc. Roy. Soc., 68, 348-352 (1901). 


—————— 


256 PROCEEDINGS OF THE AMERICAN ACADEMY. 


H. Meldau: ‘“‘ Magnetisirung eiserner Zylinder,” Phys. ZS. 4, 479. 
480 (1903). 
Raymond Jouaust : “ Les phenoménes de viscosité magnétique da 
les aciers doux industriels et leur influence sur les methodes de 
mesure,” Comp. Rend., 139, 272-274 (1904). 
Franz Riicker : “ Beitriige zur Kenntnis der stufenweisen und ste- 
tigen Magnetisirung,” Dissertation, Halle, 1905, 106 pp., 20 plates 
Elekt. ZS., 26, 904-905, 979 (1905). ' 


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See Ss. 


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LIBRARY 
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GARDEN. 


pe OUTLINES OF A NEW 
YSTEM OF THERMODYNAMIC CHEMISTRY. 


By GILBERT NEWTON LEWIS. 


CONTRIBUTIONS FROM THE RESEARCH LABORATORY OF PHYS- 
ICAL CHEMISTRY OF THE MASSACHUSETTS INSTITUTE OF 
TECHNOLOGY. — NO. 17. 


OUTLINES OF A NEW SYSTEM OF THERMODYNAMIC 
CHEMISTRY. 


By GILBERT NEWTON LEWIS. 


Received July 10, 1907. 


In the rapid development of theoretical chemistry, in which the 
two laws of energy have played so important a réle, two thermody- 
namic methods have been widely used. The first, employed by Gibbs, 
Duhem, Planck, and others, is based on the fundamental equations of 
entropy and the thermodynamic potential. The second, employed 
by such men as van’t Hoff, Ostwald, Nernst, and Arrhenius, consists 
in the direct application to special problems of the so-called cyclic 
process. 

The first method is general and exact, and has been a favorite with 
mathematicians and physicists, those who were already familiar with 
the use of the potential theory in mechanics. But unfortunately, ex- 
cept in name there is little analogy between physico-chemical equi- 
librium and the equilibrium in a mechanical system, and it is perhaps 
for this reason that the method has failed to commend itself to the 
majority of chemists. It must be admitted that it is the second 
method to which we owe nearly all of the advances that have been 
made during the last thirty years through the application of thermody- 


namics to chemical problems, and which is now chiefly used by inves- 


7 
> 


b 
D 


wwii &/J 


tigators and in the text-books of physical chemistry. 

Yet the application of this method has been unsystematic and often 
inexact, and has produced a large number of disconnected equations, 
largely of an approximate character. An inspection of any treatise on 
physical chemistry shows that the majority of the laws and equations 
obtained by the application of thermodynamics, are qualified by the 
assumption that some vapor behaves like a perfect gas, or some solu- 


260 PROCEEDINGS OF THE AMERICAN ACADEMY. 


tion like a perfect solution. As examples may be cited the mass 
law, the law of change of solubility with the temperature, the law of 
the lowering of vapor pressure by a solute, the law of Nernst for the 
electromotive force of a concentration cell, and many other equally im- 
portant generalizations. 

It is probable that no one of these laws is ever strictly true. As 
approximations to the truth they have been of the greatest service, 
But now that their utility has been demonstrated, the attention of a 
progressive science cannot rest upon their acknowledged triumphs, 
but must turn to the investigation of their inaccuracies and their limi- 
tations. From the study of the deviations from the simple gas laws 
has grown one of the most interesting chapters of chemistry. So from 
a study of the deviations from such a law as the mass law we may ex- 
pect results of the highest value. 

In such more exact investigations the old approximate equations of 
thermodynamic chemistry will no longer suffice. We must either turn 
to the precise, but rather abstruse, equations of entropy and the ther- 
modynamic potential, or modify the methods which are in more com- 
mon use, in such a way as to render them exact. 

The latter plan is the one followed in the present paper, the aim of 
which is to develop by familiar methods a systematic set of thermody- 
namic equations entirely similar in form to those which are now 
use, but rigorously exact. 

The following development is necessarily brief and concise, but I 
have hoped, nevertheless, to make it intelligible to any chemist who is 
familiar with the simpler theorems of elementary calculus. 


Tue Escapinc TENDENCY. 


The meaning of the term “escaping tendency” may be illustrated 
an analogy taken from another branch of applied thermodynamics, 
the theory of heat. 

The conception of temperature owes its utility to the existence 0 
two fundamental laws of heft exchange. When two bodies are broughi 

together and there is no transfer of heat from one to the other, they 
are said to be at the same temperature ; but if such a transfer ta 
place, the body which loses heat is said to be at a higher temperatur 
than the other. Now the two laws of temperature are the following 
(1) Two bodies which have the same temperature as a third, have 


1 We may speak of a perfect solution as we speak of a perfect gas, that is, on 
which obeys the laws of an infinitely dilute solution. 


LEWIS. — A NEW SYSTEM OF THERMODYNAMIC CHEMISTRY. 261 


same temperature as each other. (2) If a body A has a higher tem- 
perature than the body B, it has a higher temperature than any other 
body of the same temperature as B. 

These are not self-evident truths, but empirical laws. If they did 
not exist, the idea of temperature would lose all value. Temperature 
determines the distribution of energy in a system, and we may regard 
the temperature of a body as a measure of the tendency of its internal 
heat to escape into other bodies. 

There are in chemistry two laws which are in every way analogous 
to the laws of thermal exchange. If a system is composed of several 
parts, A,B, C, D, containing a ἘΠῚ molecular species, X, the two fun- 
damental laws concerning the distribution of X throughout the system 
are the following: (1) If when the phases A and B are brought to- 
gether there is no transfer of X from one to the other, and if the same 
is true of A and C, then when Band C are brought together there will 
likewise be no transfer of X. (2) If X passes from the phase D to the 
phase A when they are brought together, then it will also pass from D 
to B, or to C, or to any phase which is in equilibrium with A as regards 
the distribution of X. [Ὁ is obvious that these two laws follow directly 
from the fundamental laws of thermodynamics, for if they were not 
true a system could be constructed capable of perpetual motion. 

The escaping tendency of a given molecular species in a given state 
is therefore analogous to temperature, and the two laws of escaping tend- 


_ency are as follows: If the escaping tendency of a given molecular 


species, X, is the same in two phases, then X will not of itself pass from 
one phase to the other. If the escaping tendency of X is greater in 
one phase, it will pass from this phase into the other, when the two are 
brought together. 

Let us illustrate the meaning of the escaping tendency by an exam- 
ple. When in a pure liquid a small quantity of some other substance 
is dissolved, the vapor pressure of the liquid is diminished, its freezing 
point is lowered, its boiling point is raised, its solubility in another sol- 
vent is diminished.2 All these laws are comprised in the simple state- 
ment, that the escaping tendency of the solvent is diminished by the 


addition of the solute. 


The idea of temperature was understood lone bertore any suitable 
measure of temperature was found. Then the mercury thermometer 
was invented, later the gas thermometer, and finally in the absolute 


2 So also the tendency of the liquid to take part in any chemical reaction is 
diminished, but until a later section of this paper our discussion will be limited 
to processes in which a given molecular species passes from one phase to another 
without any other change. 


262 PROCEEDINGS OF THE AMERICAN ACADEMY. 


thermodynamic scale we possess the ideal measure of temperature, 
So indeed the idea of escaping tendency, although not distinctly formu- 
lated, has been tacitly recognized and used, and as a measure of the 
escaping tendency the vapor pressure has been employed. Now if all 
vapors obeyed the laws of a perfect gas, probably no better measure 
could be found. But this is never strictly the case, and the more the 
vapor departs from the ideal condition the more unsatisfactory is the 
vapor pressure as a measure of escaping tendency. By introducing a 
more satisfactory measure of escaping tendency we may gain advan 
tages similar to those which resulted from the substitution of the 
absolute scale of temperature for the mercury scale. : ; 

Such a measure of the escaping tendency I have described and used 
ina previous paper.? It was called the fugacity, and so defined that 
the fugacity of a perfect gas is equal to its pressure. The fugacity of 
an imperfect gas differs, however, from the gas pressure by an amount 
which is greater, the more the gas deviates from the gas law. 

The idea of fugacity is thus evolved from the use of vapor pressure 
as a measure of escaping tendency. When a substance is in equilib- 
rium with its vapor, the fugacity, in order to fulfil the laws of escap- 
ing tendency, must be the same ia both. The fugacity of a substane 
is therefore equal to its vapor pressure if the vapor behaves like a per- 
fect gas. Speaking in terms not very precise, we may say that the 
fugacity of a substance is equal to the vapor pressure that the substance 
would have if its vapor were a perfect gas. It has been shown in the 
preceding paper that for a given substance in a given state the fugacity 
is a definite property of which the numerical value can in most 
be readily determined, and which is well suited to serve as an exae 
measure of the escaping tendency. : 

In many thermodynamic equations it is convenient to use concentra- 
tions instead of pressures. Likewise we shall find it desirable to intro: 
duce besides the fugacity, which has the dimensions of pressure, another 
quantity which has the dimensions of concentration. This quantity 
we will call the activity, and denote by the symbol & The activity ¥ 
be defined in terms of the fugacity, Ψψ, by the following equation, 


i δ 
¢= 7’ 
where 7 is the gas constant and 7’ is the absolute temperature. Since 
the fugacity of a perfect gas is equal to its pressure, it is obvious tha’ 


3 The Law of Physico-Chemical Change. Zeit. phys. Chem., 38, 205 (1901) 
These Proceedings, 37, 49 (1901). i. 


| 
| 
| 


| 


LEWIS. — A NEW SYSTEM OF THERMODYNAMIC CHEMISTRY. 263 


the activity of a perfect gas is equal to its concentration. If / has its 
ordinary value, € will be given in mols per liter. 

Both the fugacity and the activity are well adapted to serve as 
measures of the escaping tendency. Indeed, for isothermal changes 
the equations in which the two quantities enter are as a rule identical. 
However, since the equations for the change of fugacity with the tem- 
perature are a little less simple than those of the activity, we shall 
choose the latter quantity for our present purpose. We shall start 
with a simple definition of the activity, and proceed to show that the 
change of the activity with the variables which determine the state of 
the system may be expressed by a series of exact equations which are 
of the same form as many of the familiar approximate equations for 
vapor pressure, solubility, ete. 

On account of the large scope of this undertaking our consideration 
will be limited to those systems which are completely determined by 
the temperature, the pressure, and the composition of the various 
phases. How the work may be extended to include other variables, 
such as surface tension, has been indicated in the preceding paper. 


FUNDAMENTAL Laws AND ASSUMPTIONS. 


The following work will be based on the two laws of thermodynamics 
and upon the law that every gas and every solution as the concentra- 
tion diminishes approaches as a limit the perfect gas and the per- 
fect solution. Besides these we shall use the following definitions of 
the activity. 

When the activity of.a substance is the same in two phases, that 
substance will not of itself pass from one phase to the other. 

When the activity of a substance is greater in one phase than in 
another, the substance will pass from the one phase to the other, when 
they are brought together. 

The activity of a perfect gas is equal to its concentration. 

The activity of the solute in a perfect solution, at constant tempera- 
ture and pressure, is proportional to its concentration. 

We shall see that these statements suffice to define the activity of 
a substance in any state, and except in unusual cases enable us to 
calculate its numerical value. 

No further assumptions are necessary, but since owr aim will be to 
lay stress rather on the exactness of the results obtained than upon the 
mathematical rigor of the method by which they are demonstrated, we 
shall adopt as working aids the following assumptions : 

(1) For every molecular species we will assume that an ideal solvent 


--....---.ἔ.- -.- ----- 


264 PROCEEDINGS OF THE AMERICAN ACADEMY. 


may be found (or imagined) in which that species dissolves to form a 
perfect solution, at all concentrations up to that of the saturated 
solution. . 

(2) We may further assume that the ideal solvent chosen is one 
which suffers neither increase nor decrease of volume when the sub- 
stance in question is dissolved at constant temperature and pressure. 
In other words, the volume of the ideal solution is the same as that of 
the ideal solvent it contains.* | 

(3) In dealing with mixtures, use will be made of any kind of 
semipermeable membrane, real or imaginable, that may prove serviceable, 

Probably in no case can the ideal solvent or the perfect semiperme- 
able membrane be actually found. hey will be employed as conven- 
ient fictions for the purpose of obtaining results which could be obtained 
without their aid, but by less simple methods. 


EQUATIONS OF A SOLUTION IN THE IDEAL SOLVENT. 


Let us consider the vapor of a substance X, together with a solutior 
of Χ in an ideal solvent. From the laws stated in the preceding sec- 
tion it may readily be shown that as the quantity of X is diminished 
and the solution and the vapor become less concentrated, the ratio 
between the concentrations of X in the two phases approaches a con- 
stant value.5 In other words, if ¢ represents the concentration of X in 
the solution, οἱ in the vapor, then at infinite dilution, 1 


co’ = pe, 


where p is a constant, when the temperature and pressure are constant, 
and may be called the distribution coefficient between solution ané 
vapor at infinite dilution. This equation is merely the exact statement 
of Henry’s law. Ι ἃ 

Since the two phases are kept in equilibrium, the activity of X mus’ 
always be the same in one phase as in the other, that is, | 


* This assumption is of minor consequence, and is introduced merely to sim 
plify some of the mathematical work. It can be omitted without materia 
changing the following work. 

5 Since our purpose is to develop a set of exact equations, but not to place te 
much emphasis upon the formal rigor with which those equations are obtaineé 
it will not be necessary to repeat the proof of propositions which have alread, 
been proved elsewhere and which can obviously be obtained by familiar method: 


LEWIS. — A NEW SYSTEM OF THERMODYNAMIC CHEMISTRY. 265 


At infinite dilution the vapor of X becomes a perfect gas, and by defi- 
nition 


~ 


= cl. 
Hence at infinite dilution 


g=cl =pe. 


ξ is the activity of X in the ideal solvent, and ὁ is its concentration, 
and by definition € is proportional to ¢ for all concentrations which we 
shall consider. Hence, not merely at infinite dilution but in general 
one of the fundamental equations of the ideal soluticn is, 


ἔξ = pe. 11 8 


From this another useful equation may be obtained. In the case of 
the ideal solution we have for the osmotic pressure, H, the equation, 


11. ΤΉΝ 
il ᾿. 
Hence é — a Ill* 


The quantity p varies with the temperature. In order to find the 
law of this variation we may once more consider the equilibrium at 
infinite dilution between the vapor of X and the solution of X in the 
ideal solvent. 

Since we are dealing here with the ideal solution and with a perfect 
gas, the following special form of the equation of van’t Hoff can be 
proved by familiar methods to be entirely exact. 


d\np ae Un) 
dl ~ RT?’ 


IV 


where In signifies natural logarithm, and ἔχιν] is the increase of 
internal energy when one mol of X passes from the ideal solvent into 
the infinitely attenuated vapor. 

With the aid of these equations we are now prepared to undertake 
a systematic study of the laws of physico-chemical change. It is to be 
noted that from each one of the following exact equations two important 
approximate equations may be obtained directly, —one for solubility, 


§ Numbered equations, such as those of the ideal solution, which are only true 
under special conditions, will be marked with the asterisk. 

7 Since it will be necessary to use the symbol U for various kinds of internal 
energy change, a particular value of U will be designated by the number of the 
equation in which it first appears. 


266 PROCEEDINGS OF THE AMERICAN ACADEMY. 


by substituting for the activity the concentration of a saturated solu- 
tion, and one for vapor pressure, by substituting for the activity the 
concentration of the saturated vapor. 


Tre INFLUENCE OF PRESSURE AND TEMPERATURE UPON THE ACTIVITY 
OF A SIMPLE SUBSTANCE. 


Let us consider a pure substance in any state, — solid, liquid, or 
gaseous, — and find the effect upon its activity : first, of a change of 
pressure at constant temperature, and second, of a change of temperature 
at constant pressure. Since the equations we are about to obtain are 
special cases of equations IX and XII, of which a complete proof is 
given in a later section, a less thorough derivation will here suffice. 

In the preceding paper a formula was obtained (equation 14) for 
the influence of pressure on the fugacity of a pure substance, namely, 


@lIny\ _— v 
OP jr BT 


where w is the fugacity and » the molecular volume. Combining this 
equation with equation I of the present paper, we find, since 27’ is 


constant, 
(3 eS eae 
Fae ox i 


This is a perfectly general equation for the influence of pressure upon 
the activity of a pure substance. Since the second member of th 
equation is always a positive quantity, it is obvious that an increase ¢ 
pressure always causes an increase in the activity. 

In order to determine the influence of temperature, let us consider 
a substance X, in contact with its saturated solution in an ideal solvent. 
The solubility as measured by the osmotic pressure, II, varies with th 
temperature according to the well-known equation 


(ar),= 7] 
- τῆν f 


entirely exact. @ is the total heat absorbed when one mol of X dis: 
solves reversibly in the ideal solvent. It is obviously the sum of thre 
terms, — the increase in internal energy, the osmotic work done, an 
the work done against the external pressure, P. (According to one ¢ 
our fundamental assumptions the volume of the ideal solvent does n¢ 


LEWIS. — A NEW SYSTEM OF THERMODYNAMIC CHEMISTRY. 267 


change when X dissolves.) The first of these terms we will call ym; 
the second, according to the principle of van’t Hoff, is equal to R7’; and 
the third is equal to —Pv, where v is the molecular volume of pure X. 
We may write equation VI, therefore, in the form 


ὙΠ’ 


aS vm + RT — Pv 
ae ye 


Now the activity, ¢, of X in the pure state is always equal to that in 
the saturated solution. The latter is related to II, according to equation 
III, by the formula, 


ERT 
ρ 


Me 


Substituting this value of II in equation VII gives, 


Olné ny Clnp Ἢ 1 _ ὑπ + kT — Pv 
ar jp ( ΕΣ Re? 
Substituting for the second term the value given by equation IV, and 


simplifying, we have, 


@iné\ 2 Onm ἘΞ Van — Lo 
or _ nie 


Uv is the increase in internal energy-when a mol of X dissolves in 
the ideal solvent and Uy, is the increase when it passes from that 
solution into the state of infinitely attenuated vapor. The sum of 
these two is the increase in internal energy when a mol of X is evapo- 
rated and the vapor expanded indefinitely, or in other words it is the 
increase in internal energy when a mol of X evaporates into a vacuum. 
This important quantity, which we may call for the sake of brevity the 
ideal heat of evaporation, will be designated by the symbol Y. Sub- 
stituting it in the last equation gives, 


@né\ Y—Pv 
or ).= a ὙΠῚ 


This is the general equation for the effect of temperature on the 
activity of any pure solid, liquid, or gas. Except in very rare cases 
the second member is positive and é increases with 7. 


268 PROCEEDINGS OF THE AMERICAN ACADEMY. 


APPLICATIONS OF THE PRECEDING EQuarTions. 


A few examples will serve to illustrate the mode of application of 
equations V and VIII. 

‘wo phases of the same substance, ice and water, for example, are in 
equilibrium at a given temperature and pressure. If the pressure on 
either phase alone is increased, the activity in that phase is increased, 
and the phase must disappear. If the pressure upon both phases is 
increased by the same amount, the activity is increased more in the 
phase of largest molecular volume, namely the ice, and it will disappear. 
By increasing the pressure on the ice by the amount d/, and that on 
the water by a greater amount, dP’, it is possible to maintain equilib- 
rium. Let us see what relation these two increments of pressure 
must bear to each other. Let ἕ, P, v, and &, P’, οἱ, represent the 
activity, pressure, and molecular volume of the ice and the water, re- 
spectively. From equation V, 


J 
pis eT 
diné= pee, and dlnég Rr" 


In order to maintain equilibrium we must always keep € equal to ¢/. 


Hence, 
az=di. or dné=dln€. 


Therefore the condition of continued equilibrium is, 


Caen dP vw 
FPP = = Ree and dp! a Ἐς 
In order to maintain equilibrium the increments of pressure on the 
two phases must be inversely proportional to the molecular volumes.8 
As a second illustration let us consider the same system of ice and 
water subject to a simultaneous change of pressure and temperature. 
The effect of increasing the pressure equally on both phases is to in 
crease the activity of the ice more than that of the water. An increasé 
of temperature has the same effect. By increasing the pressure and at 
the same time lowering the temperature, equilibrium may be maintaine 
The condition of equilibrium, as in the preceding case, is, 


ding=diné 


but in this case the change in é and in £ is due in part to change ἢ 
temperature, in part to change in pressure, that is, 


8 For a proof of this equation by other methods, see Lewis, Z. physik. Chem 
35, 348 (1900); These Proceedings, 36, 145 (1900). 


LEWIS. — A NEW SYSTEM OF THERMODYNAMIC CHEMISTRY. 269 


din nt= (5573), aT + + (So) @P 


0 \n é! ln & 
Cie. | ΞΕ ΞΕ ; 
and diné ( ar Ne aT + ( AP ) a. 


Equating the second members of these equations and substituting for 
the partial differential coefficient their values from equations V- “and 


VIII, 


ἘΞ ΕΣ ΑΗΘ τα uy 
= aT + ΠᾺΡ = ae Sao rp 
ave ΟΝ Pow =. y! -- Pd! = a! —v 
or RT? the bm RT dP. 


The numerator of the first fraction is obviously equal to the heat of 
fusion of one mol of ice. Calling this Q, we have 


ΟἹ (w—v)T 
dP Ome: 


which is the familiar equation of Thomson for the change of freezing 
point with the pressure. 

Asa third illustration of the application of these equations we will 
consider a general method for determining the numerical value of the 
activity of a substance. Let us first consider a gas which is at such 
a pressure as no longer to obey the gas law. According to equation V 
we may write, for the influence of pressure on the activity, at constant 
temperature, 


dilné= atl 


From this equation we may find the activity at one pressure when it is 
known at any other, if we know the molecular volume, Ὁ, as a function 
of the pressure, P. For this purpose we may use any empirical 
equation, such as that of van der Waals, namely, 


Differentiating this equation, substituting the value of dP in the pre- 
ceding equation, and integrating between v and v!, we obtain the 
equation, 


: b b 2a 2a 
Sem Δ τὺ... τ ΤΟΣ 


υ' - ᾿ 


a that the constants a and ὁ are known for a given substance, the 
activity of that substance can be found at the volume v when it is: 
known at any other volume, ο΄. At infinite volume the activity of the 
gas, by definition, is equal to its concentration, which is the reciprocal 
of its molecular volume. It is evident, aston ae if in the above 


equation οὐ approaches infinity, ¢ approaches + pt ae and the see- 


ond, fourth, and sixth terms in the equation nee δ zero. Omitting 
these terms, therefore, and rearranging slightly, we have, } 


b 
n= 5 — Bers 


— ἰὴ (ὺ --- ὁ). 
From this equation € can be found for any gas at any volume, v, pro- 
vided the formula of van der Waals holds, and the values of a and 
are known. Similarly any other empirical equation of condition me 
be used. 

According to Amagat’s experiments upon carbon dioxide at 60° th 
molecular volumes of this gas at 50, 100, 200, and 300 atmospheres, are, 
respectively, 0.439, 0.147, 0.0605, and 0.0527 liters. From these dat 


a=31; b= 0.034 


sequently having the value 0.0820). Ἷ : 

Substituting these values in the above equations, we obtain the 
values for the activity of carbon dioxide at 60° given in the following 
table : 


Ϊ 
] 
‘ 

ῃ 

a 
᾿ 


ΗῈᾺἢ eee 


eee 


express, following Ostwald, 


LEWIS. — A NEW SYSTEM OF THERMODYNAMIC CHEMISTRY. 271 


The first column gives the pressure, the second gives the concentration 
: 1 Σ ὡ hone : 
in mols per liter (5) the third gives the activity, also in mols per 


liter, and the fourth gives the ratio of activity to concentration, which 
for a perfect gas is always unity. ‘The increase in this quotient between 
200 and 300 atmospheres is interesting, and the whole table shows how 
little either the pressure or the concentration of a compressed gas 
is suited to act as a measure of the escaping tendency. 

If instead of determining the activity of gaseous carbon dioxide we 
desired to determine that of CO, in some other phase, for example in 
a solution of sodium bicarbonate in water at a given temperature and 
concentration, it would be only necessary to know the pressure or the 
concentration of carbon dioxide gas in equilibrium with that phase. 
For the activity there would be the same as in the gas, and the latter 
could be determined by the above method. 

This, therefore, is a perfectly general method for determining the 
numerical value of the activity. However, it is to be emphasized that 
in most cases where the conception of activity is useful, it is not necessary 
to know the numerical value, but only the ratio of the activities in two 
given states. his will be illustrated in another section. 


INFLUENCE OF PrEssuRE, TEMPERATURE, AND CONCENTRATION UPON 
THE ACTIVITY OF THE CONSTITUENTS OF A Bryary MIxtTurRE. 


The equations in this section will apply not only to a homogeneous 
liquid mixture, but also to a gaseous mixture, or solid solution, in fact 
to any homogeneous phase 
whatever which is composed 
of the two molecular species, 
X,and X,. The composition meet 
of a binary mixture we shall De 


by the molecular fractions 
(Molenbruche), N, and Nz, 
so defined that N, + N.=1. 
By one mol of the mixture 
we shall mean that amount ices 
which contains N, mols of 
X, and N,of X,. Later, in dealing with sinner of more than two 
constituents, the fractions N,, N., Ns, etc., will be similarly defined, 
ΕΠ ΠΗ N; + No+Ns+...=1. 

The influence of pressure upon the activity of either constituent of 


272 PROCEEDINGS OF THE AMERICAN ACADEMY. 


a binary mixture may be found by means of the apparatus shown in 
Figure 1. A contains the mixture of X; and X,. D is a piston 
which determines the pressure on A. Eis a membrane permeable only 
to Χι. Bceontains a solution of X, in its ideal solvent. Fis a piston 
permeable only to the latter. Above [δ is the pure solvent. 

The pressure on the piston F is the osmotic pressure, I, of the ideal 
solution in B. In general if the pressure, ?, on D is changed, the 
equilibrium will be disturbed and the substance X, will pass through 
E, unless at the same time the pressure on F is changed by a suitable 
amount. Let us find*the mathematical expression for the change in I, 
which just compensates a given change in P. 

Starting with the piston F at E and with a large (better, an infinite) 
amount of the mixture in A, occupying the volume V, let us perfo n 
isothermally the following cycle of reversible operations. 

(1) Keeping the pressure P constant on the piston D, and keeping 
the pressure on F also constant and equal to the corresponding osmotic 
pressure, II, raise F until one mol of X; passes into B, where it occu 
pies the volume »’. The diminution in the volume of A we will denote 
by the symbol v. The work done by the system by means of the pistons 
F and D is, therefore, 


A, = Πυ' — Pr. 


(2) Now increase the pressure on the piston D to P + dP, and at 
the same time increase the pressure on F to II + df, dil being the in 
crement in Π which is necessary to prevent X, from passing in either 
direction through E. The volume of A will change from V—v to 
(V —dV)—(v—d?r), and the volume of the solution will change 
from v! to οἱ" —dv!. The work done by the system by means of the 
pistons F and D is, 


A, =— Idv! — P (dV — de). 


(3) Keeping the pressures on the two pistons constant and equal to 
Tl + dil and P + dP respectively, lower F to E, forcing the mol of X 
back into A. The work done by the two pistons is 


A, =— (11 + 4Π}00] — de’) + (P+ dP)(v — de). 


(4) Change the pressure in A back to P. The piston F is station 
ary, and the work done by the piston D is, 


A,=FPdV. 


a 


LEWIS. — A NEW SYSTEM OF THERMODYNAMIC CHEMISTRY. 273 


The surface C does not change its position during these operations 
(according to the definition of the ideal solvent). The total work 
done by the system is therefore equal to the sum of 41, Az, A;, and 
A,, and since the cycle is isothermal and reversible this sum is equal 
to zero, by the second law of thermodynamics. Equating the terms to 
zero and simplifying gives, 


vdP — v'dil = 0. 


: : eee ΤΠ 
v', the molecular volume in the ideal solution, is equal to Tr: Sub- 
stituting this value in the last equation gives, 
dinll_ ἢ 
dP. RP 


The activity of X,, ¢ is the same in the mixture A and the solution B 
and its value in terms of I is given by equation III. Substituting for 
If and expressing in the equation the constancy of temperature and com- 


position,? we have, 
(: Iné ) a: ἢ 
PP ny RE (IX) 


This is the general equation for the influence of pressure upon the 
activity of one constituent of a binary mixture. The quantity v is of 
very great importance in the thermodynamics of mixtures. It is the 
Increase in volume of an infinite quantity of a mixture when one mol 
of the constituent in question is added to it. We will call v the par- 
tial molecular volume of that constituent. 

Similarly we may define the partial molecular energy, entropy, etc., 
and these quantities play the same rdle in the thermodynamics of 
mixtures that the molecular volume, energy, entropy, etc., do in the 


' treatment of pure substances. 


An important difference between the partial molecular volume in a 
mixture and the molecular volume of a pure substance is that while 
the latter is always positive the former need not be. Therefore the 
activity of one of the constituents of a mixture may either be increased 
or diminished by increase of pressure on the mixture. 


9 We will use the subscript NV with the partial differential coefficient to denote 
constancy of composition in the mixture. 


VOL. ΧΊ,111. ---- 18 


274 PROCEEDINGS OF THE AMERICAN ACADEMY. 


If a mixture contains X, and X, in the proportion of Vy; mols of the 
former to JV, of the latter, the relation of the partial molecular volumes, 
τι and vy is readily seen. If we add to an infinite quantity of the 
mixture NV, mols of X,, the mixture will increase in volume by 47. 
Then adding NV, mols of ΧΩ the volume increases by Vr. Altogether 
we have done nothing more than add one mol more of the original mix- 
ture. The total change of volume must therefore equal v, the volume 
of one mol of the mixture. Hence, 


Mit a Neve = v. x 


From equation IX we have the following two equations for the two 
constituents : 

N,@ln & _ Ny, 

( OP Jan RT’ 


wee) _ Nets 
DP Jay) Br 


Adding these two, we obtain the important equation, 


Die Net Waa, ee 
oP nu. LT 


The influence of temperature upon the activity of one of the con: 
stituents of a mixture may also be determined with the aid of 
apparatus of Figure 1. Starting with the piston F at E, we may per 
form the following cycle of reversible operations, keeping the press 
constant upon both D and C. 

(1) At the temperature 7’ raise the piston F until 1 mol of X; passe 
into B, where it occupies the volume οἱ. ‘The pressure on F is kept 
such a pressure, I, that the activity of X, is always the same in Bg 
in A. 

(2) Lower the temperature to 7’— d7, moving the piston F so the 
none of X; passes through E. ‘The volume of B is changed to v! — di 
and the osmotic pressure to IT — dT. 


10 The equation is written in this form rather than in the more conventions 


form, 
ἐπ ὴ δ: ont) Ae 2 
™;( aP Inet ONE ee ee 
in order to emphasize the peculiar significance of the term N,d1né, + N.dIn 
In general we shall see that the equations of a mixture may be obtained fre 
those of a pure substance by substituting this series of terms in place of dlné 


LEWIS. — A NEW SYSTEM OF THERMODYNAMIC CHEMISTRY. 2795 


(3) Lower F once more to E, under the constant pressure If — 0Π, 

(4) Raise the temperature to T. 

The total work done by the pistons D and C is zero, since they are 
under constant pressure and finally return to their original positions. 
The whole work done by the system is, therefore, the work done by the 


piston F, This is obviously the sum of the following four terms : 


“A, = Iv’, 

A, = — Ildv’, 

A; = — (ἢ -- ἀ«Πγῴυ! — dv’), 
ΤΠ ΞΞΤΟ: 


The sum of these terms, neglecting the differential of the second order, 
is dU. This is the total work done by the system during the cycle, 
and therefore from the second law of thermodynamics, 


“aT, 

where @ is the heat absorbed in process (1). @ is the sum of three 
terms. ‘The first is the increase in internal energy when one mol of X, 
passes from A to B, which we may call (x;y. The second is the 
osmotic work, IIv’, which is equal to R7. The third is the work done 
by the pressure P acting on piston D, which is equal to — Pv where v 
is the partial molecular volume of X, as before. 


vd] = 


Hence, 
ol ΟἹ ἔχῃ τ RT — Lay 
Oh a T 
RT 
‘— 
Now oa, 


din _ Oxn + RT Po. 


and therefore Fie Ξ RT? 


Combining this equation with equations III and IV, as we did in 
deriving equation VIII, we have 


élné a U xm Ἔ Oa) a Po 
FT ae ν RT? 


The sum of Uxy), and Uy) is the increase in internal energy when 
one mol of X; passes from an infinite quantity of the mixture into a 


276 PROCEEDINGS OF THE AMERICAN ACADEMY. 


state of infinitely attenuated vapor. We will denote this quantity by 
Y. It bears the same relation to the value Y of a pure substance as 
the quantity v does tov. We may call it the partial “ideal heat of 
evaporation.” 

The above equation then becomes, 


élné _Y¥—Pv 
Cae = eee 
which is a general equation for the influence of temperature upon the 
activity of one of the constituents of a mixture when the pressure and 
the composition are constant.11 
Just as equation X was proved we may show that for one mol of the 


mixture, 
ἘΞ NW; + Nos. KIT 


Hence we obtain an equation analogous to equation XI, namely 


( 7.2 ln & + N26 In =) _Y—Pv 
7) hk — — p72 Ὁ ; 

et 81 P,N RI d 
Here as before v is the volume occupied by one mol of the mixture 
and Y the increase in internal energy when one mol of the mixture 
converted into infinitely attenuated vapor, or in other words when ii 
evaporates in a vacuum.12 


11 The approximate equation for the vapor pressure of one constituent of 4 


binary mixture obtained from equation XII is, © 
d\n a) ee") 
OL Jpn” RT?’ 


where Q is the partial heat of vaporization (including the external work). phi 
is in a simpler form than the equation obtained by Kirchhoff, 7 


dino dQx 
( Ρ ADE 
Ol Jpn kT? 


(see Nernst, Theoretische Chemie, 4 Edit., p. 118). 
12 Equation XII bears the same relation to XIV that the equation of Kirchho 
does to one obtained by Nernst, namely, 


Po Po 
dln = 4+- rd ln ΟΣ As) 
dT τῆς ΚΤ 
(Nernst Theor. Chem., 4 Edit, p. 117). 


LEWIS. — A NEW SYSTEM OF THERMODYNAMIC CHEMISTRY. 277 


Finally we must determine how the activities of the components of a 
mixture vary when the composition is changed at constant temperature 
and pressure. In order to solve this problem we may employ the ap- 
paratus shown in Figure 2. A contains a mixture of X, and X,._ Εἰ is 
a membrane permeable only to X;, E, one permeable only to Xz. In B, 
and B, are ideal solutions of X, and X,. The two pure ideal solvents 
lie above the pistons, δὶ and F,, which are permeable only to these 
solvents. D is a piston which exerts a constant pressure on A. The 
pressure at C, and ©, will also be held constant. We may perform the 
following isothermal cycle of reversible operations, starting with Ny 
mols of X; and VV, mols of X, in A, and none of these substances in B, 
and B,, the pistons F; and I’, being at E, and E,. 

(1) Keeping the pressures on ΕἾ and F, constant and at such values, 
TI, and f1,, as to maintain equilibrium with the mixture in A, raise 
these two pistons at such 
rates that as X; and X, 
pass into B, and B, the 
remaining mixture in A 
still keeps its original com- 
position. Finally, when all 
the mixture has disap- 
peared from A there will 
be Wi mols of X, in B, 
where it exerts the os- 
motic pressure II,, and oc- 
cupies a volume which we 
| will call V;, and there will 
| be NV. mols of X, in B,, the osmotic pressure being I», and the 

volume Vy, 

(2) By simultaneous movements of the pistons ΠῚ and F, change the 
volumes in B, and B, to V, —dV, and V,—dV%._ The osmotic pres- 
sures will change to IJ, + dil, and 1, + dil, The solutions in B, and 

| B, are now able to exist in equilibrium, not with the original mixture, 

_ but with a mixture containing X; and X, in another proportion, say ΔΊ 
mols to V, — dN, mols. 

| (3) Form a mixture of this composition in A by lowering the pistons 

F, and F,, This operation will be just the reverse of (1), except that 
| X,and X, enter the mixture in the constant proportion, not of ΔΊ to 

WV, but of Δ᾽ to N, dN, At the end of this process all of X, and 

all but dN, of X, will have passed into A. 

(4) Finally force into A the remaining dN, mols of Xz, whereby the 
whole system returns to its original condition. 


FIGuRE 2. 


278 PROCEEDINGS OF THE AMERICAN ACADEMY. 


each case the final position is the same as the initial, and the pressure 
is constant throughout the cycle. Therefore the total work done by 
the system during the cycle is that done by the pistons F, and F,, 
which is as follows: 7 
In operation (1), 


A, =); + 1, V2 
In operation (2), 
A, oe, II,d Vi — 1,6] Vs 


In operations (3) and (4), except for a differential of the se 
order, 


A, + A, = — (απ, + dll,)(Vi — dV,) — (ας + ἀπὸ, τ 


By the second law of thermodynamics the sum of these terms, the tota 
work of a reversible isothermal process, rust be zero. Hence 
neglecting differentials of the second order, 


Vid0, + Vidil, = 0. 


Since we are dealing with ideal solutions, 


NRT ὧν atte 
ta re ; 
i= il, and V,= il, 
hence N,dln Tl, + Nedln OW, = 0. 


Now the activity & of X, in A is always the same as in B,, and & in 
is the same as in B,; hence, applying equation III (p and 7 bei 
constants) we have, 


Νὰ & τον Nd ln & =O, 


which may also be written 


Δι In & + Δ᾽ In & ΞΞῸ 
ὟΝ PT , 


(nes In ἕξ, + N22 In ey 
= 0, 
ΟΝ, Ρ,Τ 


LEWIS. — A NEW SYSTEM OF THERMODYNAMIC CHEMISTRY. 279 


It is not possible from thermodynamics alone to predict how the 
activity of each of the constituents of a binary mixture will change with 
a change in composition. But if the change in one of the activities is 
known, the change in the other may be found from the above simple 
relation.1% 

Mrxtures oF More tHan Two Components. 


In the derivation of equations IX and XII no use was made of the 
provision that the mixture contained but two constituents, and these 
equations therefore show the effect of pressure and of temperature upon 
the activity of one of the constituents of a mixture of any number of 
constituents. In the same way that equations XI, XIV, and XV were 
found we may obtain the following equations : 


Δι 10 ξὶ + ΛΟ 1 ᾧ + N; ln & +.-. _ 9 ω 
Δ 9]η δι + NolIné + Δ).2]η ὃ; -Ἐ - -' ΠΡ 
( oT ae τ Rie XVII 
ΡΟΣ eo Inte le wets 
(= In €, + ΛΠ, In fa + 30 In €3 + ) Bs XVIII 
OM, P,T 


DILUTE SOLUTIONS. 


Equations XV and XVIII assume a very simple form when one of 
the constituents of a mixture is present in such small amount as to 
constitute a perfect solution. If a mixture consist of a very small 
amount of a substance X, and a large amount of a substance X., we may 
call the latter the solvent and the former the solute. If the solute is 
extremely dilute, then, according to equation II, its activity & is pro- 
portional to its concentration and therefore to Ny. Hence, 


dlné, =dlnM™,, 
and equation XV becomes, 


Ned In £ ΞΞΞ- -- dN;, XIx* 
or yi oN, XIX* A 
Δι 


18. An approximate equation which is a special form of equation XV is 
Duhem’s equation for the vapor pressures of a binary mixture, namely, 
Nydin py + Nod1in py=0. This equation is true only when the vapors obey 
the gas law. See Lewis, Journ, Amer. Chem. Soc., 28, 569 (1906). 


280 PROCEEDINGS OF THE AMERICAN ACADEMY. 


This equation states that the relative lowering of the activity of : 
solvent by the addition of a small quantity of a solute is equal to the 
number of mols of solute divided by the number of mols of solvent, 

This statement comprises in itself practically all the laws of dilute 
solutions. Raoult’s law is a special but only approximate form of 
equation XIX, for equation XIX is true of every solution when infi- 
nitely dilute, but Raoult’s law is not true even at infinite dilution, 
except when the vapor of the solvent is a perfect gas. 

If the solute, X,, is dissolved, not in a pure solvent, but in a mixture 
of Xs, Xs, ete., then for the perfect dilute solution we find in place 
equation XIX, 


Ned\n& + Neding;+ --- =—dN,. 


Some APPLICATIONS OF THE PRECEDING EQuarIons. 


Equations I-XX can be combined in a very great variety of ways 
to give important results. A few examples, however, will suffice t 
show the manner in which these equations may be employed. 

First, as a simple example, we may derive the formula for the lower 
ing of the freezing point of a perfect solution. According to equatic 
XIX, the activity of a pure liquid is always lowered by the addition 
asolute. If therefore a liquid and solid are together at the freezin, 
point and a solute is added to the liquid, the activity of the latter wi 
become lower than that of the solid, and the solid will melt. On th 
other hand, if we start again with liquid and solid at the freezing poit 
and lower the temperature, we see from equation VIII that the activi 
of the solid will decrease faster than that of the liquid and the liqui 
will disappear. It is obvious, therefore, that by adding a solute to’ 
freezing mixture and at the same time lowering the temperature by 
suitable amount, the equilibrium between solid and liquid can be mai 
tained. The necessary condition for the maintenance of equilibriw 
is that the activity & of the solvent X, in the liquid state remain equ 
to the activity ἔξ! of X, in the solid state. Hence, 


din, =dln ἕῳ 
Now, assuming that the solid does not dissolve any of the solute, ; 


change in activity of the solid X, is due merely to change of temper 
ture, and thus from equation VIII, 


dln é!, = ἜΣ 20T. 


LEWIS. —A NEW SYSTEM OF THERMODYNAMIC CHEMISTRY. 281 


But the activity of the solvent in the liquid phase is changed both by 
the change in temperature and by the presence of dV, mols of solute. 


That is, 
d\n & = (πὸ dT + (Ge *\ aN. 
fi ON, 
Whence by means of equations XII and XIX 


— Pr, dN, 
= -Ξ ὦ 
d\n = yt IT — Ne 


Equating the second members of this equation and the one above, 


or ae Nz — = 


But it is obvious on inspection that the denominator of the second 
member is merely the heat of fusion of one mol of solid, which we may 
call @. If the solution is very dilute we may also simplify by writing 
N,=1. Hence, 

CY ieee (a bg 

dN, ῳ 


This is the familiar equation of van’t Hoff for the lowering of the 
freezing point by a dissolved substance. 

As a second example we may study the following system. A mix- 
ture of X, and X; in.the molecular proportion of Vy, to NV are in equi- 
librium with a second phase consisting of pure X, Let us determine 
the change in activity of X; when a small quantity dN, of a substance 


ΟΣ, is dissolved in the mixture. At constant temperature and pressure 


the activity £2 of the pure phase of X, is a constant, and therefore 
the activity, ἕω, of X, in the mixture is also constant. Equation XX 
therefore becomes, 

Nd ln &, = — dy. ».O.4| 


This interesting equation has, I believe, not hitherto been obtained, 
even in an approximate form. Its meaning may be illustrated by the 
following example: If a saturated solution of salt in 1000 grams of 
water is in contact with solid salt, and 1 gram of sugar is added, then 


282 PROCEEDINGS OF THE AMERICAN ACADEMY. 


the activity of the water is lowered by the same per cent as when 
1 gram of sugar is added to 1000 grams of pure water. 

An interesting system is one composed of two phases, both of 1 
are mixtures of the same composition. An important example of suc h 
a system is a constant boiling mixture and its saturated vapor. Here 
N., Nz, ete., which are the molecular fractions in the one phase, are 
equal respeatively to ΔΊ; N's, ete., in the other phase. If the condi- 
tions are changed by changing the temperature or pressure or by adding 
a third substance X, to one or both of the phases, then equilibrium ea 
only be maintained by keeping the activity of each component the same 
in both phases ; thus we may write as usual, 


dingé;=din#, dné&=dlné, 
etc. ; but since Vz = WN, etc., we may write 
N.d\ln & + Nedln& +--- = N'edlné.+ N',d\n ἕξ +++ 


Now the first member of this equation represents a change which ma) 
be the resultant of the changes produced by change of temperature, 
change of pressure, and the addition of dN, mols of the solute X,, 
Each of these changes is represented alone by equations XVI, XVII, 
XX. Therefore, 


N20 In & + N3@1n & + Y— Po, 
(ent eS) rae 
ΔΘ In & + Ngé@ ln & + - 
( oP =) ne = aT “ 
(55: N,@\n ὅς +> - iN ae 
oN, np : 
We may therefore write the sum of these as follows : 
--: Y— Pv 
of In ἕω a Ν, 3@ In ἕς + _= RT? dT + 114} — dN, 
Likewise we find 
: Ξ ΥἹ — Po! υ! 
N'.d \n ', + Δ, α Ἰὴ é', ++ - - = —__— RT —,, --ατ + RpeP — I 


where 7’; is the number of mols of the solute in one mol of the seco 
phase. Equating the second members of these two equations we ha 


LEWIS. — A NEW SYSTEM OF THERMODYNAMIC CHEMISTRY. 283 


Bee) = 


=p op = ANG RING = 0. 


The numerator of the first term, which we may call Q, is obviously the 
heat absorbed when a mol of the mixture passes from the first phase to 
the second, and (v — v’) is the decrease in volume accompanying the 
same change. ‘Thus, 


aati ἜΤ᾽ pe dN, + dN', =0. XXII* 
Tunis extremely general equation shows how the variations in temper- 
ature, pressure, and quantity of solute must be regulated in order to 
maintain equilibrium in such a system. Several special cases are 
worthy of notice. If pressure and temperature are the only variables, 
in other words if dV, and dN’; are zero, then the equation becomes, 


Des τῶ, 
aT W—o)T 


This equation is identical with the familiar Clapeyron-Clausius equa- 
tion. It shows, for example, that the vapor pressure from a constant 
boiling mixture varies with the temperature in the same way that the 
vapor pressure of a pure substance does. 

If in equation XXII, dP and dN’, are zero, there remains an equation 
for the change in temperature which compensates for the addition of a 
solute soluble in one phase only, namely, 

if Ue 


ax 1. 


i 


Thus, for example, the boiling point of a constant boiling mixture is 
changed by the addition of a non-volatile solute according to the same 
law as that which applies in the case of a simple solvent.14 Ὁ is of 
course the heat of vaporization of one mol of the mixture. 

In the same way, by making d7’ equal to zero in equation XXII, a 
formula may be derived for the lowering of the vapor pressure of a con- 
stant boiling mixture when a solute is added at constant temperature. 


14 This equation I have already proved in a less rigorous way (Journ. Amer. 
Chem. Soc., 28, 766, 1906). It has considerable practical importance, as it in- 
creases the number of solvents in which molecular weights may be determined 
by the boiling point method. 


284 PROCEEDINGS OF THE AMERICAN ACADEMY. 


If instead of the system considered above we study a system of the 
type represented by a mixture at its eutectic point, we may derive 
a set of equations, entirely similar to the above, which show the change 
of the eutectic temperature with the pressure, and the change of the 
eutectic temperature at constant pressure, or of the eutectic pressure at 
constant temperature, when a solute is added to the mixture. 

These examples will suffice to show the way in which equations 
I-XX may be. applied to the derivation of other thermodynamic 
equations. 


Tie Laws or CuemicaL EQuiLrerivum. 


from one phase to pee We will now consider those processes i a 
which the molecular species react with each other to form new species, 
and it will be shown that the activity of a given species is not only ὃ 
measure of the tendency of that species to escape into some other phase, 
but is also a perfect measure of the tendency of the species to 
part in any chemical reaction. In other words, the activity is an exact 
measure of that which has been rather vaguely called the “ active 
mass”’ of a substance. 

Let us consider the reaction represented by the following equation, 


aA+bB+-++-<S00+pPt+.:>-:, 


where a mols of the substance A, ὁ mols of B, ete., combine to form: 
mols of O, p mols of P, ete. ‘he several substances may exist in 
pure state, or in mixtures ; may be in one phase or in different phases 
and there may be other substances present which take no part in th 
reaction. In other words, we are considering any system whatever it 
which a given chemical reaction occurs. Let us find the condition 
equilibrium in this reaction. 

We may choose a liquid which is an ideal solvent for each of 
substances taking part in the reaction. If this ideal solvent is brough 
in contact with the system through a membrane permeable only to th 


the solvent, and when the system comes to a final condition there wi 
be equilibrium in the chemical reaction, both in the original systet 
and in the ideal solution. Moreover, the activity of each of the mol 
cular species must be the same throughout the original mixture and i 
the ideal solution. 


LEWIS. — A NEW SYSTEM OF THERMODYNAMIC CHEMISTRY. 285 


Now in the ideal solution it is easy to show rigorously, as van’t Hoff 
has done, that the condition of equilibrium at a given temperature is, 


oR... 
Ae 
a COMsballt. 

ΠΩΒΕΩ͂Σ 

where C,,, etc., represent the concentrations. But in this solution the 
concentrations are proportional to the activities, and therefore, 


éo0 Ὁ 


0? _=K. XXIII 


ι ἐξ Senet 


where Λ΄ is another constant. Since the activities €,, ete., are not only 
the activities in the ideal solution, but also in the original system, it 
is obvious that equation XXIII expresses a law of extraordinary gen- 
erality. 

The above quotient, which we have called , hasa value which, for 
a given reaction at a given temperature, does not depend upon the 
medium in which the reaction occurs, nor upon the concentrations, nor 
upon the pressure, nor upon the nature or number of the phases which 
are concerned in the reaction. In other words A depends only upon 
the temperature and the specific nature of the reaction. It is there- 
fore a better measure of the true “affinity” of a chemical reaction 
than any quantity that has hitherto been used for this purpose. 

The equilibrium ratio, A, changes with the temperature according 
to a simple law. We may imagine the substances taking part in a 
given reaction all vaporized in a space so large that each. vapor be- 
haves like a perfect gas. If the reaction reaches equilibrium under 
these conditions, it is easy to show that the following equation of van’t 
Hoff is entirely exact, namely, 


ΡΘΕ. 
πηι, it 
dl! RT™ 


where C,, ’;, ete., represented the concentrations, and 11 is the increase 
in internal energy when the reaction occurs in this extremely attenu- 
ated gaseous phase. 

Since we are dealing with infinitely attenuated vapors, C,, etc., may 
be replaced by ἕ,, etc., whence 


dink τ 
TE WEP 


XXIV 


286 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Since at constant temperature A is independent of the conditions 
under which a reaction occurs, it is obvious that the change with the 
temperature of the equilibrium ratio of the reaction in any system 
whatever is given in equation XXIV. ‘The important quantity U, the 
heat of reaction in the dilute gaseous phase, is equal to the heat of re- 
action in any other condition less the algebraic sum, for all the sub- 
stances taking part in the reaction, of the quantities which we haye 
denoted by the symbol Y. 

‘The importance of this quantity U has been recognized by Berthelot, 
who wrote in 1875,15 “ J’ai défini spécialement la chaleur de combinai- 
son atomique, laquelle exprime le travail réel des forces chimique, et 
doit tre rapportée ἃ la réaction des gaz parfaits, opéré ἃ volume 
constant.” 

The following interesting example will serve to illustrate the simul- 
taneous application of equation XXIII or XXIV with the preceding equa- 
tions. Let us prove the theorem first demonstrated by Stortenbeker,1¢ 
namely, that the freezing point of a substance like CaCl, -6H,O which 
partly dissociates in the liquid phase, is not changed by the ad- 
dition to the liquid of a small quantity of either of the products of 
dissociation (CaCl, or H,O). When the solid, CaCl,-6H,O, melts, 
there are in the liquid 4, mols of CaCl,-6H,O, to Δ᾽ mols of CaCl, 
and V, mols of H,O, where V; = ΘΔ Let us find the effect produced 
by adding dN, mols of H,O at constant temperature and pressure. 
According to equation XVIII, 


(= In €, + N26 In & + N3é In =) 
Se ETS Ve Co eae eR SS ae = 0. 
ON; ὌΝ, 


From this equation, since Vs = 6 Ns, it is obvious that, 
Nyd\n & + Ne (dln & + 6d1n &) = 0. 


Now since the CaCl,-6H,0, CaCl, and H,0 are in equilibrium, 
equation XXIII states that, 

tg 

1 


Taking the logarithm of both members and differentiating we have, 


diné,+ 6dlné;=dl1n&. 


15 Ann. Chim. Phys., 4, 1 (1875). 
16 Zeit. phys. Chem., 10, 183 (1892). 


LEWIS. — A NEW SYSTEM OF THERMODYNAMIC CHEMISTRY. 287 


Combining this equation with the above gives, 
Nidin& + Nodinggs =0, or dmg, = 0. 


That is, the activity of the CaCl,-6 H,O in the liquid phase is not 
changed by the addition of a small quantity of water, and it will there- 
fore remain in equilibrium with the solid CaCl,-6 HO without change 
in the freezing point. 

This example illustrates the general manner of treatment of systems 
in which molecular species may change through dissociation, association, 
or through the mutual reaction of two or more species. 

A little consideration of the simultaneous use of equations XXIII and 
XXIV with the preceding equations shows why it is that such equations 
as V and VIII hold for the activity of a molecular species such as 
H,0, in a given pure phase, regardless of whether this phase is really 
composed entirely of the species H,0 or in part also of others such as 
(H.0)., (H20);, (H* + OH), etc., provided always that these other 
species can be formed from, and are in equilibrium with, the molecular 
species H,0. 

It may seem, at first sight, that equations XXIII and XXIV, as well 
as the preceding equations, while entirely exact and general in their 
scope, may not be readily applied to certain concrete problems where 
the value of the activity cannot be obtained from existing data. Asa 
matter of fact, however, it is seldom important to know the numerical 
value of the activity in any one state, but rather the ratio between the 
activity of a substance in one state and that in another, and this ratio 
may be obtained in a variety of ways. 

In fact one of the most important problems to which the equations 
derived in this paper may be applied, concerns the dissociation of salts 
in aqueous solutions into their ions, although from the nature of the 
ions we are never able to determine the numerical values of their 
activities. Let us consider the dissociation of such a substance as 
hydrochloric acid in aqueous solution, according to the reaction, 


HC) i Cle, 
According to the ordinary mass law, 


CiCa 


=e 
Cue 


Now this equation has been shown to be false, if we calculate the 
concentration of the ions from conductivity data. In all probability 


288 PROCEEDINGS OF THE AMERICAN ACADEMY. 


this calculation is correct for solutions more dilute than tenth normal,17 
at least we may say that the conductivity data furnish the only means - 
we have at present for calculating the ion cancentrations. Every other 
method which has been employed measures not the concentrations, but the 
activities of the tons. 

According to equation XXIII the activities of the undissociated acid 
and the ions are connected by the equation, 


Enka -- x 


Exci 


If therefore the mass law is false, it must be because the activity is not 
simply proportional to the concentration for one or more of these three 
substances. ‘I'he problem, therefore, is to determine how the activity of 
the undissociated substance and the activity of the ions vary with the 
concentrations of both. It seems that all the facts which are at present 
known concerning electrolytic dissociation can be explained by the 
assumption that the ions are normal in their behavior ; in other words, 
that the activity of each ion is simply proportional to its concentration, | 
but that the undissociated portion of a strong electrolyte is abnormal in 
its behavior, the activity being proportional to the concentration of the 
undissociated substance multiplied by a quantity which depends solely 
on the total ion concentration, and increases with the latter.18 
This simple statement suffices to explain qualitatively all the known 
anomalies of strong electrolytes. ‘The exact quantitative formulation 
of this principle can hardly be made until still more experimental 
work has been done. 
However, these considerations illustrate the method of treating 
chemical equilibrium when the ordinary mass law fails ; in other words, 
when for one or more of the reacting substances the activity is not 
proportional to its concentration. For‘a complete analysis of such a 
case it is necessary to know how the activity of each of the reacting 
substances changes with its concentration and with the concentration 
of the other substances present. 


17 The data upon which this paragraph is based are chiefly those contained 
in the very complete and instructive summary by A. A. Noyes, entitled, “ The 
Physical Properties of Aqueous Salt Solutions in Relation to the Ionic Theory. 
(Technology Quarterly, 17, 293, 1904). 

18 Probably, strictly speaking, the activity of the ions is likewise a functio 
of the concentration of the undissociated substance, decreasing as the latter in 
creases ; but since the concentration of the undissociated substance always is ver} 
small in dilute solutions of strong electrolytes, its influence on the activity of 
ions is therefore of minor importance. . 


LEWIS. — A NEW SYSTEM OF THERMODYNAMIC CHEMISTRY. 289 


Tue RELATION oF Activity To Free ENERGY AND THERMODYNAMIC 
POTENTIAL. 


It is interesting to see what relation the activity bears to certain 
other quantities which have been previously used for a similar purpose, 
especially the free energy of Helmholtz, which is itself intimately 
related to the various thermodynamic potentials. 

The diminution in free energy which accompanies a given isothermal 
process, that is, the maximum work which the process may accomplish, 
is not a definite quantity until we define not only the process but also 
the system which is to be considered. "Ὁ illustrate, we may consider 
-a cylinder containing liquid and vapor, and a piston operated on by 
a spring which exerts a force exactly balancing the vapor pressure. 
When the piston moves out an infinitesimal distance, the decrease in 
free energy of the water and vapor is equal to pdV, but on the other 
hand the free energy of the spring increases by pdV, so that the free 
energy of the system comprising water, vapor, and spring does not 
change. In general we shall depart from the most common usage and 
consider the larger system, and we may therefore define the diminution 
in free energy of a given isothermal process as the maximum work 
which the process is able to accomplish, exclusive of the work done 
against the external pressure or pressures. he negative of this quan- 
tity, the increase in free energy, we shall denote by A¥.19 [ἢ a system 
whose properties are determined when the temperature, the pressure, 
and the compositions of the various phases are fixed, the general 
condition of equilibrium is that, 


dy = 0. 


Let us now consider the change in free energy when one mol of a 
given molecular species passes from one state where its activity is ξ, to 
another state where its activity is ξ΄. This change may be effected as 
follows : (1) Pass one mol reversibly from the first state into an ideal 
solvent. The solution will have the osmotic pressure II and the vol- 
ume v. (2) Change the concentration reversibly until the volume 
becomes v! and the osmotic pressure reaches such a value, I’, that the 


19 The completely general definition of free energy is given by the equation, 
— AF = Wx t PV, +PiVit  - —PoVv,—PoV2.-°:: 
Wmax is the total work obtainable in the process in which system I, comprising 
one portion of volume V, at pressure P,, another of volume Vo, at pressure 12, 
etc., passes over into system II, comprising one portion of volume Vg, at pressure 
P,, another of volume 175, at pressure Τῆς, ete. The free energy as thus defined 


is identical with the thermodynamic potential, ¢, of Gibbs. 
VOL, XLIII.—19 


290 PROCEEDINGS OF THE AMERICAN ACADEMY. 


solution is now in equilibrium with the substance in the second state, 
(3) Let the substance pass reversibly out of the ideal solution into 
the second state. In the first step Δι = — Tv. In the second, 


Aw = RT In > In the third, Διὸ = H’v', Since by equation III 


the activities are proportional to the osmotic pressures in the ideal 
solution, and since Ilv = I'v’, the total increase in free energy is, 


é! 
é 


This is a general equation for the change in free energy in the passage 
of one mol of a given species from one state to another when the species 
itself does not change.2° When we are dealing with the most general 
case of chemical reaction, when @ mols of A, ᾧ mols of B, etc., combine 
to form o mols of O, p mols of P, ete., the total change in free energy 
will obviously be equal to that which accompanies the transfer of the 
factors of the reaction from the original system to another system 
where there is equilibrium, and the transfer of the products from this 
equilibrium system to the original system. By a combination, there 
fore, of equations XXIII and XXV, we find, 

ξοῖ 


wu -- ΠΤ Καὶ XXV 


ξαξὰ 


Δὲ = RT In XXV 


Δὲ = RT In 


Here A¥ is the increase in free energy in any reaction when &,, ἕ 
etc., are the activities of the factors, ἕο: ἕ», ete., those of the products 
and A’ is the equilibrium ratio. 


Evectromotive Force Equations. 


The change of free energy of a reversible galvanic cell is a direc 
measure of the electrical work of the cell. If # is the electromotiv 
force of the cell, and /’ is the Faraday equivalent, then, 


A¥ = — mFE, 


where m is the number of Faraday equivalents which pass through th 
cell during the reaction in question, and in the direction in which th 
electromotive force / tends to send the current. 


20 Tt would have been possible at the beginning to define the activity by meat 
of this equation, and this would have led to a development of our set of equation 
which from a mathematical standpoint would have been simpler than the 0} 
here adopted. 


LEWIS. — A NEW SYSTEM OF THERMODYNAMIC CHEMISTRY. 291 


This value of Δὰ may now be substituted in equations XXV and 
XXVI. The former gives a formula for the electromotive force when 
only one substance takes part in the electrolytic process, as in certain 
concentration cells. The latter gives a general equation for any 
reversible cell whateyer. These are, 


ἣ é mea: 
= “thn ὅ, XXVII 
7 ἐο ἐ 
f= eae ζ-- ἘΠΕ ξος XXVIII 
nk Hs ah tm tae 


In XXVII, m is the number of Faraday equivalents accompanying the 
passage of one mol; in XXVIII, it is the number accompanying the 
disappearance of a mols of A, ὁ mols of B, ete. 

One application of equation XXVII is of special interest. We may 
take it for granted that whenever two phases are in contact and a given 
molecular species is present in one of them, it will be present to some 
extent in the other. For example, if a rod of metallic silver dips into 
a solution of silver nitrate, we may suppose that silver ions are present 
not only in the solution, but also in the metal. The process which 
takes place at this electrode during the passage of a current may 
therefore be regarded as consisting in the passage of silver ions out of 
the electrode into the solution, or vice versa. Equation XXVII gives 
us, therefore, an expression for the single potential difference between an 
electrode and an electrolyte. If the ion in question is an elementary 
one (and monatomic) m is equal to v, the valence of the ion, and we 
may write equation XXVII in the following form, 


2 Ὁ 
τ nH XXIX 
cs 


where # is the single potential difference, £y is the activity of the ion 
in question in the electrode, and ἕς is the activity of the same ion in 
the electrolyte. It is obvious that the quantity €, is very similar 
to the electrolytic solution pressure of Nernst, but while the latter 
depends at a given temperature, not only upon the character of the 
electrode but also upon the nature of the medium in which the elec- 
trolyte is dissolved, ἔμ depends solely upon the character of the elec- 
trode. Moreover, while equation XXIX is universally true, the 
equation of Nernst is obviously only true when the activity of the ion 
in the electrolyte is proportional to its concentration. We have in 
the application of equations XXIX (or XXVII) to the electromotive 


292 PROCEEDINGS OF THE AMERICAN ACADEMY. 


force of concentration cells a remarkably useful means of determining, 
in the case of imperfect solutions, how the activity of a given molecul: 
species varies with the concentration. 


SUMMARY. 


It has been shown that a quantity named the activity, and closely 
related to the fugacity of the preceding paper, may be so defined that 
it serves as an ideal measure of the tendency of a given molecular 
species to escape from the condition in which it is. With the aid o 
this quantity a series of equations has been obtained, which have th 
same form as the approximate equations now in common use, but 
which are perfectly exact and general. ‘The utility of these equations 
has been illustrated by their application to a number of special prob 
lems. From each equation two approximate equations can be immedi- 
ately obtained, one for the vapor pressure of a substance, the other fe 
its solubility. From equations XXIII, and following, important approxi- 
mate equations are obtained by substituting concentrations for activi 
ties. ‘The most general of the equations are collected for reference it 


the following list : 
( OIné\ _ cs 
OP Jr RT 


For a pure substance, 
a Iné c Y — Pv 
(or) = err vu 


For one constituent of a mixture, 
élné μ ΚΣ 
OP την RT 


éln 3 _Y¥- Pr 
OT jan RE 


For all the constituents of a mixture, 


Ne ln& + Ne @In&+ See mt. ‘a 

πα 1: nv RT’ Ὕ 

(Fe Ing, + N.é@ln&+-:-:- _Y—Pv στ 
or pwn kT?’ 


LEWIS. — A NEW SYSTEM OF THERMODYNAMIC CHEMISTRY. 


293 
(- eng + Nb tS ee ) ΞΞΞ XVUI 
OL 1 a Jed 
& ; 
For a perfect dilute solution, 
(== In £, ἼΕ Διοῦ In ἕξ mikes ) se XX* 
oN 1 ΡΤ 


For the most general case of chemical equilibrium at a given 
temperature, 


nso - ΕἸΣ 
== = K (a constant). XXII 


ἴοι °° 
For the change in the equilibrium ratio of any reaction with the 
temperature, 
dink τ 


SS See al (VA 
aE RT? ey 


For the increase in free energy when one mol of a given substance 
‘passes from one state to another, 


él 
Ay = EP In=- XXV 


ς 
For the increase in free energy in any chemical reaction, 
Ag = kT In oi ai — RTWK. XXVI 


For the electromotive force of any reversible cell, 


ΞΟ Le XXVIII 
mk Ol RA 
For the single potential at any electrode, 
οὐ XXIX 
vif &s 


» 
A 
ΝΡ 
ΟΝ 
"ἀῶ 


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4. ΒΕΓ, L.— The Physiological Basis of INumination. pp. 75-96. ΘΕ ἘΠῚ 
δ. ῬΕεῖποε, Β, Ὁ. --- On the Determination of the Magnetic Behavior of the Finely 
an Electromagnet while a Steady Current is being Established in ἐπι Ex 
97-182. September, 1907. $1.20. μὰ 
6. Ssuppemacen, C. L. Β. -- The Demaguetizing Factors for Cylindrical eg ; 
September, 1907. $1.15, ; 
7. Lewis, G. N. — Outlines of a New System of Thermodynamic Chemistry. PP. 
1907. 40c. 
8. Sanoer, C. R., and Buack, O. F. — The Quantitative Determination of ined 
Method. pp. 295-324. 2 pl. October, 1907. 40e. 5 
9. Sanoer, C. R., and Brack, O. F. ~ The Determination of Sey in Urine, 
October, 1907, 25c. ‘ 


- Proceedings of the American Academy of Arts and Sciences. 


ΒΕ τς, 


Vou. XLIII. No. 8. — ΟΟΤΟΒΕΒ, 1907. 


CONTRIBUTIONS FROM THE CHEMICAL LABORATORY 
OF HARVARD COLLEGE. 


ν᾿, ἡ 
weg 
By CHArves RopertT SANGER AND Oris FISHER BLACK. 


LIBRARY 
NEW YORK 


Wirn Two Prartes. BOTANICAL 
GARDEN. 


THE QUANTITATIVE DETERMINATION OF ARSENIC 
BY THE GUTZEIT METHOD. 


By CHARLES ROBERT SANGER AND Otis FisHER BLACK. 


SEVERAL attempts have been made to apply the so-called Gutzeit 
reactions to the quantitative determination of arsenic, especially in 
England since the epidemic in 1900 of arsenical poisoning from beer. 

Kelynack and Kirkby?! suggested that an approximate valuation 
of the amount of arsenic in a sample of beer may be made by compar- 
ing the stain produced on mercuric chloride paper by the arsenical 
hydrogen from a given portion of the sample with that produced by a 
definite quantity of a standard solution of arsenic. 

Bird? made a careful study of the conditions under which the arseni- 
cal stain on mercuric chloride paper may be best obtained and identi- 
fied, with especial reference to the interference of the hydrides of 
sulphur, phosphorus, and antimony. Although his work is extremely 
suggestive of a quantitative application, he himself considers that the 
test is only approximately quantitative, in that the stain obtained from 
a given amount of substance, say beer, may be shown to be greater or 
less than the stain representing a fixed limit of arsenic for that amount. 
He also regards it as a true negative test. 

Treadwell and Comment 8 compared the stain obtained from the 
action of arsine on argentic nitrate paper with a series of stains from 
definite quantities of a standard solution of arsenic. The method, 
applied by these authors to the detection of arsenic in mineral waters, 
is said to have given good results. 

Dowzard, * after describing a modification of the Gutzeit test which 
allows the detection of minute traces of arsenic ina small volume of 
solution, suggested the preparation of a standard set of stains, which 
should be kept in a tightly stoppered bottle in a dark place. 


1 Arsenical Poisoning in Beer Drinkers, p. 88. London, Balliére, Tindall, and 
Cox, 1901. 

2 Analyst, 26, 181 (1901). 

3 Treadwell, Kurzes Lehrbuch der Analytischen Chemie, 2, s. 138 (1902). 

* Chem. News, 86, 3 (1902). 


298 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Thomson5 attempted to make the reaction quantitative by passing 
the arsenical hydrogen through a tube in which was hung a cotton 
thread or a paper, saturated with mercuric chloride solution, which, 
from the intensity of the stain produced upon it, should show the 
amount of arsenic present. ‘Thomson states, however, that his results 
were untrustworthy. 

Goode and Perkin 8 made a series of experiments to ascertain if the 
Gutzeit test could be made quantitative, and if a set of standards could 
be prepared which should be at least as permanent as the standard 
mirrors of the Berzelius-Marsh process. Stains were made as usual 
on paper treated with mercuric chloride, but the impossibility of mak- 
ing them permanent led to their abandonment for quantitative pur- 
poses, except that a given stain might be matched with freshly 
prepared standards. 

Langmuir,” in order to detect the presence of undecomposed arsine 
in the Marsh test, placed in the end of the exit tube a slip of paper 
moistened with a saturated solution of mercuric chloride. It appar- 
ently did not oceur to him that this might also be used quantitatively, 
but he seems to have employed the ordinary color stains successfully 
in the approximate analysis of glycerine for arsenic. 

Aside from the above-quoted authors, there are doubtless many who 
have been able to use the Gutzeit reactions as a means of approximate 
analysis, but we have not met with a careful study of the conditions 
under which the reactions may be employed quantitatively with any 
degree of accuracy. 

The chief difficulty in differentiating between stains caused by vari- 
ous amounts of arsine on either argentic nitrate or mercuric chloride 
paper lies in the fact that the action is partly over the surface and 
partly within the fibre of the paper. Further, a single layer of paper 
is not always sufficient to retain all the arsenic evolved, and stains 
from equal amounts of arsine may not always be of the same density. 
These difficulties disappear almost entirely if one allows the arsenical 
hydrogen to act not against, but along a surface. The principle, there- 
fore, of the modification we suggest in order to make the Gutzeit re- 
actions more accurately quantitative, is to allow the arsine to pass 
over a strip of paper impregnated with mercuric chloride and to com- 
pare the band of color thus obtained with a series of bands prepared 
from known amounts of a standard solution of arsenic. We think that 


® Royal Commission on Arsenical Poisoning, Final Report, 2, 58. London, 
Eyre and Spottiswoode, 1903. 

§ Jour. Soc. Chem. Ind., 25, 507 (1906). 

T Jour. Amer. Chem. Soc., 21, 133 (1899). 


SANGER AND BLACK. — QUANTITATIVE DETERMINATION OF ARSENIC. 299 


4 
the failure of Thomson to get good results was merely due to unsuit- 
able conditions. 

Our experience has not only confirmed the conclusion which has been 
reached by most of those who have investigated the Gutzeit reactions, 
that the use of mercuric chloride is preferable to that of argentic 
nitrate from a qualitative standpoint, but it has also shown that the 
former reagent is the one better suited to the quantitative analysis. 

A careful study of the conditions of the reaction, following the prin- 
ciple stated above and made for the most part without knowledge of 
the work of the above-quoted authors, has shown that the reaction 
can be made the basis of a simple and fairly accurate quantitative 
method with no more than ordinary analytical precautions. 


Tue Metnop. 


Sensitized Mercurie Chloride Paper. For this purpose we used 
at first a smooth filter paper of close texture, but we have recently em- 
ployed to greater advantage a cold pressed drawing paper made by 
Whatman. The latter not only gives better color results, but also, on 
account of its greater strength, withstands better any subsequent treat- 
ment for development or identification of the color. A square meter 
of this paper weighs about 160 grams (4 1-4 ounces per square yard). 
It is cut into strips having a uniform width of 4 mm., and we use for 
this purpose a carefully made brass rule of exactly this width. ‘The 
cutting may be done with a sharp knife, but more accurately and in 
large quantity by the machine which should be accessible at any print- 
ing office. 

The strips, which must be clean and free from dust, are sensitized 
by drawing them repeatedly through a five per cent solution of recrys- 
tallized mercuric chloride until they are thoroughly soaked. They are 
then placed to dry on a horizontal rack of glass rods or tubing, and, 
when dry, are at once cut into short lengths of 7 cm., discarding the 
ends by which the strips were held during the immersion. A bundle 
of these strips is placed in a stoppered tube or bottle containing calcic 
chloride covered by cotton wool, and is kept in the dark until needed. 


The Reduction Apparatus. (See Figure A.) This consists of a 
glass bottle of 30 6.0. capacity, closed by a pure rubber stopper with 
two holes. Through one of these holes passes a small thistle tube, 
about 15 cm. long, reaching to the bottom of the bottle and constricted 
at its lower end to an opening of about 1mm. ‘The other hole carries 
an exit tube bent first at a right angle, then back again in the same 


800 PROCEEDINGS OF THE AMERICAN ACADEMY. 


plane in the form of a C. To this is fastened by means of a rubber 
stopper a short bulb tube about 12 mm. in diameter, terminating in a 
longer tube which has a bore of slightly over 4mm. The bulb of this 
tube (deposition tube) is loosely filled with clean absorbent cotton 
which has been kept over sulphuric acid to insure uniform dryness. 
Instead of the bulb tube, the rubber stopper of the exit tube may 
carry a short piece of glass tubing of about 12 mm. diameter, in which 
is placed the absorbent cotton, and to which, by means of another 
rubber stopper, is attached the deposition tube. 


Ficure A. 


The simplicity and compactness of this apparatus allow a number of _ 
determinations to be carried on at the same time by the use of several 
pieces. It is important, however, that the bottles be of the same size, 
and it is also advisable to have the rest of the apparatus of as nearly 
definite size as possible. 


Reagents. We have used zine and hydrochloric acid in preference 
to zine and sulphuric acid, as the action goes on more regularly and 
without the addition of a sensitizer. The chance for the formation of 
hydrogen sulphide is also less. The zinc, known as Bertha spelter, 15. 
from the New Jersey Zinc Company of New York, and has been proved 
by exhaustive tests to be free from arsenic. It contains not over 0.019 


SANGER AND BLACK. — QUANTITATIVE DETERMINATION OF ARSENIC. 90] 
« 

per cent of lead and not more than 0.013 per cent of iron. The hydro- 
chloric acid is obtained of the Baker and Adamson Company of Easton, 
Pennsylvania, and has been shown by careful analysis to contain not 
over 0.02 milligram of arsenious oxide per liter. The dilution em- 
ployed, one part of acid to six of water, is equivalent to a normality of 
about 1.5. The quantity of diluted acid used in the analysis would 
not contain over 0.00004 mg. of arsenious oxide, an amount beyond 
the practical limit of the delicacy of the method.8 No evidence of 
sulphur, phosphorus, antimony, or arsenic has been obtained from these 
reagents when used in long continued blank tests. 


Procedure. Three grams of carefully and uniformly granulated zinc 
are placed in the bottle, and a strip of sensitized paper is slipped into 
the deposition tube to a definite distance, the paper being wholly within 
the tube. Fifteen cubic centimeters of diluted acid are then added 
through the thistle tube, and the evolution of hydrogen is allowed to 
continue for at least ten minutes. At the end of this time the rate of 
flow of the gas has become as regular as possible, and the atmosphere 
in the deposition tube has a nearly definite degree of saturation with 
aqueous vapor. On these two conditions depends chiefly the uni- 
formity of color bands from equal amounts of arsenic. In this time, 
also, the absence of arsenic in reagents and apparatus is assured, in the 
great majority of cases, by the non-appearance of color on the sensitized 
paper, but the blank test may be as long continued as circumstances 
demand. 

The solution to be tested is then introduced, either wholly or in 
aliquot part, which may be determined by weighing or measuring. In 
the former case we use a side-neck test tube of about 30 6.0. capacity, 
and weigh to the second decimal place. Unless the amount of arsenic 
be exceedingly small, it is not necessary to add the whole of the solu- 
tion, but in that case the volume must be obviously not over 15 c.c., 
on account of the capacity of the bottle. 

After introduction of the solution the color appears upon the paper 
in a few minutes and the deposit reaches its maximum within thirty 
minutes. The band of color thus obtained is then compared with a set 
of standard bands. From the amount of arsenic as estimated from the 
comparison, and the amount of solution from which the band was 
obtained, the calculation of the arsenic in the entire solution is 
simple. 

8 We are also indebted to the Baker and Adamson Company for a preparation 
of hydrochloric acid containing a still smaller quantity of arsenic, the use of 


which will be later explained in the discussion of the absolute delicacy of the 
method. 


902 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Standard Color Bands. A standard solution is made by dissolving 
one gram of re-sublimed arsenious oxide in a small quantity of sodie 
hydroxide free from arsenic, acidifying with sulphuric acid and making 
up to one liter with recently boiled water. Of this solution (1) 10 ce. 
are diluted to a liter with freshly boiled water, giving a solution (II) 
which contains 0.01 mg. or 10 micromilligrams (mmg.) of arsenious 
oxide per cubic centimeter. In testing the delicacy of the method we 
have also prepared solutions containing 1 mmg. (III) and 0.1 mmg. 
(IV) per cubic centimeter. 

From definite portions of solution 11, measured from a burette, a 
series of color bands is made by the above procedure, using a fresh 
charge of zinc and acid for each portion. Figure 1 (Plate 1) shows in 
colors the actual size of the set of bands made by us, corresponding to 
the following amounts of arsenious oxide in micromilligrams: 2, 5, 
10, 15, 20, 25, 30, 35, 40, 50, 60, 70. The color in the lowest values 
is a lemon yellow, shading from this to an orange yellow and through 
orange yellow to reddish brown in the higher values. 


Preservation and Development of the Color Bands. The rapid fading 
of the stains has been a serious obstacle to the use of the Gutzeit re- 
action for a quantitative method, and it became very soon evident to 
us that some means of preserving the color bands must be found before 
the method could be considered an entirely practical one. It was 
clear that the chief factors in the change of color were light and mois- 
ture, the latter being by far the more important. Concerning the 
mechanism of the reactions, either for the formation of the color or for 
its decomposition with water, the work of those who have investigated 
the reactions was not sufficient to guide us. 

The early work of Rose ® on the action of arsine on excess of mer 
curie chloride in solution showed that a yellowish brown precipitate 
was formed having the empirical formula AsHgsCls. ‘This was con- 
sidered by Rose to be made up of mercurous chloride and a compound 
of mereury and arsenic, to which the formula As,Hgs might be given. 

Mayengon and Bergeret 10 consider the compound to be a mixture 
of arsenic and mercurous chloride. 

Franceschi,!! apparently without knowledge of Rose’s work, passed 
arsine through an aqueous solution of mercuric chloride. The liquid 
became at first a light yellow, then red, and: there was precipitated a 
substance at first yellow, but with excess of gas a dark red, “of the 


9 Pogg. Annal., 51, 425 (1840). 
10 Comptes Rendues, 79, 118 (1874). 
11 L’Orosi, 13, 289 (1890). 


SANGER AND BLACK. — QUANTITATIVE BETERMINATION OF ARSENIC. 303 


color of Spanish tobacco.” For this compound Franceschi assumes 
from the analysis and properties the formula AsHHg,Cl., which he 
writes: 
—H 
As — HgCl 
— HegCl 


Lohmann,!? who does not mention the results of Franceschi, finds 
the reaction to run ina similar manner. But the red product decom- 
posed with water, becoming black, and with such rapidity that an 
analysis was impossible except through the decomposition products. 
From this the formula AsHg;Cl; was assigned. Lohmann considers 
that the reaction is always 


8 HeCl, + AsH, = AsHHg,Cl, + 3 HCl, 


whether the precipitation is complete or not, and that the decomposi- 
tion of the product depends () on the presence of mercuric chloride, 
in which case arsenic and mercurous chloride are the products, or (d) 
on absence of mercuric chloride, in which case mercury, arsenious acid, 
and hydrochloric acid are the products. 

Partheil and Amort!* note the formula given by Franceschi, 
AsHHg.Cls, but evidently assume that it was for the yellow body (if 
such indeed exists) and not for the red, which was clearly indicated 
from Franceschi’s paper. On this assumption and from Lohmann’s 
work, they consider that the following is the reaction for the formation 
of the yellow body: 


2 HgCl, ++ AsHs; = AsHH¢g.(Cl, = 2 HCl 
and for the red: 
3 HeCl, + AsH; = AsHe,Cl, + 3 HCl 


These reactions were given by Franceschi and by Lohmann respec- 
tively, but both of these authors were dealing with the red body. 
Partheil and Amort further consider these bodies to have the following 
structure, respectively: 


—H — HgCl 
As — Hg(l and As — Hg(l 
— Hg(Cl — HgCl 


12 Pharm. Zeitung, 36, 748 and 756 (1891) 
13 Ber. d. deutsch. Chem. Gesell., 31, 594 (1898). 


804 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Passing excess of arsine through the solution in which the red body 
is suspended, Partheil and Amort obtain a black precipitate to which 
they give the formula As,Hg;, and this derives support from the re- 
actions with alkyl iodides described by these authors in a succeeding 
paper.* ‘The investigation is given somewhat more fully in a later 
paper by Partheil45 On partial precipitation of a mercuric chloride 
solution by arsine, a yellow body was obtained, to which, from a single 
analysis of an evidently impure substance, the formula AsH,HgCl was 
assigned. From this experiment and from the results of Franceschi 
and of Lohmann, Partheil considers that there should be added to the 
two substances given above a third, with the structure 


While the evidence appears to show that the hydrogen of arsine is 
replaced by the mercurous chloride group to a greater or less extent, 
the formula for the red substance does not seem to us to have been 
conclusively proved, and the reactions of decomposition are decidedly 
in doubt. Nothing has been brought forward to show definitely the 
relation of the yellow compound or compounds, if such exist, to the red. 
Lack of time prevents us at present from studying the reaction quanti- 
tatively, but it is hoped that the investigation may be taken up later by 
one of us. Nevertheless the following qualitative reactions have made 
it possible to treat the bands of color so that they may be kept for a 
considerable time, either in their original form or by means of a quasi 
development and fixation. 

‘he removal of the relatively large excess of mercuric chloride from 
the paper by treatment with absolute ether or alcohol did not offer a 
solution of the difficulty, as the colors faded rapidly even when kept in 
the dark and over sulphuric acid. The color is quickly bleached by 
boiling with water, as is well known. Cold water acts more slowly, the 
color not being completely changed until after a day or two, and then 
not bleached, but converted to a dull gray. Bird,16 and also Goode 
and Perkin,+7 have observed the action of hydrochloric acid upon the 
original color, which is thereby considerably changed. Goode and — 
Perkin also note the action of ammonia upon the original color, but do 
not find the action of service in preparing standards. 

From the evident effect of even a slight amount of moisture we were 


14 Thid., 31, 596 (1898). 16 Archiv. ἃ. Pharm., 237, 121 (1899). 
16 Loc. cit. 17 Loc. cit. 


> 
SANGER AND BLACK. — QUANTITATIVE DETERMINATION OF ARSENIC. 805 


led to adopt the suggestion of Panzer,18 as applied to the standard 
Marsh mirrors, for the preservation of our standards. A clean, dry, 
glass tube, about 5 mm. in diameter, is sealed at one end, at which is 
placed a small quantity of phosphorus pentoxide covered by a bit of 
dry cotton wool. ‘The strip is then inserted, colored end down, fastened 
by a drop of Canada balsam, and the tube is sealed. The set of stand- 
ards prepared in this way can be used for several months, although the 
brilliancy of the color is lost after a few weeks. a 

The color band may be developed by treatment with rather concen- 
trated hydrochloric acid, of a normality of about 6 (one part acid to 
one of water). ‘This is done in a small test tube, at a temperature not 
exceeding 60° and for not over two minutes, else, with this concentration 
of acid, the paper is likely to become disintegrated. ‘The strip is then 
thoroughly washed with running water and dried. The color on the 
wet strip is a brilliant dark red in the higher values, while the smaller 
amounts show a deeper yellow than in the initial set. The length of 
the bands is considerably greater than that of the original. On drying, 
the color becomes duller. ‘These bands must also be sealed as above 
with phosphorus pentoxide, and are somewhat more permanent than 
the initial set. Figure 2 (Plate 1) represents the set obtained by 
development of the initial set with hydrochloric acid. 

If the original color band is treated for a few minutes with normal 
ammonic hydroxide, a dense coal black color is produced, of slightly 
greater length than the original. ‘This color is far more permanent 
than the others, but it is nevertheless necessary to seal the dry strips 
in glass, using fresh, powdered quicklime instead of phosphorus pent- 
oxide. Figure 3 (Plate 2) shows the set obtained by development of 
the initial set with ammonia. 


GENERAL PRECAUTIONS. 


As far as concerns the reduction of the arsenic, no other precautions 
are necessary than those which must be observed in the proper conduct 
of the Berzelius-Marsh method when applied to small amounts. The 
solution to be reduced should contain no interfering organic matter, 
nor any metals which prevent or retard the formation of arsine. Sul- 
phur in any form reducible to hydrogen sulphide should be absent. It 
is well known that small amounts of hydrogen sulphide interfere with 
the Gutzeit reactions, and it is the custom of most analysts to pass the 
arsenical hydrogen over paper or cotton wool containing plumbous 
acetate, or even through a lead solution, before it reaches the mercuric 


18 Zentralbl., 74 (1), 821 (1903). 
VOL, xLi11.— 20 


306 PROCEEDINGS OF THE AMERICAN ACADEMY. 


chloride. As we have been careful to eliminate the sulphur before 
testing, we have not found this necessary, except in certain cases, when, 
with a sufficiently long deposition tube, it is very simple to insert a 
strip of paper saturated with normal plumbous acetate and dried. 
Phosphites and hypophosphites will also have been oxidized before 
introduction of the solution, and there is little danger in ordinary work 
from small amounts of phosphine which might result from the acci- 
dental presence of reducible compounds of phosphorus. Antimony 
should of course be absent, but very small amounts of stibine do not 
interfere with the recognition, though they may prevent the estimation 
of arsenic. Free nitric acid must be avoided. Arseniates require 
especial treatment, as will be discussed below. 


SPECIAL PRECAUTIONS. 


In order to be certain of uniformity in length and color of the bands 
from the same amount of solution, the following points must be 
observed: 

1. ‘The reduction bottles must be of equal capacity and the deposi- 
tion tubes of equal bore. 

2. The amount of zinc must be the same always, and the granulation 
must be uniform. 

3. ‘The volume and concentration of the acid must be definite. 

4. The absorbent cotton must be perfectly clean and reasonably dry, 
and is therefore best stored in a desiccator before use. ‘The amount 
used should be approximately the same in all cases, packed in the bulb 
tube to about the same density. 

5. The sensitized paper must be acted upon by a gas in which the 
moisture is as nearly constant as possible. For this reason the paper 
cannot be allowéd to become moist, nor can the gas be dried. In the 
first case the band is short and imperfectly shaded ; in the second, it is 
scattered along the whole length of the strip, or even partially escapes 
the paper. ‘This we have shown by attaching a hard glass tube with 
capillary, in which, on heating, a mirror of arsenic was obtained. Con- 
versely, under carefully regulated conditions, no evidence of escaping 
arsenic was found, either by the use of a hot tube or by the introduc- 
tion of a second strip of sensitized paper. 

6. After ten or twelve runs with the same bottle, the atmosphere of 
the deposition tube becomes too moist, and the bands are consequently 
too short. It is then necessary to replace the cotton. In order to 
get a sufficient degree of saturation in the next run, the evolution of © 
hydrogen must go on for a longer time than usual before adding the — 


> 
SANGER AND BLACK. — QUANTITATIVE DETERMINATION OF ARSENIC. 907 


test solution, say for an hour. This preliminary saturation may be 
also conveniently secured by leaving zine and acid in the apparatus 
over night. 

By observation of the above precautions we have obtained fairly 
regular and uniform bands of color from equal amounts of arsenic, — 


TABLE I. 


Total Weight 

τὰ ae Diluted 

No. of Weight Solution 
Analysis. Diluted 


5 taken for 
Solution. Analysis. 


As,0, ae 


Reading of 
AE found. ἢ 


found. 


grm. 
21.21 


24.13 


9 
vo 
‘ 


9 
6 


i pe 
as 


[or] 


OS SS OS SSS 
ω μῶν ὧϑ 
mo 


Average percentage 


using apparatus of definite size, reagents of definite concentration, care- 
fully sensitized paper, and by passing the arsenical gas over the paper 
in a condition of moisture which is as carefully regulated as possible. 
Without these precautions, which involve no great care, the method 
will not give satisfactory quantitative results. 


208 PROCEEDINGS OF THE AMERICAN ACADEMY. 


ANALYTICAL Data. 


"he method, as far as it concerns the determination of arsenic in a 
solution properly prepared for reduction, was tested by the analyses 
of solutions containing varying amounts of arsenic, which, with the ex- 
ception of Nos. 5, 8,7, and 9, were unknown to the analyst (see Table I). 
In analysis No. 9 the arsenic was present as arsenic acid. In Nos. 5, 8, 
7, and 9, the comparison was made with standards which had been kept 
over three months, and the reading of the bands was confirmed by the 
standards obtained by development of the initial bands with ammonia. 

We do not claim for the method, under ordinary circumstances, a 
greater accuracy than from five to ten per cent. 


AwatyticaL Notes. 


Sensitized Paper. We have found that the prepared paper, if kept 
dry and away from the light, does not lose its sensitiveness to a great 
extent after several months. On long keeping there is apparently a 
very slight reduction to mercurous chloride, since an old paper after 
treatment with hydrochloric acid and washing gives a slight darkening 
with ammonia or auric chloride (for this test, see below). Although 
this change does not greatly influence the result, it is better not to use 
paper which has been kept too long. 

Contrary to Goode and Perkin,1® we have found no advantage in 
using mercuric bromide instead of the chloride. Neither the aqueous 
solution of the former, which is, in addition, too dilute, nor the alco- — 
holic solution, gives a paper of greater sensitiveness than that prepared 
from the chloride. ‘The alcoholic solution of the chloride, since it 
evaporates more rapidly, leaves a less even surface of the salt upon — 
the paper than is obtained by the slower evaporation of the aqueous 
solution. 


Apparatus. Tn ease it is necessary to examine larger quantities of 
solution for arsenic, a larger reduction bottle will naturally suggest 
itself. In this ease, slight variations from the procedure may be found 
necessary, and the absolute delicacy of the method may be some- 
what less. 

We have found no sign of arsenical contamination from the rubber 
stoppers used in the apparatus, and we have therefore not lessened the 
simplicity of the apparatus by making it entirely of glass. ‘The βίορ- 
pers are boiled with dilute alkali and washed before use. 


19 Loc. cit. 


rt 


.« 
SANGER AND BLACK. — QUANTITATIVE DETERMINATION OF ARSENIC. 309 


Although we have not tried it for ourselves, it would seem obvious 
that the electrolytic reduction of the solution could be employed if 
desired. 


Reagents. From the delicacy of the method, as discussed below, the 
zine used by us is evidently highly sensitive. Indeed, the amount of 
iron present, to which metal, from the work of Chapman and Law,?° 
Parsons and Stewart, 21 and others, may be attributed the insensitive- 
ness of most samples of zinc, is about one-seventh of the amount in a 
zinc which Chapman and Law show to be sufficiently sensitive in the 
Marsh process. 

We have also in this connection studied the effect of the presence 
of other metals on the sensitiveness of the zinc. The retention of 
arsenic by the addition of platinic chloride or cupric sulphate, con- 
firmed by one of us 2? (S) several years ago, is well known. With a 
bright platinum foil in contact with our zine and using either sulphuric 
or hydrochloric acid, we have never noticed any loss of arsenic in the 
Marsh procedure. Similarly, there is no diminution in the delicacy of 
our method when platinum foil is used. The use of zine carefully 
covered with copper after the procedure of Lockemann 2? makes no 
difference whatever in the results, nor does the addition of tin or lead 
salts to the solution during the reduction. 

The zine is granulated by pouring the metal, melted in a porcelain 
casserole, from a height of six feet through a hot porcelain sieve into 
two feet of cold water. 

The estimation of the arsenic in the hydrochloric acid was made on 
samples of 100 c.c. in two ways. The acid was distilled to half its 
volume, a treatment which we have shown in the following paper 35 to be 
sufficient to expel all the arsenic. The distillate was collected in 
35 6.0. nitric acid and evaporated with a small amount of sulphuric 
acid. Again, the acid was allowed to drop slowly into hot nitric acid 
and the mixture was then evaporated. Several residues obtained by 
both of these procedures from lots of 100 6.0. gave closely agreeing re- 
sults, both from the reading of the Marsh mirrors and the Gutzeit 
color bands. The mean of all determinations was 0.002 mg. for 100 
¢.c., or 0.02 mg. per liter. 


20 Analyst, 31, 3 (1906). 

21 Jour. Amer. Chem. Soc., 24, 1005 (1902). 

22 These Proceedings, 26, 24 (1891) ; Amer. Chem. Jour., 13, 431 (1891). 

23 Zeitschr. f. angew. Chem., 18, 416 (1905). 

24 These Proceedings, 43, 327 (1907); Jour. Soc. Chem. Ind., Vol. 26 (1907) ; 
Zeitschr. f. anorg. Chem., Vol. 56 (1907). 


510 PROCEEDINGS OF THE AMERICAN ACADEMY. 


This acid was shipped in carboy, and we have not observed any in- 
erease of arsenic in the acid on standing, such as might result from 
the action upon the glass if the latter contained arsenic. It is better, 
however, that such acid should be shipped, or at least stored, whether 
concentrated or dilute, in ceresine bottles. 

We have noticed that the nitric acid from the carboy, which gave no 
test for arsenic, took up traces from the storage bottle on long stand- 
ing. We have therefore stored the nitric acid in ceresine. A slight 
but unimportant amount of paraffine is taken up. 50 6.6. lots of this 
acid, evaporated with a small quantity of sulphuric acid, gave residues 
which showed no traces of arsenic. It must be borne in mind that a 
nitric acid residue contains the arsenic as arsenic acid and that the 
procedure must accordingly be modified as explained below. 

The second sample of hydrochloric acid, referred to in the footnote 
above, was shipped in ceresine, and the diluted acid is also kept in 
ceresine. ‘I'wo 100 ο.6. lots of this acid were dropped into nitric acid 
and evaporated with sulphuric acid. ‘The residues were reduced with 
sulphurous acid free from arsenic and gave color bands equal to 0.3 
and 0.5 mmg. arsenious oxide respectively. This is equivalent to 0.004 
mg. of arsenious oxide per liter. 


Procedure. At the end of a run, a slight annular sublimate is often 
observed on the inside of the deposition tube where the color band is 
in contact with the glass. With very small amounts of arsenic this 
sublimate is white, but is ordinarily slightly colored. It is probably 
due to transference of mercuric chloride, either through velatilization 
or capillary action, and a slight color reaction may take place on the 
deposit. ‘The amount is without influence on the result, but the tube 
should be cleaned with a bit of dry cotton before being used again. 

‘he temperature during reduction should not be allowed to rise 
very much, as the moisture equilibrium in the deposition tube is 
disturbed from the excess of moisture carried over. For this reason 
the procedure of Bird,2° which consists in heating the liquid under 
reduction to the boiling point, is not adapted to this method. 

We have found no advantage in using very large amounts of zine, 
as recommended by many, especially in the Marsh process, nor do we 
think it necessary that the zine should be entirely dissolved. 


Standard Bands. We have long noticed that solutions of the dilu- 
tion of 0.01 mg. per cubic centimeter undergo a change on standing, 


-«-.-.--. a 


25 Loc. cit. 


.»»-.-.-...-..-..-.-..--. θ“-Ὁο--ς-ς-.- - 


a 
SANGER AND BLACK. — QUANTITATIVE DETERMINATION OF ARSENIC. 811 


with the result that a given volume will not yield the same depth of 
band as when first prepared, or, in the Marsh process, the same inten- 
sity of mirror. In more dilute solutions the change is very rapid, and 
solution IV, containing 0.1 mmg. per cubic centimeter, is of no value as 
a standard in a day or two. The use of boiled water for dilution 
greatly retards the change, which would lead to the conjecture that 
the reaction might be one of oxidation, with formation of arsenic acid, 
which, as shown below, does not give the same depth of color in a given 
time as its equivalent of arsenious acid. Yet the treatment of an old 
solution with sulphurous acid does not increase the amount of arsenic 
from a given portion of it, as far as we have been able to determine. 
Solution IV (0.1 mmg.) should be freshly prepared before use; solu- 
tion II (10 mmg.) will hold its strength for a few weeks, and solution I 
(1 mg.) should not be used if it has stood for a very long time. 

The deposit of color is of course on both sides of the paper. If the 
strip exactly bisects the tube and the flow of hydrogen is the same in 
both segments, the intensity of color should be the same on each side 
of the strip. It often happens that there is a slight difference, and in 
consequence the band may appear on one side greater than the stand- 
ard, on the other less. ‘The set of standards is also a series of mean, 
though not greatly varying color densities, and when viewed from one 
side or the other may not seem regularly graded. The set should be 
mounted in such a way that both sides of the strip can be examined, 
and the mean density of the test band should be compared with the 
mean density of the standard. ‘The judgment is greatly assisted by 
treating the band or its duplicate with hydrochloric acid or ammonic 
hydroxide (particularly the latter), and comparing the result with the 
corresponding standards. 


Treatment of the Bands. Whatever may be the formula of the red 
compound, it is probable that the reaction is only complete in the 
presence of an excess of hydrochloric acid. As previously mentioned, 
the color fades completely on treatment with hot water. Cold water 
brings about a gradual fading, but this is succeeded by a secondary 
reaction by which a gray substance is formed. This action of water 
was further studied by treatment with sodic acetate. A set of stand- 
ard bands was immersed in half-normal sodic acetate for two hours in 
the cold. The red color gave place to a uniformly graded light yellow 
with a tinge of orange. The set, after pressing between filter paper, 
was then sealed while still moist. In twenty-four hours the yellow 
had changed to a dull white, with no color except in the higher values. 


$12 PROCEEDINGS OF THE AMERICAN ACADEMY. 


On the next day there was a change to a faint gray, becoming darker 
on further standing. 

The black color with ammonie hydroxide suggests the presence of 
mercurous chloride, but it is not clear whether a decomposition into 
mercurous chloride takes place before the black color is formed. If — 
the red band is treated with hydrochloric acid, washed, and then 
placed in ammonic hydroxide, the color is not an intense black, but 
rather grayish in tone. 

Another reaction of interest is that with auric chloride. If the 
band, after treatment with hydrochloric acid, is placed in a small test 
tube with a few drops of hundredth normal auric chloride and allowed 
to stand for five or ten minutes, a beautiful purple color results. The 
reaction is characteristic for larger amounts of arsenic. 

The reaction of the formation, development, and decomposition of 
the color bands are susceptible of various interpretations, but, as we 
have said before, a quantitative study is necessary before expressing 
an opinion, not only as to the formula of the red body and the mech- 
anism of its formation and decomposition, but also on the existence 
of intermediate yellow compounds or their formulae. 

Bird 28 has applied Bettendorff’s reaction to the stains, substantially 
as follows: The disk of paper containing the color is extracted with 
one or two cubic centimeters of warm, concentrated hydrochloric acid. 
The extract is oxidized by a few drops of bromine in hydrochloric acid 
and treated in a small test tube with an equal volume of 30 per cent 
stannous chloride. On warming, the pinkish brown color appears. 


INTERFERENCE OF THE Hypripgs oF SuLpHUR, PHospHorvs, 
AND ANTIMONY. 


There is considerable confusion in the statements of various authors 
as to the color stains from these gases on mercuric chloride paper, and 
even Bird’s more careful study is open to the common criticism that 
the descriptions are not given with reference to known amounts of the 
hydrides, In determining to what extent these substances interfere 
in our method, we have at first ascertained by trial how much of the 
particular hydride will give a comparable band on the mercuric chlo-— 
ride paper under the same conditions, — particularly in the same time. 
We then studied the effect of a given treatment upon each color band, 
and afterward compared the effect of each reagent upon the four ap- 
proximately equivalent bands. 


26 Loc. cit, 


* 


SANGER AND BLACK. — QUANTITATIVE DETERMINATION OF ARSENIC. 313 


Hydrogen Sulphide. In a freshly prepared solution of sulphurous 
acid, which gave no test for arsenic, the amount of sulphur was deter- 
mined by titration with iodine. A solution was made containing 
1 mg. of sulphur per cubic centimeter, and from this, in turn, a second 
containing 0.01 mg. Of this solution amounts corresponding to 10, 
30, 50, and 70 mmg. sulphur were added to separate reduction bottles 
and the action continued for thirty minutes. Bands of a pale yellow 
were obtained, slightly darker in shade than those from phosphine. 
The respective lengths corresponded to those from:2, 25, 30, and 
40 mmg. arsenious oxide. Fresh strips of paper were now substituted 
and each experiment was continued for thirty minutes longer. No 
additional band was obtained from the first ; from the others the 
values were approximately 1, 5,and 10 mmg. ‘This shows that under 
the same conditions and in equal time the band from 50 mmg. sulphur 
will be of about the same length as that from 30 mmg. of arsenious 
oxide, and further, that the reduction cf the sulphurous acid is not com- 
pleted in thirty minutes, like the arsenic, but requires a longer time. 

The color of the sulphur band is somewhat brightened by hydro- 
chloric acid (6 N) but not essentially changed, nor was the length 
increased. Auric chloride produced a dirty light brown. Ammonia 
on the original band gave also a light brown color. 


Phosphine. A sample of sodic hypophosphite, containing no arsenic 
on testing, was shown by analysis to contain 28.94 per cent of oxidiz- 
able phosphorus (theory, 29.23). Of this a solution was made contain- 
ing 1 mg. of phosphorus per cubic centimeter, from which two others 
were prepared having 0.1 and 0.01 mg. to the cubic centimeter. Of 
the last solution, 10, 30, 50, and 70mmg. were reduced for thirty min- 
utes in separate bottles. From 10 mmg. no color was obtained, from 
30 mmg. a very faint indication, and from 50 and 70 mmg. bands cor- 
responding in length to only about 2 and 10 mmg. of arsenious oxide 
respectively. After continuing the action for thirty minutes longer, 
with fresh strips, there was again no color on the first, a faint indication 
on the second, and about 1 and 10 mmg. on the third and fourth. It 
was evident that the reduction was very slow. Next were taken 100, 
300, and 500 mmg. After thirty minutes the length of the first band 
corresponded to about 2 mmg. of arsenious oxide, the second 30, and 
the third 50, showing that not over one tenth of the phosphorus had 
been reduced in the given time. On opening the bottles the odor of 
phosphine was strong. 

To obtain a band from the hypophosphite equal to that from 
30 mmg. arsenious oxide in the standard time, an amount equivalent 


814 PROCEEDINGS OF THE AMERICAN ACADEMY. 


to 200 or 300 mmg. phosphorus is necessary. The color of the bands 
was a bright yellow, somewhat resembling that from hydrogen sul- 
phide. Hydrochloric acid makes the band a bright lemon yellow, but 
without increasing its length. ‘The yellow turns slowly brown when 
exposed to light. Auric chloride acts very slowly, giving at first a 
characteristic brownish red, which changes to purple. Ammonia acts 
more slowly than on the arsenic band, giving a less intense black. 


Stibine. Thessolutions used were made from a sample of pure tar- 
tar emetic, which had been shown to be free from arsenic. ‘They con- 
tained respectively 1.0, 0.1, and 0.01 mg. of antimonious oxide per 
cubie centimeter. Volumes corresponding to 10, 30, 50, and 70 mmg. 
of the oxide were added to separate bottles and the reduction carried 
on for thirty minutes. No color was obtained in any case. Hydrochlo- 
ric acid did not develope. Auric chloride brought out slowly a purple 
color, duller finally than that of a similarly treated arsenic band. Am- 
monia turned the band quite quickly black, and a comparison with the 
arsenic ammonia standards showed amounts equal to about 20 to 40 
per cent of the arsenic values. On further reduction for thirty minutes, 
with fresh strips, there was no additional deposit on the paper which 
could be developed by ammonia. Continuing the experiments, it was 
found necessary to add 100 mmg. of antimonious oxide before any vis- 
ible band was obtained, and 200 mmg. before the band appeared to be 
of the same length as that from 30 mmg. of arsenious oxide. The color 
was a faint gray when first visible ; darker with increasing amounts. 
The development with hydrochloric acid and auric chloride or with 
ammonia showed of course that the paper had been originally affected 
over a much greater length than was then visible. 

These results agree with those obtained by Franceschi,27 who - 
found by the action of stibine on mercuric chloride a white body to 
which he gave the formula SbHH¢g,Cl., analogous to the formula as- 
signed by him to the red arsenic compound. Dowzard,?® also, was 
unable to obtain a stain on mercuric chloride paper from 0.01 to 
0.1 mg. of tartar emetic, while from 0.2 mg. he got a faint black- 
ish brown color, a result which is essentially confirmed by our 
experiments. 


Comparative Eject of Reagents. From the necessary amounts of 
each substance, as shown by the above trials, approximately equal 
color bands were prepared from arsine, stibine, phosphine, and hydro- 


37 L’Orosi, 13, 397 (1890), 28 Jour. Chem. Soc., 79, 715 (1901). 


* 


SANGER AND BLACK. — QUANTITATIVE DETERMINATION OF ARSENIC. 315 


gen sulphide, with a reduction of thirty minutes’ duration. Each set of 
four was then treated with various reagents and the effects compared. 

Initial Band. The arsenic band appears in a few minutes and is 
nearly complete before the others begin to form. The deposit is char- 
acteristic and unmistakable. ‘The phosphorus and sulphur bands are 
a uniform pale yellow, rather difficult to distinguish from each other. 
The antimony band 15 a faint gray. 

Exposure to Air. Qn standing over night in rather moist, warm 
air, the arsenic band was slightly bleached, the others unchanged. On 
longer exposure the phosphorus band was turned slightly brown on 
the upper side, and the sulphur band became slightly dark on the 
upper edge. Heating to 105° had no additional effect on any of the 
bands. 

Cold Water. The initial set was placed in cold water. After fifteen 
minutes the antimony band was bleached completely, the phosphorus 
became paler, while the arsenic and sulphur were unchanged. After 
fourteen hours the arsenic was considerably bleached, but was still orange 
red, while the phosphorus had become a very faint yellow and the sul- 
phur was unchanged. 

Hot Water. ‘The set was boiled with water for one minute. The 
arsenic and antimony bands were changed to a grayish white, the 
phosphorus was bleached to a faint yellow, while the sulphur was 
unchanged. On standing, the sulphur band became light brown. 

Hydrochloric Acid. ‘The set was warmed to 60° with hydrochloric 
acid (6 N) for one minute and thoroughly washed. The arsenic band 
was lengthened and became the usual brilliant red. The antimony 
was turned slightly gray. The phosphorus became a brilliant lemon 
yellow, and the sulphur was also brightened, but not so strikingly. 
On drying, the colors became duller, and on the upper end of the 
sulphur band was a fringe of dark gray. 

Auric Chloride. The dried sct from the last treatment was im- 
mersed in auric chloride (n/100) for five minutes. The arsenic band 
became at once a brilliant purple ; the antimony changed more slowly. 
The phosphorus slowly turned a characteristic red brown, then to pur- 
ple, and the final colors of these three bands differed chiefly in inten- 
sity. The sulphur band had only a slight brownish tinge. 

Ammonia. ‘The set was placed in normal ammonic hydroxide for 
five minutes. ‘The arsenic band became at once a brilliant black ; the 
antimony also quickly, but the band was longer and duller in shade. 
The phosphorus turned slowly black and was not equal finally to the 
other two in intensity. The sulphur band was not blackened, but 
changed slightly to a pale brown, somewhat darker on drying. 


316 PROCEEDINGS OF THE AMERICAN ACADEMY. 


From these results it will be seen that if we have a color band from 
pure material, within or above the range of the 4 mm. arsenic stand- 
ards, the differentiation of arsenic from antimony, phosphorus, and 
sulphur is perfectly simple. With smaller amounts, or especially with 
mere traces, there can be no confusion with antimony, since stibine 
gives no yellow color on the paper. With sulphur, while the small 
initial band might be mistaken for arsenic, the treatment with hot 
water, ammonia, and auric chloride will easily identify it. But with 
phosphorus there is likely to be a doubt if the 2 mm. band 29 is very 
small, since the amount and length of the color do not permit the 
same comparison as in the larger bands. As we have shown, however, 
that even as much as 0.1 mg. of phosphorus gives very little color in 
thirty minutes of reduction, and as this is a quantity which can be easily 
oxidized in the preparation of the solution for analysis, we should have 
little to fear from smaller amounts than 0.1 mg. Such amounts might 
be considered quite accidental. 


Effect of Hydrogen Sulphide, Phosphine, or Stibine on the Arsenic 
Band. Very different is it, however, when the arsenic solution also 
gives by reduction as much of any one of these gases as would alone 
yield a band equal to the arsenic band in length. 'This is shown by the 
following experiments. 

Hydrogen Sulphide. Amounts of the respective solutions, equal to 
30 mmg. of arsenious oxide and 50 mmg. of sulphur, were added to- 
gether to a bottle and reduced for thirty minutes. Instead of the sbort, 
well-defined band of the arsenic, a band nearly three quarters of the 
length of the strip was formed, of a reddish yellow color. Hydrochlo- 
ric acid turned it slightly redder, but the appearance was not definitely 
characteristic of arsenic. On another similar band ammonia brought 
out splotches of black on a red ground. ‘The arsenic had evidently 
acted as an accelerator in the reduction of the sulphurous acid, and the 
resulting band was due to a mixture of the arsenic and sulphur com- 
pounds, spread over a greater surface. 

Phosphine. Solutions containing 30 mmg. arsenious oxide and 
200 mmg. phosphorus were added to a bottle and reduced for thirty 
minutes. ‘The band was longer than the corresponding band of ar- 
senic, but with the characteristic appearance of the latter, — well 
shaded, except that it was somewhat lighter at the top. Hydrochloric 
acid converted the color to the well-marked red of arsenic and the 
length agreed with the hydrochloric acid standard for 30 mmg. Αὐτὶο 


29 For the use of the 2 mm. band, see below. 


SANGER AND BLACK. — QUANTITATIVE DETERMINATION OF ARSENIC. 317 


chloride acted more slowly than with arsenic alone, giving a slight 
brownish red at first and finally a somewhat lighter purple than the 
pure arsenic color. There was apparently little increase in evolution 
of phosphine in the presence of the arsenic, and the arsenic compound 
in the mixed band was not appreciably obscured. 

Stibine. Solutions containing 30 mmg. arsenious oxide and 70 mmg. 
antimonious oxide were reduced together for thirty minutes. The re- 
sulting band was pale red in color and over twice as long as the band 
from 30 mmg. of arsenious oxide. Hydrochloric acid gave a color not 
essentially different, which faded on drying to a rather dirty brownish 
red. ‘he evolution of the two hydrides was apparently more rapid 
than either alone, and the mixed band was longer than from either 
amount. 


It is evident from the above results that if we have with the arsenic 
an amount of hydrogen sulphide even below that required to give a 
band of the same length as the arsenic, the latter will be so altered as 
to make its quantitative estimation impossible and its detection doubt- 
ful. But, as unavoidable amounts of hydrogen sulphide would be held 
back completely by lead acetate paper, we should have no difficulty in 
estimating the arsenic if the solution had not been properly oxidized 
before testing. Even if the solution contains considerable reducible 
sulphur, the lead acetate paper will protect the mercuric chloride 
strip. 

We have also little to fear from phosphine, since we should not put 
a solution into the reduction bottle until the phosphorus had been 
oxidized as completely as possible. Accidental amounts of phosphine 
would not affect the quantitative estimation of the arsenic. We have 
not thought it necessary, for this reason, to verify the statement of 
Dowzard °° that phosphine is held back by cuprous chloride in hydro- 
chlorie acid solution, nor have we sought any other reagent which 
could be adapted to this purpose under the conditions of our method. 

In the presence of stibine arsenic may be qualitatively recognized, 
but not quantitatively determined, when the amount of antimony is 
enough to give, if alone, an ammonia band equal to that of the arsenic. 
But we should not test a solution without getting rid of any antimony 
it might contain, and the methods for that purpose are satisfactory. 
Slight traces of antimony would not affect the determination. 

If the arsenic is accompanied by any two or all three of the sub- 
stances in question, cases which we think would seldom arise, their in- 


30 Loc. cit. 


818 PROCEEDINGS OF THE AMERICAN ACADEMY. 


fluence on the determination of the arsenie could be predicated from 
the foregoing investigation. 

ΤῸ sum up, then, we think that small amounts of arsenic can be 
determined by our method without danger of interference from sul- 
phur, phosphorus, and antimony, provided the solution to be tested is 
freed as carefully as possible from these substances and the additional 
precaution is taken to place a strip of lead acetate paper in front of 
the test paper. 

From the comparative rarity of the hydrides of selenium and tellu- 
rium and the unlikelihood of their occurrence in ordinary practice, we 
have made no study of their action on mercuric chloride paper. One 
would suppose from analogy, also, that the reactions in small amount 
would be similar to that of hydrogen sulphide. We note in this con- 
nection that Rosenheim * states that hydrogen selenide has no influ- 
ence on the Gutzeit test, unless in large quantity, if lead acetate paper 
is used. 

The results of the above experiments are tabulated for comparison 
as follows : 

TABLE II. 


Reactions or Coton BANDS WITHIN THE RANGE OF THE ARSENIC STANDARDS 


rroM APPROXIMATELY EQUIVALENT AMOUNTS OF ARSINE, STIBINE, PHOSPHINE, 
AND HyproGEN SULPHIDE. 


Amounts | 


Element. taken for 
Reduction. 


Initial | Action of | 
Band. | Air. 


80 mmg. Orange Slightly Consid- |Grayish 
(AsoQOs). yellow faded jerably |white red 
Ig red bleached 
Sb 200 mmg. Faint Un- Bleached Grayish |Grayish 
(ΞΡ, 4). |gray |changed white 


»- 200 mmg.' Pale |Pale Consid- (Faint Bright 
| (P). yellow |brown jerably |yellow. |lemon 
where  |bleached yellow 
exposed 
to light 


50mmg. Dull | Un- Un- Un-_ |Brighter|/Slightly Pale 
(5). yellow changed changed |changed.|yellow |brown |brown. 
On stand- 


ing, light 
brown. 


31 Chem. News, 83, 277 (1901). 


i 
i 
) 
i 


: 


SANGER AND BLACK. — QUANTITATIVE DETERMINATION OF ARSENIC. 319 


THe PROCEDURE IN PRESENCE OF ARSENIATES. 


It is well known that the reduction of an arseniate solution to arsine 
goes on more slowly than that of an arsenite. his is provided for in 
the Marsh procedure by continuing the reduction for a longer time when 
arsenic acid is present; fully an hour, or, if small amounts are present, 
still longer. The deposition of the mirror being in a comparatively 
small compass, its size and appearance are not appreciably changed, 
within the range of the standards, by the slower accumulation of the 
arsenic particles. In the Gutzeit procedure the case is different for 
two reasons. ‘I'he formation of the color bands is over a greater sur- 
face and the standard set is based on the deposition of the color in a 
short time, which, in turn, depends upon a comparatively- quick reduc- 
tion of the arsenious acid. Not only will some arsenic escape reduction 
during this time, if arsenic acid is present, but the slower congregation 
of the particles will result in a shorter band. Hence, from a given 
amount of arsenic as arseniate, the reading of the color after thirty min- 
utes is invariably low. ‘The subsequent reduction may be studied frac- 
tionally for sixty to ninety minutes, with successive strips, although the 
colors from the last fractions may only be shown by the 2 mm. strips (see 
below). ‘The proportion of color within thirty minutes has been shown 
by us from repeated trials to be reasonably definite. It is rarely over 
50 per cent of the standards, rarely under 40 per cent, and the bands 
formed are somewhat denser in appearance. ‘This implies that the band 
from an arseniate, though shorter, contains more arsenical substance 
than a band of the same length from an equivalent amount of arsenite, 
and this is borne out by the fact that the subsequent color estimations 
from the continued reduction do not apparently carry the total per- 
centage of arsenic to more than 80. 

There are two ways of approximately estimating the value of the 
color bands derived from arseniates. We may either make a series of 
standards from known amounts of arsenic as arsenic acid, with which 
the test band from an arseniate may be compared, or we may multiply 
the reading of the ordinary standards by 2 or 2.5. Either of these 
alternatives will answer, more simply the latter, —though both are 
obviously inexact, — if one’s object is only to get a rough idea of the 
amount of arsenic present. ‘The estimation can be made, however, 
within the ordinary limits of the method, if the arseniate is converted 
to arsenite before reduction to arsine. 

Before arriving at the procedure finally adopted, we studied the 
effect on the reduction of an increase of temperature and also that of 
various catalyzers. A solution containing 10 mmg. of arsenious oxide 


320 PROCEEDINGS OF THE AMERICAN ACADEMY. 


as arsenic acid was prepared by evaporating 10 c.c. of solution I repeat- 
edly with nitric acid and making up to one liter. The bottles were 
heated during the reduction in an air bath in such a way that all above 
the necks protruded. At 60° the bands obtained from 38 c.c. of the 
arseniate solution after thirty minutes of reduction were only about 43 
per cent of the standard for 30 mmg. of arsenious oxide. Parallel trials 
with 8 ¢.c. of the arsenite solution gave bands of the standard length. 
Another experiment at 90° gave no better results. he bands from 
the arseniate solution were not over 50 per cent of the standard, while 
the parallel arsenite reductions gave shorter bands than at ordinary 
temperature, owing to the larger amount of moisture carried over. 
That a reduction at the boiling point would cause a practically com- 
plete conversion to arsine, as claimed by Bird, seems improbable, while 
the moisture equilibrium would be so disturbed as to invalidate the 
procedure. 

Returning to the reduction at ordinary temperature, it was found 
that no increased effect was produced within the standard time by the 
addition of stannous chloride or potassic iodide. Platinum in contact 
with the zinc, even when the acid was more concentrated, was of no 
service, and the use of copper-covered zinc did not help. An appre- 
ciable increase but not a complete reduction was effected by sesquisul- 
phate of titanium. It was evident that the use of a catalytic agent did 
not solve the problem with such small amounts of’arsenic, and we 
were therefore forced to a reduction of the arseniate to arsenite before 
testing. For this purpose we found sulphurous acid the simplest 
substance, since comparatively little is needed, no excess of reagent 
need be left in solution, and it can easily be prepared free from 
arsenic. 

The sulphurous acid solution was made from pure copper and pure 
sulphuric acid, and was saturated at 0°. The solution gave no test for 
arsenic when tested in quantities larger than would be used in an 
analysis. ‘I'he tests were made after boiling out the sulphur dioxide 
from the samples. 

We tested the efficacy of the sulphurous acid as follows : Four por- 
tions of the arsenic acid solution, corresponding to 10, 20, 30, and 40 
mmg. of arsenious oxide, were evaporated in small glass dishes with 
6 c.c. of the sulphurous acid until the excess of sulphur dioxide was 
apparently expelled. On adding the residues to the reduction bottles, 
the color bands came up quickly 8 as in the case of arsenites, and in thirty 
minutes all the bands were equal to the corresponding standards in 
length and intensity of color. Subsequent trials conducted similarly 
confirmed these results. The precaution was taken to use the lead 


—————— 


SANGER AND BLACK. — QUANTITATIVE DETERMINATION OF ARSENIC. 321 


acetate paper, on which in some cases there was a slight deposit of the 
sulphide. 32 

In practice, when the solution contains an arseniate, or when the 
substance has been oxidized, say by nitric acid, one may add a suffi- 
cient quantity of sulphurous acid to the entire solution or to the ali- 
quot portion taken for reduction. In analysis No. 9, Table I, we 
followed the latter plan, adding 10 6.0. of sulphurous acid in two parts, 
the second after partial evaporation. ‘The excess of sulphur dioxide 
is then expelled, but the evaporation must not be carried too far, as 
chlorides, if present, would cause a loss of arsenic. In testing the 
residues the lead acetate paper should be used. 


Tue Apsotute Deticacy oF THE METHOD. 


For most practical purposes the set of standards from 2 to 70 mmg. 
is sufficient. Amounts of arsenic between 2.0 and 0.5 mmg. can be ap- 
proximated by the 4 mm. strip, but in studying the limit of delicacy 
we have allowed the action to take place within a smaller compass. 
The ordinary strip is cut in two, and these pieces are again divided 
lengthwise, giving a piece 2 mm. wide and 35 mm. long. ‘This is in- 
serted in a tube of slightly more than 2 mm. in diameter, which is 
fitted into the usual deposition tube by a washer of rubber tubing. 
With these small strips a series of standards may be made from 
10 mmg. down. “I'he yellow color appears definitely, though of course 
slightly, from 0.5 mmg. ‘Treated with hydrochloric acid, ammonia, or 
hydrochloric acid and auric chloride, the indication is much sharper, 
and from this amount up to 10 mmg. the gradation of the 2 mm. stan- 


_ dards is well marked. From 0.3 mmg. the yellow color is exceedingly 


faint, but development with the reagents brings it out. At 0.2 mmg. 
the formation of yellow is no longer seen, but treatment with hydro- 
chloric acid gives a faint but definite color, which under the glass is 
seen to be greater than the effect produced by 0.1 mmg. Development 
with ammonia or auric chloride is also definite. From 0.08 mmg. a 
faint fringe of color is visible under the glass after treatment with 
hydrochloric acid, and the indication is even sharper with ammonia 
or auric chloride. From 0.05 mmg. no results were obtained. ‘These 
tests were made on two solutions, prepared at different times. 

Between 0.05 and 0.08 mmg. is clearly the limit at which we have 
been able to detect any arsenic by the mercuric chloride paper under 
the conditions of our method. [0 is safe to set this limit at 0.08 mmg. 


32 We have found that the lead acetate paper is more sensitive to hydrogen 
sulphide than the mercuric chloride. 
VOL, XLiti1. —21 


822 PROCEEDINGS OF THE AMERICAN ACADEMY. 


(0.00008 mg.) of arsenious oxide, which is equivalent to 0.00006 mg. 
of metallic arsenic or one seventeen-thousandth of a milligram. 

In the above tests, on quantities under 10 mmg., the hydrochloric 
acid containing 0.004 mg. arsenious oxide per liter was used. ‘This, in 
15 c.c. of the diluted acid, assured a quantity of arsenic far below the 
above limit, while blank tests of over an hour’s duration gave negative 
results. ‘he deposits from these small amounts were formed within 
thirty minutes, and each reduction was continued thirty minutes 
longer. 

Although the method is a very delicate one, as shown by the above 
tests, we are far from claiming that 0.08 mmg. of arsenious oxide can 
be recognized by it with certainty under the varying conditions of 
analytical practice. We are not so much concerned with the absolute 
delicacy, however, as with the amount which may be considered a 
practical limit, the recognition of which is definite under all conditions, 
and which, when obtained from an aliquot portion of a solution, may 
safely be used as a factor in the quantitative determination of the 
arsenic. In this particular we agree fully with Chapman and Law,3% 
who have expressed the opinion that in the Marsh method 5 mmg. 
should be taken as a practical limit, and that one’s efforts should be 
directed toward recognizing this amount with certainty. We consider, 
therefore, that 1 mmg. (0.001 mg.) of arsenious oxide may be set as 
the practical limit of our method, although less than one tenth of this 
amount may be recognized under favorable conditions. ‘he color 
produced on the large or small strip by 1 mmg. need not be confused 
with that from hydrogen sulphide, stibine, or phosphine, if these are 
unavoidably present, while the more minute traces of color, though 
not easily confounded with those from the first two, are similar in 
appearance to that from the last. We have found by trial that 0.1 
mmg. of arsenious oxide, if present as arseniate, can be recognized after 
reduction with sulphurous acid. 

Previous estimates of the delicacy of the Gutzeit test have not been 
under 0.1 mmg., so far as we know, with the exception of that made 
by Dowzard,3* who states that one fifteen-thousandth to one twenty- 
thousandth of a milligram can be recognized by the modification 
described by him. ‘This figure is practically the same as ours. 


Tue Use or tHe Mernop. 


The method naturally suggests comparison with the Marsh in the 
present accepted form of the latter. In the modification described by 


83 Zeits. f. angew. Chem., 20, 67 (1907). 84 Loc. prim. cit. 


SANGER AND BLACK. — QUANTITATIVE DETERMINATION OF ARSENIC. 323 


one of us (S.) in 1891,25in which a standard set of mirrors was em- 
ployed for the first time, the absolute limit of delicacy was placed at 
1 mmg. of arsenious oxide. ‘The most important improvement in pro- 
cedure which has been made of late years is the cooling of the capil- 
lary tube, described by Gautier,3® Thomson,37 Lockemann,?8 and 
others. By this means the scattering of the deposit of arsenic is pre- 
vented and the mirror takes a more compact and hence more easily 
identifiable form. In spite of this advantage, we have not been able, 
as yet, to reach the absolute limit of delicacy in the Marsh process 
which is set by Thomson at 0.4 mmg. of arsenious oxide, by Locke- 
mann and others at 0.1 mmg. arsenic. We cannot think that this 
failure is due to insensitiveness of the zinc, but to other reasons not 
yet discovered. Sanger and Gibson 39 have shown, for example, that 
the nature of the antimony mirror depends upon the kind of glass 
tubing used, and they suggest that a greater or less oxidation of the 
stibine may take place in the accidental presence of air, if the glass 
contains a catalyzing agent. If this were true, it is easy to imagine a 
slight retention of the arsenic from the same cause, since the oxide 
formed would be fixed by the base of the glass. This point will be 
soon investigated in this laboratory. 

Not only, as far as our experience goes, has the Gutzeit method 
proved to be more sensitive than the Marsh, but we think it will be 
found so by others. In certain lines of work, in which the sample 
may be tested directly or quickly freed from interfering substances, 
the Gutzeit in the form proposed by us may be preferable to the 
Marsh, particularly when the routine analysis of a large number of 
samples is concerned. In toxicological or legal work it will serve as a 
valuable adjunct to the Marsh method, since the exhibits from both 
methods can be presented and will corroborate each other, qualita- 
tively or quantitatively. Though not convertible, like the Marsh 
mirror, to a definite and obvious compound of arsenic, yet the color 
band can be easily differentiated from the effect produced by other 
substances on mercuric chloride. 

We have not studied the application of the method to the analysis 
of many products, though we have used it successfully for the deter- 
mination of arsenic in wall paper, in the urine, and in certain salts. 


35 Toe. cit. 

36 Bull. Soc. Chim., 27, 1030 (1902). 

37 Chem. News, 88, 228 (1903) ; also, 94, 156 and 166 (1906). 

88 Loc. cit. 

39 These Proceedings, 42, 719 (1907); Jour. Soc. Chem. Ind., 26, 585 (1907) ; 
Zeits. f. anorg. Chem., 55, 205 (1907). 


824 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Its usefulness will depend upon its adaptability to the needs of the 
analyst, and it may be modified to meet his conditions. For instance, 
in the examination of beer, if the analyst must add the sample to the 
reduction bottle without previous treatment, there should be adequate 
provision for the retention of hydrogen sulphide, the prevention of 
frothing, ete. We are not at all sanguine of the success of the method, 
however, unless the test solution has had adequate treatment before 
reduction. 

During the study of the interference of sulphur, phosphorus, and 
antimony, as given above, the possibility of quantitatively determin- 
ing small amounts of these substances by this method, particularly of 
antimony, suggested itself. We desire to note also that the principle 
of allowing the gas to be tested to act along the surface of the react- 
ing substance has a useful application in other cases, notably in the 
determination of fluorine, and we are at present engaged in developing 
a method for the estimation of small amounts of that substance 
according to this principle. 


In conclusion, it gives us pleasure to acknowledge our indebtedness 
to the C. M. Warren Fund of Harvard University for material assist- 
ance in the preparation of the colored plates used in this article. 


Harvarp University, Camprince, Mass., U.S. A,, 
August, 1907. 


ἵννν...... ahs τ 


SANGER AND BLACK.—ARSENIC BY GUTZEIT METHOD. PLATE 1. 


Εἰαᾳ, 1. 


STANDARD ARSENIC BANDS IN MICROMILLIGRAMS OF AS,0, 
INITIAL. 


BiGH2: 


STANDARD ARSENIC BANDS IN MICROMILLIGRAMS OF AS,0, 
HYDROCHLORIC ACID DEVELOPMENT. 


PROC AMER. ACAD. ARTS AND SCIENCES. VOL. XLIII. 


SANGER AND BLACK.—ARSENIC BY GUTZEIT METHOD. 


a 
" 
ee Μ ὲ ἡ i 


2 5 10 lis) 20 25 30 35 40 50 


FIG. 


wo 


STANDARD ARSENIC BANDS IN MICROMILLIGRAMS OF AS,0, 


AMMONiA DEVELOPMENT. 


Proc. AMER. ACAD. ARTS AND SCIENCES. VOL. XLIII. 


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By CHARLES ROBERT SANGER AND OTIS FISHER BLACK. 


f 

ἕν 

re ν» 

᾿ 

i ot 1 
τὴ 


THE DETERMINATION OF ARSENIC IN URINE. 


By CHARLES ROBERT SANGER AND OTIS FISHER BLACK. 


Presented January 9, 1907. Received August 20, 1907. 


SomE years ago one of us (S.) had occasion to make a number of 
analyses of urine in cases of suspected chronic arsenical poisoning.? In 
looking up the literature of the subject at that time, it was found that 
the analysis of the urine in case of chronic arsenical poisoning had 
been comparatively rare. In the twenty-three cases cited by Sanger 
in which the urine had been examined and the methods of analysis de- 
scribed, the latter were generally open to adverse criticism. They were 
usually tedious and often involved the use of many reagents, thereby 
adding to the possibility of introduction of arsenic. ‘The amounts of 
arsenic found, in the absence at that time of any method for the deter- 
mination of small quantities, could only be judged from the descrip- 
tions of the mirrors, but probably did not exceed 1 mg. of arsenious 
oxide per liter, and in many cases must have been less than 0.1 mg. 
In the only analysis found in which quantitative results were given, 
-the amount was stated to have been 16.8 mg. in 1700 6.6., but the 
method of analysis was not given, hence this case was not included in 
the twenty-three above mentioned. 

The method used by Sanger for the treatment of the urine was based 
on that proposed by Gautier? for the general treatment of animal 
tissue. ΤῸ ὃ measured volume of urine was added about one tenth the 
volume of concentrated nitric acid, and the whole was evaporated over 
a free flame. As the mass neared dryness the flame was lowered, and 
more acid was added, if necessary, in order to avoid carbonization at 
the end. Deflagration often ensued, but it was thought that loss of 
arsenic should not be feared in presence of excess of nitric acid. ΤῸ 
destroy the organic matter completely, the residue from evaporation 
was transferred to a smaller dish, treated with sulphuric acid, and 
heated for some time, with addition of nitric acid, until a clear, white, 
partly melted mass was obtained. The residue, free from nitric acid, 


1 These Proceedings, 29, 148 (1894). 
2 Ann. ἃ. Chim. et ἃ. Phys., [5] 8, 384 (1876); Bull. Soc. Chim., [2] 24, 250 
(1875). 


OCT 28 1907 


328 PROCEEDINGS OF THE AMERICAN ACADEMY. 


was diluted with water and introduced into the Marsh flask. The 
amount of arsenic was determined by Sanger’s? modification of the 
Berzelius-Marsh method. 

In the twenty cases of suspected arsenical poisoning referred to in 
the above paper, thirty-one samples of urine were examined by this 
method, and in no instance was the amount of arsenic (as arsenious 
oxide) greater than 0.07 mg. per liter. ‘The analytical precautions 
were such as to preclude the introduction of arsenic from any outside 
source. Prior to these analyses but one instance had been found in 
which a method for the quantitative estimation of arsenic in urine had 
been described. Hubbard,* in studying the elimination of arsenic by 
the kidneys, added the urine directly to the Marsh flask and deter- 
mined the weight of the mirror according to the gravimetric Berzelius- 
Marsh method, first applied by Gautier,® and afterwards elaborated by 
Chittenden and Donaldson ® and others. While the amounts of 
arsenic found by Hubbard (varying from 0.35 to 1.12 mg. per liter) 
were undoubtedly a close approximation, the method cannot be applied 
to minimal amounts with certainty on account of the impossibility of 
accurately weighing small mirrors and the effect of the presence of 
organic matter on their deposition. 

The treatment described above has been used by several analysts 7 
in the determination of arsenic in urine. Unfortunately it was not 
accurately tested by the analysis of urines containing known amounts 
of arsenic, partly on account of lack of time, partly through acceptance 
of the Gautier method. The assumption that all of the arsenic pres- 
ent was accounted for was probably incorrect, as our present work 
will show. 

The method is a troublesome one, requiring much time for evapora- 


tion and the destruction of the organic matter, as care must be taken — 


to have the latter entirely eliminated, since the accurate determination 
of the arsenic is impossible in its presence. ‘The use of large quanti- 
ties of nitric acid is unpleasant and may introduce error. ‘I‘hese con- 
siderations, together with the much more important one of possible loss 
of arsenic, have led us to substitute for the destruction of the organie 
matter with nitric acid a distillation of the arsenic from the evaporated 
urine by means of hydrochloric acid. 


3 These Proceedings, 26, 24 (1891); Amer. Chem. Jour., 13, 431 (1891). 


4 Physician and Surgeon, Ann Arbor, Mich., 4, 348 (1882) ; Contr. Chem. Lab. — / 


Univ. Mich., 1, Part I (1882). 5 Loc. cit. 
6 Amer. Chem. Jour., 2, 235 (1881). 
7 Putnam-Worcester, Bost. Med. Surg. Jour., 124, 623 (1891); Wood, Ibid., 


128, 414 (1898); and others. 


SANGER AND BLACK. — DETERMINATION OF ARSENIC IN URINE. 329 


The distillation of arsenic from organic matter by hydrochloric acid, 
first used successfully by Schneider 8 and Fyffe, is a common proced- 
-ure and needs no explanation. We have not been able, however, to 
find any instance of its application to the analysis of urine. The only 
serious objection is the difficulty of obtaining hydrochloric acid with a 
negligible amount of arsenic. Fortunately such an acid is obtainable 
at low cost in this country,!° and one does not have to resort to the 
troublesome methods of purification, which to some are prohibitive of 
the use of hydrochloric acid in arsenic work. 

Not only is the distillation method more accurate, but it will also 
be shown that, in point of time for the entire operation, the advantage 
is greatly in its favor, particularly, as we have said before, if the careful 
elimination of the organic matter is made a prerequisite to the intro- 
duction of the solution into the Marsh flask. 


THe ΜΈΕΤΗΟΡ. 


Apparatus. For distillation, a 300 ὁ. 6. round-bottom flask is used, 
with a neck about 20cm. long. The side tube, which is about half- 
way up the neck, is 20 cm. in length, and is bent downward in the 
middle at an obtuse angle, so that it passes into an upright condenser 
parallel to the neck of the boiling flask, which is closed by a short glass 
tube sealed off at each end, over which is slipped a short piece of rub- 
ber tubing. A glass-stoppered boiling flask could advantageously be 
used. ‘he cooling tube is 50 cm. long, with a jacket of 35cm. The 
side tube of the flask passes through a rubber stopper in the neck of 
the condenser and as far into the cooling tube as possible. The con- 
densing tube passes at the bottom through a rubber stopper, over which 
is shipped a wide tube 15 cm. long, similar to a chloride of calcium 
tube, having a bulb of about 25 6.6. capacity near the lower end, which 
terminates in a tube of ordinary bore. ‘l'o this end is fused a tube of 
equal diameter about 15 cm. long. The arrangement is practically a 
pipette-shaped adapter, similar to that used in ammonia distillation, 
and is intended to prevent the rise of distillate into the condenser in 
case of back pressure. The distilling apparatus is conveniently set up 
in duplicate, mounted on two stands (see Figure A), and is placed in 
the hood under a strong draught. 


Distillation. 200 6.6. of urine are evaporated in a porcelain dish 
over a low flame or on the steam bath to about 35 ¢.c., cooled, and in- 


8 Pogg. Ann., 85, 433 (1851). 
9 Jour. f. prakt. Chem., 55, 105 (1852). 
10 Baker and Adamson Chemical Company, Easton, Pa. 


990 PROCEEDINGS OF THE AMERICAN ACADEMY. 


troduced into the flask, which is then connected with the condenser. 
Under the adapter is placed a small flask containing 25 c.c. concen- 
trated nitric acid, which should just cover the end of the adapter. 
There are then added, through a long funnel tube, 100 6.0 cool, con- 


Ficgure A. 


centrated hydrochloric acid, in which the amount of arsenic is as small 
as possible and accurately determined. ‘I'he stopper of the flask is at 
once inserted. 

Distillation is begun with a low flame and is continued at such a 
rate that the volume of the liquid in the flask is reduced to about half 
in the course of thirty to forty minutes. Repeated trials have shown 
that all the arsenic, in the quantities for which this method is intended, 
goes over by this operation, whether the arsenic is present as arsenious 
or arsenic acid. As by far the greater part of the arsenic goes over 


SANGER AND BLACK. — DETERMINATION OF ARSENIC IN URINE. 991 


with the gaseous hydrochloric acid and meets the concentrated nitric 
acid, no loss is to be feared from the dilution of the nitric acid by the 
acid distillate. Comparatively little organic matter is distilled, and 
this is entirely destroyed by the subsequent procedure. 


Treatment of the Distillate. 'o the distillate are added 25 c.c. con- 
centrated nitric acid, in order to decompose completely during evapora- 
tion any excess of hydrochloric acid and thus guard against loss of 
arsenic. The mixture is then evaporated to a small bulk, three to 
five cubic centimeters of concentrated sulphuric acid added, and the 
evaporation continued until the nitric acid is expelled. "ΤῸ destroy the 
slight amount of organic matter which usually remains, a few drops of 
nitric acid are added, and the heating is continued until only the small 
residue of sulphuric acid is left, which must be colorless. The residue 
is then diluted with water to a measured volume of about 25 c.c., or, 
if preferred, to a quantity which is weighed in a side-neck test tube to 
the second decimal! place. 


Determination of the Arsenic. The subsequent procedure, as in the 
paper above referred to, follows closely the method of Sanger 11 for 
determining small amounts of arsenic, except that the capillary tube 
should be cooled at the deposition point of the mirror, as advised by 
Gautier,12 Thomson,1% Lockemann,!* and others. An aliquot portion 
of the ultimate solution, accurately measured or weighed, is introduced 
into the Marsh flask, the entire apparatus having been in action for a 
sufficient time to show absence of arsenic. ‘This time varies according 
to the importance of the test in hand, but should not be less than twenty 
minutes. If, after the addition of the solution, a mirror does not make 
its appearance in the capillary tube within ten minutes, a larger portion 
or the whole of the solution is added. After the appearance of the 
mirror the heating of the tube is continued for a sufficient time to 
insure the complete deposition of the arsenic, which usually occurs 
within an hour. During this time the flow of hydrogen is regulated 
by the constant generator, so that the height of the flame at the end 
of the heated tube is about one millimeter, the regular deposition of 
the mirror being dependent on this condition. The mirror obtained 
is compared with a set of standards, which is prepared as explained in 
the paper referred to. From the amount of solution used and the 


11 Loc. cit. 

12 Bull. Soc. Chim., [2] 27, 1030 (1902.) 

13 Chem. News, 88, 228 (1993). 

14 Zeitschr. f. angew. Chem., 18, 416 (1905). 


882 PROCEEDINGS OF THE AMERICAN ACADEMY. 


volume of urine taken, the quantity of arsenic per liter is calculated. 
Should the mirror exceed in size the standard of 0.06 mg., it may be 
necessary to obtain another mirror from a smaller portion of the solution 
or from a smaller volume of urine, since the reading of mirrors above 
0.06 mg. is not accurate. 

The determination of the amount of arsenic in the solution may also 
be made by the modification of the Gutzeit method described by us in 
the preceding paper.15 In this case, owing to the size of reduction flask 
used, the volume of the solution should not exceed 20 c.c., of which an 
aliquot part or all may be taken. This method consists briefly in 
allowing the arsenical hydrogen to pass through a tube containing a 
strip of paper saturated with a five per cent solution of mercuric 
chloride and dried. The resulting band of color is compared with 
a set of standard bands. 


Reagents. The zine used, known as Bertha spelter, from the New 
Jersey Zine Company of New York, has been used in this laboratory 
for many years, and has been exhaustively tested for arsenic with nega- 
tive results. It contains not over 0.013 per cent of iron and not more 
than 0.019 per cent of lead. The amount taken is from five to ten 
grams. We have used it in a rather finely granulated form in the 
reduction bottle, reserving the larger pieces for the constant generator. 
As the metal is too pure to generate hydrogen with sufficient rapidity 
from sulphuric acid, we place in the reduction bottle a thin disk of 
platinum foil nearly as large as the bottom of the bottle. With this 
the evolution of the hydrogen is most regular. That the platinum 
does not cause arsenic to be held back, we have assured ourselves by 
obtaining mirrors of equal size and same appearance as those formed 
without the disk. The deposition of platinum on the zinc by use of 
platinic chloride is, however, not allowable, as one of us has shown,26 
and cupric sulphate is equally inadmissible. The formation of a coat- 
ing of copper on our zine, after the procedure of Lockemann,17 does 
not add to its sensitiveness, nor does the addition of tin or lead salts 
to the solution during reduction. In the constant generator, the zinc 
is sensitized, according to the suggestion of Gooch,!8 by treatment 
with a solution of cupric sulphate, but we take the precaution to pass 
the hydrogen from the generator through a ten per cent solution of 


15 These Proceedings, 43, 297 (1907) ; Jour. Soc. Chem. Ind., Vol. 26 (1907) ; 
Zeitschr. f. anorg. Chem., Vol. 56 (1907). 

16 Loc. cit., p. 39. 

17 Loc. cit. 


18 Amer. Jour. Science, [3] 48, 292 (1894). 


SANGER AND BLACK. — DETERMINATION OF ARSENIC IN URINE. 9833 


cupric sulphate in order to retain any hydrogen sulphide which may 
_be formed. 

The sulphuric acid is from the Baker and Adamson Chemical Com- 
pany, and has never shown a trace of arsenic when tested in greater 
quantity and for a longer time than in a single determination. In the 
constant generator it is used at a dilution of 1 to 8; in the reduction 
bottle somewhat more dilute (1.5 normal). 

The hydrochloric acid is also obtained of the Baker and Adamson 
Company. Two grades? have been used: the ordinary chemically 
pure acid (A), which was found by repeated trials to contain 0.4 mg. 
arsenious oxide per liter ; and a second (B), in which we have determined 
by careful analysis an amount equal to 0.02 mg. per liter. 

The nitric acid is an ordinary, chemically pure acid, tested in large 
quantity after evaporation with sulphuric acid and found to be entirely 
free from arsenic, both by the Marsh and Gutzeit tests. 


Utensils. All glass and porcelain vessels were new, and, after freedom 
from arsenic was assured by blank tests, were reserved for this purpose 
alone. 


ANALYTICAL RESULTS. 


Blank Tests. 1. 100 ¢.c. hydrochloric acid (A) were diluted with 
85 6.0. water and distilled into 25 ὁ.0. nitric acid. From the evaporated 
distillate a mirror was obtained equal to 0.04 mg. arsenic.2° Amount 
per liter, 0.4 mg. 

2. 100 cc. acid (A) were added, drop by drop, to 50 6.6. hot nitric 
acid in a porcelain dish. The mixture evaporated with sulphuric acid 
gave a mirror equal to 0.04 mg. arsenic. Amount per liter, 0.4 mg. 

3. 100 6.6. hydrochloric acid (B) were diluted with 35 ¢.c. water and 
distilled into 25 6.6. nitric acid. The evaporated distillate gave a 
mirror which was judged to be about 0.003 mg. arsenic. 

4, 200 c.c. acid (B) were added, drop by drop, to 100 ¢.c. hot nitric 
acid and the resulting mixture evaporated with sulphuric acid until 
the nitric acid was expelled. From this was obtained a mirror which 
was read as 0.002 mg. arsenic. 

From analyses 3 and 4 it was evident that there was a trace of 


19 A third grade (C) has been obtained from the same source since the comple- 
tion of the analytical work on this paper. In this acid, which is of exceptional 
purity, the amount of arsenic is not over 0.004 mg. per Liter. 

20 In these analyses “arsenic,” unless otherwise specified, means arsenious 
oxide. 


834 PROCEEDINGS OF THE AMERICAN ACADEMY. 


arsenic in the acid (B), probably about 0.002 mg. in 100 cc. or 
0.02 mg. per liter. 

5. 300 τὸν urine were evaporated to 30 ¢.c. and distilled with 100 e.c. 
hydrochloric acid (A) into 25 ¢.e. nitric acid. One half of the solu- 
tion from the evaporated distillate gave a mirror equal to 0.02 mg. 
arsenic ; the other half, a color band (Gutzeit) equal to 0.02 mg. ‘The 
amount of arsenic per liter is therefore 0.4 mg., which confirms the 
results of analyses 1 and 2, and the test shows the urine to be free 
from arsenic. 

6. 200 ο.6. urine were evaporated to 30 c.c., and distilled with 100 ὁ.0. 
acid (B) into 25 ee. nitric acid. The distillate, evaporated with a 
little more nitric acid, gave a mirror which, as nearly as could be 
judged, was equal to 0.002 mg. This confirms, within the limits of 
reading, the results of analyses 3 and 4, and enables us to fix the cor- 
rection for 100 cc. of this acid at 0.002 mg. ‘This has been since 
confirmed by the analysis of the acid by the Gutzeit method. The 
correction is only appreciable, as will be seen from Series B, below, when 
the entire solution gives a very low mirror, and entirely disappears 
when the mirror, even if a low one, is obtained from a small part of the 
solution (see Series C). , 

The third grade of hydrochloric acid (C), which will hereafter be 
used in all urine work in this laboratory, was tested as in analyses 2 
and4. After reduction of the residues from two lots of 100 ¢.c. with sul- 
phurous acid, color bands were obtained equal to 0.3 and 0.5 micro-milli- 
grams (0.001 milligram) of arsenic. This is equivalent to 0.004 mg. 
arsenic per liter. The correction for 100 ¢.c. of this acid, 0.0004 mg., 
would be practically inappreciable under ordinary conditions of the 
Marsh procedure, even if the mirror was obtained from the entire solution. 


Analyses. For use in the subsequent analytical work, a solution of 
arsenious acid was made as follows: One gram of pure arsenious oxide, 
twice resublimed, was dissolved in a small amount of sodic hydroxide 
free from arsenic. After acidification with sulphuric acid, this solu- 
tion was made up toa liter. Of this, 10 ¢.c. were diluted to a liter, 
giving a solution containing 0.01 mg. arsenious oxide to the cubic 
centimeter. 

7. 150 66. urine, to which had been added 0.025 mg. arsenic, were 
evaporated to 25 c.c. and distilled with 100 ¢.c. hydrochloric acid con- 
taining 0.035 mg. arsenic. The total amount was 0.06 mg. 3 0 6. 
of distillate were collected in 25 ο.0. nitric acid, and from this was ob- 
tained a mirror equal to 0.06 mg. 50 6.6. more of the distillate were 
collected in 15 c.c. nitric acid, and from this no mirror was found. 


SANGER AND BLACK. — DETERMINATION OF ARSENIC IN URINE. 335 


8. By the same procedure as in analysis 7, and also with 150 cc. 
urine, 25 6.6. distillate gave 0.06 mg. arsenic, equal to the amount 
taken. 50 ¢.c. additional distillate gave no mirror. 

9. With 200 c.c. urine and the same amount of arsenic, the same 
procedure gave 25 c.c. distillate containing 0.06 mg. arsenic, and 
50 6.6. additional distillate yielded no further mirror. 

The results of analyses 7, 8, and 9 show that by distilling one half 
the contents of the flask, according to the method above described, all 
the arsenic passes over. 

The following series shows that by the former method of destroying 
the organic matter by evaporation with nitric acid a very large error 
is made : 


SERIES A. 


Nitric Acip Meruop. 


Per cent ἢ 


Volume of Urine As,0, added. er ¢ 
5 recovered. 


No. of Analysis. taken. 


As,Oz recovered. 


mg. 


6.0 24 


044 
0.00 
0.00 


In analyses 10 and 11, actual deflagration took place; in Nos. 12 
and 13 the residues were blackened. 

The next series, B, p. 336, gives the results of a preliminary trial of 
the distillation treatment, and shows that by the distillation method 
very small amounts of arsenic can be recovered with practical com- 
pleteness. As a more severe test of the method, 0.01 mg. arsenic 
was added to a liter of urine and the analysis carried out as usual, 
using acid B (Analysis 39). A mirror was obtained fully equal to the 
standard for 0.01 mg. 

Even with the correction for this acid, we thus recover from 80 to 
100 per cent of the amount of arsenic taken, which shows that, con- 
sidering the amount of organic matter involved and the hydrochloric 
acid used, the method is a delicate one. By the use of an acid of such 
purity as that of grade C, it will be possible to eliminate entirely the 
correction for arsenic in the acid, even if the amount of arsenic in the 


336 PROCEEDINGS OF THE AMERICAN ACADEMY. 


SERIES B. 


DisTILLaATIOoN Metuop. 


No. of Anal- Volume As,O, in 100 Total As,05 Per cent 
ysis. Urine taken. | 4820s added. [΄ or. HCl. | Ars,O, taken. | recovered. | recovered. 


Average per cent recovered, Nos. 16 to 20 . 


0.07 0.002 
0.06 
0.04 
0.03 
0.02 
0.01 


Average per cent recovered, Nos. 38 to 33 . 


entire test solution is as low as 0.01 mg., since the correction is only 
four per cent of this quantity, which is well within the limit of accu- 
racy of the method itself. With larger amounts than 0.01 mg. the cor- 
rection for this acid is of course of even less account. 


Presence of Arseniates in the Urine. The compound in which arsenic 
occurs in the urine has never to our knowledge been thoroughly inves- 
tigated. ‘Io determine accurately the condition of such small amounts 
as would ordinarily occur would be a matter of considerable difficulty. 
Schmidt and Bredtschneider 31 claim to have found arsenic acid and 


21 Moleschott’s Untersuchungen, 6, 146 (1859). 


SANGER AND BLACK. — DETERMINATION OF ARSENIC IN URINE. 8337 


no arsenious when arsenic was ingested as the trioxide. Selmi?? states 
that he found in the urine of a dog poisoned by arsenic a volatile com- 
pound of the element. ‘The reference gives no analytical details and 
the original is not accessible to us. It is not improbable, however, 
from the analogy to phosphorus, that arsenic finds its way into the 
urine as an arseniate. If this be the case, the question will perhaps 
be asked if small amounts of arseniate, when distilled with hydrochlo- 
ric acid, would be recovered in the distillate or would require a pre- 
liminary reduction before distillation. 

Mayerhofer 2% has shown that if arsenic acid is distilled with a suf- 
ficiently large quantity of hydrochloric acid, it is converted to arsenic 
trichloride, chlorine being given off, since the pentachloride does not 
exist under ordinary conditions. In our method the concentration of 
the hydrochloric acid in 100 c.c. of its solution would be so great 
compared with that of the arseniate that a complete conversion to tri- 
chloride might be predicted. ‘That this is the case is shown by the 
following analyses, in which the arsenic acid used was prepared by 
evaporating a measured quantity of arsenious acid solution to dryness 
with nitric acid before adding to the urine. 


SERIES C. 


DISTILLATION Metnop IN PRESENCE OF ARSENIATES. 


No. of τς As,0s As,O, in Total AsO, As,03 Per cent 


pas Urine added, as nt ᾿ over ᾿ 
Analysis. | κοι. H,AsO,. | 100 c.c. HCl. taken. recovered. recovered. 


6:0. Ing. mg. mg. mg. 


0.25 0,252 0.25 
0.50 0.502 0.50 


Analyses of Urine. The method was finally tested by the analysis 
of six samples of urine to which varying amounts of arsenic had been 
added by one of us, the amounts not being known to the analyst. 


22 Mem. d. Accad. d. Scienze, Bologna, [4] 1, 299 (1882) ; ref., Gazz. Chim. Ital., 
12, 558 (1882). 
23 Ann. Chem. u. Pharm., 158, 326 (1871). 
VOL. XLIII. — 22 


338 PROCEEDINGS OF THE AMERICAN ACADEMY. 


SERIES D. 


DistiLLatTion ΜΕΤΗΟΡ. 


| AsO, Total Ae,0, | 
| Volume | present a found or 


Ἵ Urine i in ; D 
Liter. taken. y Volume 0.04 me) 
taken. τ" 5. 


τ ἢ 
0.15 0.11 


0.38 0.34 
0.23 0.19 
0.33 0.29 
0.17 0.13 
0.28 0.24 


No. of Volume Urine Volume of Volume of Reading of Reading of 
Analysis. taken. Solution used. | Solution taken. Mirror. Mirror, Average. 


Amount in solution taken, 10 0.028. 
Less correction for HCl 
Amount per liter urine, 5 X 0.24 


Comparison of Methods. In order to compare more fairly the distil- 
lation method with the method of evaporation, the latter was slightly 
modified to secure the most favorable conditions for the recovery of 
the arsenic. 200 6.6. urine were evaporated to about 50c.c., and then 
treated with 25 6.6. concentrated nitric acid and 5 e.c. sulphurie acid. 
Evaporation was continued until the fumes of sulphuric acid appeared, 
which left a dark residue containing a large amount of organic matter. 
By successive addition of small amounts of nitric acid and heating, 


SANGER AND BLACK. — DETERMINATION OF ARSENIC IN URINE. 339 


this residue was oxidized after a very long time, so that it appeared 
nearly colorless. The diluted residue was then added to the reduction 
bottle. A series of analyses was made by this method in which the 
amounts of arsenic were not known to the analyst. 


SERIES E. 


Nirric σὶρ ΜΈΤΗΟΡ, Mopiriep. 


As,O; found 


As,O. present το σ᾿ 
295 P in Volume 


in Volume 
taken. 


As,O3 
found per 
Liter. 


Per cent 
found. 


No. of As,O3 per Volume 
Analysis. Liter. Urine taken. taken. 


(Corrected. ) 


mg. 


0.15 
0.08 
0.10 


0.24 
0.12 
0.18 


Average per cent found . 


From comparison of Series D and EH, it will be seen that the distilla- 
tion method is more accurate than the evaporation method, even if 
the latter is carefully conducted so that the loss from carbonization is 
avoided as far as possible. But the time needed for a proper treatment 
with nitric acid by the latter method is very great, and the manipula- 
tion uncleanly. The entire preparation of the solution for testing, in 
the distillation method, does not consume more than three fifths of the 
time required in the other, and the procedure is much cleaner. 


Use oF THE MeEtTHOD. 


We have not studied the question of how small an amount of 
arsenic can be recovered from the urine by this method, but have been 
content to show that very small amounts, even as little as 0.01 mg. 
per liter, can be detected and estimated with reasonable accuracy. 
(Series A and Analysis No. 39.) For the examination of abnormal 
urine, —in studying the elimination of arsenic through the kidneys, 
for instance, — it would be seldom necessary to consider a quantity 


340 PROCEEDINGS OF THE AMERICAN ACADEMY. 


smaller than 0.01 mg., although the delicacy of the Marsh and Gutzeit 
methods permits a fairly exact estimation of much smaller amounts. 
If the question of the occurrence of arsenic in normal urine is to 
be investigated, — and we hope that opportunity for such an important 
study may be found at some future time in this laboratory, — the deli- 
cacy of the methods is secondary in importance to that of the source 
and manner of collection of the urine. The absolute delicacy of the 
Marsh method is claimed by Thomson 24 to be 0.0004 mg. of arsenious 
oxide, by Lockemann 35 and others, 0.0001 mg. arsenic, and we have 
been able to recognize by our modification of the Gutzeit method as 
little as 0.00008 mg. of arsenious oxide. But until it is shown that a 
urine has had absolutely no arsenical contamination, such extreme 
delicacy is apt to be misleading. 

The use of the method in the analysis of other liquids containing 
organic matter suggests itself, for example in the more exact determin- 
ation of arsenic in beer. Although the distillation of small quantities 
of arsenic from animal tissue with hydrochloric acid has been rejected 
by Lockemann 2° and others, either on account of the amount of arsenic 
in commercial, pure acid, or the difficulty of purifying the acid, yet 
we believe that the distillation of organic matter with acid of only 
0.004 mg. arsenic to the liter would not introduce a serious error into 
an investigation of the normal occurrence of arsenic in the organs 
of man. 


Harvarp University, Camprince, Mass., U.S. A., 
August, 1907. 


24 Loc. cit. 25 Loc. cit. 


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Vou. XLIII. No. 10.— Novemser, 1907. ΝΥ 


IBUTIONS FROM THE FIRST CHEMICAL INSTITUTE OF 
ROYAL FRIEDRICH-WILHELM UNIVERSITY OF BERLIN. : 


1 TRANSITION TEMPERATURE OF MANGANOUS 
CHLORIDE: A NEW FIXED POINT 
IN THERMOMETRY. 


By THEODORE W. RICHARDS AND FRANZ WREDE. 


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Proceedings of the American Academy of Arts and Sciences. 


Vou. XLIII. No. 10.— NovemMBER, 1907. 


CONTRIBUTIONS FROM THE FIRST CHEMICAL- INSTITUTE OF 
THE ROYAL FRIEDRICH-WILHELM UNIVERSITY OF BERLIN. 


THE TRANSITION TEMPERATURE OF MANGANOUS 
CHLORIDE: A NEW FIXED POINT 
IN THERMOMETRY. 


FROM THE RumPORD FUND. 


By THEODORE W. RICHARDS AND FRANZ WrReEDE. ὃ Αἰ.“ 


ant ae he a 


3, =e 


Se Oe ae ee, τἄμ" 00 


CONTRIBUTIONS FROM THE FIRST CHEMICAL INSTITUTE OF THE 
ROYAL FRIEDRICH-WILHELM UNIVERSITY OF BERLIN. 


THE TRANSITION TEMPERATURE OF MANGANOUS 
CHLORIDE: A NEW FIXED POINT 
IN THERMOMETRY. 


By THEODORE W. RICHARDS AND FRANZ WREDE. 


Presented by T. W. Richards. Received October 7, 1907. 


In several previous articles one of us! has set forth in detail the 
advantages of the transition temperatures of crystallized salts as fixed 
points for thermometry. A number of suitable salts have been sug- 
gested, and in particular the sulphate and bromide of sodium have 
been carefully investigated. For these salts the transition tempera- 
tures, referred to the international hydrogen scale, have been found to 
be, respectively, 32.383°C. and 50.674°C. ; and both of these salts have 
been shown to give points constant and definite enough for convenient 
use for the above-mentioned purpose. 

Among the salts studied by Richards and Churchill in an approxi- 
mate fashion was manganous chloride (MnCl,-4H2O). This salt has 
also been investigated roughly by Kuznetzoff, and by Dawson and 
Williams.2 All of these investigations were merely approximate ; no 
attempt was made to correct the thermometer for the errors of ordinary 
thermometry. Therefore they were none of them suitable for defining 
the point with sufficient exactness for the present purpose. On the 
other hand all of the investigators agreed in maintaining that the point 
was constant and definite. Therefore it promises well ; and the pres- 


1 πὶ W. Richards, Am. J. Sci. [4], 6, 201 (1898) ; Richards and Churchill, These 
Proceedings, 34, 10 (1899) ; Richards and Wells, These Proceedings, 38, 431 (1902), 
jw 41, 485 (1906). These four papers are all to be found in full in the Zeitschr. 
© fiir phys. Chem., the references being respectively 26, 690 (1898) ; 28, 313 (1899) ; 
σ: 43, 465 (1908) ; 56, 848 (1906). The present paper also will appear in German in 
y that periodical. 
in 2 Kuznetzoff, Chem. Centralblatt, 1899, I, 246; Dawson and Williams, Zeit. 
Cs fiir phys. Chem., 31, 59, 1899. 
μι. 


ΕΞ: 


344 PROCEEDINGS OF THE AMERICAN ACADEMY. 


ent paper recites briefly a series of experiments giving much greater 
definiteness to the point in question and making it available for the 
verification of thermometers. 


PREPARATION OF THE MANGANOUS CHLORIDE. 


As material for preparation the purest manganous chloride and 
nitrate of commerce were used. Several preparations made in different 
ways assured certainty in the product. 

The manganous chloride was purified in the first place by crystalliza- 
tion and centrifugal treatment. ‘Through these processes it was passed 
four times, after solution in ordinary distilled water, and twice after 
solution in the purest water. Porcelain and platinum dishes were 
used. This preparation was called Ia. 'Two more crystallizations gave 
Ib, which was found to have essentially the same transition point. 
Sample Ic was made from the two last mother liquors by further re- 
crystallization. This also gave the same point. During these crystal- 
lizations traces of iron were found to exist in the otherwise very pure 
initial salt ; these traces disappeared in the very early stages of the 
crystallization. ‘This was proved by qualitative tests, which were care- 
fully verified by suitable blank determinations. 

The purity of the salt, as indicated by the transition temperature, is 
shown by the following table. Obviously the transition temperature 
may be used as a guide concerning the freedom of the salt from every- 
thing except isomorphous substances, especially for the present purpose. 
The crude original substance had a transition temperature of 57.91°: 
the first fraction, 58.03°; the second, 58.05°; the fourth, 58.072° ; 
the sixth, 58.089°; the eighth, 58.090° ; and the ninth, 58.089°. 

For the preparation of the chloride from the nitrate of manganese, 
this nitrate was recrystallized until wholly free from iron. It was 
precipitated as carbonate by means of redistilled ammonium carbonate. 
This substance was prepared by distillation with water in a platinum 
condenser and collected in a platinum dish in which the manganous 
carbonate was precipitated. The precipitate was boiled with many 
portions of pure water until no more trace of nitric acid was found in 
the wash water. It was then dissolved in concentrated pure hydro- 
chloric acid and the chloride was three times recrystallized to eliminate 
the traces of chlorine due to the excess of nitric acid, and also the 
traces of hydrochloric acid. The salt gave the same transition tem- 
perature as the previous sample, although it had been passed through 
such different treatment. Therefore it seems reasonable to infer that 
both samples were pure. 


RICHARDS AND WREDE. — TEMPERATURE OF MANGANOUS CHLORIDE. 345 


It is perhaps worthy of note that manganous chloride has been found 
by Kahlenberg, Davis, and Fowler ® to be only very slightly hydrolyzed 
at 56°, a temperature very near the transition temperature, 58°. ‘The 
hydrolysis at this temperature is not enough to cause, during the time 
of the transition experiment, any considerable chance for the forma- 
tion of the higher oxides of manganese by action of the air on the 
slightly hydrolyzed solution. This is of course particularly true of the 
highly concentrated saturated solution at 58°. 


DETERMINATION OF TRANSITION ‘TEMPERATURE. 


Great care was taken in this work. Besides common thermometers 
for the determination of the temperature of the thermostat, etc., three 
instruments of great precision were used. 

These were as follows : 

1. Normal thermometer (of Jena glass, 59™) about 48 cm. long. 
The scale of this thermometer extended from 0° to 100° with bulbs 
between 5° and 18°, and between 65° and 95°. This instrument was 
made by Richter of Berlin especially for this determination, and was 
used in the preliminary experiments which were made to show the 
constancy point of the purest salt. The results are given in the sixth 
column of Table I. An accident to the thermometer prevented its 
exact calibration, but its results are exact relatively to one another, 
and in this respect are just as good as if this calibration had been 
carried out. 

2. A Beckmann thermometer, No. 30, Richter (Jena glass, No. 59"). 
This thermometer was somewhat larger than usual and made with 
great care. Its column showed an unusually slight tendency to ad- 
here to the glass, and gave, as will be seen, extraordinarily constant 
readings. The scale was divided into one-hundredths. All deter- 
minations made with the other thermometers were also made with this 
instrument, which thus served as a means of comparing and controlling 
them. The results are given in the Tables. The particular point in 
question, 0.508° on this scale, was standardized with great care by the 
Physikalisch-Technischen Reichsanstalt and found to correspond to the 
temperature 58.090° on the international standard. After it had been 
standardized, the same thermometer was used again for determining 
the transition temperature, and gave the same results, thus showing 
that the mercury in the bulb had remained constant in amount under 
the very careful treatment which it had received. 

On account of the breaking of thermometer 1, we desired to confirm 


3 Kahlenberg, Davis, and Fowler, J. Am. Chem. Soc., 21, 1, 1899. 


346 PROCEEDINGS OF THE AMERICAN ACADEMY. 


the results of the Beckmann instrument with another carefully standard- 
ized normal thermometer which had been directly compared with the 
standard of the Reichsanstalt. Accordingly another one was procured. 

3. Normal thermometer No. 512, Richter (Jena glass, 59%). This 
thermometer was 65.5 em. long ; the whole scale between 0° and 100° 
was divided into one-tenth degrees. The scale itself had a length of 
57cm. ‘This instrument was tested with the greatest care in the 
Reichsanstalt, not only as regards its calibration and behavior under 
pressure, but also as regards the exact position of particular points, 
especially the point 59.090°. This was found to read upon this 
thermometer 58.330°, referred to the hydrogen standard, after cor- 
rection for the ice point and for external pressure; the error here 
being +0.240°. 

The observed values for the transition point in question, determined 
with the third thermometer, and also the correction for the tempera- 
ture of the thread, external pressure, and position of the ice point, are 
to be found in Table II. Further, in that table are given the exact 
temperature computed in terms of the hydrogen scale, and also the 
control determinations made simultaneously with the Beckmann ther- 
mometer. The errors of the small extra thermometers for the thermo- 
stat, ete., were also carefully determined at this point in their scales. 

In order to carry out the determination of the transition temperature 
with a mercury thermometer, it is necessary to have the stem of the 
thermometer at the same temperature as the bulb. With high tem- 
perature the error, due to neglect of this precaution, may be very great. 
In determining a transition temperature, it is impracticable to immerse 
the whole thermometer in the melting mixture; therefore some other 
device is necessary in order to maintain the thread of the thermometer 
at the right temperature. In the past we have used two devices for 
this purpose. In one case the thermometer was surrounded by a glass 
tube, through which circulated water of the right temperature. ‘This 
device works very well, except that it is difficult to prevent cooling of 
the water. ‘The other device consisted in a deep thermostat, above 
which the thermometer just projected. In the present series of deter- 
minations we have altered this latter arrangement by making the 
thermostat of glass, using a very tall glass beaker 52 centimeters in 
height and 14 centimeters in diameter, surrounded at the sides with 
asbestos paper and with long narrow windows in front and behind for 
observation. A sketch of this apparatus is given in the accompanying 
diagram. Into the water was immersed, quite to its top, a strong, very 
large tube (A) closed below, of about 5 centimeters diameter. In this 
there was contained, isolated by pieces of cork, the slightly smaller 


ψ 


RICHARDS AND WREDE. — TEMPERATURE OF MANGANOUS CHLORIDE. 347 
tube (B) designed to contain the substance. This tube, and also the 


stirrer, were made out of good insoluble glass. Because the mercury- 
thread, which we needed to consider, was 2 centimeters shorter than 


5 
K 


Θ 


ΤΥΙΙΤΙΤΙΤΤΥΤΤΤΙΤΙΤΙ 


iii ὃὁΦΘΦΘ ἐς. «--------- 


( 


the second tube, it was contained entirely within it when the ther- 
mometer was raised about a centimeter above the bottom of the tube. 
This inner tube was closed by a cork cover (C), which was bound by 
means of two small glass tubes (τ and p) to the cork stopper (K) of 
the outer tube. The two little tubes binding these two pieces of cork 


848 PROCEEDINGS OF THE AMERICAN ACADEMY. 


served to admit the thermometer (®) and the stirrer. The tempera- 
ture in the outer very large tube fluctuated but very slightly, and that 
in the inner tube containing the substance was almost exactly con- 
stant. There was no difficulty in regulating the heat of the water in 
the thermostat to within less than one tenth of a degree by an ordinary 
gas regulator. For reading the thermometer (®), a telescope with a 
very exact micrometer was used, by means of which the smallest scale 
divisions could easily be divided into hundredths. The danger of irreg- 
ular readings of the thermometer through the various media, which 
might cause errors due to parallax, was wholly overcome, in that on the 
one hand all the glass walls were arranged as vertically as possible, 
and the telescope was made exactly horizontal, and on the other hand 
every reading of the thermometer was made both from before and from 
behind. Obviously, the mean of these two readings must represent the 
true value, even if a slight displacement due to refraction had been 
present. The thermometer was so arranged that it could easily be 
turned on a vertical axis, so that there was no difficulty in making 
these readings. As a matter of fact, the readings before and behind 
never differed more than four thousandths of a degree, and usually 
differed much less than that. The true value was always taken as the 
mean of these readings. In the case of the Beckmann thermometer, 
the telescope was so placed that the scale division lines appeared 
perfectly straight through the tube, without a trace of bending. 

The concordance of the results furnishes yet another proof that these 
methods of reading were entirely satisfactory and thoroughly trust- 
worthy. The great advantage of this apparatus is that the tempera- 
ture of the scale can be kept indefinitely at a temperature as nearly as 
possible to the true value, and this is no small advantage, because with 
such a length of thread a single tenth of a degree difference of tempera- 
ture causes a thread-correction of y 455°. We conclusively proved that 
it was not possible to attain the necessary constancy if even a milli- 
meter of the mercury thread projected beyond the thermostat into the 
temperature of the room. 

As has been said, in T'able I the accurate results with the first ther- 
mometer and the Beckmann are given, and also the corrections, in so far 
as these could be determined. ‘The final determinations with the large 
new thermometer are given in Table II. On the basis of these results, 
we think it is safe to say that the transition temperature of manganous 
chloride for the transition from the crystal form with 4 molecules of 
water into that with 2 of water, has a value 58.089° (+0.005) referred 
to the international hydrogen scale. 

In conclusion, it is a great pleasure to express our thanks to the 


RICHARDS AND WREDE. — TEMPERATURE OF MANGANOUS CHLORIDE. 349 


TABLE I. 


Thermometer I. 
Result cor- 
δ, cor: rected to H, 
Correction (z5'55°)- Result not _ | recte Standard 
Observed corrected pape Press. (Reichs- 
Reading. to H, Stan- anstalt). 
Thread.| Ice. | Press. dard. 


Reading of 
Beckmann 


58.084 58.089° 
68.081 
58.079 
68.081 
58.081 


58.081 
58.081 
58 084 
58.082 


58.078 58 089 


58 081 2 | 58.082 58.089 
58.083 58.083 


58.089 
58.089 


TABLE IL. 


New Thermometer. 


58.334 
58.330 
68.384 
58.330 J 0.5072° 


Ib 58.324 : 0.5076° | —1 58.089 


350 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Director of the laboratory, Professor Emil Fischer, and to the President 
of the Physikalisch-echnischen Reichsanstalt, Professor Warburg, for 
their interest in and support of this investigation, and to Dr. Griitz- 
macher of the Reichsanstalt for his prompt and thorough testing of 
our thermometer. 


SuMMARY. 


1. For the transition temperature of manganous chloride from the 
tetrahydrate to the dihydrate the point 58.089° upon the international 
hydrogen scale has been found. ‘This point is probably not more than 
0.005 degree in error. 

2. This transition temperature of manganous chloride was found to 
be suitable for serving as a fixed point in thermometry, on account of 
the ease of preparation of the salt and the satisfactory definiteness 
of the transition. 

3. In this paper is described a tall transparent thermostat which 
makes it possible to determine exactly the temperature of the whole 
length of the thermometer. 


First Cuaemicat ἸΝΒΤΙΤΌΤΕ OF THE 
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= 


IFFERENCE IN WAVE-LENGTHS OF TITANIUM 
A 3900 AND 3913 IN ARC AND SPARK. © , 


_ By Norton A. Kent AND ALFRED H. AVERY. 


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Proceedings of the American Academy of Arts and Sciences 


Vou. XLII. No. 11.— Novemser, 1907. 


DIFFERENCE IN WAVE-LENGTHS OF TITANIUM 
AA 8900 AND 38913 IN ARC AND SPARK. 


By Norton A. KENT AND ALFRED H. AVFRY. 


INVESTIGATIONS ON LIGHT AND HEAT MADE AND PUBLISHED, WHOLLY OR IN PART, WITH APPROPRIATION 
FROM THE RumforD FUND. 


DIFFERENCE IN WAVE-LENGTHS OF TITANIUM 
λλ 3900 AND 3913 IN ARC AND SPARK. 


By Norton A. KENT AND ALFRED H. AVERY. 


Presented by J. Trowbridge October 9, 1907. Received October 9, 1907. 


In June, 1905, one of the writers of the present paper published the 
results of a careful series of experiments dealing with the variation 
in the wave-length of certain lines of the spark spectra of titanium, 
iron, and zine with the electrical conditions of the discharge.t Sub- 
sequently Keller, working under Kayser, published a paper? in which 
the suggestion was made that the apparent non-coincidences of the 
spark and the comparison arc lines were due to the fact that the slit 
was not accurately adjusted to parallelism with the grating ruling ; 
and the statement was made that the plumb-line method of adjustment 
employed by the writer was of less delicacy than the spectroscopic. 

The substance of Keller’s explanation of the manner in which shifts 
could be introduced by orientation of the spectrometer slit is as 
follows: Given a perpendicular grating ruling, an astigmatic instru- 
ment such as the concave grating will give a perpendicular line image 
for every point of the line source as object. If, then, the line source 
or slit be at an angle (say clockwise as one faces it) with the grating 
ruling, each spectral line will be a composite of lines arranged as in 
Figure 1. 

The result will be an image which is apparently rotated in the direc- 
tion of the slit. If, then, on one photographic plate two exposures be 
made, one each of arc and spark, and the position of the adjacent tips 
of the images of any spectral line be measured by a comparator, any 
displacement desired may be introduced by a rotation of the slit. 

But Keller’s explanation does not apply to the method of exposure 
employed by the writer of the former paper —a method of triple 
exposure, two of the arc (the first and the third) superimposed hori- 

®zontally but not wholly vertically and spanned by the spark exposure, 
Das in Figure 2. 


) 
LO 1 These Proceedings, 41, No. 10, July, 1905. 
ra Ueber die angebliche Verschiebung der Funkenlinien. Inaugural-Disser- 
ly tation Christian Keller. 1906. 
Q VOL. XLIII. — 23 


854 PROCEEDINGS OF THE AMERICAN ACADEMY. 


It is difficult to see how non-parallelism of slit and ruling could in 
this case introduce a shift. Keller seems to have overlooked the fact 


F 

A 

͵ 

Α 

Ι! 

Ε 

Figure 1. FiGcure 2. 
AA’, direction of grating rul- AA’, two exposures of an arc line 
ing; EE’, direction of slit; LL’, superimposed horizontally, but not 
direction of resultant line. vertically; FF’, spark line. 


that this triple method was employed, for no mention is made of it in 
his paper. However, despite the fact that it was not apparent how 


KENT AND AVERY. — WAVE-LENGTHS OF TITANIUM. 355 


the above mentioned criticism could apply, it seemed advisable to 
test the matter, and the following experiments were undertaken to 
decide the two following questions: 

(1) Is the plumb-line method of adjustment of slit and grating rul- 
ing to parallelism more or less accurate than the spectroscopic ? 

(2) Will an orientation of the slit introduce a shift if the triple 
method of exposure be used ? 


CoNDITIONS OF EXPERIMENT. 


The conditions under which the present work was carried on were, 
as far as possible, those of the previous series of experiments. By the 
courtesy of Professor 'l'rowbridge and Professor Sabine every facility 
of the Jefferson Physical Laboratory was placed at our disposal. The 
grating — a 6” Rowland concave, of 20,000 lines to the inch and 21-foot 
radius of curvature, an excellent instrument — was kindly loaned by 
Professor Trowbridge, and the mount was that belonging to the labora- 
tory and located on the third story of the building. The beams were 
heavy timbers supported wholly from the walls of the building. The 
slit, grating holder, camera-box, rheostat, transformer, and condenser 
were those used in the former work. ‘T'he usual precautions relative 
to temperature changes were taken, the whole mount being wrapped 
in several layers of newspaper. ‘The vibrations of the building due to 
wind and heavy machinery necessitated working at times when these 
disturbing influences were absent. All plates not showing horizontal 
coincidence of the arc exposures were rejected. The current used for 
both arc and spark was the 110 volt, 66 cycle alternating current of 
the Cambridge Electric Light Company. ‘he frequency of the current 
used in the previous work was 133, but as the transformer was built 
for 66 cycles no difficulty was experienced in this regard. The volt- 
meter, ammeter, and wattmeter were of Thompson form, and of ranges 
0—65 volts; 0—60 amperes; and 0 —45 hecto-watts, respectively. 
Thus the conditions were the same as those formerly employed in all 
respects but location, frequency of current, and grating. 


RESULTS OBTAINED. 


(1) Relative merits of plumb-line and spectroscopic methods of adjust- 
ment. The grating holder was fitted with two opposing screws moving 
in a horizontal direction and controlling the orientation of the grating. 
It was found by trial that by the unaided eye the parallelism of either 
end of the ruled space of the grating with the silk thread of a plumb- 
line suspended from the grating holder could be adjusted so that the 


356 


Arc vertical: length 3mm. 


PROCEEDINGS OF THE AMERICAN ACADEMY. 


TABLE 1. 


Shift of spark lines AA 3900 and 3913 to red from position of arc lines. 
Metal used: Titanium Carbide, 85 per cent Ti, 15 per cent C. 


End of spark image always used. 
Capacity of condenser: 0.0226 microfarads. 
Times of exposures: arc 5 + 5 seconds, spark 75 seconds. 


Plate Number. 


Date. 


Mar. 16 


Mar. 23 | ; 


Apr. 12 
ae 18 


Apr. 27 


Mean 


Constants of 
Primary Circuit. 


Clockwise 
360°, 


0.035 | 0.041 
0.021 | 0.031 


0.082 | 0.042 
0.016 | 0.023 


0.021 
0.026 


16.0 | 0.025 
16.0 | 0.018 
17.0 
19.0 
19.0 
15.0 
15.5 
19.0 
18.5 
19.5 
17,0'|oeee ANS 
19.0 | 0.014 | 0.014 
17.0 0.013 | 0.012 
| 17.0 0.011 | 0.010 


41.8 
41.5 
42.0 
41.3 
41.8] 
41.5 


Means of means at all orientations 
Kent ae Maat ee 
Avery 


Kent. | Avery. 


0.021 | 0.024 | 0.016 


Spark horizontal: length 9mm. 


Sarr ΙΝ 


A 3900.68 
Orientation of Slit. 


Kent. Avery.|| Kent. | Avery.|| Kent. 


0.015 0.020 
0.014 0.013 


0.018 
0.022 


0.015 
0.013 


+ | 


0.020 | 0.021 | 0.021 || 0.019 


A 3900.68 | A8 
0018 
0.020 


180°. 


Parallel, or 0°. Counter clock- 


"Avery. 


0019 
913.58 


0.017 
0.019 


—_ 


KENT AND AVERY. — WAVE-LENGTHS OF TITANIUM. 30T 


TABLE I-—continued. 


Plates: Seed “ Gilt Edge,” No. 27. 

Developer: Metol, adurol, hydrochinon. 

Second order spectrum. 

Width of slit: 0.025 to 0.050 mm.; length: 5 mm. 
Length of grating lines: 14 mm. 


TENTH-METRES. 


A 3913.58. 


Orientation of Slit. 


re | πὴ || Uae || arenes, arom. || onntes sank || Counter aoe 
Kent. | Avery. Avery.|,; Kent. | Avery.|| Kent. | Avery.|| Kent. | Avery.|| Kent. | Avery. 
0.035 
56 . + ||0.018 | 0.028 oe 40 
0.012)0.012}) .. tr 0.014 | 0013 
0.029 | 0.034 0.027 | 0.040 
0010 | 0.023 0.011 | 0.013 
0.006 | 0.020 = = 0.008 | 0.016 
aes yt ἊΣ .«. |{0.015 | 0.017 ae > 
0.026 | 0.022|| .. ἣν 
ΘΌΙ0᾽ 0.019}; .. ae 
St . . || 0.023 | 0.024 
0.004 | 0.012 
0.029 | 0.033 
0.021 | 0.029 
we εν 10.014 0.017 
0018..00117}} .. as 
ae .- |/0.015 | 0.015 
0.031 | 0.026}| .. ae 
aie . - || 0.016 | 0.020 ben ac 
0.012} 0.016); .. πες bis “Ως 0.015 | 0.015 
Gia be 0.016 | 0.017 ae 5. Ὁ 
0.005 | 0.005 
0.023 | 0.025 


0.042 | 0.034]| .. a 

ὙΠ . . [0024] 0029 
| 0.016 | 0.008 
0.032 | 0.027 


0.028 | 0.023 ἐν εν Π||00024] 0.022 
τς ee ate ae 0.020 | 0.018 || .. He 
0.019 | 0.024 δ δ᾽ ὦ 
ΝΣ εν ||0.016 | 0.020 
0.018 | 0.012]; .. a 
0.021 | 0.028 ΤΑ 56 
ὦ one Ac 0.006 | 0.019 
: 00140.00Ὼ14||.. ἊΣ 
0 012 | 0.007 met εν ||0.012 | 0.009 
0.015 | 0.009 0.014 | 0012 
0.014 | 0.011 sie .. ||0.013 | 0014 
Ab me 0.013} 0.010); .. oc 
τ 5": 55 0.015 | 0.010 
: 0.016 | 0.025 ae 0 ic 


Sic .- |/0.0138 | 0018 
0.012 | 0.012 σι 
0.012 | 0.016 
0.007 | 0.014 


0.015 | 0.017 ||0.018 | 0.021 || 0.017 | 0.020 || 0 019 | 0.021 || 0.018 | 0.017 


Weighted means of all measurements . 0.019 | 0.018 
Weighted means at parallelism . . . ..... .-.. 0.021 | 0.020 
Means as given by previous investigation under similar conditions | 0.019 | 0.018 


0.015 | 0.017 


358 PROCEEDINGS OF THE AMERICAN ACADEMY. 


separate settings made by each of us agreed to within 45° on the head 
of one of the screws. ‘his means that the grating can be set by 
plumb-line to within 3.3 minutes of are. 

Opening the slit and hanging the bob so that the thread could be 
seen through it, the various settings made by each of us agreed to 10° 
on a divided head fitted to the tangent screw. This means by caleu- 
lation 1.7 minutes of are of rotation of the slit. 

On the other hand, using full length of slit, as in the previous case, 
and appropriate width, about 1/1000 inch, various exposures of the are 
were taken on the same plate in the manner customary in making 
focus plates, except that the camera box was left clamped and the slit 
was oriented. Plates so taken showed no difference in the spectra 
when the scale on the divided head of the tangent screw was rotated 
90° clockwise or counter clockwise from the position of parallelism as 
determined by plumb-line, making a change of 15.3 minutes in the 
orientation of the slit —a change nine times-as great as that in the 
case of the plumb-line. However, the relative merits of the two 
methods must not be taken as nine to one, but merely as about four to 
one, for the plumb-line adjustment for the grating is only about one 
half as accurate as that for the slit. 


The above facts make it extremely probable that the adjustment of 


the slit in the previous investigation was good. And, further, if with 
full length of slit no change in definition could be detected for a rota- 
tion of 90°, it is all the more probable that with a slit of 5 mm. length, 
as used in making regular exposures, the definition was the best 
obtainable. 

(2) Further, as to shift as a function of the orientation of the slit, 
series of plates were taken with the slit oriented approximately 1° and 
0.5° of are clockwise and counter clockwise, including a series at 
parallelism ; or 360° and 180° counter clockwise, 0°, 180°, and 360° 
clockwise on the divided head. If orientation introduce shift, the 
shift-orientation curve should either show a point of inflection at zero 
orientation or cross the displacement axis at that point. ‘T'able I, on 
pages 356 and 357, is self-explanatory. The data given in the table 
and the curves of Figure III show that for the two lines studied the 
shift is not influenced by the orientation of the slit. 

The values of the shift obtained are, within the limits of error of 
experiment, the same as those obtained in the previous investigation. 

The average deviation from the mean of two measurements (of the 
shift of a line) on any one plate is 0.003 (Kent) and 0.004 (Avery) 
t. m. for A 3900.68 ; and 0.002 (Kent) and 0.003 (Avery) t. m. for 
A 3913.58. [Ὁ will be noticed that the value of the shift given on the 


KENT AND AVERY. — WAVE-LENGTHS OF TITANIUM. 359 


SHIFT-ORIENTATION CURVE FOR Ti. aa 5900 AND 3913. 


— 
a 
~ 


360 180 0 


180 
Counter clockwise Clockwise 


FIGURE 3. 
Abscissas, Orientation in degrees. Ordinates, Shift in t.m. X 108, 


TABLE II. 


Arc AND ARC. 


A 3913.58. 


Orientation of Slit. 


Counter clock- Counter clock- 
Parallel, or 0°. wise 360°. Parallel, or 0°. wise 360°. 


Kent. Avery. | Kent. | Avery. Kent, Avery. | Kent. | Avery. 


106 | April 27 | —0.001 | 0.003 | .. Ὁ —0.002 | 0.002 
0.001 | 0.002 | .. ac 0.004 | 0.008 
0.002 | 0.005 τς οι Ὁ 0.003 | 0.002 


> 


“40. 


900 PROCEEDINGS OF THE AMERICAN ACADEMY. 


different plates varies considerably. This is probably due to the fact 
that it was difficult to set the very end of the spark image accurately 
upon the slit. As shown in the previous paper, the part of the image 
employed influences the character of the line and the value of the 
shift. } 

During the progress of the work it was suggested to us that the use 
of the tip of the spark line as that part of the line upon which to set 
the thread of the microscope in measuring was perhaps objectionable 
owing to the fact that there might be a shift due to diffraction result- 
ing from reducing the virtual aperture of the grating by strips of 
black paper set only roughly perpendicular to the ruling, the measure- 
ment being made by a mm. scale. ‘Three exposures on one plate were 
therefore made, —all of the are, and the first and third superimposed 
as usual. No shift was shown when the slit was either parallel or 
oriented, as indicated in the table on page 359. 

At the end of the series of experiments the water rheostat was cut 
out of the transformer circuit, and in its place was inserted a choke 
coil of closed magnetic circuit of U form with adjustable armature. 
When adjusted roughly to show maximum power as measured by the 
wattmeter, with a spark-length as indicated in Table ILI, the shift was 
increased to 0,032 t. m. in the mean for A 3900.68 and 0.033 t. m. for 
A 3913.58. 


TABLE II. 


Conditions same as in Table I, except spark-length = 9mm. in plate 125 and 15mm, 
in plates 126 to 128. Time of exposures for spark = 60 seconds. 


A 3913.58. 


Conditions of Primary 
Circuit. 
Orientation of Slit: Parallel, or 0°. 


Amperes. | Watts. Kent. Avery. Kent. Avery. 


1000 0.040 0.038 0.031 
950 0.033 0.033 
800 0.080 0.030 


0.026 0,029 


ΒΘ δ᾽ ἡ <5" 2) sive 6 ee 0.032 0.032 0.029 


KENT AND AVERY. — WAVE-LENGTHS OF TITANIUM. 3861 


It is the purpose of the author of the former paper to study with an 
echelon the position of the narrow and less diffuse lines of the titanium 
spectrum. 

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Professor Trowbridge and those associated with him in so generously 
putting at our disposal all the facilities of the Jefferson Physical Labo- 
ratory ; and our thanks are due also to the Rumford Committee for 
the grant made in aid of this research. 


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Lee aes eee we ee se “ree ΤΕ ΨΥ, ΨΚ Ὁ ee ee 


HARVARD COLLEGE. 


By GrREGoRY PAUL BAXTER AND JoHN Hunt WILSON. 


LIBRARY 
NEW YORK ᾿ 
BOTANICA. 
GARDEN. 


“2τ ὧν hue 


CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF 


HARVARD COLLEGE. 
LIBRARY 
A REVISION OF THE ATOMIC WEIGHT OF LEAD. “EW eee 
BOTANICAL. 
PRELIMINARY PAPER.—THE ANALYSIS OF LEAD CHLORIDE. GARDEN. 


By GREGORY PAUL BAXTER AND JOHN Hunt WILSON. 


Presented November 13, 1907. Received October 18, 1907. 


AutuoucH lead is one of the most common elements, its atomic 
weight has received comparatively little attention, the value at present 
accepted being based almost wholly upon the work of Stas.1_ Of the 
earlier determinations of this constant those of Débereiner 2 and Long- 
champs? can hardly be considered as possessing other than historic 
interest. The first results which can lay claim to accuracy are those 
of Berzelius,* who obtained values ranging from 206.7 to 207.3 by re- 
duction of litharge in a current of hydrogen. Berzelius also synthe- 
sized the sulphate from metallic lead with the result 207.0.5 Shortly 
after, Turner ὁ criticized the first method employed by Berzelius and 
attributed the irregularity of his results to the action of lead oxide on 
the silicious matter of the tube at the temperature employed in the 
reduction. By the conversion of both the metal and the oxide into 
sulphate Turner in a painstaking research deduced the values 207.0 


1 Earlier work on the atomic weight of lead has been carefully summarized 
by Clarke. Smithsonian Miscellaneous Collections, Constants of Nature, “A 
Recalculation of the Atomic Weights,” 1897. 

In recalculating the data of earlier determinations the following atomic 
weights have been used in this paper: 

0= 16.000; Ag= 107.88; Cl=35.46; N=14.01; S=32.07 
Richards and Wells, Pub. Car. Inst., No. 28 (1905); Richards and Forbes, Ibid., 
No. 69, p. 47 (1907) ; Richards and Jones, Ibid., No. 69, p. 69; Report of Inter- 
national Committee on Atomic Weights, Jour. Amer. Chem. Soc., 29, 110 
(1907). 

2 Schweig. Jour., 17, 241 (1816). 

3 Ann. Chim. Phys., 34, 105 (1827). 

# Pogg. Ann., 19, 314 (1830). 

5 Lehrbuch, 5th ed., 3, 1187 (1845). 

6 Phil. Trans., 527 (1833). 


366 PROCEEDINGS OF THE AMERICAN ACADEMY. 


and 207.6 respectively, and by converting the nitrate into sulphate, 
204.2. Marignac 7 converted metallic lead into the chloride by heat- 
ing in a stream of chlorine and obtained the result 207.42. Both 
Marignac 8 and Dumas ® analyzed lead chloride. Marignac, who dried 
the salt at 200°, by titration against silver found the atomic weight of 
lead to be 206.81, and from the ratio of lead chloride to silver chlo- 
ride, 206.85. Dumas subsequently showed that lead chloride, even 
when dried at 250°, retains moisture and is somewhat basic, and in 
one analysis in which corrections are applied for these errors, found a 
somewhat higher value, 207.07, as was to be expected. Chloride 
analyses by early investigators are, however, to be universally dis- 
trusted, owing to neglect of the very considerable solubility of silver 
chloride, thus producing too low results. - 

Stas’s work upon the syntheses of lead nitrate and sulphate from the 
metal is undoubtedly the most accurate contribution upon the subject, 
although a careful consideration of his work discloses minor defects, 
many of which he recognized himself. The metallic lead used in the 
syntheses was finally fused under potassium cyanide. Whether or not 
this treatment introduced impurities into the metal is uncertain. 
Stas himself suspected the presence of alkalies in the metal. Since 
the nitrate could not be dried above 150° without decomposition, it un- 
doubtedly contained moisture, and Stas calls attention to this point. 
The sulphate was made by treatment of lead nitrate, resulting from 
the nitrate syntheses, with sulphuric acid. The sulphate was dried 
finally at dull redness, and was probably free, or nearly free, from mois- 
ture, although it may have contained traces of lead oxide resulting from 
occluded nitrate, as well as sulphuric acid. Most of these probable errors 
tend to lower the observed atomic weight, so that Stas’s value from the 
series of nitrate syntheses, 206.81, and that from the sulphate series, 
206.92, are to be regarded as minimum values. The reader of Stas’s 
own account of his work upon lead cannot fail to be impressed with 
the fact that he was somewhat dissatisfied with the outcome of his 
research. Mention should also be made of the work of Anderson 
and Svanberg 11 on the conversion of lead nitrate into oxide, although 
the method was primarily employed in an endeavor to fix the atomic 
weight of nitrogen. heir results yield the value 207.37. 

The discrepancies between the results of these various experiments 


7 Lieb. Ann., 59, 289 (1846). 

8 Jour. Prakt. Chem., 74, 218 (1858). 
9 Lieb. Ann., 113, 35 (1860). 

10 (Huvres Completes, 1, 383. 

11 Ann. Chim..Phys. (3), 9, 264 (1848). 


BAXTER AND WILSON. THE ATOMIC WEIGHT OF LEAD. 367 


only serve to emphasize the need of a redetermination of the value in 
question, and it was with this object in view that the work embodied 
in this paper was undertaken. 

The search for a suitable method for determining the atomic weight 
of lead failed to reveal any more promising line of attack than those al- 
ready employed for the purpose. With an element of so high an atomic 
weight as lead, in any method involving the change of one of its 
compounds into another, errors which may be insignificant with 
elements of small atomic weight are magnified in the calculations to 
undesirable proportions. Furthermore, during the following investi- 
gation, reduction of the chloride and oxide in hydrogen was investi- 
gated far enough to show that complete reduction of either compound 
was extremely difficult, if not impossible, without loss of material from 
the containing vessel by sublimation, aside from the fact that all 
available material for containing vessels is acted upon by either the 
fused salt or the reduced metal. ‘he elimination of moisture from 
lead nitrate or lead sulphate without decomposition of the salts 
seemed likely to prove a stumbling block in the use of these substances. 
Finally, in spite of the slight solubility of lead chloride, the determin- 
ation of the chlorine in this salt by precipitation with silver nitrate 
was chosen as presenting fewest difficulties. In the first place, the 
determination of a halogen can be effected with great accuracy. In the 
second place, the elimination of moisture from lead chloride is an easy 
matter, since the salt may be fused in a platinum vessel in a current 
of hydrochloric acid gas without attacking the platinum in the least 
and without the production of basic salts. In the third place, silver 
chloride, which has been precipitated from a dilute solution of lead 
chloride by means of silver nitrate, does not contain an amount of 
occluded lead salt large enough to be detected. 


PURIFICATION OF MATERIALS. 


Water. — All of the water used in either the purification or the 
analyses was distilled twice, once from an alkaline permanganate solu- 
tion and once from very dilute sulphuric acid. Block tin condens- 
ers were used in both distillations, and rubber and cork connections 
were avoided. Generally receivers of Jena glass were employed, but 
in certain cases the water was collected in platinum or quartz vessels. 

Hydrochloric acid. — Commercial C. P. hydrochloric acid was diluted 
with an equal volume of water and distilled with a quartz condenser, 
only the middle fraction being collected. 

Nitric acid. — Nitric acid was distilled with a platinum condenser, 


368 PROCEEDINGS OF THE AMERICAN ACADEMY. 


until free from chlorine. ‘T'wo distillations were invariably sufficient 
to accomplish this end, if the first third of each distillate was rejected. 

Silver. — Pure silver was obtained by methods already many times 
employed in this laboratory. Silver nitrate was dissolved in a large 
volume of water and the silver was precipitated as chloride with an 
excess of hydrochloric acid. ‘The precipitate was thoroughly washed 
and reduced with alkaline invert sugar. ‘The reduced silver, after 
being washed, was dried and fused on charcoal in the flame of a clean 
blast lamp. After the buttons had been cleaned by scrubbing with sand 
and etching with nitric acid, they were dissolved in pure dilute nitric 
acid and the silver was precipitated as metal with ammonium for- 
mate.12 ‘This silver was washed and fused in the flame of a blast lamp 
on a crucible of the purest lime. The buttons were cleaned as before, 
and then electrolyzed.13 Finally the electrolytic crystals were fused 
in a boat of the purest lime in a porcelain tube in a current of pure 
electrolytic hydrogen.1# The bars of silver were cut in pieces with a 
fine steel saw, etched with dilute nitric acid until free from iron, washed, 
dried, and heated in a vacuum to 400°C. The silver was kept in a 
desiccator containing solid potassium hydroxide. 

Lead chloride. —Three samples of lead chloride from two entirely 
different sources were employed. Sample A was prepared from me- 
tallic lead. Commercial lead was dissolved in dilute nitric acid, and 
the solution, after filtration, was precipitated with a slight excess of 
sulphuric acid. The lead sulphate was thoroughly washed, suspended 
in water, and hydrogen sulphide was passed in until the sulphate was 
almost completely converted into sulphide. Next the sulphide was 
washed with water, dissolved in hot dilute nitric acid, and the solution 
was freed from sulphur and unchanged sulphate by filtration. The 
lead nitrate thus obtained was crystallized twice, dissolved in water, 
and precipitated in glass vessels with a slight excess of hydrochloric 
acid. The chloride was washed several times with cold water and then 
crystallized from hot water eight times, the last five crystallizations 
being carried out wholly in platinum, with centrifugal drainage after 
each crystallization. In crystallizing the lead chloride the whole sam- 
ple was not dissolved at one time, but the same mother liquor was u 
for dissolving several portions of the original salt. Needless to say, 
the chloride was not exposed to contact with the products of combus- 
tion of illuminating gas, lest lead sulphate be formed. 

Sample B was prepared from commercial lead nitrate. This salt 


12 Richards and Wells, Pub. Car. Inst., No. 28, 19 (1905). 
13 Abrahall, Jour. Chem. Soc. Proc., 1892, p. 660. 
14 Baxter, These Proceedings, 39, 249 (1903). 


BAXTER AND WILSON. — THE ATOMIC WEIGHT OF LEAD. 369 


dissolved and crystallized from dilute nitric acid once in glass and six 
times in platinum vessels, with centrifugal drainage. Hydrochloric 
acid was then distilled into a large quartz dish, and the solution of 
the nitrate was slowly added with constant stirring with a quartz rod. 
The chloride was freed from aqua regia as far as possible by washing 
with cold water, and was once crystallized from aqueous solution in 
quartz dishes to remove last traces of aqua regia. Finally the salt 
was crystallized three times in platinum. 

It could reasonably be expected that both of these samples were of a 
high degree of purity ; nevertheless, upon heating the salt in an atmos- 
phere of hydrochloric acid, the salt itself turned somewhat dark, and 
upon solution of the fused salt in water a slight dark residue remained. 
Although in a few preliminary experiments attempts were made to 
‘determine this residue by filtration and ignition, it was subsequently 
found that even a small filter paper adsorbs appreciable amounts of 
lead compounds from a solution of the chloride, which cannot be re- 
moved by washing with water. From three to thirteen hundredths of 
a milligram of residue were obtained in several blank experiments, by 
ignition of filters through which half per cent solutions of lead chloride 
had been passed, with subsequent very thorough washing. In order to 
avoid the uncertainty of this correction, further attempts were made 
to obtain a sample of the salt which would give a perfectly clear solu- 
tion in water after fusion, and thus render filtration unnecessary. With 
this end in view a considerable quantity of Sample A was fused in a 
large platinum boat in a current of hydrochloric acid. The fused salt 
was powdered in an agate mortar, dissolved in water in a platinum 
vessel, and the solution was freed from the residue by filtration through 
a tiny filter in a platinum funnel into a platinum dish, where it was 
allowed to crystallize. This sample was then twice recrystallized with 
centrifugal drainage. Notwithstanding the drastic treatment to which 
it had been subjected, when a portion of this material was fused in hy- 
drochloric acid, the same darkening as before was observed, and the 
same residue was obtained. ‘he suspicion that the difficulty was due 
to dissolving of the filter paper by the solution of the salt15 led to 
a second more successful attempt by crystallization from hydrochloric 
acid solution in platinum vessels. In this way it was found possible 
to prepare salt which showed no tendency to darken upon heating, and 
which, after fusion, left absolutely no residue upon solution in water. 
Portions of Samples A and B were thus recrystallized three times 
more. Since these two specimens of material gave identical results, 


15 Mr. P. B. Goode in this laboratory has recently found a similar difficulty 
with the chlorides of the alkaline earths. 
VOL, XLII —24 


370 PROCEEDINGS OF THE AMERICAN ACADEMY. 


for two final experiments, portions from each of these samples were 
mixed and then subjected to three additional crystallizations. This 
last sample was designated Sample C. 


Metuop or ANALYSIS. 


The lead chloride contained in a weighed platinum boat was first 
fused in a current of pure dry hydrochloric acid gas. This gas was 
generated by dropping concentrated sulphuric acid into concentrated 
hydrochloric acid, and after being washed with a saturated solution of 
hydrochloric acid, was passed through five towers filled with beads 
moistened with freshly boiled concentrated sulphuric acid, to dry the 
gas. It has already been shown that phosphorus pentoxide may not 
be used for this purpose.4® After the salt had cooled, the hydro- 
chloric acid was displaced by dry nitrogen, and this in turn by dry air. 
Nitrogen was prepared by passing air charged with ammonia over red- 
hot rolls of copper gauze, the excess of ammonia being removed by means 
of dilute sulphuric acid. The gas was passed over beads moistened 
with a dilute silver nitrate solution and over solid caustic potash to 
remove sulphur compounds and carbon dioxide respectively, and was 
finally dried by concentrated sulphuric acid and phosphorus pentoxide. 
The air was purified and dried in a similar fashion. The apparatus 
for generating the hydrochloric acid and for purifying the hydrochloric — 
acid and nitrogen was constructed wholly of glass with ground-glass 
joints. The platinum boat containing the fused chloride was next 
transferred to a weighing bottle without exposure to moist air, by 
means of the bottling apparatus, which has frequently served for a 
similar purpose in many atomic weight investigations in this labora- 
tory.17 After standing some time in a desiccator in the balance room, — 
the weighing bottle was weighed. In most of the analyses the lead 
chloride was dissolved from the boat by prolonged contact with boil- 
ing water in a Jena glass flask. In the last two analyses, in order 
to show that no error was introduced through solubility of the glass, 
the solution was prepared in a large platinum retort, and was not 
transferred to the precipitating flask until cold. 

Very nearly the necessary amount of pure silver was then weighed 
out and dissolved in redistilled nitric acid diluted with an equal 
volume of water in a flask provided with a column of bulbs to pre- 
vent loss by spattering. After the silver was all dissolved, an equal 
volume of water was added, and the nitrous fumes were expelled 


16 Baxter and Hines, Jour. Amer. Chem. Soc., 28, 779 (1906). 
11 Richards and Parker, These Proceedings, 32, 59 (1896). 


BAXTER AND WILSON. —THE ATOMIC WEIGHT OF LEAD. 371 


by gentle heating. The solution was then further diluted until 
not stronger than one per cent, and added slowly, with constant 
agitation, to the solution of lead chloride contained in the precipi- 
tating flask. The precipitation and handling of the silver chloride 
were conducted in a room lighted with ruby light. The flask was 
shaken for some time and allowed to stand for a few days, with 
occasional agitation, until the supernatant liquid had become clear. 
Thirty cubic centimeter portions of the solution were then removed 
and tested with hundredth normal silver nitrate and sodium chloride, 
in a nephelometer,!® for excess of either chloride or silver, and, if 
necessary, standard silver nitrate or sodium chloride was added, and 
the process of shaking and testing repeated until the amounts of silver 
and chloride were equivalent. ‘The test solutions were always returned 
to the flask, since they contained appreciable amounts of silver chlo- 
ride, and the weight of silver chloride subsequently obtained was cor- 
rected for the quantity thus introduced. Furthermore, if an excess of 
silver was found, a negative correction of an equivalent quantity of 
silver chloride was necessary. 

After the exact end point had been obtained, about two tenths of a 
gram of silver nitrate in excess was added in order to precipitate the 
dissolved silver chloride, and the flask was thoroughly shaken, and 
allowed to stand again until the solution was perfectly clear. The 
silver chloride was washed, first several times with a very dilute silver 
nitrate solution containing four hundredths of a gram per litre, and 
then eight times with pure water. It was next transferred to a Gooch 
crucible and dried for several hours in an electric oven, the tempera- 
ture being gradually raised to 180°, and was cooled in a desiccator and 
weighed. In every case the moisture retained by the precipitate was 
determined by fusion in a small porcelain crucible. The silver chlo- 
ride, dissolved in the filtrate and washing, was determined by comparison 
with standard solutions in the nephelometer in the usual manner. 
Care was taken to treat both tubes in exactly the same manner, and 
final readings were taken only when the ratio had become constant. 
Before proceeding to the nephelometer tests, however, the filtrate and 
washings were passed through a very small filter in order to collect a 
small quantity of asbestos shreds mechanically detached from the Gooch 
crucible. The filter was ignited and weighed, the ash being treated 
with a drop of nitric and hydrochloric acid in order to convert any 
reduced silver into chloride. In order to find out whether lead or 
silver nitrates were appreciably adsorbed by the filter paper, a solution 


18 Richards and Wells, Am. Ch. J., 31, 235 (1904) ; 35, 510 (1906). 


3872 PROCEEDINGS OF THE AMERICAN ACADEMY. 


THE ATOMIC WEIGHT OF LEAD. 
Series I. PbCl,:2 Ag. 
Ag = 107.980 ; Cl = 35.478 


Number | Sample | Weight of Weight of Weight of 
of of PvCcl, Ag in ad Weight of 
Analysis. | PbCl,. in Vacuum. Pb. 


4.67691 3.63061 : 3.62987 207.179 
8.67705 2.853875 ᾿ 2.85375 207.189 
4.14110 3.21888 ; 8.21408 201.178 
4.56988 3.54672 3.54672 207.185 
5.12287 3.97596 ὶ 8.97568 207.201 
3.85844 2.99456 ᾿ 2.99456 207.186 
4.67244 3.62628 : 3.62628 207.189 
3.10317 2.40837 N 2.40837 207.188 
4.29613 3.98427 O00: 3.33407 207.202 


Average. . .ὄ . Ὁ «tin aU elite) 6 be oe 
Number Weight of | Weight of Corrected 
f 


PbCl, in | AgClin ο Weight 
Vacuum. | Vacuum. | Fusion. | Asbestos. of AgCl. 


grams grams gram gram grams 


4.67691 | 4.82148 | 0.00100 | 0.00021 | 0.00204 | 4.82275 

414110 | 4 26848 | 0.00020 | 0.00008 | 0.00180 | 4.27016 | ' 

5.12287 | 5.28116 | 0.00054 | 0.00013 | 0.00197 | 5.28272 

8.85844 | 8.97759 | 0.00035 | 0.00033 | 0.00192 | 3.97949 
8.19751 | 0.00045 | 000014 0.00189 | 3.19909 

| 4.29613 | 4.42780 | 0.00020 1 0.00004 | 0.00268 | 4.42982 


Average 


Average, rejecting the least satisfactory analyses, 13 and 14 
Average of Series I and II 


BAXTER AND WILSON. — THE ATOMIC WEIGHT OF LEAD. 3190 


containing lead nitrate, silver nitrate, and nitric acid of the concentra- 
tion of these filtrates, was passed through several small filter papers, 
which were then very carefully washed. In four cases, after incinera- 
tion of the papers, there was found, —0.00001, +0.00002, +0.00003, 
+0.00001 gram of residue, exclusive of ash. This correction is so small 
that it is neglected in the calculations. In all the analyses the plati- 
num boat behaved admirably, the loss in weight never amounting to 
more than a few hundredths of a milligram. 

The balance used was a short arm 'T'roemner, easily sensitive to a 
fiftieth of a milligram. The gold-plated brass weights were carefully 
standardized to hundredths of a milligram. All the weighings were 
made by substitution with tare vessels as nearly like those to be 
weighed as possible. 

Vacuum corrections: The values of the density of lead chloride as 
given by various observers range from 5.78 to 5.805,1® the mean of 
the more accurate determinations being 5.80. This gives rise to 
ἃ vacuum correction of +0.000062 for each apparent gram of lead 
chloride, the density of the weights being assumed to be 8.3. The 
other vacuum corrections applied were silver chloride, +0.000071, and 
silver, —0.000031. 

All analyses which were carried to a successful completion are 
recorded in the preceding tables. 

The close agreement of the averages of the two series is strong 
evidence that no constant error, such as occlusion, affects the results. 
Furthermore, in all, 19.55663 grams of silver produced 25.98401 grams 
of silver chloride, whence the ratio of silver to silver chloride is 132.865, 
a value in close agreement with the result 132.867 obtained by Richards 
and Wells.2° Furthermore, the different samples, A, B, and OC, all 
give essentially identical results. 

_It appears, then, that if the atomic weight of silver is taken as 107.93 
(0 = 16.000), the atomic weight of lead is 207.19, nearly three tenths 
of a unit higher than the value now in use. If the atomic weiglit of 
silver is 107.88, a value probably nearer the truth than 107.93, lead 
becomes 207.09, a number still much higher than that depending upon 
Stas’s syntheses, as is to be expected. 

We are greatly indebted to the Carnegie Institution of Washington 
for assistance in pursuing this investigation, also to Dr. Wolcott Gibbs 
and to the Cyrus M. Warren Fund for Research in Harvard University 
for many indispensable platinum vessels. 


CamprinGE, Mass., October 18, 1907. 


19 Landolt-Bornstein-Meyerhoffer, Tabellen. 20 Loe. cit. 


Ut Pa POT ον τ)" δου νυ ἀν δ δ Σὰ τὸ τὴ ΟἿΣ SS a ae πὰ SLE A ὦ 


VOLUME 42. 


ἜΟΒΙΝΒΟΝ, B. L.— Studies in the Eupatorieae: (1.) Revision of the Genus Piqueria; (II.} 

; Revision of the Genus Ophryosporus ; (III.) The Genus Helogyne and its Synonyms; (IV.) 

Diagnoses and Synonymy of Zupatorieae and of Certain Other Compositae which have been 
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Sazine, W. C. — Architectural Acoustics: (I.) Introduction; (II.) The Accuracy of Musical 
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Ἂς 3. Ῥεῖβοε, B. Ο. --- On the Permeability and the Retentiveness of a Mass of Fine Iron Particles. 

πος. pp. 85-91. June, 1906. 15c. 

_ 4, Peirce, B. O.— On the Length of the Time of Contact in the Case of a Quick Tap on a Tele- 

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5. Mark, E. L., and Copetanp, M.—Some Stages in the Spermatogenesis of the Honey Bee. 

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. Hoga, J. L. — Friction and Force due to Transpiration as Dependent on Pressure in Gases. 
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Peirce, B. O. — On the Correction for the Effect of the Counter Electromotive Force induced 
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Femce, B. 0. —A Simple Device for Measuring the Deflections of a Mirror Galvanometer. 
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-Ripprz, L. W. —On the Cytology of the Entomophthoraceae. pp. 175-197. 3 pls. August, 
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Baxter, α. P. —A Revision of the Atomic Weight of Bromine. pp. 199-214. August, 1906. 

LARRABEE, A. P. —The Optic Chiasma of Teleosts: A Study of Inheritance. pp, 215-231. 

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HARVARD UNIVERSITY. 


PLE METHOD OF MEASURING THE INTENSITY 
OF SOUND. 


By GEORGE W. PIERCE. 


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oceedings of the American Academy of Arts and Sciences. 


Vou. XLIII. No. 13.— Fesruary, 1908. . 


HARVARD UNIVERSITY. 


OF SOUND. 


By GrorRGE W. PIERCE. ἢ 


| <a ΒΗ δ. ™ ae ΕἾΝ ee ae, Se ) ian aoa Dee ae ee 6.55.“ a ee eee ae ἘΦ oe, ee <_ aa 7 eS eae eee 


MAR 2 -- 1908 


CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY, 
HARVARD UNIVERSITY. 


A SIMPLE METHOD OF MEASURING THE INTENSITY 


OF SOUND. 
By GEORGE W. PIERCE. ΝΕ ΟΣ 
Presented January 8, 1908. Received January 4, 1908. BOTANK 
GARDEN 


I. Inrropuction. 


In the course of a series of experiments on Detectors for Electro- 
magnetic waves the writer has found a number of solid substances 
which, when supplied with contact electrodes and put into electric 
circuits, serve as rectifiers for small electric oscillations. Some of 
these substances used in connection with a galvanometer prove to be 
extremely sensitive and constant in their action and permit the meas- 
urement of the currents generated by the vibration of the diaphragm 
of a magneto-telephone under the action of sound waves even when 
the telephone is at a considerable distance from the source of sound. 

With the use of this device the relative intensity of sound at differ- 
ent positions in a room may be measured, and many interesting results 
as to the acoustic properties of an auditorium may be obtained. 

The study of the rectifiers themselves is the subject of a series of 
papers by the writer, on “Crystal Rectifiers for Electric Currents and 
Electric Oscillations.” Part I of this series of papers appeared in the 
Physical Review for July, 1907, Vol. XXV, pp. 31-60. The rectifier 
there investigated is Carborundum. Several other crystal bodies, 
some of which are in their action much more sensitive than car- 
borundum, possess similar properties and are being experimentally 
studied in detail with reference to their electrical characteristics and 
with reference to their use in electric-wave telegraphy. 

The results of this study will constitute the subject matter of 
succeeding parts of the Physical Review article. 


Il. MotyppEniTe AS A ΒΕΟΤΙΕΙΕΝ FOR ELEcTRIc OSCILLATIONS. 


One of the most sensitive of the rectifiers thus far investigated is 
Molybdenite. The present paper deals with the use of the molyb- 
denite rectifier in the measurement of sound. 


3738 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Molybdenite is also an extremely sensitive detector for electric 
waves in wireless telegraphy, and may also be employed in experi- 
ments on telephony and in many other experiments where it is required 
to measure small electric oscillations. 

The manner of mounting and employing the substance is substan- 
tially the same in these several applications, and is capable of several 
variations, only one of which will be given here. Molybdenite, Mos,, 
is a mineral occurring in nature in the form of hexagonal prisms with 
eminent cleavage parallel to the base, and may be scaled off in thin 
sheets, a few sq. cm. in area, resembling bits of tin-foil. In the present 
experiments a thin sheet so obtained was mounted in the manner 
shown in the sectional drawing of Figure 1. 


7 


1) 


2 


= 


SS 


My [mmm 
- Ξ 


VZV 


Ficure 1. — Rectifier. 


A thin, circular piece of molybdenite? (M, Figure 1), about 1 sq. em. 
in area, is clamped tightly between a piece of mica N and the hollow 
brass post A, by means of a brass cap C screwed down on the post A. 
‘The molybdenite is thus held in electrical connection with the annular 
surface of the end of the hollow brass post A, which is in turn metal- 
lically connected with the binding post G. Separated from A by an 
air space, a small pointed brass rod B is screwed up through a metallic 
strip H attached to a second binding post F. The binding posts and 
the holder for the molybdenite are rigidly supported by a porcelain 
base PP. The seat of the action of the molybdenite as a rectifier is 
at the small region of contact between the molybdenite and the pointed 
rod. In the construction of the rectifier this contact is adjusted by 
screwing the rod up through H until a galvanometer in series with 
the device and a source of alternating voltage (of about .05 volt) gives 


1 Molybdenite free from iron should be used. 


PIERCE. — A METHOD OF MEASURING THE INTENSITY OF SOUND. 379 


a maximum deflection. ‘The adjustment of the contact is made once 
for all, and subsequent accidental changes of the apparatus is prevented 
by filling the cavity about H with melted wax or plaster of Paris. 

When made in this manner the rectifier will stand considerable 
abuse in the way of jar and overload. It is, however, subject to 
changes due to the expansion and contraction of the mounting, and 
due also possibly to a temperature coeflicient of the molybdenite itself. 
Effort to get a mounting without such changes with temperature and 
a study of the temperature coefficient of the substance itself are now 
in progress. Up to the present it is found advisable to use the rectifier 
in a thermostat at constant temperature, when accurate quantitative 
agreement between observations extending over a considerable period 
of time is required. 

Whether or not the direct current obtained from the molybdenite 
in contact with two unequal electrodes is a thermo-electric action due 
to the unequal heating of the electrodes by the oscillating current is 
at present not known. It will be seen that the conditions are favor- 
able for such thermo-electric action. In order not to commit one’s 
self to any particular theory as to the nature of the action, the device 
is here referred to as a “rectifier,” in that the current in one direction 
due to an impressed voltage is very different from the current in the 
opposite direction under the same voltage. 


11. Execrric Crrcurrs Emptoyep witH THE MOLYBDENITE 
RECTIFIER IN EXPERIMENTS ON SOUND. 


In the measurement of sound, the rectifier was at first placed 
directly in series with a sensitive galvanometer and a Bell magneto- 
telephone receiver. With this arrangement, when sound was made in the 
neighborhood of the receiver, the vibration of the telephone diaphragm 
generated electric oscillations in the circuit. These oscillations passed 
through the rectifier more strongly in one direction than in the oppo- 
site direction, and caused a deflection of the galvanometer. 

However, on account of the high resistance of the rectifier, and in 
order to take advantage of electrical resonance in the circuits, it was 
found better to employ an arrangement of circuits containing a 
step-up transformer, as is shown in Figure 2. 

In Figure 2 PS is a transformer, the primary P of which is con- 
nected in series with the telephone ‘I’ and an adjustable condenser C. 
The secondary S of the transformer is connected in series with the 
rectifier R, the galvanometer G, and a calibrating device at W. By 
adjusting the condenser ©, the electric circuit TCP was brought to 


380 PROCEEDINGS OF THE AMERICAN ACADEMY. 


resonance with the alternating voltage impressed on the system by the 
periodic impact of the sound waves. ‘This adjustment was easily made 
experimentally. 

The proper choice of the transformer PS and the telephone 'T’ was a 
more difficult problem. A theoretical solution of this problem was not 
at hand, on account of lack of knowledge of the characteristics of the 
telephone when used as a generator of oscillatory currents and on ac- 
count of the fact that the current through the crystal in the secondary 
is not a simple function of the voltage in this circuit (see Figure 6). 
Some aid in the choice was had in the following considerations, which 
served to point vaguely the direction in which experiment was to be 
made : 

1. Since the primary circuit was to be brought to resonance with the 
oscillations, the inductance of the primary circuit is negligible, if we 


PAV 


Figure 2.— Electric circuit. 


may neglect the reaction of the secondary circuit on the primary. With 
this approximation it follows from elementary considerations that the 
resistance of the primary.coil should be equal to the resistance of the 
telephone. Experiment soon showed that the reaction of the secondary 
circuit was not negligible, and since the effect of the reaction of the 
secondary is to increase the apparent resistance of the primary, it fol- 
lows that the resistance of the primary coil should be somewhat less 
than that of the telephone. 

2. The iron core of the transformer should be such as to be properly 
magnetizable by the current generated by the telephone, which in fre- 
quency and intensity approaches to the current used in telephony. 
Whence it seemed probable that the small terminal transformers use 
in telephony would have about the proper amount of iron for use in 
the present experiments. 


PIERCE. — A METHOD OF MEASURING THE INTENSITY OF SOUND. 381 


3. The resistance of the secondary of the transformer and that of the 
galvanometer should be high because the resistance of the crystal for a 
small current is several thousand ohms. 

Guided by these considerations, and by the results of preliminary 
experiments with several small induction coils, two transformers were 
wound, of which the one that proved the more satisfactory had the 
following dimensions : 

Length of iron core, 9.5 em. 

Diameter of iron core, 1 em. 

Depth of channel, 1.5 em. 
In this channel were three coils of which either pair could be used as 
primary and secondary. ‘'hese three coils had respectively 16, 280, 
and 720 ohms resistance. 

With this transformer experiments were made with three different 
telephones, of which a Siemens and Halske “ Lautsprecher,” rewound to 
466 ohms, and provided with a small conical sound collector 10 em. in 
diameter, proved the most sensitive. This telephone was ordinarily 
used with the 280 ohm primary and the 720 ohm secondary. The 
other two telephones used had resistances of 53.8 and 99.8 ohms re- 
spectively, and were used with the 16 ohm primary and the 720 ohm 
secondary. 


Experiment I. Adjustment of the Receiving Telephone Circuit to 
Resonance with the Sound. — After having made a preliminary selec- 
tion of the pitch to be employed in a particular experiment, it becomes 
important to adjust the electrical circuit to resonance with this pitch. 
The following data is given to show the manner in which this adjust- 
ment is made, and to show the effect of such a resonant adjustment in 
_ increasing the sensitiveness of the apparatus. 

An organ-pipe FZ, giving 705 complete vibrations per second, sup- 
plied by air from bellows operated by an electric blower and set up in 
the Constant Temperature Room 3 of the Jefferson Physical Laboratory, 
served as source of the sound. 

The telephone receiver, having a resistance of 53.8 ohms, and pro- 


2 This room is described in Professor Sabine’s paper on “ Architectural Acous- 
tics, Part I, Reverberation,” published in the American Architect, Vol. XLVIII, 
April-June, 1900, and in Contributions from the Jefferson Physical Laboratory, 
Vol. IV, 1906. This room was used in some of the present experiments because the 
apparatus for producing the sound happened to be in place there. The appara- 
tus was in use by Professor Sabine, and together with other parts of the appa- 
ratus, including two of the receiving telephones, was kindly placed by him at my 
disposal. 


382 PROCEEDINGS OF THE AMERICAN ACADEMY. 


vided with a conical sound-collector 29 cm. in diameter, was placed at 
a distance of about 1.5 meters from the organ-pipe. The 16 ohm prim- 
ary and the 720 ohm secondary of the transformer, Figure 2, were em- 
ployed. ‘I'he galvanometer G was a d’Arsonval type and had a resistance 
of 538 ohms, and gave a throw of one scale division (75 inch) for a 
current of 1.53 Χ 10. amperes. 

The condenser C, Figure 2, having a total capacity of 1 microfarad, 
and adjustable by steps of .05 microfarads, was given various values, 
and the corresponding throws of the galvanometer when the pipe 
was sounded were taken. In taking these readings the pipe was left 
sounding until the coil of the galvanometer had completed its swing. 

The results are recorded in ‘Table I. 


TABLE I. 
ADJUSTMENT OF ELEcTRIC CrrcuIT TO RESONANCE WITH 


Sounp FREQUENCY. 


Capacity of C Current through Galva- 
in Microfarads. nometer in Microamperes, 


.00 000 

064 
30 
45 
50 
60 
.80 
1.00 


C short-circuited 


The curve of Figure 3 is plotted from the data of Table I. The hori- 
zontal dotted line through the figure is the current with the condenser 
short-circuited. This curve gives an idea of the advantage obtained 
by the use of the proper capacity in the primary circuit of Figure 2. 
The maximum of the curve shows a value of the current that is 
nearly eight times the current obtained when the condenser was 
short-circuited. 


PIERCE. — A METHOD OF MEASURING THE INTENSITY OF SOUND. 989 


IV. Srationary Sounp Waves. DIstripuTion oF INTENSITY. 


In taking the data of Experiment I, the position of the telephone re- 
ceiver and that of the organ-pipe were left constant. When the tele- 
phone was removed to different parts of the room, very striking evidence 
of a stationary-wave system 
was obtained. his station- 
ary system was, however, ex- ese ei, 
tremely complicated. In πὰ 
some positions, for example,  - (REN LS 
avery slight change of the 
inclination of the sound-col- ΩΝ ἄν 
lecting cone, without any 
motion of the receiver as a 
whole toward or away from 
the source of sound, would 
cause several hundred per 
cent change of the reading of 
the galvanometer. Professor 
Sabine has already called at- 
tention to the existence in 
this room of a striking inter- 
ference system. The follow- Figure 5.— Resonance curve. 
ing paragraph descriptive of 
the phenomenon is quoted from his writings on the subject : 

“This room is here described at length because it will be frequently 
referred to, particularly in this matter of interference of sound. While 
working in this room with a treble ὁ gemshorn organ-pipe blown by a 
steady wind pressure, it was observed that the pitch of the pipe appar- 
ently changed an octave when the observer straightened up in his chair 
from a position in which he was leaning forward. The explanation is 
this : The organ-pipe did not give a single pure note, but gave a funda- 
mental treble ¢ accompanied by several overtones, of which the strong- 
est was in this case the octave above. Each note in the whole complex 
sound had its own interference system, which, as long as the sound re- 
mained constant, remained fixed in position. It so happened that at 
these two points the region of silence for one note coincided with the 
region of reinforcement for the other, and wee versa. Thus the ob- 
server in one position heard the fundamental note, and in the other, 
the first overtone. The change was exceedingly striking, and as the 
note remained constant, the experiment could be tried again and 
again. With a little search it was possible to find other points in the 


MICROAMPERES 


CAPACITY. MICROFARAD. 


284 PROCEEDINGS OF THE AMERICAN ACADEMY. 


room at which the same phenomenon appeared, but generally in less 
perfection.” % 

Before undertaking the study of the complicated distribution of 
sound intensity in a room with highly reflective walls, it was decided 
to become better acquainted with the present experimental method by 
an examination of a much simpler interference system ; namely, that 
produced as nearly as may be by a single reflecting surface. ‘This is 
done in Experiment II following. Afterward, in Experiment III, it is 
shown to be practicable to extend the investigation to a quantitative 
determination of the distribution in a large auditorium. 


Experiment II. Stationary Wave Produced by a Single Reflecting 
Surface. — The arrangement of apparatus is shown in Figure 4. In 
order to reduce the effects of reflection from the walls of the room, 


Ficure 4.— Position of apparatus in constant temperature room. 


they were curtained off with felt, Εἰ, 1.1 cm. thick, hung at a distance 
of about 50 cm. from the walls. Felt of the same thickness was also 
placed overhead, separated from the ceiling by about 50 em. 

The organ-pipe, ΕΖ, 705, serving as a source of sound, was placed 
at P, near the center of the room. ‘The telephone receiver, used in 
Experiment I, was placed at 1, about 70 cm. from the pipe. Leads 
ran from the telephone to the condenser and transformer, which 
together with the observer and galvanometer were in a distant 
room. 

A reflecting surface of wood, 73 em. wide by 122 em. high, was placed 
vertically at W, and was mounted on a track so as to be capable of dis- 


3 Sabine, loc. cit. p. 8. 


PIERCE. — A METHOD OF MEASURING THE INTENSITY OF SOUND. 3885 


placement along the scale ὃ. The open end of the pipe was placed at a 
height of 61 cm., and was therefore on a level with the middle of the 
reflector. 


MICROAMPERES 


10 20 30 40 60 60 70 80 90 ῖοο 10 120 130 


DISTANCE FROM WALL TO PIPE—CM. 


Ficure 5.—Curve 1, stationary wave in terms of current in secondary. 
Curves 2 and 3, stationary waves in terms of voltage in secondary. 


The distance from the reflector W to the pipe P could be varied and 
was read off on the scale ὃ. Readings of the galvanometer were taken 
with the reflector at various stages, 5 cm. apart, along the scale. The 


values of the current in the galvanometer circuit are plotted against 
VOL. xXLi11.— 25 


886 PROCEEDINGS OF THE AMERICAN ACADEMY. 


the distance of the reflector from the pipe, in Curve 1 of Figure 5. 
This curve shows the stationary wave system set up by the interfer- 
ence of the direct and the reflected waves. The distances between al- 
ternate nodes and alternate loops of the curve give the following values 
of the wave-length : 


49.7, 49. 45.8, 51, 46.5; Average, 48.4. 


The velocity of sound at the temperature of the room, 18°, was 34200 
cm. per second, whence the period 


__ 34200 
~ 48.4 


= 706, 


while the actual value of the pitch of the pipe FS, is 705 vibrations 
per second. ‘This agreement is evidently better than is to be expected 
from the method, on account of ἐμ uncertainty of locating the nodes 
and loops of the curve. 

It is seen, however, that the pbints of the stationary wave lie well on 
the curve. A repetition of the observation on a succeeding day gave 
substantial agreement with Curve 1. It is to be observed that the 
first maximum, with the reflector in the neighborhood of 23.5 em. from 
the pipe, is weaker than the second and third maxima. This is prob- 
ably caused by the fact that the wind-chest on which the pipe was 
mounted intercepted the reflected wave more strongly when the re- 
flector was close up than when it was more distant from the pipe. 

The horizontal dotted line through the curve at 3.30 gives the mag- 
nitude of the current when the reflector was removed. It is seen that 
the peaks of the curve above the line of no reflector are much greater 
than the neighboring depressions of the curve below the line. ‘This 
distortion was found to be chiefly due to the current-voltage character- 
istic of the rectifier, and is eliminated by the calibration of the recti-— 
fier with an alternating voltage, and by plotting the stationary wave 
in terms of alternating voltage instead of galvanometer current. 

In making the substitution of voltage for current it would be in- 
structive to impress the known alternating voltage on the primary of 
Figure 2, and take the corresponding throws of the galvanometer in 
the secondary. We should then be able to know the voltage generated 
by the telephone when we know the galvanometer current. However, 
on account of the influence of the transformer, this could be properly 
done only with an alternating voltage of the same frequency as the 
sound, in this case 705 cycles. A generator for this frequency was not 


PIERCE. — A METHOD OF MEASURING THE INTENSITY OF SOUND. 387 


at the writer’s disposal, so it was decided to calibrate the secondary 
circuit instead of the primary. For this, a 60 cycle alternating voltage 
could be employed without much error ; for a preliminary experiment 
had shown that the impedance of the secondary of the transformer was 
practically negligible in comparison with the resistance of the rectifier, 
and that the current-voltage characteristic of the rectifier, as far as 
tests could be made with means at hand, was independent of the 
frequency. 

The calibration of the secondary circuit was made as follows : The 
slide wire of a potentiometer was inserted at W in Figure 2, and a source 
of alternating voltage was applied at AV. The drop of potential in W 


MICROAMPERES 


VOLTS ALTERNATING 


Figure 6, —Current-voltage characteristic of rectifier. 


was known from the resistance of W and the readings of an alternat- 
ing current ammeter at I. The alternating voltage in W was varied 
by varying the resistance of W, and the corresponding direct current 
in the galvanometer was read. ‘These values are plotted in Figure 6. 

If now we replace the current values in Figure 5 by the correspond- 
ing voltage values in the secondary of the transformer we obtain Curve 
2 of Figure 5. This curve is independent of the rectifier, and shows 
the number of alternating volts at the terminals of the secondary of the 
transformer of Figure 2 for various positions of the reflecting wall in 
Figure 4. Except for distortion of the wave when the reflector was 
too close to the pipe this curve is nearly symmetrical about the line 
of no reflector. 


385 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Curve 3 of Figure 5 is another curve obtained in the same way with 
a slate reflector at W and a pipe of slightly higher pitch, and with the 
Siemens and Halske telephone, which had a much smaller sound col- 
lecting cone, 10 cm. in diameter. ‘This curve is somewhat more nearly 
symmetrical in character. 

[Ὁ should be noted in respect to these curves that there was still con- 
siderable reflection from the room, in spite of the felt curtains, and 
that these reflected waves act in a manner to distort the stationary 
system. 

The curves of Figure 5, although taken under somewhat artificial 
conditions are in themselves instructive, in showing the marked effect 
of a reflecting wall on the loudness and quality of sounds. When a 
speaker or an orchestra is at any given distance in front of a reflecting 
wall certain tones will be greatly reduced in intensity while tones of a 
different pitch will be greatly intensified, thus it may be changing 
completely the emphasis and quality of the composition. When there 
is only a single strongly reflecting wall (the other walls being strongly 
absorbtive) this distortion occurs over practically the whole room, al- 
though, of course, at different points in the room different notes will be 
suppressed or emphasized depending on the phase difference between 
the direct and reflected waves to the auditor. 


Experiment III. Interference af Sound Waves in a Large Lecture 
Room. — In order to extend the investigation to the study of the dis- 
tribution of sound intensity in a room of considerable proportions, an 
organ-pipe and the telephone receiver were set up in the large lecture 
room of the Jefferson Physical Laboratory. This room, of which a 
diagram is shown in Figure 7, is 18.6 meters long, 12.7 meters wide, 
and 7.7 meters high at one end. It contains seats for about 300 stu- 
dents. ‘These seats are progressively raised toward the back of the 
room so that the height of the ceiling above the seats in the rear is 
about 4 meters. The walls of the room are of brick. 

he organ-pipe used as a source of sound, G,, 768, was placed at the 
position P in the diagram, and was supplied with wind at a constant 
pressure from a reservoir, from which the air supply to the pipe was 
turned on and off by an electro-pneumatic valve operated by a battery 
and clock work. 

The Siemens and Halske telephone receiver, 466 ohms, with the 
sound-collecting cone 10 cm. in diameter, was used as a receiver for 
the sound and was provided with a long double lead so that it could 
be placed anywhere in the room. 

The first position chosen for the receiver was at the extreme rear of 


PIERCE. — A METHOD OF MEASURING THE INTENSITY OF SOUND. 389 


the room (1, Figure 7), where a small track 10 cm. wide and 2 meters 
long was run out perpendicularly from the wall. The telephone was 
placed on this track with the opening of the sound collector toward the 
wall, and readings of the galvanometer were taken with the telephone 
at various distances from the wall. ‘lhe results obtained are plotted in 
Curve 4 of Figure 8. The abscissae of this curve are the distances in 
centimeters from the wall measured to the opening of the sound col- 


Figure 7.— Diagram of large lecture room. P is the position of the source 
of sound; 1, 2, and 3, positions of the receiver. 


lector ; the ordinates are the corresponding values of the current ob- 
tained in the galvanometer when the organ-pipe was sounded. ‘The 
first reading, .73 X 1077 amperes, was obtained with the opening of the 
sound collector of the telephone jammed tight against the brick wall. 
On withdrawing the receiver from the wall by stages of 5 cm., while 
keeping the opening of the sound collector always toward the wall, the 
succeeding values of the curve were obtained, showing the occurrence 
in this part of the room of very decided maxima and minima of 


390 PROCEEDINGS OF THE AMERICAN ACADEMY. 


sound intensity. ‘The irregularities of the curve were actually exist- 
ent in the interference system and were verified by a repetition of the 
experiment. 

In the above curve the current obtained at the best of the maxima 
was 3.30 Χ 1077 ampere. When it is noted that this was at a distance 
of 15 meters from the source of sound, it will be seen that the receiving 
apparatus possesses quite remarkable sensitiveness. Of course, too 
much importance must not be given to the distance from the source 
as a determining factor of the intensity, for, as will soon appear, this 
particular position, accidentally chosen, in the rear of the room was 
a position in which the sound was more intense than at many places 
much nearer to the source. However, even with a galvanometer of 
only moderate sensitiveness it was possible to extend the investigation 
satisfactorily to any part of the room. Curves of results at two other 
positions in the room are discussed below. 

The question arises, how may we determine the exact region of 
space to which the indications belong? In Curve 1 of Figure 8 a 
maximum was found when the opening of the receiver was 5 em. from 
the wall. Is the maximum of sound vibration at the opening of the 
cone, and, therefore, 5 em. from the wall or is it inside the cone or 
outside the cone? Can we locate its exact position? In attempting to 
answer these questions it was decided to try the effect of reversing the 
telephone so that the opening pointed away from the wall. With the 
telephone thus reversed Curve 5 of Figure 8 was obtained. Unfortu- 
nately, on account of the size of the telephone and cone, it was not 
possible to extend the observations to points nearer the wall than 
40 cm. ‘The distance measurements for this curve were also made 
from the wall to the opening of the cone. By a comparison of this 
curve with Curve 4 we may get some evidence of the location in space 
of the sound vibration. 

he two maxima of Curve 5 probably correspond respectively to the 
two right band maxima of Curve 4, as is evidenced by their distance 
apart, and their relative amplitudes, and by the distance apart of the 
minima of Curve 5 as compared with the minima at 75 and 108 of 
Curve 4. Now it is seen by inspection that these two curves would be 
brought into coincidence as to location of maxima and minima, if, 
instead of having measured from the wall to the opening of the cone 
of the telephone, we had measured to a point 5.7 cm. outside of the 
cone; that is to say, the indications of the galvanometer are indica- 
tions as to the relative amplitude of the sound vibration at a point 5.7 em. 
outside of the opening of the sound-collecting cone. 

While this reasoning is not entirely conclusive without further 


δος τῇ 


= 


΄ 


PIERCE. — A METHOD OF MEASURING THE INTENSITY OF soUND. 391 


evidence, because of the possible actual disturbance of the stationary 
system by the reversal of the telephone, yet the result seems highly 
probable on account of its agreement with the familiar fact that the 
maximum of motion of the air column of a tubular resonator is outside 
the end of the resonator. ‘he sound-collecting cone of the present 
apparatus is a resonator for the pitch employed — in fact, the particu- 
lar pitch was selected by a preliminary experiment which showed that 
the air column of this cone was in resonance with the pitch — and this 
resonant air column, according to deductions from the above experi- 
ment, is thrown into most active. vibration when a region just outside 
(5.7 cm.) the opening of the cone is coincident with a region of large 
displacement. 

This result enables us to locate the actual position of the nodes and 
loops of Curve 4, Figure 8. Hach point of the curve belongs to a 
region of space 5.7 cm. nearer to the wall than the corresponding 
abscissa ; therefore, the first maximum of motion, which was obtained 
with the opening of the cone 5 cm. from the wall, is really .7 cm. 
behind the wall, — that is to say, practically coincident with the wall. 

In order to examine the distribution of sound intensity in the 
neighborhood of another portion of the wl of the room, the telephone 
receiver and its track were placed at 2%in Figure 7, and the galvan- 
ometer readings were taken with the opening of the cone turned 
toward the wall and placed at various distances from the wall. Curve 
6 of Figure 8 was obtained as representative of the distribution at this 
position. Here again the corrected position of the first maximum is 
practically coincident with the wall. ‘The interference system in this 
locality is much more irregular than in position 1, and the maxima 
with the exception of the maximum at 90 cm. are less intense than 
those at position 1. This is interesting when we note the fact that 
the distance of the position 2 from the source of sound is only one 
half as great as the distance of position 1. For hearing this particu- 
lar note the position at the back of the room is more favorable than 
the much nearer position at the side of the room, notwithstanding the 
fact that the side position was directly in front of the lip of the pipe 
and was unobscured by intervening objects, while a line running from 
the source of sound to the position in the rear of the room passed 
immediately over the backs of numerous benches with which the room 
was furnished. . 

At a third position in the room, position 3, Figure 7, an interval 
of 100 cm. was investigated. ‘The results obtained are shown in 
Curve 7, Figure 8. These distances (abscissae) are measured from 
an arbitrary origin. The opening of the cone of the telephone was 


392 PROCEEDINGS OF THE AMERICAN ACADEMY. 


turned toward the spot marked “3” in the elevation drawing of 
Figure 7. Here again a fairly definite stationary system was found. 
This position is also less favorable for hearing this particular tone 
than the position 1 in the rear of the room. 


Hf |- 

HH a - 
π᾿, {ΠΡ ΤΩΝ 
PE ROA 
10 {Π} TY ALY TC 
me ΕΡ py ML | 

DISTANCE FROM WALL —CM 


eae αν ἘΠῚ 
ΒΕ ΜΕ ance 
RECA ον εν 


MICROAMPERES 


MICROAMPERES 


MICROAMPERES 
aS 
te 
a 
SE 
ΕΞ 


8 40. 60 τῶι Del 


Berane: —CM 


Ficure 8.— Stationary waves in large lecture room. 


These experiments were made in the large lecture room which is 
immediately over the machine shop of the laboratory, and were 
apparently not in any way affected by the very considerable vibration 
and noise of several motors and lathes in almost continual operation. 
The rectifier is, however, extremely sensitive to electric waves; and 
electric disturbances, when they happen to be in syntony with the 
rectifier circuit may prove troublesome. In the course of the present 


PIERCE. — A METHOD OF MEASURING THE INTENSITY OF SoUND. 3923 


experiments the breaking of a chronograph circuit by an electric clock 
in a distant room gave noticeable deflections. Most of these electric 
disturbances may be easily tuned out by a change of the inductance 
or capacity either in the disturbing circuit or in the rectifier circuit. 
By wearing a head telephone connected in series with the galvan- 
ometer during the observations, the observer may easily recognize any 
foreign disturbances by their characteristic tones in the telephone. 

It was not the purpose of the present note to multiply observations 
on the acoustic properties of a particular room. However, apart from 
the interest attaching to the method of the experiment, the result that 
for a sustained tone, even in a large room, there are practically all 
over the room definite positions of sharp maxima and minima of 
intensity is rather a striking fact when brought out objectively. The 
results show that an auditor may sometimes greatly improve his 
hearing of a discourse or a musical rendition by a slight motion of 
his head so as to bring his ear into a position of maximum intensity. 
Perhaps he already unconsciously does this, which may account for 
the fixed attitude of an audience in close attention. 

The occurrence of these definite maxima and minima of intensity 
of sound, due to reflection from the walls, should be borne in mind 
when one attempts to interpret any experiment on sound performed 
in a closed room. As Professor Sabine has repeatedly emphasized, the 
mere fact that the walls are distant from the source of sound, while 
the observer, or sound-receiving apparatus, is near to the source, is 
not sufficient precaution against the influence of reflection, because 
the reflecting surfaces are on all sides and act many times, and may 
combine in their action in such a manner as to be a very considerable 
factor in the resulting intensity. 

The curves of Figure 8 are plotted in terms of current in the 
galvanometer. It was shown above, in Experiment II, how the indi- 
cations of the galvanometer may be made independent of the rec- 
tifier by substituting voltage from the curve of Figure 6 for the 
corresponding current values. When this substitution is made, the 
proportional differences between the maxima and minima, expressed in 
voltage values, become somewhat smaller than these differences ex- 
pressed in current values. However, on account of the intermedia- 
tion of the telephone receiver between the sound vibrations and the 
electrical indications, it is still not possible, without further calibration 
of the apparatus, to obtain absolute or even relative values of the 
sound intensity. Several methods of obtaining this calibration in 
terms of sound intensity suggest themselves. One method is to 
employ the distance law in connection with experiments performed 


394 PROCEEDINGS OF THE AMERICAN ACADEMY. 


in the open. Another method, which is perhaps more interesting, 
would be to study directly the characteristics of the magneto-telephone 
when used as a generator, by measuring directly the amplitude of 
vibration of the telephone diaphragm and then measure with the rec- 
tifier the resulting alternating voltage. 


V. SENSITIVENESS OF THE METHOD. 


The galvanometer employed in the above experiments was not 
particularly sensitive. Its resistance was decidedly too low and 
entirely inappreciable in comparison with the resistance of the rec- 
tifier. A galvanometer of the highest attainable resistance would 
hardly be appreciable in resistance in comparison with the resistance 
of the rectifier. Also the transformer employed between the telephone 
circuit and the rectifier circuit did not have high enough resistance in 
its secondary. With evident improvements in these respects the sensi- 
tiveness of the apparatus could be greatly increased, in case one should 
desire to measure extremely feeble sounds. However, without such 
improvements the sensitiveness of the apparatus seems to greatly 
exceed that of any of the physical methods heretofore employed for 
the measurement of sound. 

For a deflection of .2 millimeters on the galvanometer scale, the 
power in the galvanometer circuit, calculated from the current-voltage 
curve of Figure 6, amounted to 1.53 x 10° ergs per second, while 
Lord Rayleigh finds the minimum energy that will affect the human 
ear to be 1.11 X 10~ ergs per second, for a pitch of 2730 vibrations 
per second. hat is to say, with the apparatus of the present experi- 
ments, in order to get .2 mm. deflection it is necessary to develop 
energy in the galvanometer circuit at about the rate at which energy 
is received by the human ear at minimum audible intensity. On 
account of the inefficiency of the magneto-telephone receiver when 
used as a phono-electric generator, energy at a rate much greater than 
this is required by the magneto-telephone receiver in order that this 
amount of power may get into the electric circuits. 

The use of a carbon transmitter in place of the magneto-telephone 
receiver for the sound receptor, while not so constant as the magneto- 
telephone, is of course enormously more sensitive. With this arrange- 
ment the condenser C of Figure 2 was replaced by a battery of four 
storage cells, and a transformer of lower resistance primary was em- 
ployed. Preliminary tests showed that the galvanometer would then 


4 Lord Rayleigh, Proceedings of the Royal Society, 1877, Vol. 26, p. 248, 


PIERCE. — A METHOD OF MEASURING THE INTENSITY OF SOUND. 395 


be thrown off the scale when a small organ-pipe was sounded almost 
anywhere on the same floor of the building, even when the passage of 
the sound from the pipe to the transmitter was through long corridors 
and several partly closed doors. With the pipe at P and the trans- 
mitter, without sound-collector, placed at 3 in the room shown in 
Figure 7, a delicate Weston ammeter gave a whole scale deflection, 
which corresponded to a current of 392 microamperes. With the use of 
this ammeter instead of the galvanometer readings could be taken with 
great rapidity and may be easily made self-recording. 

To test further the sensitiveness of the apparatus with the carbon 
transmitter substituted for the magneto-telephone receiver, this trans- 
mitter was supplied with long leads and placed outside the building. 
An assistant was sent off across an open field. When the assistant 
blew a small organ-pipe, C;, 1024, at a distance of 100 meters away, a 
deflection of 5 mm. corresponding to a current of 3.06 Χ 107° amperes 
was obtained. A locomotive whistle at a distance of perhaps a mile 
gave 75 millimeters deflection. 


JEFFERSON PHYSICAL LABORATORY, 
HarvarRpD UNIVERSITY, CAMBRIDGE, Mass. 
December 27, 1907. 


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= 


IBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY, 
Las HARVARD UNIVERSITY. 


NGITUDINAL MAGNETIC FIELD AND THE 
hones CATHODE RAYS 


By Joun TROWBRIDGE. 


a Nery ΣΝ Ὧν ‘ 


eh 
γρ ὅν 


ag = es ΩΣ 
=~ ~~ 


ΩΝ 
Ἵ 
VOLUME 43,” ce ΤΡ ΆΜΌΝ 
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᾿ 


My Proceedings of the American Academy of Arts and Sciences. 


Vou. XIII. No. 14. — Fesruary, 1908. 


TRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY, 
᾿ HARVARD UNIVERSITY. 


LONGITUDINAL MAGNETIC FIELD AND THE 
CATHODE RAYS. 


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By JoHn TROWBRIDGE. 


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CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY, 
HARVARD UNIVERSITY. 


LONGITUDINAL MAGNETIC FIELD AND THE 
CATHODE RAYS. 


By JoHN TROWBRIDGE. 


Presented December 11, 1907. Received January 6, 1908. 


Ivy a previous article on the Magnetic Field and Electric Discharges 1 
I described various phenomena which occur under the effect of a lon- 
gitudinal field, both at the anode and the cathode. The present 
article deals with the effects of the field on the cathode rays after they 
have passed into the region beyond the anode. The form of tube which 
contained the rarefied gas was similiar to that generally employed to 
study the canal rays : a cylindrical tube with a concave aluminium cath- 
ode, an iron anode with an orifice at its centre, and a prolongation of 
the cylindrical tube behind the anode.  'I'wo exactly similiar tubes of 
this form, equal in size, were connected by the same adjunct to the 
exhausting pump, and were, therefore, under the same pressure. 

In one of these tubes (Figure 1) the back of the anode, or iron termi- 
nal, was completely shielded from the prolongation of the tube in which 
canal rays are usually studied. A glass tube passed through the orifice 
in the iron terminal and was welded to the walls of the prolonged larger 
tube. No rays could enter the canal ray region except through the 
orifice in the iron terminal. In the companion tube the back of the ter- 
minal was not protected, and rays could pass over the periphery of the 
iron terminal and also through the orifice at the centre of the terminal. 

It was found that the tube (Figure 1) apparently reached a much 
higher state of exhaustion than the companion tube, which I shall call 
B, although they were connected by the same large adjunct to the 
pump and, therefore, there could be no question of slow transpiration. 
One tube, A, was close to the X-ray stage, while B was hardly beyond 
the stratification stage. 

I replaced these tubes by two spherical bulbs (Figure 2) similiar to 
those commonly employed as X-ray tubes ; these tubes also had pro- 
longations, or canal regions, similiar to those of the previously mentioned 


1 These Proceedings, 28. 


400 PROCEEDINGS OF THE AMERICAN ACADEMY. 


cylindrical tubes. In one, A, the back of the terminal was protected as 
in Figure 1; in the other, B, the back was not protected. The same 
phenomenon was observed. ‘I'ube A came up nearly to the X-ray 
stage, while the other was apparently far below this stage. 

Figure 2 is a photograph of the state of the two tubes. It is evi- 
dent that the mere appearance of the discharge between the terminals 
is no criterion of the state of exhaustion unless one carefully considers 
the forms of the tubes and the extent of 
wall surface submitted to the bombardment 
of the cathode rays. The difference which — 
I describe is probably due to the walls οὖ 
the prolongation of the vacuum tubes, A 
being more protected from this bombard- 
ment than those of tubes B. 

The forms A apparently showed the canal 
rays as perfectly as the forms B, when the — 
iron terminal was made the cathode ; and 
these rays did not seem to be modified by 
the protection of the edges of the orifice in 
the iron tube by the glass tube. ‘The canal 
A rays, therefore, come entirely from the space — 

between the anode and the cathode. 

A solenoid (ὃ, Figure 1) was next slipped 
over the prolongation of the tubes. This — 
prolongation, therefore, formed the core of 
the solenoid, and the rays passing throughila 
the orifice in the terminal could be sub- 
mitted to a longitudinal magnetic field. 
By a proper adjustment of the position — 
of the solenoid the cathode beam passing — 
through the orifice in the iron terminal or — 
the anode could be brought to a sharp / 
focus on the end of the prolongation tube. — 

Binns a This was also the case in tube B; but in 

the latter there was also a phosphores-— 

cent ring surrounding the focus of the central beam which was due- 
to bringing to a focus the rays which passed over the periphery of the 
circular iron anode. ‘The phenomenon of focussing or convergence 
of the rays is due to these rays seeking the weakest part of the 
magnetic field. The field formed by the iron dise terminal outside 
the solenoid, together with that of the short solenoid, had two 
channels in which the field was weakest : one through the orifice at . 


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TROWBRIDGE. — MAGNETIC FIELD AND THE CATHODE RAYS. 401 


the centre of the iron terminal, the other around the periphery of this 
terminal. 

It was to be expected that the Canalstrahlen could not be brought 
to convergence by this application of a longitudinal magnetic field. 
The phosphorescence of these rays remained unaffected. 


PHOSPHORESCENCE OF THE CANAL Rays. 


In most cases the phosphorescence caused by the Canalstrahlen is 
similiar in color to that produced by the cathode rays. When, how- 


FiGureE 2. 


ever, the Canalstrahlen fall upon lithium chloride, there seems to be a 
marked difference. Professor J. J. Thomson in his treatise on Con- 
duction of Electricity through Gases ? describes a form of tube in which 
a layer of lithium chloride can be bombarded alternately by both kinds 
of rays, and says that when the layer is struck by the Canalstrahlen it 
shines with a bright red light ; the lines of the lithium spectrum are 
very bright, and when the direction of the discharge is reversed, so that 
the layer is struck by the cathode rays, its color changes from bright red 
to steely blue, giving only a faint continuous spectrum but not the 
lithinm lines. The layer speedily becomes black in hydrogen. 


2 University Press, Cambridge, 1906, p. 642. 
VOL. XLIII. — 26 


402 PROCEEDINGS OF THE AMERICAN ACADEMY. 


I have succeeded in producing the red phosphorescence by the cath- 
ode rays, thus annihilating the distinction, in this case, between the 
two kinds of rays. ‘Ihe method adopted seems to have a general 
application in the study of phosphorescence and is as follows : 

‘he vacuum tube was of cylindrical form. Figure 1 shows the arrange- 
ment. A represents the circular iron terminal with its central orifice 
perforated by a glass tube ; 8, the solenoid ; L, the ground-glass stopper 
with the layer of lithium chloride at its end. 

When the solenoid is excited, the cathode rays can be brought to a 
sharp focus on the layer at L, and the apparatus can be called in pop- 
ular language a magnetic lens. A very intense cathode beam can be 
made to converge at L by suitably adjusting the solenoid. The rays seek 
the weakest part of the magnetic field. Immediately on striking the 
layer of lithium chloride the red phosphorescence appears at the centre 
of the focus, and is surrounded by the blue phosphorescence ; either the 
red or the blue can be produced at pleasure. 

It seems, therefore, that if x is the number of cathode particles, m their 
mass, © their velocity, and μη! the number of positive particles, m! their 
mass, v! their velocity, that the equation 


! 


/2 


nme? = n'm!v 
holds on the unit of area, and that the distinction, in this case between 
the color produced by the cathode rays and the Canalstrahlen disap- 
pears. ‘The production of the two colors is a question of energy on the 
unit of area. 

[ have examined the phosphorescence of the other metals of the same 
group as lithium chloride. Caesium chloride gives a very bright blue 
color for both the cathode and the canal rays, and the blue lines of the 
spectrum appear with the application of the cathode beam. Rubidium 
gives both a red and a blue color; the red, however, is much less bright 
than in the case of lithium chloride. All of these salts are quickly de- 
composed. Calcium tungstate recovers from fatigue very quickly, and 
is not decomposed appreciably, even after long exposures. Its use for 
X-ray screens is therefore substantiated by these experiments. 


APPLICATION oF A LonerirupINAL MaaGnetic Fretp to X-ray Tuses. 


In the article on the Magnetic Field and Electric Discharges,? 1 
stated that the application of a longitudinal field at the anode might 
form a useful method of concentrating the cathode rays. Since this 


3 These Proceedings, 28. 


TROWBRIDGE. — MAGNETIC FIELD AND THE CATHODE RAYS. 403 


article was written I have studied the subject more carefully, and have 
devised a safe and practical method, which is analogous to that I have 
used in the study of the phosphorescence of the Canalstrahlen. 

The form of tube is shown in Figure 1. A is an iron disc anode 
(Figure 3) with a perforation at its middle. S is a solenoid which can 
be adjusted along an appendix to the X-ray bulb. F is the usual focal 
plane of polished platinum. Opposite this focal plane the glass 15 
blown thin to permit the egress of the X-rays. The cathode beam is 
brought to a focus at F by adjustment of 
the longitudinal field of the solenoid. 

The dimensions of the apparatus are as 
follows : 

Diameter of the spherical bulb, 10 cm. 
Distance between the concave aluminium ca- 
thode and the iron disc anode, 6cm. Length 
of the cylindrical appendix containing the 
focal plane, 10cm. Internal diameter of the 
cylindrical appendix, approximately 3 cm. 
The outer diameter of the solenoid was 10 
em., the internal diameter 6 cm. Length, 
4cm. ‘There were 10 layers of no. 18 wire, 
Brown and Sharpe gauge. ‘he solenoid 
was excited by two or five storage cells. A 
narrower appendix and a smaller bulb oppo- 
site the focal plane would give a stronger 
field with less current. 

When the cathode stream is made to con- 
verge by the solenoid on the focal plane F, 
the intensity of the X-rays is increased in 
a marked manner. Judging the intensity , 
by the distance at which equal intensity is ἘΠ 
obtained with and without the magnetic 
field, I have more than doubled the intensity of the X-rays by the 
application of the field. The method has the advantage of producing 
the X-rays from a sharp focus and should, therefore, give better 
definition. 

It may be urged that the amount of energy employed in exciting the 
magnetic field could, with equal advantage, be added to that which ex- 
cites the tube; but this would result in possible strain or danger to 
the tube and would not result in bringing the stream to a sharp focus. 
The large bulb need not be blown thin, and therefore the danger of per- 
foration can be greatly lessened ; moreover, the application of the mag- 


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404 PROCEEDINGS OF THE AMERICAN ACADEMY. 


netic field serves as a rectifier, and when a Leyden jar is used it allows 
only the oscillation from the cathode to reach the focal plane. 

he canal rays appear to fatigue certain substances, — for instance, 
lithium chloride and rubidium chloride, — and after the application of 
these rays the blue phosphorescence of the cathode rays is diminished. 
It can, however, be restored by increasing the strength of the cathode 
beam. ‘This can be accomplished by the following arrangement. A 
storage battery was connected to the exhausted tube through a large 
running water resistance, and a spark gap was inserted in the circuit. 
The coatings of a small Leyden jar were connected to the spark gap ; 
the spark seemed continuous to the eye. Under the effect of the 
longitudinal magnetic field a very brilliant phosphorescence could be 
produced even after extreme fatigue of the group lithium, caesium, and 
rubidium chlorides. It is therefore probable that the cathode phos- 
phorescence can be restored by stronger and stronger cathode rays 
condensed in the manner 1 have described. 


JEFFERSON PuysicaAL LABORATORY, 
Harvarp UNIVERSITY. 


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᾿ Proceedings of the American Academy of Arts and Sciences. 


me? Vou. XLIII. No. 15.— Marcu, 1908. 


LIBRARY 
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BOTANICAL 

GARDEN, 


OTE ON SOME METEOROLOGICAL USES OF THE 
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By Louis BELL. 


GATIONS ON LIGHT AND HEAT MADE AND PUBLISHED, WHOLLY OR IN PART, WITH APPROPRIATION 
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NOTE ON SOME METEOROLOGICAL USES OF THE 
POLARISCOPE. 


By Louis Bey. 


Presented January 8, 1908. Received January 27, 1908. 


Tis is merely a preliminary notice of certain facts regarding atmos- 
pheric polarization which may prove to have some prognostic value. 
They were incidental to a proposed study of the character of autumnal 
haze which the writer undertook last year at Mount Moosilauke, N. H. 
This peak, 4811 feet high, has an almost uninterrupted sweep of horizon 
over a radius of one hundred miles or so and offers an excellent chance 
for investigating the distribution and nature of the haze that veils the 
landscape in early autumn. For instruments I took along a Savart 
polariscope, merely a Savart plate with a bit of tourmaline as analyzer, 
an extemporized double-image polarimeter of the type outlined in the 
early and valuable paper of Professor E. C. Pickering,! a couple of 
carefully calibrated photographic wedges for determining opacities, 
and a direct vision spectroscope. 

A prolonged easterly storm, about the only thing which could have 
defeated the program, cut short observations upon the summit, but a 
week of preliminary observations at Breezy Point (elevation 1650 feet) 
at the base of the mountain yielded results which seem to be of sufh- 
cient interest to put upon record. 

These were made mostly with the Savart polariscope, an instrument 
which, from its very wide field of view and great sensitiveness, showing 
even one or two per cent of polarization, enables sky conditions to be 
very readily investigated. The character of the sky polarization, with 
its general symmetry and maximum in a plane at 90° solar distance, is 
well known, but the nature and causes of its casual variations have not, 
perhaps, received the attention that is their due. Nearly everything in 
the landscape polarizes by reflection to a greater or less extent, the 
more as the specular component of reflection is the greater. For 
example, the glossy upper surface of a maple leaf polarizes strongly at 
fairly large angles of incidence, while the mat lower surface has only 


1 These Proceedings, 9, 1 et seq. 


408 PROCEEDINGS OF THE AMERICAN ACADEMY. 


a trifling effect — which facts explain the old observation of Spottis- 
woode that ivy leaves polarize particularly well. Grass, trees, stones, 
especially if wetted, all produce their effect, which, when sky polariza- 
tion is cut off by white cloud, is generally a maximum in the vertical 
plane. 

Ι have several times observed this terrestrial polarization carried up 
by reflection into low-lying cloud as noted by Pickering (loc. cit.), or 
even into near-by dense fog otherwise entirely neutral. A completely 
cloudy sky is otherwise practically free of polarization, but in a partially 
clear sky white cumuli commonly show some effects with the Savart 
plate, and light cirri often give bands almost as strongly as the clear 
sky. This may be due to the usually considerable height of cir, 
— quite enough to allow noticeable polarization to have origin below 
them, —or to their letting through considerable polarized sky light 
from above, “ἃ phenomenon which I observed from the summit 
station in the case of rather thin layers of cloud in which it was 
immersed. 

One of the most striking features of the sky polarization observed 
from Breezy Point was the extent to wh‘ch it appeared while originating 
over short stretches of air. Mounts Kineo and Cushman, about three 
miles distant and dark with a heavy growth of conifers, repeatedly 
showed strong polarization effects from intervening haze, and at times 
slopes within a mile brought out the bands, although less conspicuously. 
‘On several occasions the polarization on Kineo and Cushman was sen- 
sibly as considerable as on peaks at ten or fifteen miles distance. 
Similarly, in the brief observations on the summit, the Green Mountains 
and the almost effaced Adirondacks showed little if any more polari- 
zation than the peaks in the same direction in the middle distance, 
although the former were eighty to one hundred miles away and the 
latter only twenty to forty miles. ‘These results follow from the ex- 
ponential relation between distance and apparent absorption, but show 
clearly the magnitude of the effects due to comparatively short reaches 
of air. 

At no time was I able to repeat the results obtained by Tyndall in 
the apparent clearing up of the haze by observation through a crossed 
Nicol. In this case the mountains remained dim, Nicol or no Nicol, 
showing that the typical autumnal haze, often whitish blue near the 
horizon, acts mainly by general obstruction and diffusely reflecting 
a good deal of light, the polarized component being usually only 
moderately strong. 

Haze in general is well known to be due simply to suspended par- 
ticles of one sort or another, and haze which produces polarization, as 


BELL. — SOME METEOROLOGICAL USES OF THE POLARISCOPE. 409 


well as the ordinary sky polarization, is well known to be due to par- 
ticles, whether of dust or water, or of other nature, small compared with 
the wave-length of light. Lord Rayleigh ? has given the theory of this 
action in considerable detail. 

The polariscope integrates the effect of such particles along the line 
of sight, and this information may have considerable meteorological sig- 
nificance. ‘The light-scattering particles which produce sky polariza- 
tion are much finer than those which produce coronae and similar 
phenomena, with the beginnings of ordinary reflection. In artificial 
fogs the nuclei gradually grow from the polarizing dimensions to those 
which scatter white light and become visible. It is not easy to assign 
exact dimensions to the finer particles. ‘They are quite certainly much 
less than a quarter wave-length in diameter, that is, say 100 pp, and 
probably run very much smaller. From the very exhaustive work of 
Barus? it appears that the diameter of the particles to which visible 
fog and coronae in a fog chamber of laboratory dimensions are due 
range from .0005 » upwards, those near this limit showing as fog, while 
the coronae began to form as the diameters reached 10 μ᾽ and above. 
The fog particles to which lunar coronae are due often rise to greater 
dimensions, 20 or 30 μ. 

Now such fog particles are the preliminary to rain, which forms by 
the accretion of these particles to a size that readily falls ; and it is 
well known that water vapor, even when saturated as shown by the 
psychrometer, will not begin to condense to visible fog unless in the 
presence of nuclei about which aggregation takes place. ‘These may 
be of very fine dust, or even of water particles electrically charged to 
an extent that resists the surface tension that would otherwise promote 
evaporation. Such charged aqueous nuclei may exist in unsaturated 
air at very small diameters, down to 1 or 2 μμ, as has been shown by 
J. J. Thomson,* by Wilson,® and by others. Between these almost mo- 
lecular dimensions and those indicated by coronae are the light scat- 
tering particles active in sky polarization. Their effect, that is, the 
amount of light scattered, varies, as Rayleigh ὁ has shown, as the inverse 
fourth power of the wave-length of the light affected and directly as 
their volume, assumed to be small compared with a wave-length. Now 


: : , A F 
plotting the resulting equation, 7 = a one obtains a group of curves 


shown in Figure 1 which discloses the cause of the familiar intense blue 


2 Phil. Mag., 1871, p. 107 et seq. 3 Smithsonian Cont., No. 1979. 
4 The Discharge of Electricity through Gases. 
5 Phil. Trans., 1897. 6 Rayleigh, loc. cit. 


410 PROCEEDINGS OF THE AMERICAN ACADEMY. 


of the scattered light. As larger particles grow during the process of 
nucleation or are present as dust, the blue gets weak and whitish 
from the scattering of white light. Near the horizon, where the light 


eet elec og 1 11 
: τῇ 


{ΝΠ ΩΣ ΤΌΠΩΙ 

ΠΕ ΙΕ ΠΝ 
Be es ΓΙ 
are eee 
AA: a WF νὰ 
τ Sa a με 
Be a ΜΝ 
ef 


12 


Xin pp x 10° 


Ficure 1. 


traverses a long reach of atmosphere and coarser dust is common, one 
gets the familiar weakening of the sky blue, 

The process of increasing nucleation, which results in cloud formation 
and frequently in subsequent rain, can be followed very closely by the 
‘polariscope. A fall in polarization, particularly when the spectroscope 


BELL. —SOME METEOROLOGICAL USES OF THE POLARISCOPE. 411 


shows the presence of much aqueous vapor, indicates the progress of 
nucleation. 

On several occasions I noted this phenomenon in the Breezy Point 
observations. Starting with strong polarization on the distant hills to 
the southward and a strong rain band visible in the spectroscope, the 
next few hours showed a conspicuous weakening of the polarization, 
followed presently by the formation of visible clouds, and in at least 
two cases by precipitation. In short, if from change of temperature or 
other cause cloud is due to form in any particular direction, the nuclea- 
tion which precedes visible fog formation is bound, other things being 
equal, to cut down the polarization. ‘The prognostic value of this pro- 
cess depends largely upén the rate at which it progresses. In two 
instances which I noted, the decrease toward the south occupied most 
of an afternoon. Of course a drifting in of coarser dust particles would 


_ produce weakening of polarization, but the concurrence of weaken- 


ing with a heavy rain band intimates very strongly that nucleation is 
progressing. 

A detailed study of the changes would require the use of a sensitive 
polarimeter, by which variations from the theoretical polarization could 
be accurately measured. Observations of this kind, made where there 
is a wide sweep of horizon, should frequently disclose incipient cloud 
formation and the causes which produce it. The use of a spectro- 
polarimeter would be very desirable, as showing by the change in the 
quality of the scattered light the progress of events. The nature of 
the minute nuclei, whether dust or water particles, is not definitely 
known. After a heavy rain storm the lower strata seemed to have 
been cleared pretty effectively of polarizing nuclei, while the upper sky 
remained much as before. On one occasion, more than twenty years 
ago, I was taking rain band observations on Moosilauke and was favored 
with a day in which the distant peaks, even up to one hundred miles, 
stood out almost as black as silhouettes, while the sky took on a deep 
hue almost startling in its unfamiliarity. A polarimeter would cer- 
tainly have given extremely interesting results had it been at hand. 
It seems quite possible that one might get a fairly clear idea of the 
relative number and distribution of nuclei in the upper air by such 
means. 

It would certainly be interesting also to find out whether the appar- 
ently very strong absorption of ultra-violet rays by the atmosphere is 
due to any genuine absorption or merely to a serious loss of light by 
lateral scattering, which Rayleigh has shown may perhaps be due to 
the air molecules themselves. In the lower strata my observations 
pointed rather to dust than to minute water nuclei, since a whitish 


412 PROCEEDINGS OF THE AMERICAN ACADEMY. 


haze showed powerful polarization on near-by peaks, making it clear 
that the haze was extremely heterogeneous. ‘he conditions which 
would produce stable water nuclei of strongly polarizing size on a clear 
day would tend to reduce larger droplets to the similar order of mag- 
nitude instead of leaving them to superimpose specular reflection. 

I am not disposed to suggest that in the polariscope we have a 
meteorological tool of vast importance, but my preliminary observations 
certainly show that it gives a most instructive view of the very early 
stages of atmospheric nucleation, and especially if combined with rain- 
band observations it should have material prognostic value as regards 
comparatively local conditions. There is also a chance for forming a 
clearer idea of the conditions of nucleation in the upper air, including 
the very high altitudes, since polarization is manifest after the sun is 
so far below the horizon as to illumine only the upper strata. I bring 
the preliminary facts to notice here in the hope that some one with a 
suitable location and opportunity for systematic observation may find 
them useful as a guide to further work along this line. 


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rd 


4 


if 


: THE SENSORY REACTIONS OF AMPHIOXUS. 


ῳ 


By G. H. PARKER. 


LIBRARY 
NEW YORK 
BOTANICAL 

GARDEN. 


CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY OF THE 
MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD COLLEGE. 
E. 1. MARK, DIRECTOR. — No. 195. 


THE SENSORY REACTIONS OF AMPHIOXUS.1 LIBRARY 
NEW YORK 
By G. H. PARKER. BOTANICAL 

GARDIIN, 


Presented March 11, 1908. Received March 5, 1908. 


TABLE OF CONTENTS. 


Introduction . . ... . . . 415] Central nervous system and sen- 
Hight. . . . - +... =. ; 416] sory mechanisms in amphioxus 441 
Heat. ..... . . . . «+ 428] Sensory mechanisms in amphioxus 
Mechanical stimulation . . . . 481 and their relations to vertebrate 
Chemical stimulation . . . . . 436 sense organs . . « . « «..., 448 
Interrelation of sensory mechan- PUMMATY 0, τοόΠρὦρ'ΘοέΠρὁἐσωφοἔΕο ee Ὁ dS 
isms in amphioxus . . . . . 489) Bibliography . . ..... . 450 


1. INTRODUCTION. 


WuateEVER position may be assigned to amphioxus in the classifi- 
eation of the chordates, it is now generally admitted that this animal 
retains many of the more primitive features of the ancestors of the 
vertebrates. Such features not only occur in its anatomy and em- 
bryology, but are to be expected in its activities. As the structure 
of amphioxus throws light on the complex organization of the verte- 
brates, so its activities may give some indication of the way in which 
the more complex functions of these animals have come into being. 
It is from this standpoint that I have undertaken the study of the 
sensory reactions of amphioxus. 

The material upon which this work was based is the so-called West 
Indian amphioxus or lancelet, Branchiostoma caribbaeum Sundevall, a 
close relative of the common European form, B. lanceolatum (Pallas). 
This material was collected and studied during the summer of 1905 

CSwhile I was at the laboratory of the Bermuda Biological Station 
S located at Hotel Frascati, Flatts Village, Bermuda. The living 


1 Contributions from the Bermuda Biological Station for Research, No. 12. 


APR 27 


416 PROCEEDINGS OF THE AMERICAN ACADEMY. 


lancelets were obtained from the Flatts Inlet, which leads from the 
outer waters to Harrington Sound. This inlet, through which a 
strong tidal current is almost always running in one direction or the 
other, contains long stretches of coarse coral and shell sand, and it 
was in these sandy stretches, especially near the open mouth of the 
inlet, that the lancelets were found in abundance. ‘They likewise 
occurred, as recorded by Barbour (;05, p. 110), in the sandspit near 
the inner end of the inlet opposite Hotel Frascati, but they were by no 
means so abundant there as in the coarse shelly stretches which were 
near the outer mouth of the inlet and at low tide were still covered 
by several feet of water. From this source, with the assistance of 
some of the negro boys from the neighborhood, a daily supply of large, 
vigorous lancelets was obtained, and, as the animals were available in 
the laboratory almost immediately after they were caught, the con- 
ditions were unusually favorable for a study of their sensory reactions. 
For experimental purposes these lancelets proved to be very satis- 
factory. They could be kept for a number of days in a vigorous 
condition in large glass jars containing sea water and some coral sand, 
provided that from time to time the sea water was renewed, and their 
resistance to the adverse conditions of operative experiments was as 
great as that of B. lanceolatum (Haeckel, ’80, p. 141). 

In the shoal water of Harrington Sound northwest of Trunk Island 
the expeditions from the laboratory on several occasions dredged 
Andrew’s lancelet, Asymmetron lucayanum Andrews, but’ this species 
was not sufficiently accessible nor abundant to make it a satisfactory 
form for experimentation. In testing the sensory reactions of the 
lancelets I therefore limited my work to the more common species, 
Branchiostoma caribbaeum, and attempted to determine the re- 
actions of this species to light, to heat, and to mechanical and chemical 
stimuli. 


2. Liacut. 


Although the sensitiveness of amphioxus to light was known to 
Costa (’39, p. 4)2 and many other earlier investigators, and has since 
been generally admitted, much difference of opinion has been expressed 
as to the degree of this sensitiveness. Willey (’94, p. 10) declares that 
“if a lighted candle is carried into a dark room in which amphioxus 
are being kept in glass jars, the excitement produced among the small 


2 The statements concerning the reactions of amphioxus to light given by 
Costa do not occur in his first account of this animal (Costa, '34, p. 49) as 
cited by Krause (97, p. 513), but in his later and more lengthy description 
(Costa, ’39, p. 4). 


PARKER. — THE SENSORY REACTIONS OF AMPHIOXUS. 417 


fish is indescribable,” and Nagel (096, p. 79) states that “ plétzliche 
Belichtung lisst dann die siimtlichen Exemplare wild durchs Wasser 
jagen.” Hesse (’98°, p. 461) confirms these observations and records 
that light calls forth vigorous swimming. On the other hand, Niisslin 
(77, p. 23), who also tried sudden illumination, affirms that amphioxus 
is only very slightly sensitive to light, and Rohon (’82, p. 38) ex- 
presses the belief based on experimental evidence that the so-called 
light reactions of this animal are really reactions to heat, and that it 
is not sensitive to light at all, or at most only to a very slight degree, 
—an opinion concurred in by Kohl (’90, p. 185). 

In consequence of this difference of opinion the first question to be 
settled was, whether amphioxus was or was not sensitive to light. I 
therefore repeated the experiments made by Willey, Nagel, and Hesse, 
and with confirmatory results. When sunlight, daylight, lamplight, 
or even candle-light was allowed to fall into a previously darkened 
glass dish containing a dozen or more amphioxus, the whole company 
swam about for a minute or so in wild confusion and then dropped as 
though exhausted to the bottom. At first sight this seemed to be 
conclusive evidence of the great sensitiveness of amphioxus to light, 
but a more careful scrutiny of the steps in the experiment showed that 
this was not necessarily so. When light first fell upon the dish, all 
the lancelets did not begin at once to swim about excitedly. What 
usually happened was that a few moved slightly, and in doing so they 
touched others; these then sprang suddenly into active locomotion, 
and in an instant the whole assembly was swimming in wild confusion. 
Thus it would seem that, while light was the initial stimulus for a 
few individuals, the wild and excited swimming which gave the im- 
pression of great sensitiveness to light was not due directly to this 
factor, but to mechanical stimulation caused by mutual contact. 

To test this hypothesis I placed a shallow dish of sea water con- 
taining twenty live amphioxus in a dark room and, after about an 
hour, I threw upon it the light of a strong lamp; in a few seconds all 
the animals were swimming as though in the utmost excitement. I 
then let them rest in the dark for a full hour, whereupon, without 
illuminating the dish, I felt for one with a glass rod, and, having 
touched it, I soon heard an agitated movement in the dish such as 
had followed the previous sudden illumination. Upon turning on 
the light the animals were found to be in as much commotion as at 
the trial in which light had been the initial stimulus. I then took the 
twenty animals that had been used in these two experiments and put 
each one in a separate dish of sea water and placed each dish in an 
approximately light-proof compartment by itself. After an hour 1 


VOL. XLIII. — 27 


418 PROCEEDINGS OF THE AMERICAN ACADEMY. 


illuminated dish by dish in turn with the same lamp that had caused 
the whole assembly of lancelets to swim wildly about when together, 
and noted the individual reactions. Of the twenty animals tested, 
twelve reacted, some more, some less, but none vigorously ; eight ab- 
solutely failed to give any response whatsoever, even after continued 
illumination. ‘The twenty animals were then placed together in a 
single glass dish, and, after about an hour, they were suddenly sub- 
jected to bright illumination, with the result that they exhibited the 
same commotion as was seen in the first of these experiments. I 
therefore conclude that the wild swimming recorded by Willey, Nagel, 
and Hesse is not, as they believed, evidence of great sensitiveness to 
light, but is the result of the mechanical stimulation of one amphioxus 
touching another, and that amphioxus, as stated by Niisslin, is really 
only very slightly sensitive to light. 

Rohon’s belief that the so-called light reactions of amphioxus are 
really reactions to radiant heat is not supported by my observations. 
Contrary to the statements of Rohon, amphioxus is responsive to 
light that has passed through a heat screen ; nor does Rohon seem 
to have been aware of the fact, pointed out later by Krause (097, 
p. 514), that a few centimeters of sea water is as effective a heat screen 
as the alum solution that he used, and that consequently in all his 
experiments that were carried on with some depth of sea water, the 
animals that were supposed to be subjected to radiant heat were as 
a matter of fact as completely shielded from it as though they were 
behind an alum screen. Kohl’s concurrence in Rohon’s opinion does 
not seem to be founded on any observations of his own, for he (90, 
p. 182) states that he had no opportunity to work with living material. 
I therefore believe that the slight initial locomotor response that am- 
phioxus usually makes when a beam of light is suddenly thrown on 
it is dependent upon the light waves themselves and not upon radiant 
heat. 

Although amphioxus is assuredly not so sensitive to light as many 
investigators have supposed it to be, it does show a capacity to 
respond to a considerable range of this form of stimulus. Nagel 
(96, p. 80) stated that its characteristic reactions could often be 
called forth by a relatively weak stimulus, such as the diffuse light of 
a cloudy day. In my own experience animals that have been kept in 
the dark for some time will usually react to light of not more than a 
few candle-meters intensity, but the same individuals after lengthy 
exposure to ordinary daylight will often fail to respond to a beam of 
strong sunlight. Obviously the capacity of the animal to respond to 
light is more or less determined by its previous condition, its sensi- 


PARKER. — THE SENSORY REACTIONS OF AMPHIOXUS. 419 


tiveness diminishing with continual exposure to light and increasing 
when the light is excluded from it. But even under the most favor- 
able circumstances the reactions to light as compared with those to 
other kinds of stimuli are relatively slight in amphioxus. 

Although amphioxus shows much diversity as to the intensity of 
light to which it will react, in another respect its responses to this 
form of stimulus are very uniform. In all the tests I carried out, I 
never observed a reaction to a rapid diminution of light, and the 
reactions to light that did occur were always the result of a rapid 
increase of intensity. When an animal was resting quietly on its side 
in a shaded aquarium and a beam of sunlight, was suddenly thrown 
upon it, it would usually respond by one or two vigorous locomotor 
leaps, after which it might come to rest even in the sunlight. If now 
the sunlight was suddenly cut off, no response followed. ‘That this 
failure to respond was not due to exhaustion from over-exposure to 
light was easily shown by quickly throwing on the sunlight a second 
time, whereupon a reaction much like the first one usually followed 
immediately. In fact, a moderately rapid alternation of full light and 
shadow was generally followed for a number of times by reactions to 
the light and no reactions to the shadow till, after numerous trials, the 
animal ceased to respond at all. Amphioxus is therefore stimulated 
only by such rapid changes of light intensity as involve an ¢ncrease in 
the illumination. This agrees fairly well with Nagel’s statement 
(94, p. 811; ’96, p. 80) that sudden shadow calls forth from amphi- 
oxus either faint responses or none at all. In my experience the latter 
part of this statement is correct. 

Having ascertained that amphioxus is sensitive to light, the next 
question that naturally arises is what portion of its body serves as the 
receptive organ for this stimulus. Numerous answers have already 
been given to this question. ‘The conspicuous pigment spot at the 
anterior end of the nerve-tube discovered, according to J. Miiller (’39, 
p. 198), by Retzius, was held by the former (’44, p. 95) and many other 
investigators to be a primitive eye. Hasse (’76, p. 287) believed that 
the light receptors were two lateral patches of integumentary cells, 
one on each side of the flattened anterior end of the animal. Niisslin 
(77, p. 25) was of opinion that the extreme anterior portion of the 
dorsal fin was the part sensitive to light. Krause (’88, p. 136), who 
discovered in the substance of the nerve-tube a pigment that he believed 
resembled visual purple, was thereby led to assume that this tube was 
the receptive organ for light. Nagel (094:, p. 811) claimed that the 
whole outer skin was receptive to light. Hesse (98°, ’98°) maintained 
that the numerous small pigment spots of the nerve-tube were each a 


420 PROCEEDINGS OF THE AMERICAN ACADEMY. 


single eye comparable to the eye of a planarian ; and to these Joseph 
(:04) added certain large cells in the anterior part of the tube which, 
from their structure, he believed also to be light-receptors. 

To ascertain what part of the body of amphioxus is sensitive to light, 
I had planned to use local stimulation, and with this in view I arranged 
an acetylin light with a condensing lens and a pinhole diaphragm, so 
that I could have at command a small beam of strong light with which 
to test locally the various parts of the animal’s body. Unfortunately 
the strongest artificial light that I could get was insufficient to call 
forth an invariable reaction, and I was at last driven to use con- 
centrated sunlight for this purpose. ‘This was obtained by mounting 
a mirror in an open space adjacent to the laboratory, and so directing 
it that a horizontal beam of sunlight was thrown through a window 
into the laboratory. This beam of light was screened of its heat by 
being made to pass through seven centimeters of water contained in a 
glass vessel with flat sides, and it was concentrated by a large lens 
whose principal focus was about twenty-five centimeters. A few centi- 
meters nearer the lens than its principal focus and in the cone of con- 
centrating light, an iron diaphragm with a pinhole was placed that 
intercepted all the light except that which passed through the pin- 
hole. In this way a well-circumscribed minute beam of intense light 
was obtained, and by means of this beam the body of the amphioxus 
was explored while it rested in a glass dish of sea water with flat sides. 
It was found by experiment that the dish containing the amphioxus 
could be moved about with considerable freedom without disturbing 
the animal. In this way the beam of light was brought to bear on any 
desired part of the animal’s body. 

My first experiments were directed toward ascertaining the value of 
the so-called eye-spot at the anterior end of the nerve-tube as a recep- 
tive organ for light. Experiments had already been made on this 
organ by Nagel (94, p. 811 ; ’96, pp. 40, 80), who recorded that after 
the animal’s anterior end, including the eye-spot, had been cut off, 
the lancelet was found to be as sensitive to light as ever, a condition 
confirmed by Hesse (98, p. 461). I repeated this experiment on 
six lancelets. All were first tested with light and found to respond 
when suddenly illuminated. The anterior tip of the body with the eye- 
spot was then cut off, and after an hour all were tested again. I was 
unable to distinguish in this second test that the lancelets were any 
less sensitive to light than before the removal of the eye-spot, and my 
results thus confirm those of Nagel and Hesse. 

Although these results demonstrate conclusively that the so-called 
eye-spot is not essential to the light reactions of amphioxus, they do 


PARKER. — THE SENSORY REACTIONS OF AMPHIOXUS. 421 


not show that this spot may not be a light-receptive organ. ΤῸ test 
this possibility I attempted by means of the minute beam of light 
already described to illuminate the spot exclusively, and to see if a 
reaction resulted. This was by no means easily done, for the spot is 
so small that its position in the living animal cannot well be observed 
directly, but must be surmised. Furthermore, when the light enters 
the substance of the animal, it becomes much scattered, and hence 
may reach other parts than those it is intended to illuminate. Never- 
theless, it was possible on a number of animals to throw intense light 
on the eye-spot without getting a response, though, when the light was 
moved to a position somewhat posterior to the spot in question, a 
vigorous response followed. I therefore conclude that not only is the 
so-called eye-spot of amphioxus unessential to its light reactions, but 
that this organ is in no sense a light-receptor. These physiological 
results, then, support the view long ago advanced by Stieda (’73, p. 51) 
on the basis of anatomical evidence, that this spot is not a visual organ. 
For this reason I shall in future call it simply the anterior pigment 
spot, though its nervous nature seems well established by the recent 
work of Edinger (:06). In a similar way [ tried to get reactions from 
lancelets by directing the beam of light on the flattened sides of their 
anterior ends, where, according to Hasse (’76), light-receptive organs 
were supposed to be located. In no instance did 1 get a reaction, and 
I therefore agree with Niisslin (77, p. 12) and with Kohl (090, p. 183) 
in denying the existence of light-receiving organs in this region. 
Lancelets from which the anterior end of the dorsal fin had been 
removed were as sensitive to light as before the removal, nor did 
normal lancelets react to the small beam of light when it was thrown 
on this part of the fin. I therefore believe that Niisslin (77, p. 25) 
was in error when he declared that the anterior end of the dorsal fin 
was the portion of the animal that was sensitive to light. 
The part of the body of amphioxus that can be stimulated by light 
extends from a point a little behind the anterior end posteriorly to 
the tip of the tail. A beam of concentrated sunlight thrown across 
the body in any region between these two points always elicits some 
response. Krause (’97, p. 514) states that the anterior end somewhat 
distal 8 to the anterior pigment spot is most sensitive to light, and 
that the tail end is not sensitive at all. My results, as already stated, 
are almost precisely the reverse of these. I have found the anterior 
end, both in front of the anterior pigment spot and at least immediately 
posterior to it, insensitive to light, and the tail end extremely sensi- 


3 By distal Krause means, judging from the context, posterior. 


422 PROCEEDINGS OF THE AMERICAN ACADEMY. 


tive. As Krause in his first description of the animal (’88, pp. 132 
135) stated that it rests with its ¢ai/ out of the sand, and in his 
later account (097, p. 513) that the head usually projects, a fact well 
established since the time of J. Miiller ('41, p. 399), is it not possible 
that in his study of the light reactions of this somewhat ambiguous 
form Krause has fallen into the not unnatural error of confusing 
the ends ? 

The extent of the region that is sensitive to light in amphioxus very 
nearly coincides with that of the nerve tube, and evidence obtained by 
local stimulation points to this structure as the part of the animal 
stimulated by light. Krause (’88, p. 132; 97, p. 513) has advanced 
the opinion that the bluish coloring matter that appears in the walls 
of the tube when this structure is treated with alkali is similar to the 
visual purple of the retina, and is in this way connected with the light 
receptive function of the tube. On treatment with alkali this coloring 
matter, according to Krause, becomes visible around the pigment spots 
in the tube, and among these are included the anterior pigment spot as 
well as the series of smaller spots that extend through almost the whole 
length of the tube; but it has just been stated that by local stimula- 
tion the anterior pigment spot can be shown to be insensitive to light, 
and since this coloring matter is as characteristic of that spot as of the 
other spots in the tube, I do not believe that the blue substance de- 
scribed by Krause has any essential connection with the light-receptive 
apparatus. As Hesse (98°, p. 556) has pointed out, Krause’s belief 
that the blue is analogous to visual purple is unsupported by any good 
evidence, for this material shows no such relation to light as is charac- 
teristic of visual purple. It therefore seems to me that Krause’s view 
is untenable. 

Since amphioxus shows no response when strong light is thrown on 
the anterior end of its nerve-tube in front of the third or fourth seg- 
ment, a region in which occur certain large cells supposed by Joseph 
(: 04, p. 21) to be sensitive to light, I conclude that these cells are not 
open to that kind of stimulation and that the light-receptive organs 
must lie posterior to this region. 

Although it is impossible, for reasons already given, to illuminate 
amphioxus locally with great precision, the exact portion of the animal 
that is stimulated by light can be determined with fair accuracy. 
This portion corresponds to the region in which the nerve-tube contains 
the small eye-cups described by Hesse. This correspondence is so pre- 
cise that it seems very probable that these organs are the true photo- 
receptors. It must not be forgotten, however, that, in all regions where 
light has proved stimulating, this agent in its passage into the more or 


δ..." 


PARKER. — THE SENSORY REACTIONS OF AMPHIOXUS. 423 


less transparent animal first penetrates the skin, and it is not impossi- 
ble that the receptive organs for light really lie in this layer, as main- 
tained by Nagel (94, p. 811) and Jelgersma (:06, p. 390). This 
opinion is strengthened by what has recently been made out concern- 
ing the sensitiveness to light of the skin of certain reptiles, amphibians, 
and fishes, particularly ammocoetes (Parker, : 03°, : 05"), 

Since I was unable to devise an experiment whereby the nerve-tube 
in amphioxus could be illuminated without having the light pass through 
the skin, I cannot be absolutely sure where the light-receiving organs 
lie, but there is a certain amount of indirect evidence on this question, 
all of which points in one direction. As has already been shown, the 
skin on the anterior end of the animal is not sensitive to light, this 
form of sensitiveness beginning posteriorly at no special region so far as 
the skin is concerned, but exactly where the eye-cups first occur in the 
nerve-tube. ‘This evidence, so far as it goes, favors Hesse’s view that 
these eye-cups are the true light-receptive organs. Another piece of 
evidence has to do with the exact distribution of the animal’s photo- 
receptiveness and that of the eye-cups. If different regions on the 
length of a lancelet are tested for their sensitiveness to light, they will 
be found to vary considerably. The most sensitive region is that 
which extends from a point several segments behind the anterior tip of 
the nerve-tube posteriorly over about one quarter of the length of the 
animal ; the region next in sensitiveness is the most posterior quarter 
of the animal ; and the least sensitive part of the whole region which 
is at all sensitive is approximately the middle half. In a series of 
trials in which was determined the relative intensity of the minimum 
amount of light necessary to stimulate in these three regions, it ap- 
peared that, if the minimum intensity for the anterior portion, the 
most sensitive part, is called 1, that for the posterior part was 1.5, and 
for the middle part 25.0, while an intensity of 0.5 was not stimulating 
to any part of the animal. If, now, the distribution of the eye-cups 
described by Hesse be taken into account, a striking correspondence to 
the sensitiveness to light will be found. In Branchiostoma caribbaeum 
the most anterior eye-cups occur in the third segment, and the remain- 
ing cups form a more or less segmentally arranged series reaching to 
the last segment of the body, which is practically the tip of the tail. 
In this series, so far as numbers are concerned, three general regions 
can be distinguished. The first region, the one in which the cups are 
most numerous, extends from about the fourth segment to about the 
twentieth ; the region second in abundance covers about the last twelve 
segments of the body ; and the third region, or the one in which they 
are fewest, is the middle portion of the body between the two regions 


424 PROCEEDINGS OF THE AMERICAN ACADEMY. 


just defined. Hesse (’98", p. 457) states that in Branchiostoma lan- 
ceolatum the eye-cups are most abundant anteriorly and diminish 
in numbers posteriorly, till in the tail there may be not more than 
one cup to a segment. But this description, as Boeke (:02, p. 352) 
and Joseph (:04, p. 18) have noted, is somewhat defective. In five 
specimens of B. lanceolatum from Naples that I have examined, the 
distribution was essentially like that in B. caribbaeum, in that, in ad- 
dition to the considerably increased number of cups anteriorly, there 
was also an increase in the number in the tail region. ‘This confirms 
Joseph’s statement (:04, p. 18) for this species and agrees with the 
discovery of Boeke (: 02, p. 352), that in young pelagic individuals of 
B. lanceolatum there are to be seen ¢wo groups of eye-cups, one anterior 
and the other posterior, corresponding to the two concentrations men- 
tioned. ‘These two groups presumably unite later to form one series. 
The general plans of distribution of the cups in the two species, then, 
undoubtedly agree, and, since these plans of distribution correspond 
to the different degrees of sensitiveness to light for the different parts 
of the body in B. caribbaeum, I believe that the eye-cups described by 
Hesse, and not the skin, are the light-receptive organs. 

In Branchiostoma caribbaeum, as in B. lanceolatum according to 
Hesse (98°, p. 458) and Boeke (: 02, p. 351), the ventral eye-cups, as 
well as those of the right side, poimt in the main ventrally, while those 
of the left side point mostly dorsally. Hesse states further that in 
B. lanceolatum the cups of the two sides tend toward the right, and he 
suspected that this might be correlated with a possible habit of resting 
on a particular side. But in testing this hypothesis Hesse (’98°, 
p. 459) found that the animals rested about as frequently on one side as 
on the other, and he therefore abandoned it. In B. caribbaeum I could 
not see that the cups were directed more toward the right than toward 
the left, but it was apparent that the majority pointed ventrally. This 
position seemed to me entirely consistent with the habits of this species, 
for it naturally lies in the sand with the ventral side obliquely wpper- 
most, the majority of eyes being thus directed toward the most prob- 
able source for light. However, individuals that were in a glass dish 
without sand were, so far as I could see, equally sensitive to light fall- 
ing on them in any direction. 

If the light-receptive organs in amphioxus are the eye-cups of the 
nerve-tube, any part of the animal containing these organs might be 
expected to retain its sensitiveness to light. Nagel (94*, p. 811; 96, 
p- 79), after cutting these animals in two transversely, found that both 
halves still reacted promptly to light, but less energetically than the 
whole animal did. Krause (97, p. 514) declared that after halving 


» 


PARKER. — THE SENSORY REACTIONS OF AMPHIOXUS. 495 


amphioxus the posterior part is much less reactive to light than the 
anterior, and Hesse (98°, p. 462), who repeated these experiments, 
could get only a trembling response to light from the anterior half and 
no response at all from the posterior one. My own results agree ex- 
actly with those of Hesse. I tested six fresh animals with strong sun- 
light, and, having found them sensitive to it, I cut each one transversely 
in two. After an hour, and again after two hours, I tested them with 
strong sunlight: the anterier halves always trembled markedly, but I 
could perceive no reaction at all to light from the posterior halves. 
When, however, I touched the posterior halves with very dilute nitric 
acid in sea water, they sprang and wriggled forward through the water 
most energetically, showing that they were still capable of active re- 
sponse. Iam therefore convinced that cutting the animal in two has 
a profound effect upon its powers of reaction to light, greatly dimin- 
ishing this capacity in the anterior half and practically nullifying it in 
the posterior half. 

Although amphioxus reacts to light thrown upon almost any part 
of its body except the anterior end, its reactions are characteristically 
different in accordance with the region stimulated. When lght is ap- 
plied to the sensitive anterior fourth of the body, amphioxus almost 
invariably gives a vigorous backward spring, often accompanied with 
backward swimming. If light is applied to the less sensitive middle 
portion of the body, there is usually a slight backward spring, but 
sometimes the animal simply curls the body slightly. If the light is 
applied to the most posterior fourth, the animal almost invariably 
springs forward. In extreme cases, at least, the resulting movement is 
the most effective one for removing the animal from the source of 
stimulation. This is still more clearly seen when a beam of strong 
light parallel with the longitudinal axis of the amphioxus is directed 
against its anterior or its posterior end. In the former case the animal 
darts backward, and in the latter forward ; in each instance it moves 
away from the source of light. For animals generally backward swim- 
ming is unusual, since the majority of negatively phototropic animals 
when illuminated from in front first orient by turning the anterior end 
away from the light before they begin active locomotion, whereas in 
amphioxus the locomotion is executed without the initial step of ori- 
entation. The case is parallel to that of a positively phototropic 
pycnogonid described by Cole (:01, p. 201) ; this animal moves toward 
the source of light either with the anterior or the posterior end first. 
In the pyenogonid, however, the two kinds of movement are associated 
with somewhat different types of locomotion, for the animal sw7ms 
backward toward the light or creeps forward toward it, whereas in 
amphioxus the reaction in both cases is simply swimming. 


426 PROCEEDINGS OF THE AMERICAN ACADEMY. 


As a result of such a system of reactions, Branchiostoma caribbaeum 
falls under the head of negatively phototropic animals, and this is also 
the case with B. lanceolatum, which, according to W. Miiller ('74, p. 7) 
and others, avoids light as far as possible when in captivity, and with 
Asymmetron lucayanum, whose habit, according to Andrews ('93, 
p- 214), is to collect on the side of the dish away from the light. Evi- 
dence of the same kind is also at hand for B. caribbaeum. If, into the 
middle of a large square glass vessel so placed that the sunlight falls 
obliquely into it through one side, living lancelets are dropped one by 
one, they fall to the bottom as a rule without response, whereupon 
they often begin swimming, and in practically every trial come to rest 
near the side of the glass away from the sun. 

If a large glass aquarium is arranged so that one side and the halves 
of the two ends adjacent to it, as well as the corresponding portion of 
the top, are covered with light-proof paper and a number of amphioxus 
are allowed to swim freely about in it, they will be found during the 
day resting almost exclusively on the bottom of the darkened part, 
whereas during the night they will be found about equally distributed 
over the bottom. 

Since amphioxus swims away from a source of light, it is negatively 
phototropie (Parker, :06, p. 61), and, since it is active in the light and 
comes to rest in darkened situations, it is photokinetic (photodynamic). 

Light acts on amphioxus in a distinctly local way, and not as it 
does on animals, like most vertebrates, which possess eyes capable of 
forming images. ‘This power enables a vertebrate to discriminate at a 
distance areas of light from areas of shade in a general field. If an 
amphioxus lying quietly in deep shade is stimulated to locomotion by a 
minute beam of strong light, it will dart off in almost any direction 
irrespective of the shadows and lights about it. Should it by accident 
come into the sunlight, it usually continues to swim; should it come 
into shade, it usually comes to rest. The light about amphioxus has 
little or no influence on the animal except when it falls with full 
intensity on the animal’s body. ‘This is dependent upon the fact that 
amphioxus is not very sensitive to light, and therefore reflected light 
of low intensity does not stimulate it, and, further, that the light- 
receptive organs of the animal have no adequate means for the forma- 
tion of images. 

Under ordinary conditions amphioxus is buried in the sand, except- 
ing for oneend. Which end this is has been a matter of some dispute. 
Yarrell (36, p. 468) stated that the specimen from which he took his 
description was found by Mr. Cough with its tail sticking out from 
under a stone; and Steiner (86, p. 497) declared that the animal 


coy» es pena 


—_ 


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= a eo 7 < - - 
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PARKER. — THE SENSORY REACTIONS OF AMPHIOXUS. 427 


usually rests with its tail out of the sand, a statement repeated by 
Krause (’88, pp. 132, 135). Subsequently and without explanation 
both Steiner (88, p. 41) and Krause (’97, p. 513) abandoned this 
opinion for the opposite one. ‘That the animals ordinarily rest with 
the anterior end out of the sand was the opinion of J. Miiller (’41, 
p. 399; ’44, p. 84), Niisslin (77, p. 18), Rohon (’82, p. 37), Willey 
(94, p. 9), Nagel (96, p. 79), and others, and any one who carefully 
inspects a number of lancelets at rest will soon be convinced that this 
is the normal position. Although the extruded anterior end is the 
portion of the animal least sensitive to light, lancelets in their resting 
positions in ordinary sand will respond quickly enough to this stimulus. 
Thus in a large dish of coral sand, over which there were a few inches 
of sea water, the anterior ends of twenty-three lancelets were counted 
in dim light. Asa result of throwing on a beam of very strong light, 
most of the heads were quickly withdrawn under the sand, only two 
remaining visible. ‘his reaction is doubtless dependent on the stimu- 
lation of the most anterior eye-cups, and as a rule the resting position 
‘of the animal is such that this naturally occurs. 

The negative phototropism of amphioxus has led to the belief that 
during the day it remains buried in the sand, except perhaps for its 
anterior end, but that during the night it leaves the sand and leads 
a more active existence. W. Miiller (74, p. 7) states that Branchi- 
ostoma lanceolatum is nocturnal, and at twilight comes to the surface 
of the sandbank in which during the day it is buried. Rice (’80, p. 9) 
mentions that individuals of this species which were seen swimming 
at night in the Naples Aquarium were quiescent in the daytime, and 
Rohon (82, p. 36) and Krause (97, p. 513) also speak of this species 
as having nocturnal habits. B. caribbaeum showed no evidence of 
such habits. All inspections of the aquaria that I made after night- 
fall, and with caution as far as light was concerned, demonstrated that 
the lancelets remained in the same position in the dark as in the light. 
Further, several glass vessels containing coral sand and known numbers 
of lancelets that were sunk over night to the natural level of the sand 
in the bed of the inlet, contained, when taken up the next day, the 
same numbers of animals, thus indicating that the lancelets had re- 
mained buried and had not come out on the surface of the sand, where 
the current would surely have swept them away, even supposing that 
they had not started swimming. Although this experiment was tried 
only a few times, the results always led to the same conclusion, and it 
therefore seems probable that at least B. caribbaeum is essentially a 
burrowing animal, and that it leaves its native sand only when forced 
to by the accidental action of currents, ete. 


428 PROCEEDINGS OF THE AMERICAN ACADEMY. 


3. Heat. 


The reactions of amphioxus to heat have been scarcely more than 
touched upon by the numerous investigators who have studied the re- 
actions and habits of thisanimal. As has already been pointed ont, the 
opinion of Rohon (82, p. 38) and of Kohl (90, p. 185), that the light 
reactions of amphioxus are really reactions to radiant heat, is erroneous ; 
moreover it is not to be expected that animals like amphioxus, which 
live always under some depth of water, would have any special organs 
for the reception of radiant heat, since such heat penetrates water only 
a centimeter or two and hence would almost never reach these forms. 
The kind of heat that is a factor in the environment of amphioxus is 
the molecular vibration such as we recognize in the temperature of 
water, and this certainly has a distinctly circumscribing influence on 
the lancelets. 

In testing the effect of heat on amphioxus, the temperature of the 
water in which they were living in the Flatts Inlet, 31° C. (July, 1905), 
was taken as the normal, and two series of experiments were conducted, 
one at temperatures above this and another at temperatures below it. 

When lancelets were transferred from sea water at 31° C. to sea water 
at 35° C., they responded by darting about several times and then sink- 
ing quietly in the characteristic way to the bottom of the dish. Their 
subsequent reactions were essentially normal. 

When transferred to sea water at 37° C., they made several quick 
darts, and finally fell quietly to the bottom, where they rested. When 
under these circumstances dilute acid was applied to them, they were 
found still to be actively responsive. 

When transferred to water at 40° C., they made one or two sudden 
plunges, after which they dropped to the bottom, while their semi- 
transparent substance gradually whitened. When touched with dilute 
acid, the animals quivered slightly, but did not react otherwise. Ina 
short time they were dead. 

At 42° C. the animals darted once or twice, whitened quickly, and 
dropped to the bottom dead. Bert (69, p. 21) states that water at 
41° C. kills amphioxus in two minutes. 

At 45° C. no locomotor response at all was given, and the animals 
began to whiten at once; they were apparently dead before they 
reached the bottom of the dish. 

It is plain from these records that heat has at least two influences 
on amphioxus. It stimulates them to momentarily vigorous locomo- 
tion, and it also brings about death by the coagulation (whitening) of 
certain materials in their living substance. The coagulation begins 


Ὁ 


PARKER. — THE SENSORY REACTIONS OF AMPHIOXUS. 429 


apparently at about 40° C., and may be so rapid at 45° ( as to 
prevent the characteristic locomotor reaction which occurs at lower 
temperatures. 

Having ascertained something of the general effect of heat on amphi- 
oxus, I next endeavored to determine what parts of its body were 
sensitive to this stimulus. To this end I used a temperature 39° C., 
a little lower than that which caused coagulation. I attempted to 
apply this temperature locally by touching the animal in the region 
to be tested with a sharply bent glass tube kept at the required 
temperature by a rapid flow of hot water through it. The bent tube 
thus heated was applied successively, but at considerable intervals, to 
the anterior end, middle, and tail of several animals, and their reactions 
recorded. Asa check on this method the bent tube filled with water 
at 31° C. was also applied to the animals, with the outcome that the 
mechanical stimulation was found to be so considerable that the results 
dependent upon temperature could not be rightly judged, and the 
method was therefore necessarily abandoned. 

I next tried running a gentle stream of warm sea water on different 
parts of the lancelet’s body while it was resting in a dish of sea water 
at 31° C., and I checked this method by using the same strength of 
stream, but at the normal temperature. ‘This procedure proved much 
more satisfactory than the use of the bent tube, for the current of 
water at the normal temperature seldom, if ever, gave rise to a re- 
sponse, while that at 39° C. very generally did. 

When the heated current was applied to the anterior end of a lance- 
let, the animal very usually swam immediately backward a short dis- 
tance. When it was applied to the tail, the animal often moved 
forward. When it was applied to the middle of the body, the reaction 
never was locomotor, but only a slight bending or jerking of the body, 
and even this was apparent in only about one out of every ten trials. 

The reactions of amphioxus on being immersed in warm water or 
touched by a current of warm water follow so quickly on the appli- 
cation of the stimulus that I am convinced that stimulation takes 
place on the surface of the animal, for there was scarcely time for the 


heat to reach by conduction any relatively deep-lying part. I there- 


fore conclude that heat is a sensory stimulus for amphioxus, and that 
it is very probably effective for the whole outer surface of the animal, 
the head being most sensitive to it, the tail less, and the middle 


_ portion of the body least. 


In a second series of tests, water cooler than 31° C. was used 
with which to stimulate the amphioxus. When animals were trans- 


_ ferred from water at 31°C. to water at 25°C., they swam about with 


430 PROCEEDINGS OF THE AMERICAN ACADEMY. 


more energy than at the normal temperature. Finally they dropped 
quietly to the bottom. 

At 20°C. they swam very energetically and near the top of the 
water, but finally dropped to the bottom; subsequently, on being 
touched with a rod, they swam, but not so energetically as at the 
normal temperature. 

At 15° C. they swam vigorously, but soon dropped to the bottom. 

At 10° C. they passed into the water without swimming, dropped to 
the bottom, and remained quietly there. 

At 5° C. they behaved as at 10°C. After remaining on the bottom 
at 5° ©. for five minutes, they were removed to water of ordinary tem- 
perature, where their reactions seemed to be entirely normal. 

Five active amphioxus were then dropped into water at 4° C., and 
after half an hour they were tested and all found to be dead. The 
temperature of the water at the end of half an hour had fallen to 
2.5°C. This experiment was several times repeated, and always with 
the result that death followed exposure to extreme cold for half an 
hour or so. 

Cold water from 25°C. to 15° C. is certainly stimulating to amphi- 
oxus. At 10°C. and lower no response is given, but death may 
intervene, particularly at lower temperatures, from unknown causes. 

All attempts at local stimulation with cold water were entirely 
unsuccessful. Water at 15°C., when applied as a current to the 
anterior end, tail, or trunk, was without effect, though, as already 
mentioned, immersion in water at this temperature called forth vigor- 
ous swimming. A current of water at 2° C., when applied locally to 
the anterior end, tail, or trunk, gave rise, as might have been 
expected, to no reaction. 

The reactions to cold water, when they occurred, were quite as quick 
as those to warm water, and must therefore have been the result of 
a very superficial stimulation ; but whether this was a stimulation of 
the whole outer surface, or of a special part of it, or of some special 
region like the entrance to the mouth, I am unable to say. 

The fact that amphioxus swims away from any source of considerable 
heat places it among negatively thermotropic animals. That it can 
be stimulated to active, non-directive swimming by both heat and 
cold shows it to be thermokinetic. That it should be stimulated by 
cold, but not influenced in a directive way by this stimulus as it is 
by heat, favors the view that it possesses, like some higher vertebrates, 
separate receptors for heat and for cold. 


PARKER. — THE SENSORY REACTIONS OF AMPHIOXUS. 431 


4. MECHANICAL STIMULATION. 


As has been pointed out already, the apparently great sensitiveness 
of amphioxus to light is really sensitiveness to mechanical stimulation, 
a form of sensitiveness long ago remarked by Merkel (80, p. 7), who 
observed that a vigorous amphioxus would respond by very active 
locomotion to the lightest touch of the forceps. 

To test the reactions of amphioxus to mechanical stimulation I 
first used a course pig-bristle mounted so that the rounded end could 
be brought into contact with any part of the animal’s exterior. When 
the anterior end of an amphioxus resting in a shallow dish of sea water 
was touched even lightly with the bristle, the animal usually sprang 
backward, though occasionally forward. The backward spring was 
often accompanied by a somersault-like movement, whereby the animal 
became turned end for end. When the stimulus was applied to the 
posterior part of the body, the result was almost invariably a forward 
leap. This portion of the body, though sensitive, was not so much so 
as the anterior end. The middle of the body was much less sensitive 
than either of the ends, and when the tip of the bristle was applied to 
it, there was often no reaction. When, however, a reaction did occur, 
it was almost always a backward leap. 

In general the reactions of amphioxus to mechanical stimulation 
resemble in essential respects their reactions to light, showing that 
the anterior end of the animal is most sensitive to such stimuli, the 
posterior end less so, and the middle of the body least, and that back- 
ward locomotion usually results from stimuli applied at the anterior 
end or the middle, and forward locomotion from stimuli at the 
posterior end. 

By means of local stimulation the sensitiveness of different portions 
of the body could be roughly determined. At the anterior end, though 
the rostrum can be stimulated, the most sensitive parts are the oral 
hood and the buccal cirri. When any of these parts is touched, back- 
ward locomotion almost invariably follows. If the hood, but especially 
the cirri, are touched only very lightly, they close and open with a 
sudden movement not unlike winking. In resting animals this is 
often carried out in what seems to be a spontaneous manner, but 
close inspection shows that it is dependent upon the accumulation 
on the cirri of debris from the current of water usually passing in at 
the anterior end. When the cirri become fairly covered with minute 
particles of coral sand, ete. this winking movement loosens these 
particles, and at the same time vigorously expels the water from just 
within the anterior opening of the animal, and thus removes the ac- 


432 PROCEEDINGS OF THE AMERICAN ACADEMY. 


cumulated debris. This reaction is doubtless dependent upon the 
mechanical stimulation caused by the particles of sand, οἷο, on the 
cirri, for, as already stated, the momentary contact of the end of 
the bristle with the cirri will call it forth. 

‘The great sensitiveness of the anterior end of amphioxus, which has 
already been noticed by Krause (’88, p. 146), is resident chiefly in the 
outer surface of the oral hood. ‘This part of the animal is easily stimu- 
lated by contact with any moving body and is the region especially 
concerned with the reception of stimuli when, through the movements 
of a few individuals, a whole assembly is set in violent commotion. 
It is also probable that this part is especially stimulated when an 
amphioxus, almost buried in sand, is made to draw back under the 
sand by directing a fine stream of water on the exposed anterior end. 

In the middle-trunk region the firm dorsal and lateral walls, and 
even the delicate ventral one, are relatively insensitive to mechanical 
stimulation. 

The whole of the caudal region is more sensitive to mechanical 
stimuli than the trunk region, but less so than the anterior end. 
The surface about the atrial pore is especially sensitive to touch, and 
a stimulation of this region not only results often in forward loco- 
motion, but also in a wave of contraction that passes anteriorly from 
the atrial opening over perhaps half the length of the thin ventral 
atrial wall. 

As amphioxus is so easily stimulated by gross mechanical disturb- 
ances, it is not surprising to find that it will respond to such delicate 
mechanical stimuli as sound waves. If a glass vessel that contains 
resting ‘amphioxus partly buried in the sand is gently tapped on the 
side, the animals, as Rice (80, p. 8) long ago observed, usually with- 
draw temporarily below the sand, or at least move their cirri in a way 
that resembles winking. hat this is not due to the vibration of par- 
ticles of sand against their bodies is seen from the fact that at least 
the reaction of the cirri can be called forth from animals that are rest- 
ing on a bed of cotton wool in a glass vessel of sea water when the 
walls of the vessel are tapped. Another common form of response to 
sound vibrations, often seen under the conditions just mentioned, is a 
wave-like contraction of the atrial membrane. This membrane in fact 
is so placed that it may be especially open to stimulation by sound 
waves, for it is suspended between the atrial cavity and the outer space, 
both of which are filled with sea water. 

It is very probable that all these reactions to sound depend upon the 
stimulation of some part of the tactile mechanism, for in the first place 
amphioxus has no special organ that can serve it as an ear (Stieda, 


PARKER. — THE SENSORY REACTIONS OF AMPHIOXUS. 433 


’73, p. 52), and secondly, many sound vibrations can be sensed through 
our tactile organs as well as our ears. 

That mechanical stimulation serves as a basis for thigmotropic, geo- 
tropic, and even rkeotropic reactions cannot be doubted, though Lyon 
(:05) has shown that rheotropism in certain fishes depends more upon 
sight than upon touch. All three kinds of reactions are shown by 
amphioxus. 

The thigmotropism of amphioxus is evident from the following ex- 
periments. ‘len amphioxus were liberated in a flat-bottomed glass 
aquarium containing a depth of 10 centimeters of sea water and five 
centimeters of coral sand. After half an hour all the animals had 
buried themselves in the sand, and after an hour and a half seven of 
them had come to rest with their anterior ends a little above the level 
of the sand, their usual position (p. 426). That these reactions were 
not the result of the light that fell into the dish from above is seen 
from the fact that similar reactions were obtained from animals that 
were liberated in a covered glass dish of sea water containing a layer of 
sand between one and two centimeters thick and illuminated by a mir- 
ror from below only. Under these circumstances the amphioxus came 
to rest in the sand, but in such positions that in many cases their bodies 
were exposed to light through the glass bottom of the dish, though their 
anterior ends projected into the darkness above the sand. ‘Thus it is 
evident that they did not enter the sand to escape the light. Moreover, 
amphioxus will rest quietly, much as when it is in sand, provided all 
_ but its anterior end is covered with small fragments of glass. Through 
this covering the light may pass to the animal, and apparently this does 
not disturb it, for its quiescence seems to depend merely upon the 
contact of its body with the particles of glass. 1 therefore believe that 
amphioxus is thigmotropic. 

The movements by which amphioxus buries itself are not without 
interest. As a rule the animal dropped passively through the sea 
water to the sand below. When it came in contact with the sand, it 
sometimes gave a sudden spring and disappeared below the surface. 
More frequently, however, it straightened out upon the sand, as noted 
_ by Miiller (’44, p. 84) and by Willey (94, p. 10), and later, particularly 
if it was moved by a current, it would arch and disappear below the 
surface, as described by Rice (80, p. 8). Its disappearance into the 
sand was so quickly accomplished that it was impossible for me to as- 
certain by direct observation whether the animal entered the sand with 
the anterior end first or the tail first. Steiner (86, p. 497) maintains 
that the anterior end of the animal enters the sand first, and that it 
may continue to burrow through the sand till this end emerges. He 

VOL. XLIII. — 28 


434 PROCEEDINGS OF THE AMERICAN ACADEMY. 


further asserts that the animals are incapable of burrowing with the 
tail first. Miiller (41, p. 399), however, in his description of the ani- 
mal’s habits implies that it enters the sand tail first, and often burrows 
only far enough to cover the main portion of the trunk, leaving the 
anterior end exposed. I attempted to ascertain the truth of the matter 
by carefully uncovering animals that had buried themselves, thus 
determining by direct inspection which end had probably entered 
the sand first. I also noted in instances where the animal had failed 
to cover itself completely which end was left exposed. ‘These instances 
were more conclusive than those of completely covered animals, for in 
these cases there was no chance for an unobserved reversal of ends as 
might occur where the animals were for a short time out of sight. In 
the great majority of these cases the animals had evidently entered the 
sand tail first, though there were some instances, especially among the 
imperfectly covered ones, in which it was clear that they had entered 
with the anterior end first. Other evidence on this question was de- 
rived from animals on which a slight operation had been performed. 
Amphioxus from which a part of the tail had been removed entered 
the sand only after many trials, whereas others whose rostrum had 
been cut off but whose tail was intact seemed to have no difficulty in 
making their way into the sand. ‘These observations are in agreement 
with what was noticed in animals that had partly or completely buried 
themselves, and I am therefore convinced, notwithstanding Steiner’s 
statement to the contrary, that amphioxus usually enters the sand tail 
foremost. 

In one respect the amphioxus buried in the sand were very different 
from those lying freely on the surface. The free individuals were 
usually very straight, as though held in form by the stiffness of the not- 
ochord. ‘The buried individuals, on the other hand, had when in the 
sand a very tortuous outline, as though they had crowded their way in 
between the coarse pieces of shell and coral. Such individuals imme- 
diately became straight on being released from the sand. 

Rheotropism, though present, is not a prominent feature in the re- 
actions of amphioxus. In the inlet at the small landing pier in front of 
Hotel Frascati large schools of small fish could be seen definitely ori- 
ented in reference to the swift current. These schools maintained a 
more or less constant position by swimming against the current about 
as rapidly as the current would have carried them in the opposite 
direction. When living amphioxus were dropped into these schools, 
they drifted among the small fish on the way to the bottom without as 
a rule the least locomotor movement, and, when they did move, they 
never showed any tendency to orient to the current. Moreover, when 


PARKER. — THE SENSORY REACTIONS OF AMPHIOXUS. 435 


they were placed in a floating aquarium the sides of which were of 
netting so as to permit a strong current of sea water to pass through it, 
they either drifted to the far end of the aquarium or swam irregularly 
about and without reference to the current, though a few small fish 
that were caught and put into the aquarium swam against the current 
with precision. 

These observations are in agreement with what Lyon (:05) found as 
to the rheotropism of certain fishes, namely, that in large general cur- 
rents their orientation is dependent not upon the direct stimulus of 
the current, but upon the possession of a visual organ capable of form- 
ing an image whereby they could fix their position in reference to mo- 
tionless objects on the banks and in the bed of the stream. Since 
’ amphioxus does not possess visual organs of such a character, orienta- 
tion under these circumstances is not to be expected. 

If, however, an amphioxus is put into a large cylindrical vessel filled 
with sea water and the water is made to whirl in it, the animal is quickly 
stimulated to swimming and swims vigorously against the current. 
After a short period of active swimming, in which the animal will often 
progress more rapidly than the current moves in the opposite direction, 
it will drop to the bottom as though exhausted and be carried round 
and round by the water. It was evident from the movements of the 
animal that the stimuli to its iocomotion were the momentary contacts 
with the inner sides of the vessel next which it was often swept and in 
all probability the varying rates of those parts of the current that 
touched the sides of the animal. ‘T’o such an irregular current amphi- 
oxus undoubtedly reacts, ἡ. ¢., under these circumstances it is rheotropic. 

Amphioxus can also be shown to be slightly geotropic. This fea- 
ture does not appear in its swimming, for though Steiner (86, p. 498 ; 
’88, p. 43) affirms that the whole animal, or even a quarter of it, will 
swim with full equilibrium, and is so quoted by Ayers (’92, p. 318) 
and by Sherrington (99, p. 1276), my own observations agree with 
the statements of Rice (80, p. 8) and of Willey (94, p. 10), that in 
swimming amphioxus may move with any side uppermost and may 
continually change that side. This change of attitude during loco- 
motion was so constant a phenomenon among the many amphioxus 
that I watched that there is not the least question in my mind that 
this animal during locomotion assumes no uniform position in reference 
to gravity. 

In its resting state, however, amphioxus shows some slight response 
to gravity. As it lies on the sand it may rest for considerable periods 
of time with any side uppermost, but after it has burrowed and come 
to rest near the surface of the sand, it usually lies, as Rice (80, p. 8) 


436 PROCEEDINGS OF THE AMERICAN ACADEMY. 


and Hesse (98s p. 459) have noted, with the ventral side uppermost 
and always with the anterior end higher than the posterior. This 
relation of the two ends might be supposed to be due to the need of 
having the anterior end in clear water, and therefore to be a reaction 
to the water and sand in the surroundings and not directly to gravity, 
but that this assumption is false is seen from the following experi- 
ments. If several amphioxus are placed in a closed box made of 
coarse wire gauze and filled with sand and the whole immersed in 
sea water, in a few hours they will be found at the top of the sand with 
their anterior ends projecting into the sea water. If now the box is 
cautiously inverted, some of the animals will keep their original 
positions, and thus their anterior ends will project from the under side 
of the box into the adjacent sea water ; but they will remain here only 
a short time, for sooner or later they will make their way upward 
through the sand to the top. In a similar way if, after they have 
come to rest at the top, the box is rotated through a quadrant so that 
their anterior ends project sidewise into the sea water, they will again 
desert this position and move to the top. Further, if in a funnel 
whose stem has been broken off short an amphioxus is buried in sand 
in such a way that its anterior end projects downward out of the small 
end of the funnel into the sea water, it will leave this lower end and 
make its way upward through the sand to the top, even if, in doing 
so, it emerges on sand above the level of the water. It is therefore 
evident that amphioxus will come to rest in the sand only when its 
anterior end is above its posterior one, and, from the conditions under 
which this occurs, such responses seem to be strictly geotropic. 


5. CHEMICAL STIMuULATION. 


The chemical sense of amphioxus, as remarked by Nagel (94°, p. 192), 
is not unlike that of a worm in that its seat is the whole outer surface 
of the animal and not simply the region around the mouth. This 
sense is doubtless serviceable chiefly as a means toward escape from 
unfavorable chemical surroundings and probably has little or nothing 
to do with the direct feeding habits of the animal. As is well known, 
amphioxus does not seek its food, but takes what is brought to it in 
water currents, selecting from this supply only in the erudest fashion, 
if in fact it can be said to select at all. Nagel ('94», ». 58) has shown 
that the outer surface of amphioxus is sensitive to chloroform, ete., 
and declares that, notwithstanding the presence of the so-called 
olfactory pit near the anterior end, one part of the animal’s body is 
about as sensitive to chemical stimulation as another, though the tail 
may possibly be more sensitive than any other portion. 


PARKER. — THE SENSORY REACTIONS OF AMPHIOXUS. 437 


In testing amphioxus for chemical responses I used solutions of 
sour, sweet, bitter, and alkaline substances, as well as solutions of 
certain oils and other materials. All these solutions were made up 
in sea water, and, where the strength is expressed as parts of a molec- 
ular solution, sea water was used as a basis for this mixture instead 
of distilled water. 

For a sour substance I used nitric acid. If a pipette full of sea water 
is discharged gently on the side of a resting amphioxus, there is usually 
no reaction. On animals thus previously tested a few drops of a 
” solution of nitric acid were discharged successively on the an- 
terior end, on the middle, and on the posterior end. In all these trials 
vigorous locomotion was induced ; backward when the region of appli- 
cation was the anterior end or the middle, and forward when it was 
the posterior end. When a ,”. solution was applied to the anterior 
end or to the tail, the characteristic reactions were obtained, but there 
was usually no reaction when this solution was applied to the middle 
of the animal. A /” solution called forth no reaction when applied 
to the middle or the tail, but only when applied to the anterior end. 
A ;%, solution called forth no reactions at all. Hence to solutions 
of nitric acid the anterior end is most sensitive, the tail next, and the 
middle least. 

A more detailed study of the anterior end showed the following 
conditions. In an animal that in its normal state responded when 
this end was stimulated by a .”% solution of nitric acid, the re- 
moval of the rostrum and the olfactory pit made no observable differ- 
ence in its responses, thus confirming Nagel’s statement (940, p. 192) 
that the olfactory pit is not essential to the special chemical sensi- 
tiveness of the anterior end. This pit, which was first described by 
Kiélliker (43) and was believed by him to be olfactory in function, 
was found in living animals to be lined with ciliated epithelium, by 
the movement of which particles of carmine were carried into it from 
its posterior edge and discharged from it anteriorly. Cutting off also 
the buccal cirri left the animal still receptive to a 7%, solution. 
When, however, enough of the anterior end was removed to take away 
the velar tentacles, what remained could be stimulated only by a 
7, or a stronger solution of nitric acid. The high degree of sen- 
sitiveness of the anterior end is therefore dependent upon parts not 
farther posterior than the velar tentacles. Since these tentacles and 
the buccal cirri are abundantly supplied with groups of sense cells 
(Willey, 94, p. 20), it is not impossible that the great sensitiveness 
of the anterior end is due to these groups of cells ; but to this question 
I can give no conclusive answer. 


438 PROCEEDINGS OF THE AMERICAN ACADEMY. 


To make an alkaline solution, one per cent of potassic hydrate was 
added to sea water, with the result that a somewhat milky precipitate 
was formed. The filtrate from this mixture had a strongly alkaline 
taste, but it did not call forth any response when it was applied either 
to the tail or to the middle of amphioxus. At the anterior end it 
caused the animal to dart backward vigorously. 

For a bitter material picric acid was used. About a % solution 
is very near saturation in sea water. "Ὁ this solution, when applied 
to the tail, middle, and anterior end, amphioxus reacted with charac- 
teristic locomotion. All three regions were also stimulated by a 7%, 
solution, but locomotion usually did not result. At ;¥%, occasional 
slight reactions were obtained, but only when the solution was applied 
to the anterior end, the tail and middle being apparently insensitive 
to this strength. | 

When a ten per cent solution of cane sugar in sea water was dis- | 
charged freely over the anterior end, the middle, or the tail of | 
amphioxus, no reaction of any kind was given. . 

No reactions were observed when the surface of the animal was _ 
bathed with sea water containing the following substances in solution: 
ether, chloroform, turpentine, oil of bergamot, and oil of rosemary, 
However, when any of these materials in a pure state was applied 
directly to the skin of amphioxus, a vigorous locomotor response was 
elicited, as Nagel (94°, p. 58) had previously found for chloroform and 
oil of rosemary. 

A one per cent solution of aleohol in sea water called forth no 
response when applied to the anterior end, the middle, or the tail of 
amphioxus. A five per cent solution stimulated the anterior end and 
tail but not the middle, and a ten per cent solution stimulated all 
three parts. 

Not only are many chemical solutions stimulating to amphioxus, 
but fresh water is likewise. When animals were dropped into sea 
water to which had been added one-fourth fresh water, the animals 
were observed to swim for a time more vigorously than in pure sea 
water. When the sea water was diluted by an equal volume or more> 
of fresh water, the amphioxus swam most vigorously, and in very 
dilute sea water or in fresh water they quickly died, as already ob- 
served by Bert (’69, p. 21) and by Johnston (:05, p. 115). These 
various mixtures were also locally stimulating. ‘The mixture of one- 
fourth fresh water and three-fourths sea water induced a slight back- 
ward movement when applied to the anterior end, but apparently 
stimulated no other part of the body. All mixtures containing more 
than one-fourth fresh water stimulated both the anterior end and the 


PARKER. — THE SENSORY REACTIONS OF AMPHIOXUS. 439 


tail, but not even pure fresh water stimulated the middle of the animal. 
_ When any of these stimulating mixtures were applied to the head, 

the animal swam backward ; when they were applied to the tail, the 
locomotion was forward. 

These experiments show that the surface of amphioxus is stimu- 
lated by solutions of nitric acid (sour), potassic hydrate (alkaline), 
picric acid (bitter), and alcohol, and by strong ether, chloroform, 
turpentine, etc. It is also stimulated by sea water diluted with fresh 
water, a mixture of which may prove fatal. Such stimuli were most 
effective at the anterior end of the animal, less so at the tail, and 
least of all at the middle, and the reactions were always such as to 
enable the animal to avoid the stimulus. So far as these tests go, 
amphioxus may be said to be uniformly negatively chemotropic. 


6. INTERRELATION OF SENSORY MECHANISMS IN AMPHIOXUS. 


The distribution of sensitiveness of amphioxus to the stimuli dis- 
cussed in the preceding sections follows a very simple plan. ΤῸ light, 
heat, mechanical and chemical stimuli, the anterior portion of amphi- 
oxus is more sensitive than the tail, and the tail is more sensitive than 
the middle region of the trunk. A more accurate comparison of the 
distribution of sensitiveness has shown that a response to light cannot 
be elicited when the most anterior part of the body is illuminated, 
though this region is very easily stimulated by either heat, mechanical 
orchemical means. This fact and the agreement of the degrees of sen- 
sitiveness to light with the numbers of eye-cups in different parts of 
the nerve-tube have been given a reason for the conclusion that the 
light receptors in amphioxus are the eye-cups themselves and not the 
nerve terminals in the skin. Since the receptors for heat, mechanical 
and chemical stimuli, lie in the skin, they must be distinct from the 
photoreceptors. Further evidence of this separateness is, however, 
seen in results obtained by exhaustion. If the tail of an amphioxus is 
stimulated by concentrated sunlight ten or twelve times, the animal 
will reach a state in which it no longer responds to the illumination. 
While in this state it will react, however, with great certainty when its 
tail is stimulated by water as 37°C., by contact with a camel’s-hair 
brush, or by a 7% solution of nitric acid. Thus from the standpoint 
of exhaustion the receptors for light can be shown to be physiologic- 
ally distinct from those for the other stimuli. 

The extent to which separate receptors in the skin might be distin- 
guished for the several effective stimuli cannot be judged by the distri- 
bution of sensitiveness for these stimuli, because, so far as I could make 


440 PROCEEDINGS OF THE AMERICAN ACADEMY. 


out, this distribution was the same for all such stimuli. Evidence on 
this point was to be had, however, from the following experiments on 
exhaustion. After about twenty applications of a # solution of 
nitric acid to the tail of an amphioxus, the animal usually ceased to 
respond to this stimulus. But on testing the same part of its body 
with water at 37°C. or with contact from a camel’s-hair brush, it was 
found to be immediately responsive. In a similar way about thirty 
vigorous strokes of a camel’s-hair brush were needed on the tail of an 
amphioxus before it ceased to react to this form of stimulation, where- 
upon it was found still to be sensitive to water at 37°C. and to a solu- 
tion of nitric acid. Finally after an animal had ceased to react to 
water at 37 C. it was still sensitive to contact with the brush and to 
acid. ‘Thus, notwithstanding the fact that the distribution of sensitive- 
ness for these several stimuli is such as to leave the question as to sep- 
arate receptors unsettled, exhaustion shows very conclusively that their 
operations are physiologically distinct (Parker, :07, p. 724),and as there 
is no evidence that they may not be represented by separate terminal 
organs in the skin, I believe that such organs are probably present. 
To what extent a further discrimination might be possible, as, for in- 
stance, the separation of terminal organs for cold and for heat, or for 
the different kinds of chemical stimuli, cannot be stated, for no experi- 
ments in this direction were undertaken. 

To all the forms of effective stimuli that I employed, amphioxus 
responded in but one way, namely, with such movements as would 
remove it as directly as possible from the presence of the stimulus. 
When the stimulus was applied to the anterior end or to the middle 
trunk region, the animal moved backward, and when the application 
was to the tail, it moved forward. In not a single kind of stimulus did 
the animal move regularly toward the stimulus. his negative re- 
sponse, which seems to pervade the whole sensory activity of amphioxus, 
is the basis of its habit of retreat and characterizes much of what it 
does. Even feeding, which is so usually a positive operation with 
animals, is in amphioxus a relatively passive affair and unconnected 
with any seeking reactions. It therefore seems that the whole sensory 
system of amphioxus is employed as the initial mechanism in removing 
the animal from possible danger rather than as an apparatus for leading 
it successfully into new territory. ‘This feature, as Steiner (’88, p. 42) 
has already remarked, is perhaps the most striking peculiarity of the 
sensory reactions of amphioxus. 

The negative response of amphioxus to stimulation is of importance 
in considering the question of the direction in which it swims. Rice 
(80, p. 8) declares that amphioxus always swims with its anterior end 


PARKER. — THE SENSORY REACTIONS OF AMPHIOXUS. 441 


foremost and that he never saw it move with its tail in advance. 
Steiner (’86, p. 497; ’88, p. 41) also asserts that the animal moves with 
the anterior end foremost. ‘The locomotion of amphioxus is a rapid, 
curiously irregular wriggle, often accompanied with somersault-like 
movements which make it impossible to be sure at any moment 
whether the animal is swimming backward or forward. The results of 
momentary stimulation, however, show very conclusively that amphi- 
oxus can swim both backward and forward, and that the direction of 
swimming at the beginning of any course is dependent upon the part of 
the animal’s body that was stimulated. But how long amphioxus 
keeps to one form of movement I was unable to discover. ‘The fact 
that it usually buries itself in the sand tail first (p. 433) leads me to 
believe that, though it can swim forward, as maintained by Rice and by 
Steiner, it usually swims backward. 

Another feature of the reactions of amphioxus is their great energy, 
which is quickly followed by what seems to be complete collapse. For 
a few moments the animal swims with the utmost vigor, and then drops 
down quite motionless, as though it had become entirely exhausted 
(Rice, 80, p. 9). That this is not exhaustion is seen from the fact that 
a slight stimulus will usually cause a second round of activity; but 
after a few such efforts, the animal becomes unresponsive to further 
stimulation and is doubtless temporarily exhausted. 


7. CentraL Nervous System anp Sensory MeEcHANISMS 
IN AMPHIOXUS. 


To what extent the uninjured central nervous system of amphioxus 
is essential to its sensory reactions has already been briefly alluded to 
in the account of this animal’s reactions to light (p. 424), but now that 
the other classes of stimuli have been described a more extended dis- 
cussion of this subject may be undertaken. Steiner (’86, p. 498 ; ’88, 
p. 43), who was apparently the first to investigate the functions of the 
central nervous system in amphioxus, states that after an animal had 
been cut into two, three, or even four parts, all the parts reacted to 
mechanical stimulation by swimming forward, and from these observa- 
tions he concluded that the central nervous system of amphioxus is a 
metameric structure without sufficient differentiation to allow one to 
divide it into brain and spinal cord. Although his description of the 
reactions of the pieces of amphioxus might lead one to infer that these 
fragments reacted exactly as the whole animal did, it is plain from his 
further account that such fragments were less sensitive than when they 
made a part of the whole animal ; for he goes on to remark that, when 


442 PROCEEDINGS OF THE AMERICAN ACADEMY, 


the sensitiveness of the fragment becomes much lowered, it is only 
necessary to put the piece in very dilute picric acid to call forth the 
characteristic locomotion again. Johnston (:05, p. 124), however, states 
that even a small piece of the tail of amphioxus can swim well and be- 
haves much as the whole animal does. Nagel (94, p. 811; '96, p. 79) 
declares that both halves of an amphioxus react promptly to light, but 
less energetically than the whole animal does. But Danilewsky (92) 
maintains that the halves react, at least to mechanical stimuli, very 
differently ; the anterior half is quite sensitive to this form of stimulus, 
but the posterior half can be brought to react only with difficulty. 
Krause ('97, p. 514) declares that the anterior half reacts vigorously 
to light and the posterior half only slightly. Hesse ('98», p. 462), 
however, states that after division the anterior part only trembles on 
being illuminated and the posterior part gives no reaction whatever. 

My own observations on B. caribbaeum lead me to believe that 
whether reactions will be given by both halves of this amphioxus or 
not depends quite as much upon the nature of the stimulus as upon 
any other factor. ΤῸ light, as already stated, I have never been able 
to get any response from the posterior half, though the anterior half 
regularly trembled whenever strong light was thrown upon it. In 
these respects my results agree exactly with those of Hesse, and they 
were, moreover, so uniform and regular that I am led to suspect the 
accuracy of Krause’s and of Nagel’s statements, at least so far as 
they apply to the posterior half of amphioxus. After the nerve-tube 
is cut, this part seems no longer able to respond to light. That this 
is due to the small number of eye-cups in this region, as Hesse be- 
lieved, is not true, for, as a matter of fact, these cups are almost as 
numerous in the tail region as in any other part of the animal. In 
my opinion the failure of the posterior half of amphioxus to react to 
light is not due to the lack of sensitiveness, but to the interruption 
of some centrally situated, reflex path. In the posterior half, appar- 
ently, the sensory neurones that are stimulated by light cannot trans- 
fer their impulses directly to the motor neurones of the same region, 
but only indirectly through the anterior part of the nerve-tube ; hence 
when this is removed the reflex ceases. It is in this way, rather than 
through altered sensibility, that an explanation of this phenomenon 
will, I believe, be found. 

T’o mechanical, and especially to chemical, stimuli I found both 
halves of amphioxus to be responsive, not, however, as Steiner de- 
scribes, but rather as stated by Danilewsky, in that the anterior part 
was found to be quite sensitive and the posterior part slightly so. 
These observations suggest that the central tracts over which photic 


PARKER. — THE SENSORY REACTIONS OF AMPHIOXUS. 443 


impulses pass are separate from those which transmit sensory impulses 
from the integumentary terminals. Since they show, further, that the 
anterior half of the nerve-tube is different in function from the pos- 
terior half, they are opposed to Steiner’s view of a metameric nervous 
system with equivalent segments, and favor the opinion advanced by 
Ayers (’80%, p. 223) and supported by Danilewsky (092), that the 
anterior end of the nerve-tube of amphioxus is already a primitive 
brain and the posterior portion a spinal cord. 


8. Sensory MECHANISMS IN AMPHIOXUS AND THEIR RELATIONS 
To VERTEBRATE SENSE ORGANS. 


The conditions presented by the sensory mechanisms in amphioxus 
give some clue to what was probably a step in the differentiation of the 
sense organs in primitive vertebrates. In these forms tactile organs 
doubtless covered the whole exterior, as they now do the body of amphi- 
oxus and that of the higher vertebrates, but these primitive ancestors, 
like amphioxus, probably possessed nothing by way of differentiations 
of these organs. Such differentiations are represented by the lateral- 
line organs and the ears, both of which occur in the cyclostomes and the 
higher vetebrates, but are wholly unrepresented in amphioxus, for the 
ear supposed by Peters (77, p. 854) to have been seen in this animal is 
well known not to occurthere. From the embryology of these organs it 
seems probable, as Ayers (92) has pointed out, that specialized tactile 
organs gave rise to lateral-line organs, and that from certain of these 
lateral-line organs the ear was differentiated. ‘This history, based upon 
morphological considerations, is parallel to what is known of the physi- 
ology of these parts, for the lateral-line organs are stimulated by 
material vibrations of low rate (Parker, :05*; :03*; :03°), possibly also 
effective as tactile stimuli, and the ear is stimulated by material vibra- 
tions of a higher rate, such as we recognize as sound. In my opinion the 
stimuli for these three sets of sense organs may often overlap and the 
three sets of organs constitute a genetic series, in which the tactile organs 
are the oldest members and the ear the newest. Although the primitive 
functions of these parts were doubtless (1) touch, (2) reception of slow 
vibrations, and (3) hearing, all these parts, but especially the ear, 
became involved more or less in the reflexes of equilibrium. This 
relation, however, I believe to have been entirely a secondary one, and 
not in any way to represent the original function of these organs as 
intimated by Lee (98); hence I have avoided any such expression as 
equilibration sense. Amphioxus thus represents an ancestral verte- 
brate with tactile organs, but without lateral-line organs or ears, and 


444 PROCEEDINGS OF THE AMERICAN ACADEMY. 


in it the equilibration reflex can be said scarcely to have developed as 
yet. In this respect it is like a young lobster before the statocyst has 
been formed (Prentiss, :01), and its powers of orientation to gravity, 
revealed in only a slight geotropism when at rest, are correspondingly 
small. 

As the receptive organs for mechanical stimuli probably represent a 
primitive stage from which the lateral-line organs and the ears of the 
higher forms have developed, so the receptors for light doubtless give 
some idea of what served as a source for the lateral eyes of vertebrates. 
It has already been pointed out that the only organs that are known 
to be light receptors in amphioxus are the eye-cups. Hesse (’98», 
p. 462), however, who was most instrumental in establishing this fact, 
does not regard these organs as in any way the homologues of the 
vertebrate eye, and in this opinion he is followed by Joseph (:04, p. 25). 
But I must confess that to me the evidence seems to point very defi- 
nitely to the conclusion already drawn by Boveri (:04, p. 411) that the 
sensory cell of each eye-cup is homologous to a rod- or a cone-cell. In 
my opinion the eye-cups of amphioxus represent a diffuse sensory 
material from which an eye, like the lateral eye of the vertebrate, or 
even a series of eyes, as suggested by Locy (97), could have developed, 
much as the ears of these animals have been differentiated from their 
lateral-line organs. ‘I'he objection to this view raised by Joseph (:04, 
p. 24) that the photo-receptors of amphioxus do not occur in the exact 
region from which the lateral eyes may have arisen does not appear to 
me to be really serious. 

The steps whereby the lateral eyes have come into existence are by 
no means easily retraced, and it is for this very reason that any indi- 
cation such as that afforded by amphioxus is of the utmost importance. 
Whatever has been the exact course followed by the eye in its differ- 
entiation, two remarkable but well-recognized features have resulted ; 
first, the retinal elements of the lateral eyes are inverted in relation to 
the stimulus as compared with the great majority of sense organs, and, 
secondly, the retina in vertebrates develops not directly from the 
external ectoderm, but as an outgrowth from the brain. It is rather 
striking that two investigators have published, apparently quite inde- 
pendently, essentially the same explanation of these facts. Balfour 
(85, p. 508) long ago pointed out that, if we imagine that the retinal 
part of the lateral eye was involved in the infolding that gave rise to 
the central nervous organs, then the final positions of the rods and 
cones at the surface of the retina away from the light would be satis- 
factorily explained, for this surface is the morphologically external 
surface of the ectoderm. ‘This explanation assumes that the eye was 


PARKER. — THE SENSORY REACTIONS OF AMPHIOXUS. 445 


functional on the exterior of the vertebrate ancestor before this animal 
had an infolded central nervous system, and that in the course of its 
differentiation it had passed as a functional eye into the deeper parts 
of the head and out to the surface again, a process not so difficult to 
understand when it is kept in mind that the bodies of many tunicates 
and of amphioxus are relatively transparent. Essentially the same 
explanation has been brought forward recently by Jelgersma (: 06), who 
believes that the eye in its transition between its supposed place of 
origin in the skin and its final position in the vertebrate head is well 
represented by the eye of the larval tunicates. Boveri (: 04) has called 
attention to the strong probability that the lateral eye has been derived 
from photoreceptors in the central nervous system, and has pointed out 
that the eye-cups of amphioxus are the probable source. He has not, 
however, attempted to trace these eye-cups back, as Jelgersma (: 06, 
p. 393) has done, to a possible origin in the skin, but implies that they 
may have arisen in place. 

Although I believe that the explanation first advanced by Balfour as 
to the origin of the lateral eyes of vertebrates has some truth in it, 
there are certain aspects of it which in view of the present investiga- 
tions need further consideration. Its first assumption is that the skin 
of the ancestral vertebrate contained photoreceptors. The fact already 
mentioned, that the skin of some amphibians and fishes, particularly 
ammocoetes (Parker, :03:,:05°), is so supplied, would lead to the ex- 
pectation that the skin of amphioxus would also contain such organs. 
My own studies have given no grounds for this belief, and, though I 
have not been able conclusively to prove the contrary, the evidence 
seems to favor the idea that the skin of amphioxus is not sensitive to 
light. As nothing is known, so far as I am aware, of the condition of 
the skin in this respect in tunicates, adult or young, the belief that the 
skin of the ancestral vertebrate contained photoreceptors must remain 
a pure hypothesis, and it is conceivable that the photoreceptors of the 
vertebrate eye may have arisen, not in the skin before the central 
nervous system was differentiated, as suggested by Balfour and by 
Jelgersma, but, as intimated by Boveri, from the cells of the central 
nervous system itself, in positions much as we find them now in 
amphioxus. 

The assumption of an external origin for the vertebrate photo- 
receptors is helpful only in that it appears to offer an explanation of 
the inverted positions of the rods and cones in the vertebrate retina. 
But this explanation requires that from the time the photoreceptors 
were formed in the skin till they made a part of an organized retina, 
they should occupy the morphologically outermost portion of the cellular 


446 PROCEEDINGS OF THE AMERICAN ACADEMY. 


layer in which they were imbedded and that the individual photo- 
receptors should be so oriented that their sensory ends would be toward 
the morphologically outer surface of this layer and their nervous ends 
away from it. In amphioxus it is true that the photoreceptors lie near 
the morphologically outer surface (the surface of the central canal), 
but their orientation is by no means constant in relation to this surface. 
In some the sensory ends point toward this surface, but in most such 
is not the case, and in a few they may even point away from this sur- 
face. It therefore seems to me obviously impossible to explain the 
orientation of the retinal rods and cones as transferred from the skin 
to the retina through a series of stages in one of which as much free- 
dom of position is shown as among the photoreceptors of amphioxus. 
Nor, as Metcalf (:06, p. 528) has pointed out, is the condition more 
favorable in the larvae of the tunicates, for here the photoreceptor 
cluster in the brain is so large compared with the thickness of the 
cellular wall in which it is imbedded (Froriep, :06, p. 145) that its 
orientation is no more related to the morphologically outer surface of 
the wall than that of the eye-cups of amphioxus is. For these reasons 
I believe that the inversion of the vertebrate rods and cones in relation 
to the light is not due to their origin from definitely oriented external 
photoreceptors, and since there is no positive evidence of the existence 
of these receptors in the skins of animals that may fairly represent an- 
cestors of the vertebrates, it seems to me that we are not warranted in 
assuming their presence at all. I therefore agree with Boveri in 
believing that the photoreceptors of vertebrates have arisen in the 
central nervous system and not in the skin, as assumed by Balfour and 
by Jelgersma. 

If the unusual position and orientation of the rods and cones in 
the vertebrate retina are not due to the origin of these bodies from ex- 
ternal photoreceptors, how then are these peculiarities to be accounted 
for? The position of the photoreceptor near the central canal is due 
in my opinion to the method of growth of the nerve-tube, for the epi- 
thelium surrounding the central canal is the source of the various cells 
in the wall of the tube. When, therefore, a new type of cell, like the 
photoreceptor, appears, it would be natural to expect it to arise from 
this undifferentiated material, and, in my opinion, the photoreceptors 
of amphioxus and of the tunicate larvae are in their position of origin. 
This position is retained by their derivatives the rod- and cone-cells. 

The very exact orientation of the rods and cones involves factors 
quite different from those that govern their general position. The 
eye-cups of amphioxus show only a very slight degree of orientation, 
but so far as this goes, it is correlated with habit, in that the majority 


' 
| 
᾿ 


PARKER. — THE SENSORY REACTIONS OF AMPHIOXUS. 447 


of the eye-cups are directed ventrally and the animal usually rests in 
the sand obliquely with the ventral side uppermost. Thus the ma- 
jority of the eye-cups are in a position to receive effective stimulation. 
If we imagine the body of amphioxus to be increased in muscular 
strength, etc., whereby it would approach more nearly the condition in 
the fishes and would consequently add much to its thiekness, it follows 
that the posterior portion would become less transparent and the pho- 
toreceptors of the anterior end would be the only ones left in position 
for effective stimulation. With the development of the mouth cavity, 
the gills, etc., the source of light for the anterior photoreceptors would 


' become chiefly lateral and dorsal, and their orientation would doubtless 


conform to this plan of illumination. If in accordance with this scheme 
each eye-cup assumed the best possible orientation, it would lie with 
its open end directed laterally and perhaps somewhat dorsally, 7. ¢., the 
contained sense cell would be oriented with its sensory end away from 
the light and its nervous end towards this stimulus. With the dis- 
appearance of the surrounding pigment cells as the cluster of photo- 
receptors became a single retina, these elements would be oriented as 
the rods and cones are. It is in this way, I believe, that the rods and 
cones of the vertebrate eye have become inverted, rather than that the 
inversion is inherited from a condition on the external surface of the 
body. 

Not only may the rod- and cone-cells be thus oriented at the begin- 
ning, but it seems to me that their subsequent relations to the surround- 
ing parts tend to keep them so. ‘The chief factor in this respect is the 
supply of materials necessary for their activity. Directed as they are 
away from the central dioptric part of the eye, their sensory ends, 
which are the parts most quickly exhausted by activity, are turned 
toward the chief blood-supply, the choroid layer of the eye, and are, 
therefore, in a most advantageous position to receive new materials for 
metabolism. That important substances reach them from this side is 
seen in the fact, well attested by experiment, that if the retinal pigment 
layer is removed from a live retina, the regeneration of the visual pur- 
ple in the rods is much retarded, if not completely stopped, though 
simply placing the layer back again upon the retina will cause this 
process to be resumed. ‘hus the inverted position of the rod- and 
cone-cells is the one best adapted to keep their most easily exhausted 
parts nearest the supply of materials necessary for their activities and 
still hold them open to access to light. This factor is doubtless one 
that has tended to retain the rod- and cone-cells in their inverted 
positions. 

_ The condition of light receptors in amphioxus lends no support to 


448 PROCEEDINGS OF THE AMERICAN ACADEMY, 


such views of the origin of the lateral eyes of vertebrates as have been 
advanced by Sharp ('85), Burckhardt (:02), and others, according to 
which the lens is regarded as having been derived from the primitive 
retina, now replaced by a photoreceptive differentiation of a deeper 
ganglionic part. I agree with Boveri in looking upon the eye-cups 
of amphioxus and, I may also add, the corresponding elements of the 
tunicate eye as the forerunners of the vertebrate retina, and, though 
I was at first inclined to ascribe to these a direct origin from the 
external skin, I now believe that we at least have no good reason for 
this assumption. 

The chemical sense is the only one in amphioxus that seems to 
possess a well-marked special organ, the so-called olfactory pit, and 
yet for this organ both Nagel’s experiments and mine gave no signs 
of sensitiveness other than that which characterizes the skin of the 
anterior end. Notwithstanding this negative evidence, the morpho- 
logical relations of this pit are such that I believe it is very probably 
the homologue of the olfactory organ of the higher vertebrates. ‘That 
a special function has not been discovered for the olfactory pit in 
amphioxus is perhaps not surprising when it is remembered that no 
direct physiological evidence whatsoever is at hand bearing on the 
function of the olfactory organs of fishes. That these organs are un- 
doubtedly of great significance in the life of a fish is attested by the 
extent of their surfaces and by the size of the connected parts of 
the brain, and yet, so far as the habits of fishes are concerned, we 
have no conclusive evidence as to their real uses. 

The outer surface of ampbioxus is sensitive to a variety of sub- 
stances, such as nitric acid, picric acid, alcohol, ete., and to all these 
substances the animal responds by withdrawing. Nothing could be 
discovered about its reactions that could lead to the belief that the 
chemical sense was connected with feeding. This sensitiveness was 
found in amphioxus to be dependent, not upon nerves from the region 
of the mouth that had invaded the outer skin, as Herrick (:03) has 
shown for many fishes, but upon the segmental nerves of the region 
stimulated, for the posterior third of an amphioxus will react, like the 
whole animal, to effective chemical stimuli. ‘The chemical sense of 
amphioxus is, then, not especially associated with its mouth or its 
feeding habits, but is a general integumentary sense, the function of 
which seems to be to help the animal to escape an unfavorable chemical 
environment. Apparently this is the primitive function of the chem- 


ical sense as it is met with in the skins of many animals, and this~ 


unspecialized sense has afforded a basis from which in the region of 
the mouth the specialized senses of smell and taste (both of which are 


PARKER. — THE SENSORY REACTIONS OF AMPHIOXUS. 449 


chiefly concerned with food discrimination) have been differentiated. 
This unspecialized chemical sense has been retained in the skin of the 
frog and other amphibians and in the irritable mucous surfaces of the 
higher vertebrates, but*its chief representatives in the higher forms are 
its derivatives, the senses of taste and of smell. Of these, amphioxus 
possibly possesses the sense of smell. 

Amphioxus may, therefore, be said to be an animal that possesses 
in potentia at least the sense organs of the vertebrates. Its outer 
surface is provided with tactile organs, but it does not possess the 
derivatives of these, the lateral-line organs and the ear. Its outer 
surface also contains undifferentiated chemical sense organs, but it 
cannot be said to have a sense of taste, and the only evidence of a 
sense of smell is morphological. Its outer surface, like that of the 
higher vertebrates, contains temperature organs. Amphioxus also has 
in the walls of its nerve-tube photoreceptors, which may well be the 
forerunners of the rod- and cone-cells of the vertebrate retina. It is 
thus an animal of fundamental importance for the understanding of 
the vertebrate sense organs. 


9. SuMMARY. 


1. Amphioxus is only very slightly sensitive to light. 

2. It responds to a rapid increase of light, but not to a rapid 
decrease. 

3. The only known photoreceptors in amphioxus are the eye-cups 
in the wall of the nerve-tube. 

4. Amphioxus is photokinetic and negatively phototropic. 

5. Amphioxus is stimulated by water warmer than that in which it 
lives (31° C.) and.is killed in water at 40° C. or higher. 

6. It is also stimulated by water colder than 31° C. and is killed by 
lengthy exposure to water of 4° C. or lower. 

7. It is thermokinetic and negatively thermotropic. 

8. The outer surface of amphioxus, especially the oral hood and the 
tentacular cirri, is sensitive to mechanical stimuli. 

9. Amphioxus is also sensitive to sound vibrations. 

10. It is thigmotropic, and slightly rheotropic and geotropic. 

11. The outer surface of amphioxus is sensitive to solutions of 
nitric acid, potassic hydrate, picric acid, alcohol, and to strong ether, 
chloroform, turpentine, oil of bergamot, and oil of rosemary, but not 
to solutions of sugar. It is also stimulated by diluted sea water and 
by fresh water. 

12. Amphioxus is negatively chemotropic. 

VOL, XLII. — 29 


450 PROCEEDINGS OF THE AMERICAN ACADEMY. 


13. The photoreceptors in amphioxus are anatomically distinct from 
the receptors for thermal, mechanical, and chemical stimuli, and these 
three are at least physiologically distinct one from another. 

14. To all stimuli that induce locomotion amphioxus responds by 
forward movements when the stimuli are applied to the tail, and by 
backward movements when they are applied to the middle or to the 
anterior end. 

15. Amphioxus generally buries itself tail first, and in all probability 
usually swims tail first, though it may reverse both processes. 

10. When amphioxus is cut in two, both halves lose much in sensi- 
tiveness, the posterior proportionally much more than the anterior. 
The anterior part of the nerve-tube is brain-like, the posterior part 
cord-like. 

17. ‘The skin of amphioxus contains tactile organs, but amphioxus 
possesses no derived organs such as lateral-line organs and ears. 

18. The photoreceptors of amphioxus are the eye-cups of the nerve- 
tube, and these probably represent the elements from which the rod- 
and cone-cells of the lateral eyes of vertebrates have been derived. 

19. The rod- and cone-cells of the vertebrate retina are inverted, 
not because they have retained a morphological position dependent 
upon an external origin, but because of their orientation acquired as 
effective eye-cups in the nerve-tube of a primitive vertebrate. 

20. The chemical sense organs of amphioxus are located in the 
skin and are chiefly important as organs for testing the character of 
the chemical environment rather than for the selection of food. From 
these undifferentiated chemical sense organs have probably been de- 
rived the organs of taste and smell, of which the former are appar- 
rently not present in amphioxus and the latter may be represented by 
the so-called olfactory pit. 


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Hesse, R. 
98°. Die Lichtempfindung des Amphioxus. Anat. Anz., Bd. 14, No. 21, 


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’43, Ueber das Geruchsorgan von Amphioxus. Arch. f. Anat., Physiol. 


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’88. Die Retina. II. Die Retina der Fische. Internat. Monatschr. f. 


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De ee a Δ»»- 


PARKER. — THE SENSORY REACTIONS OF AMPHIOXUS. 453 


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Locy, W. A. 
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Lyon, Εἰ. Ρ. 
705. On Rheotropism. I. Rheotropism in Fishes. Amer. Jour. Physiol., 
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Merkel, F. 
’80. Ueber die Endigungen der sensiblen Nerven in der Haut der Wir- 
belthiere. Rostock, 4to, 214 pp., 15 Taf. 


Metcalf, M. M. 
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Miiller, J. 

’44, Ueber den Bau und Lebenserscheinungen des Branchiostoma lumbri- 
cum Costa, Amphioxus lanceolatus Yarrell. Abhandl. Κρ]. Akad. Wiss., 
Berlin, 1842, pp. 79-116, Taf. 1-5. 

Miiller, W. 

’74, Ueber die Stammesentwicklung des Sehorgans der Wirbelthiere. 

Leipzig, 4to, 76 pp. 5 Taf. 
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945, Ein Beitrag zur Kenntnis des Lichtsinnes augenloser Tiere. Biol. 

Centralbl., Bd. 14, No. 21, pp. 810-813. 7 


Nagel, W. A. 
94>, Vergleichend physiologische und anatomische Untersuchungen tiber 
den Geruchs- und Geschmackssinn und ihre Organe. Bibliotheca Zool., 
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Nagle, W. A. 
’96. Der Lichtsinn augenloser Tiere. Jena, 8vo, 120 pp. 


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'77. Zur Kritik des Amphioxusauges. Inaug.-Diss., Tiibingen, 33 pp., 
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Parker, G. H. : 
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454 PROCEEDINGS OF THE AMERICAN ACADEMY, 


Parker, G. H. 
703". The Sense of Hearing in Fishes. Amer. Nat., Vol. 37, No. 435, 
pp. 185-204. 


Parker, G. H. 
:03°. The Skin and the Eyes as Receptive Organs in the Reactions of Frogs 
to Light. Amer. Jour. Physiol., Vol. 10, No. 1, pp. 28-36. 


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Parker, G. H. 
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des Hrn. Capitiin z. S. Freiherrn von Schleintz ausgefiihrten Reise 
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Koéniglichen Akademie der Wissenschaften iibersandten  Fische. 
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701. The Otocyst of Decapod Crustacea: Its Structure, Development, and 
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Sci. Philadelphia, Vol. 1884, pp. 300-310. 


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lanceolatus, und. iiber die halbcirkelférmigen Candle des Haifisches. 
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pp. 495-499. 


PARKER. — THE SENSORY REACTIONS OF AMPHIOXUS. 455 


Steiner, J. 
’88. Die Functionen des Centralnervensystems und ihre Phylogenese. 
Zweite Abtheilung: Die Fische. Braunschweig, 8vo, xii + 127 pp. 
Stieda, L. 
'73. Studien iiber den Amphioxus lanceolatus. Mém. Acad. Impér. 
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Willey, A. 4 
64. Amphioxus and the Ancestry of the Vertebrates. New York, 8vo, 


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o Ries 
Vou. XLIII. No. 17.— May, 1908. 


YS BEFORE ἀναγνωρίσεις IN GREEK 
TRAGEDY. : 


¢ 4 z νὼ“ a - ΣΝ = 
- os ., yr ee faa eg at _ a Ὡς ἫΝ eas ὌΝ Δ) 
2 Se Ay 2 Song Ps 4.5 
᾿ς - Arts Leer aes Σὰ ΕΞ 

a ee R= 


ΨΥ 


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Proceedings of the American Academy of Arts and Sciences. 


Vou. XLII. No. 17. — May, 1908. 


LIBRARY 
NEW YORK 
BOTANICAL 
a GARDEN. 


Wd) 


ON DELAYS BEFORE avayvopices IN GREEK 
TRAGEDY. 


By WILuLiIAM P. DICKEY. 


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JUN 1- 1908 


ON DELAYS BEFORE dvaywpices IN GREEK TRAGEDY. 


By WILLIAM P. Dickey. 


Presented by M. H. Morgan, March 11, 1908. Received March 26, 1908. 


THE purpose of this paper is to make a comparative study of delays 
before recognitions in Greek tragedy with a view to determining the 
justification for the disputed passage (518-544) in the Electra of Eu- 
ripides.t_ Before proceeding to a direct examination of extant recog- 
nition scenes, which shall be our chief concern, I deem it advisable 
to consult Aristotle, whose Poetics cannot be ignored by any student 
of Greek tragedy ; for in that treatise we possess the judgments of 
a Greek upon Greeks according to certain principles based upon an 
accurate and scientific study of an extensive literary material most 
of which is no longer extant. 

No one, so far as I know, has made any improvement on Aristotle’s 
definition of ἀναγνώρισις which we find in chapter xi? of the Poetics : 
ἀναγνώρισις δέ, ὥσπερ καὶ τοὔνομα onpaiver, ἐξ ἀγνοίας εἰς γνῶσιν μεταβολὴ, 
ἢ εἰς φιλίαν ἢ εἰς ἔχθραν, τῶν πρὸς εὐτυχίαν ἢ δυστυχίαν ὡρισμένων --- 
‘Recognition, as the name indicates, is a change from ignorance to 
knowledge, producing love or hate between the persons destined by 
the poet for good or bad fortune.’ In chapter vi,? along with 
περιπέτειαι, the ἀναγνώρισις is recognized as a part of the plot and 
one of ‘the most powerful elements of emotional interest in Tragedy.’ 
Finally, I am much indebted to Aristotle for his classification of 
recognitions and examples of each kind, which are to be found in 


1 The subject of this paper was suggested by the arguments advanced by 
August Mau (Zu Euripides Elektra, Commentationes Philologiae in Honorem 
Th. Mommseni, 1877, pp. 291-301) to show that verses 518-544 of the Electra are 
inartistic and inappropriate, and, therefore, an interpolation. On page 297 of 
this article Man, after remarking that the spectator knows that the recognition 
is about to take place, says: ‘In diesem Augenblick der grossten Spannung, 
muss nun zuniachst dies miissige Gerede eintreten,’ seemingly implying thereby 
that the passage in question unnecessarily delays the recognition; hence the 
reason for my consideration of this subject. 

2 I quote Bywater’s text, and Butcher’s translation. 

3 Poetics VI, 17: πρὸς δὲ τούτοις τὰ μέγιστα οἷς ψυχαγωγεῖ ἡ τραγῳδία, τοῦ μύθου 
μέρη ἐστίν, αἴ τε περιπέτειαι καὶ ἀναγνωρίσεις. . 


460 PROCEEDINGS OF THE AMERICAN ACADEMY. 


chapter xvi. Such portions of this chapter as serve my purpose will 
be mentioned later. 

My study of the above-mentioned passages of Aristotle has natur- 
ally referred me to recognition scenes in the Odyssey, from which 
it appears that such scenes are as old as Greek literature. It is in- 
teresting to note that the Homeric recognition scenes are compara- 
tively simple,* but none the less effective and in keeping with the 
general character of the epic. A brief examination of these scenes 
follows. At the beginning of the fourteenth book of the Odyssey 
Odysseus returns to Ithaca, and, in the guise of a beggar, presents 
himself at the hut of Eumaeus, the swineherd, where he receives a 
warm reception. One might expect that Odysseus, overjoyed by his 
safe return, would disclose his identity at once, but not so; even an 
epic poet could show ingenuity in delaying recognition scenes so as 
to make them occur where they suited his purpose best. In this par- 
ticular case it was necessary to interpose a delay until Telemachus 
could return from Sparta, and incidentally the poet had an opportunity 
to pit Eumaeus and Odysseus against each other as story-tellers, 
whereby the latter became acquainted with the general situation of his 
household affairs. Finally Telemachus appears at the hut of Eu- 
maeus at the beginning of Book XVI, yet there is no spontaneous 
recognition between father and son; but after Eumaeus has gone to 
the palace to inform Penelope of the arrival of Telemachus, Athena 
(1725) transforms Odysseus, the beggar, into Odysseus, the prince, 
who (188) declares to his startled son ἀλλὰ πατὴρ reds εἰμι. In spite 
of this divine manifestation, Telemachus doubts, and delays his final 
acquiescence until 214,° after Odysseus has explained the transforma- 
tion. Therefore, since we cannot regard this recognition as complete 
until 214, and inasmuch as the evidence is all in at 188, and what 
follows to 213 is a mere explanation, or résumé, of the real evidence, 
I must consider the intervening verses a conscious delay which I shall 
designate as secondary, as distinguished from that more general and 
longer delay (in this case from the beginning of Book XVI to verse 
172), which may properly be called primary. Let us take another 
case and see if we can detect a similar delay. 


4 TI am inclined to believe, however, that the recognition scenes show some 
development, though it is not my purpose now to discuss the relative chronology 
of books of the Odyssey on the basis of recognition scenes. Throughout this 
paper my references to ‘ Homer’ are in the generic sense. 

5 ἢ, καὶ χρυσείῃ ῥάβδῳ ἐπεμάσσατ᾽ ᾿Αθήνη. (I quote Cauer’s text of the Odyssey.) 

® Od. XVI, 213-214: Τηλέμαχος δέ | ἀμφιχυθεὶς πατέρ᾽ ἐσθλὸν ὀδύρετο δάκρυα 
λείβων. 


DICKEY. — ON DELAYS BEFORE RECOGNITIONS. 461 

In Book XIX, 53ff7 we find Odysseus, in response to her request, 
before Penelope ready for the interview in which he hears her story 
of her trials with the suitors, and in which he, upon request, discloses 
his fictitious lineage, adding a charming account of himself as host 
of Odysseus in Crete, and closing with the utterance of his belief that 
Odysseus will return. However much Odysseus might naturally have 
desired a recognition at this point, the poet would not allow it. The 
‘primary’ delay in this case was to continue to Book XXIII, about which 
I shall have something to say later. ΤῸ continue with Book XIX, we 
see that Odysseus so endeared himself to Penelope by his specious 
stories that she gave an order that he be well entertained. Then fol- 
lows the bath scene and the recognition of Odysseus by his old nurse, 
Eurycleia. It will be observed that this recognition is preceded by 
a ‘primary’ delay, and so managed that the scar on the foot of 
Odysseus is to be recognized by Eurycleia only, who is made to keep 
the secret and become an aid to her master in executing his plans. 
The general order of Penelope to her maids to wash the feet of Odys- 
seus and prepare his bed is met by his objection and his suggestion 
that some aged,® sober-minded woman, who had borne as many sor- 
rows as himself, might touch his feet, etc. The ‘primary’ delay in this 
case extends from 317 (where Penelope says to her maids, ἀλλά μιν, 
ἀμφίπολοι, ἀπονίψατε, κάτθετε δ᾽ εὐνήν) to 376, where Eurycleia, after a 
touching reminiscence of her master, says: τῷ σε πόδας νίψω, ἅμα τ’ 
αὐτῆς Πηνελοπείης | καὶ σέθεν εἵνεκ᾽, ἐπεί μοι ὀρώρεται ἔνδοθι θυμὸς | κήδεσιν, 
ἀλλ᾽ ἄγε viv ξυνίει ἔπος, ὅττι κεν εἴπω" πολλοὶ δὴ ξεῖνοι ταλαπείριοι ἐνθάδ᾽ 
ἵκοντο, | GAN οὔ πώ τινα φημὶ ἐοικότα ὧδε ἰδέσθαι, | ὡς σὺ δέμας 
φωνήν τε πόδας τ᾽ Ὀδυσῆι €ovxas? —almost a case of recognition 
ἐκ συλλογισμοῦ --(ο which Odysseus replies, ὦ γρηῦ, οὕτω φασὶν ὅσοι 
ἴδον ὀφθαλμοῖσιν [ ἡμέας ἀμφοτέρους, μάλα εἰκέλω αλλήλοιιν [ ἔμμεναι, ὡς 
σύ περ αὐτὴ ἐπιφρονέουσ᾽ ἀγορεύεις.10 Following close upon this in- 
tuition of Eurycleia occurs the statement in 392-393, αὐτίκα δ᾽ ἔγνω | 
οὐλήν, «td. ΤῸ be sure, the old nurse recognized the scar and im- 
mediately gave utterance to ἢ pad’ Οδυσσεύς ἐσσι, φίλον τέκος,11 κτλ., 
but, in effect, the poet’s zeal for accounting for the scar really delays 
for the reader the completion of the recognition until 474 —a rather 
remarkable continuation of the ‘secondary’ delay, which was possible 
for the epic, but impossible, 1 take it, in a similar case, for tragedy. 

A third case of recognition in the Odyssey that deserves notice is 


7 Od. XIX, 53: % δ᾽ tev ἐκ θαλάμοιο περίφρων Πηνελόπεια κτλ. 
8 Vid. XIX, 346-348. 9 Od. XIX, 376-381. 
10 Tbid. XIX, 383-385. 11 Thid. XIX, 474. 


462 PROCEEDINGS OF THE AMERICAN ACADEMY. 


found in Book XXI, 193 ff.12, where Odysseus reveals himself to Phi- 
loetius, the neatherd, and Eumaeus, the swineherd. In this case the 
‘primary’ delay is obvious; the poet purposely delayed this scene 
until it suited his purpose best, which was to prove the loyalty of these 
servants and to secure their services for the work in hand against the 
suitors. Here also a ‘secondary’ delay occurs, though it is short 3% 
and pointed. Odysseus makes sure of their loyalty, declares himself, 
and produces the scar as evidence. 

Again, in Book XXII, 35,14 Odysseus reveals himself to the suitors, a 
recognition long delayed by the poet. This recognition is momentarily 
expected from the time that Odysseus strung the mighty bow (XXI, 
409,15 and in 412, μνηστήρσιν δ᾽ ap’ ἄχος γένετο μέγα), but the poet in- 
terposes a slight delay until Odysseus has slain Antinous. Then he 
declares himself to the suitors and predicts their destruction.16 

Finally, we have to consider the recognition scene between Odysseus 
and Penelope, which is consummated in Book XXIII. How skilfully 
did the poet pass by many opportunities and delay this scene until the 
serious business of housecleaning had been finished !17_ In the begin- 
ning of Book XXIII Eurycleia, under orders from Odysseus, goes to 
awake 18 Penelope and to announce that her husband is present. Here 
begins the ‘ secondary ’ delay, which is rather longer than in the cases 
noted above, the conclusive evidence beginning at 183 ὦ γύναι, κτλ., and 
concluding at 20429—an account of Odysseus’ massive bed in his 
chamber fashioned about an olive shrub. It will be observed that the 
poet has made more of this recognition scene than any of the others. 
Penelope is rather obstinate and hard to convince ; she will not accept 
the statements of the old nurse, even when she hears of the sear, — an 
evidence of the poet’s good taste, — but must test him according to 
signs 2° hidden from the rest. ‘Thereupon Odysseus convinces her by 
his story of the bed mentioned above. In this case it appears that 
Penelope reasoned thus: only Odysseus could have such knowledge 


12 βουκόλε καὶ σύ, συφορβέ, ἔπος τί κε μυθησαίμην κτλ. 


18 103-900. 

14 ὦ κύνες, οὔ μ᾽ ἔτ᾽ ἐφάσκεθ᾽ ὑπότροπον οἴκαδ᾽ ἱκέσθαι κτλ. 

15 XXI, 409: . .  τάνυσεν μέγα τόξον ᾿Οδυσσεύς. 

16 Od. XXII, 41: viv ὑμῖν καὶ πᾶσιν ὀλέθρου πείρατ᾽ ἐφῆπται. 

17 [ maintain that our poet in thus delaying this recognition scene displays no 
little knowledge of human nature. 

18 XXIII, 5 ff. : &ypeo, Πηνελόπεια, φίλον τέκος, ὄφρα ἴδηαι, κτλ. 

19 203-204: . .. λέχος, HE τις ἤδη | avdpav ἄλλοσε θῆκε, ταμὼν ὕπο πυθμέν᾽ 
ἐλαίης. 

20 Od. XXIIT, 109-110: ἔστι γὰρ ἡμῖν [σήμαθ᾽ ἃ δὴ καὶ νῶι κεκρυμμένα ἴδμεν 


ἀπ᾿ ἄλλων. 


DICKEY. — ON DELAYS BEFORE RECOGNITIONS. 463 


about the bed, etc. ; this man has the knowledge, therefore he is Odys- 
seus —a clear case of ἀναγνώρισις ἐκ συλλογισμοῦ, which Aristotle 21 
recognizes as second best. 

Thus stand the Homeric recognition scenes that have come to my 
knowledge 22 — scenes comparatively simple, and yet such, I think, as 
show some development from the simple to the complex. In view of 
the foregoing study I conclude that the poet had full control over his 
recognitions, and did not insert them in a haphazard way, but with due 
regard for the purpose for which they were intended, in consequence of 
which his skill and ingenuity in the matter of ‘ primary’ delays had 
free play ; and that there is just reason for postulating ‘secondary’ 
(or shall I say prefatory ?) delays which in the case of the epic are, in 
effect, announcements to the reader or hearer that recognitions are 
about to take place. Now, that ‘primary’ delays before recognitions 
in Greek tragedy are evident is likely to be conceded by all. The im- 
portance of recognition scenes in Greek tragedy must be obvious to 
every student of Greek literature, regardless of his knowledge of Aris- 
totle’s Poetics. That the Greek tragic poets show much variety and 
skill in handling such scenes, particularly in the matter of delaying 
them to the point where they considered them most effective in their 
particular plots, must be patent to any one who has read the plays in 
which recognition scenes occur. Therefore, in the following study of 
recognition scenes in Greek tragedy, what I have chosen to call ‘ pri- 
mary’ delays I shall consider only incidentally, and shall give most of 
my attention to the special delays which I assume usually appear be- 
fore the final act of recognition, and which, for the want of a better 
name, I have denominated ‘ secondary.’ 

With deep regret that I am unable to determine the nature of the 
many recognition scenes, which we know existed in intervening litera- 


-ture,23 I must take a long step from the Odyssey to the Choephori of 


Aeschylus ; and, having passed from epic to tragic poetry, I am sorely 
disappointed in finding extant so few of the many tragedies 2* that 
had recognition scenes — Aeschylus furnishes us a single recognition 
scene ; Sophocles, two ; Euripides, five, if we count two for the Iphigenia 
in Tauris. 


21 Poetics, XVI, 12. 

22 It does not seem worth while to record my private consideration of that 
excellent recognition scene (XVII, 292 ff.) in which “Apyos was πρωταγωνιστής. 

23 The Νόστοι of the Trojan Cycle, the source of the Choephori, the Electras, 
Helen; the Οἰδιπόδεια of the Theban Cycle; the ᾽Ορέστεια of Stesichorus, etc. 

24 Our knowledge of lost tragedies in which recognitions existed is too meagre 
to be of any value for this report. 


464 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Tue CHorpHort oF AESCHYLUS. 


In considering the recognition scene of the Choephori I shall try to 
avoid any generalizations on Aeschylus’s mode of dealing with recogni- 
tion scenes, except to state that it seems likely that the real father 
of Greek tragedy probably adhered more closely to the models of 
his predecessors, and that his recognition scenes were simpler than 
those of his successors. What then is the nature of the recognition 
scene in the Choephori? I consider it somewhat as follows. Knowing 
that every form of the legend upon which this drama is built requires 
an ἀναγνώρισις, the audience 25 at the very outset has a preposses- 
sion that there is to be a recognition scene, and it seems safe to assume 
that to this the nimble-witted Greeks look forward, eager and curious 
to see how Aeschylus is going to handle the scene. This preposses- 
sion of the audience is reinforced by the action of Orestes in 6-7.26 
πλόκαμον Ἰνάχῳ θρεπτήριον, | τὸν δεύτερον δὲ τόνδε πενθητήριον. After 
this it is only a question of delay, and, in this case, the ‘ primary’ 
delay continues to 165 where Electra says, νέου δὲ μύθου τοῦδε κοινωνήσατε, 
and 167, ὁρῶ τομαῖον τόνδε βόστρυχον, the beginning of the ‘ secondary ’ 
delay. ‘These words of Electra mean to the audience that the recogni- 
tion is about to take place, and I venture to say that every Greek in 
the audience ‘sits up and takes notice’ accordingly. This ‘ second- 
ary’ delay continues through 211, where Electra says, πάρεστι δ᾽ ὠδὶς 
καὶ φρενῶν καταφθορά. By the locks of hair and the footprints Electra 
is almost convinced, and yet in doubt. For the resolution of this 
doubt Orestes appears at the psychological moment and the final act 
of recognition takes place, not only through Orestes’ reiteration of the 
evidence already adduced, but by producing a piece of weaving (ἰδοῦ δ᾽ 
ὕφασμα τοῦτο, 231), adding thereto all the expression of which a good 
actor 27 is capable. Thus ends the recognition, which occurs rather 
early in this play as compared with recognitions in Sophocles and Eurip- 


ides. It suited Aeschylus’ dramatic economy to make it thus. Surely | 


there is no evidence that it fell flat. The reason for its early occur- 
rence does not here concern me ; and as it stands it supports my theory 
of a ‘secondary ’ delay. 


°° Throughout this inquiry I try to consider the matter from the point of view 
of the audience. 

26 T quote the Oxford text, edited by A. Sidgwick. 

27 T am inclined to believe that modern critics too often underestimate histri- 
onic ability and effectiveness, which must have meant much to the Greeks. 


DICKEY. — ON DELAYS BEFORE RECOGNITIONS. 465 


SOPHOCLES. 


Electra. 


The recognition scene in the Electra of Sophocles presents some 
striking differences as compared with that of the Choephori; first in 
the length of the ‘primary’ delay and in the skilful management of 
the ‘secondary’ delay made possible by the introduction of the urn 
filled with the supposed ashes of Orestes. The recognition is expected 
from the beginning. ‘The audience knows that Orestes is present, and 
he heightens the interest by saying in 80,28 ἀρ’ ἐστὶν ἡ δύστηνος Ἠλέκτρα, 
upon hearing her ἰώ μοί wou in 77, likewise by depositing locks of hair 
at his father’s tomb (καρατόμοις χλιδαῖς, 52), which is particularly rein- 
forced by the announcement of Chrysothemis in 900-901, ἐσχάτης δ᾽ ὁρῶ 

| πυρᾶς νεώρη βόστρυχον τετμημένον, although developments have been 
such that Electra cannot on such evidence share the belief of her sister 
that Orestes has recently visited the tomb. Finally, the appearance of 
Orestes and Pylades (1098), face to face with Electra, must signify to 
the audience that the long delayed recognition is about to take place. 
At this point begins the ‘secondary’ delay, which is skilfully drawn 
out until Orestes is made to end it in 1221-1223, τὴνδε προσβλέψασά 
μου | σφραγῖδα πατρὸς expal? εἰ σαφῆ λέγω. 


Ocdipus Tyrannus. 


In this drama, which appears to have the most complicated plot of 
any extant Greek tragedy, one should expect to find a most highly de- 
veloped recognition scene ; such is the case. From the announcement 
_ of the oracle (106-107 39) to wreak vengeance on the murderers of Laius, 
the audience must look forward to the recognition, knowing that the 
self-discovery of Oedipus means his ruin. ‘The plot is complicated, and 
an opportunity for delay is given by the introduction of the Corinthian 
element. ‘The final act of recognition depends on the convergence of 
the evidence of the Theban and Corinthian herdsmen, the former pos- 
sessing the key to the situation. ‘This the audience understands, and 
therefore must take special interest in Oedipus’ decision (859-860, 
ἀλλ᾽ ὅμως τὸν ἀγρότην | πέμψον τινὰ στελοῦντα μηδὲ τοῦτ᾽ ἀφῇς) to summon 
the peasant who was present at the murder of Laius. But the ‘pri- 
mary’ delay is extended by the introduction of the Corinthian herds- 
man, who shows that Oedipus is not the son of Polybus and Meropé, 


NN). π-“----΄--ς--- 


28 T quote the text of Dindorf. 
29 τούτου θανόντος νῦν ἐπιστέλλει σαφῶς | τοὺς αὐτοέντας χειρὶ τιμωρεῖν τινα. 
VOL. XLIII. — 90 


466 PROCEEDINGS OF THE AMERICAN ACADEMY. 


and we are brought to the ‘secondary’ delay at 1117 (ἔγνωκα γάρ, σάφ᾽ 
ἴσθι Λαΐου yap ἦν | εἴπερ τις ἄλλος πιστὸς ὡς νομεὺς ἀνήρ) where the 
Theban herdsman is brought in and identified by the chorus. Then 
follows the triangular colloquy between the Corinthian, Oedipus, and 
the reluctant Theban herdsman, that brings us to the recognition (and 
περιπέτεια) in 1182 (ἰοὺ ἰού " τὰ πάντ᾽ ἂν ἐξῆκοι. σαφῆ, κτλ.) where Oedipus 
is finally convinced. -Here again we find a well-defined case of a 
‘secondary’ delay. 


EURIPIDES. 


Ton. 


In this drama Euripides has tried his hand at complicating the plot, 
but has cheated the imagination of the audience by disclosing every- 
thing in the prologue. The ‘primary’ delay is purposely made long 
and handled with some skill, but I have no doubt that the audience 
marked the beginning of the ‘secondary’ delay, which really begins at 
1261 3° (ὦ ταυρόμορφον ὄμμα Κηφισοῦ πατρός, κτλ.), where Ion, after the 
frustration and discovery of Creusa’s plot to kill him, discovers her at 
the altar and prepares to kill her. This delay is further prolonged 
and accentuated by the necessity for the appearance of the Pythian 
priestess (1320, ἐπίσχες, ὦ παῖ xrA.), whom the poet, in dire straits, has 
to call upon to produce the evidence 3! whereby the recognition may 
be effected at 1437, ὦ φιλτάτη μοι μῆτερ, κτλ., and 1439, ὦ τέκνον, κτλ. 
Here we find another case of ‘secondary’ delay, and that rather long. 


Iphigenia in Tauris. 


Likewise in this play Euripides, by his rather long prologue, ac- 
quaints the audience with the general situation. Immediately follow- 
ing Iphigenia’s misinterpretation of her dream, whereby she concludes 
that her brother is dead, Orestes appears at 67 (ὅρα, φύλασσε μή τις ἐν 
στίβῳ βροτῶν, words addressed to Pylades), and, in fact, 1s an- 
nounced to the audience by Pylades in 71, ἐμοιγ᾽, Opéora. Here be- 
gins the real ‘ primary’ delay, which is well managed in view of the fact 
that Iphigenia and Orestes think each other dead. It is worthy of note 
in this connection to observe the epic flavor that Euripides gave the 


301 quote the text of Nauck, 3d ed. 

31 A recognition is effected in the Rudens of Plautus (1154 ff.) in a similar 
manner, apparently a direct imitation of the scene in the Ion; Creusa establishes 
her identity by describing, previous to seeing, the ‘swaddling clothes’ of her son; 
similarly, Palaestra describes certain crepundia in order to prove that she is the 
daughter of Daemones. 


DICKEY. — ON DELAYS BEFORE RECOGNITIONS. 467 


drama by giving the herdsman, who acts in the capacity of a herald, 
such a long speech (260-339) in which to report the capture of Orestes 
and Pylades ; and thereby he adds to the delay before the recognition. 
No doubt the audience begins to suspect that the recognition is going 
to happen pretty soon after the herald’s report of their capture ; and 
certainly the searching questions, begun by Iphigenia at 472, τίς dpa μήτηρ 
ἡ τεκοῦσ᾽ ὑμᾶς ποτε | πατήρ τ᾽ ; ἀδελφή 32 τ᾽ κτλ., and continued at some 
length, reinforced by her decision (reached by her examination of the 
captives), to send a letter by one of the captives to her friends at Argos, 
etc., signify to the audience that the recognition scene ison. I should say, 
therefore, that the ‘secondary’ delay begins at 472, and that the recog- 
nition is really complete at 773, when Iphigenia says to Orestes, ἥδ᾽ ἣν 
ὁρᾷς σύ; but he is not allowed to declare himself until 795 (ὦ φιλτάτη 
μοι σύγγον᾽, κτλ.), when Iphigenia has finished reading the letter. Mark- 
ing the real completion of the recognition at 773, we have before us a 
‘secondary ’ delay of three hundred verses in which the poet shows ex- 
traordinary skill in handling a delicate situation in a manner quite as 
satisfactory to the audience, I imagine, as to Aristotle, 33 who puts his 
stamp of approval upon this recognition scene. On this splendid scene, 
whereby Orestes recognized his sister, Euripides spent his force and had 
to resort to inferior means to make Orestes known to Iphigenia. From 
the very nature of the case (for the second recognition is but a neces- 
sary sequel to the first), there is no ‘primary’ delay to the second rec- 
ognition, and therefore the short delay that does occur before the 
recognition, — a delay made necessary by the necessity of manufactur- 
ing convincing evidence, — must be called ‘prefatory’ rather than 
‘secondary.’ 
FTelen. 


The prologue to this play explains practically everything except the 
whereabouts of Menelaus. Perhaps the audience had a presentiment 
from the beginning that Menelaus would appear at the proper time, 
and that there would be a recognition. This latter is practically cer- 
tain when Menelaus appears on the scene at 386, and particularly 
when he hears in 470 (Ἑλένη κατ᾽ οἴκους ἐστὶ, κτλ.) that Helen is in the 
house. At 528 Helen appears again, having learned from Theonoe 
that her husband is still alive, and everything is ready for the recogni- 
tion. The ‘secondary’ delay begins at 541 (ἔα τίς οὗτος ;), when Helen 
sights Menelaus, and leads up to the recognition that is completed at 
Ee ee ee 555: 96" 

32 Does not Euripides ‘give the situation away’ by not calling for an 


ἀδελφός 2 
33 Poetics, XVI, 11. 


468 PROCEEDINGS OF THE AMERICAN ACADEMY. 


622-623, where Menelaus says, τοῦτ᾽ ἔστ᾽ ἐκεῖνο ξυμβεβᾶσιν οἱ λόγοι | 
οἱ τῆσδ᾽ ἀληθεῖς, κτλ. 


Electra. 


I have purposely reserved for the last the consideration of the recog- 
nition scene of Euripides’s Electra, which contains the disputed passage 
mentioned at the beginning of this paper. My consideration of this 
scene shows nothing very different from what has been noted in the 
other Euripidean recognition scenes. As usual, Euripides states his 
case in the prologue, and straightway brings on Orestes 55, who has 
paid a visit to his father’s tomb during the night and made offerings 
of his hair, with the accompanying rites. ‘The appearance of Orestes 
assures a recognition, and with the audience there is only the question 
of how Euripides will bring it about. ‘They wondered, no doubt, how 
his treatment would differ from those of Aeschylus and Sophocles. 
Orestes meets Electra (220, μέν᾽, ὦ τάλαινα, κτλ.) and assures her that 
her brother is alive but in exile (236), learns the status of the family 
affairs, assures himself of her willingness to assist in slaying the mur- 
derers of their father, learns that there is only one who would be able 
to identify him (287, πατρός ye παιδαγωγὸς ἀρχαῖος γέρων), after which 
he is about at a loss for words, when the peasant, the nominal husband 
of Electra, appears just in time to relieve the situation. After receiving 
an explanation about the presence of the strangers, he extends to them 
the hospitality of his home, for which he is censured by Electra, and 
despatched forthwith to the aged guardian®° of Agamemnon to re- 
quest that he lend material aid in providing a banquet for the stran- 
gers. The peasant goes out at 430, and is not allowed to return. 
During the supposed meantime, which is a pretty short time, the 
chorus is called upon to entertain the audience until the old man 
(πρεσβύς) can arrive with a young offspring of his flock °°, some 
fresh cheese and old wine. It happens, however, that the old gentle- 
man has stopped by the tomb of Agamemnon, whereon he discovered 
the shorn locks of hair (515, ξανθῆς τε χαίτης βοστρύχους κεκαρμένους) 
which, he ventures to assert to Electra, may have been offered by 
Orestes, and thereby provokes a discussion with Electra that has given 
certain latter-day scholars considerable trouble. 

With the situation thus before us, let us see about the ‘ secondary’ 
delay before the recognition. As stated above, the audience is assured 
of a recognition by the presence of Orestes. It may be thought that — 


84 82 ff. 
35 400: ἔλθ᾽ ὡς παλαιὸν τροφὸν ἐμοῦ φίλον πατρός. 
36 404 ff. 


DICKEY. —ON DELAYS BEFORE RECOGNITIONS. 469 


the ‘secondary ’ delay begins at 220, with the meeting of Orestes and 
Electra, but I am convinced that this whole scene between them, and 
even up to the arrival of the old man (487), is a part of the ‘ primary’ 
delay. I think the mention of the old man in the prologue is signifi- 
cant to the audience: that is, he is to play an important part in the 
drama, perhaps in the recognition scene ; and this belief of mine is 
strengthened by the statement of Electra (285) that only one of her 
friends (the παιδαγωγός) would know Orestes — and, finally, the old 
man is to appear ostensibly for another purpose, but in reality to effect 
the recognition for which the parties concerned (Orestes and Electra) 
are present and ready when he arrives at 487 and inquires for Electra. 
I assume, therefore, that the eagerly awaited arrival of the old man is 
a signal, so to speak, to the audience that the recognition is about to 
be effected. Hence the ‘secondary’ delay begins at 487, and the 
recognition is actually completed in 577-578, when Electra says, 
συμβόλοισι yap | τοῖς σοῖς πέπεισμαι θυμόν. It is not my purpose to 
discuss the disputed passage at length from an artistic point of view 
in order to combat the view of Mau, whom Mr. Tucker 37 follows ; 
but I wish to call special attention to the fact that, even counting the 
disputed passage, the ‘secondary ’ delay before the recognition is only 90 
verses in length (from 487 to 577) —and even this can reasonably be 
shortened if we eliminate the introductory remarks of the old man 
about his provisions, etc., and make the weeping of the old man 
(501-502, ἐγὼ δὲ τρύχει τῷδ᾽ ἐμῶν πέπλων κόρας | δακρύοισι τέγξας ἐξομόρ- 
ξασθαι θέλω) the real signal for the beginning of the recognition scene, 
thus making the ‘secondary ’ delay before the recognition 76 verses in 
length. In the first event we find a ‘secondary’ delay (1. e., from the 
time that the signal appears to be given to the audience that the recog- 
nition is about to take place until it is actually effected) of 90 verses ; 
in the second event, a delay of 76 verses. By eliminating 518-544, 
the interpolated passage, according to Mau, my figures for the delay 
would become 63 and 49 respectively. Let us see how these figures 
compare with those given for ‘secondary’ delays found in other trage- 
dies, especially those of Euripides. 


‘Secondary ’ delays before recognitions : 
Aeschylus — Choephori : 235-165 = 70 
Sophocles — Electra : 1291-1098’ = 723 
Oedipus Tyrannus: 1182-1117 = 65 


37 The Choephori of Aeschylus, Introd. p. Ixxi ff. 


470 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Euripides — Ion : 1437-1261 = 176 
Iphigenia in Tauris : 773-472 = 301 
Helen : 622-541 = 81 
Electra : 577-487 = 90, or 577-501 = 76 
By eliminating 518-544 : 63 49 


From these statistics I am not disposed to draw any dogmatic con- 
clusions. ‘l'o my mind they only show ina general way (a) a tendency 
toward a lengthening of the ‘ secondary ’ delay (and, even this state- 
ment must be taken with some reservation, for I find it impossible, in 
view of the uncertain date of some of the plays, to reduce this matter 
to a chronological basis), particularly on the part of Euripides ;38 
(b) ‘secondary’ delays of about equal length (accepting the full text 
of the Electra) in the Helen and the Electra, which appear to be plays 
of about the same date; (c) a ‘secondary ’ delay in the Electra (reject- 
ing the disputed passage) shorter than appears in any extant tragedy, 
and it seems to me unlikely that this should be the case. It appears 
that the very nature of the case is such in this ‘ secondary ’ delay of the 
Electra as to warrant the assumption that the audience would expect 
the loquacious old man to give a pretty full report 39 of his side trip to 
the tomb of Agamemnon, in spite of the fact that the poet apparently 
made use of it to criticise one of his predecessors.49 


38 This is especially true in the case of his better tragedies, to which distine- 
tion the Helen and the Electra can lay no claim. 

39 Otherwise I fail to see any motive for mentioning his visit to the tomb. 

40 In addition to the foregoing consideration of the bearing of delays before 
recognitions on our passage, I wish to add gratuitously at this point some observa- 
tions made while pursuing my investigation, which may lend further weight to 
my final conclusion. In the first place, I believe that the locks of hair deposited 
on the tomb of Agamemnon, though primarily deposited as a religious act of 
filial duty, had become fixed in the Orestean legend as one of the recognized 
means of bringing about the recognition. Aeschylus skilfully followed the 
legend; Sophocles delicately acknowledged the legend with negative results in 
the case of Chrysothemis; Euripides acknowledged and expressed his disapproval 
of the legend. This assumption, if justified, makes it necessary to retain the 
disputed passage. 

In the second place, why does Euripides use συμβόλοισι (577) instead of συμ- 
BéAw? May it not be that Electra, perhaps unconsciously, includes the proofs or 
tokens in the disputed passage with the scar in 573? In other cases (cf. Or. 1130; 
Ion 1386) when Euripides uses σύμβολον, the singular and plural seem to be 
properly differentiated. 

Finally, in El. 568, after the πρεσβύς has said to her in the preceding verse, 
βλέψον νυν εἰς τόνδ᾽, ὦ τέκνον, τὸν φίλτατον, Electra says πάλαι δέδοικα μὴ σύ γ᾽ 
οὐκέτ᾽ εὖ φρονῇς. Now, what is the force οἵ πάλαι here (cf. its use in ΕἸ. 367, 
where the reference is certain), and, in fact, the justification of the statement, if 


. 
“Ὁ 


DICKEY. — ON DELAYS BEFORE RECOGNITIONS. 471 


In summarizing the results of my investigation it appears (1) that 
there is sufficient evidence, in both epic and tragic poetry, for ‘ primary ’ 
and ‘secondary’ delays before ἀναγνωρίσεις ; (2) tendency to lengthen 
the ‘secondary’ delay, presumably for dramatic effect —a tendency 
that is strikingly illustrated by Euripides in contrast with Aeschylus 
and Sophocles ; (3) there is no reason to expect an abnormally short 
‘secondary’ delay in the Electra of Euripides, but rather the contrary, 
in order to give the old man an opportunity to satisfy the natural 
curiosity of Electra and the audience by giving them a detailed 
account of his startling discoveries at the tomb of Agamemnon — 
an opportunity that is met, in part, by the passage in question. In 
conclusion, therefore, I have no hesitancy in accepting the disputed 
passage (ΕἸ. 518-544), considering it so much bombast (to delay the 


recognition), wrongly employed by an indiscreet poet for critical pur- 


poses —a passage that ‘smacks’ 41 not ‘of the age of Zoilus,’ but of 
the age and flavor of Socrates and Aristophanes, the latter of whom 
might well have preferred charges against Euripides for encroaching 
on his literary province. 


there is not a reference to the old man’s statements in the disputed passage? It 
appears to me that the whole verse is a kind of reiteration and echo of Electra’s 
reproach in 524, οὐκ ἄξι᾽ ἀνδρός, ὦ γέρον σοφοῦ λέγεις. 

41 Tucker’s Choephori, p. Lxxii. 


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CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF 
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A NEW METHOD FOR THE DETERMINATION OF 
THE SPECIFIC HEATS OF LIQUIDS. 


By THEODORE WILLIAM RICHARDS AND ALLAN WINTER ROWE. 


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A NEW METHOD FOR THE DETERMINATION OF THE 
SPECIFIC HEATS OF LIQUIDS. 


By T. W. RicHARDS AND A. W. Rowe. 
Presented May 13, 1908. Received April 29, 1908. 


Durine the course of an extended research upon heats of neutral- 
ization now in progress, it became necessary to devise some method for 
the accurate determination of the specific heats of the reacting solu- 
tions. Obviously an accurate value for any thermochemical measure- 
ment can only be obtained when the factors involved in the calculation 
are accurately ascertained ; and it is well known that the existing data 
on this subject are by no means satisfactory. 'The recognized sources 
of error of the majority of the earlier methods and the discrepancies 
observed in the values obtained by the different experimenters using 
them! limit any dependence which can be placed in the constants 
thus obtained. Further, the truth of the assumptions upon which 
the corrections for their errors are based is by no means adequately 
proved. ΤῸ obviate the necessity of these corrections, and thus elim- 
inate the uncertainty attending their use, a new method has been 
devised. A brief discussion of the earlier forms of apparatus may 
assist in a better understanding of the difficulties encountered in devis- 
ing this method and the means by which they were surmounted. 

Of the various methods recorded, that of Andrews? has been, perhaps, 
the most frequently used. This depended upon the transference of a 
heated object or “ calorifer” from a source of heat to the calorimeter, 
which contained either water or the liquid to be studied. A compar- 


1 The following is a typical example: 
Specific Heat of NaOH 


% Sp. Ht. Observer. 
49.5 0.816 Hammerl. 
25.6 0 869 Hammerl. 
22.9 0.847 Thomsen. 


2 Pogg. Ann., 75, 335 (1848). 


476 PROCEEDINGS OF THE AMERICAN ACADEMY, 


ison of the observed rise with water and with the liquid under investi- 
gation gave a simple means of determining the relative heat capacities. 
A variant of this method consisted in using either water or the studied 
liquid in the calorifer, the calorimeter always being filled with the 
former. ‘This method, with various independent modifications, was 
used by Schiiller,? Person,* Pfaundler,5 Marignac,¢ Hammerl,7 and a 
number of other investigators. The simplicity of this procedure, and 
the elimination of many doubtful factors by using comparative results, 
are strong arguments for its use ; but the interchange of heat by radi- 
ation between both the calorifer and the calorimeter and their envi- 
ronments, coupled with the unavoidable lag of the thermometer, 
introduces elements of uncertainty fatal to the highest accuracy. 

The ingenious device of Thomsen,’ whereby measured amounts of 
hydrogen are burned, under constant pressure, inside the calorimetric 
system, gave concordant results ; but the values obtained are subject 
to some of the same corrections as those demanded by the Andrews 
method. Pfaundler,® using electrical energy as his source of heat, 
attempted automatically to eliminate the radiation-correction by heat- 
ing simultaneously two calorimeters, one containing water, the other 
the liquid under investigation. If the rise of temperature were the 
same, the loss by radiation would cancel. But as varying heat capac- 
ities involve varying amounts of electrical energy to secure this result, 
the electrical heat unit enters the computation, and by its uncertainty 
detracts from the absolute accuracy of the determination. This device 
has been recently applied in a modified form by Magie 19 with consid- 
erable success ; but it is by no means easy to find a heat-producing 
electrical resistance suitable for immersion in electrolytes. 

Several other different methods have been suggested by others, 
but these also are not wholly free from defect. In one, the radiation 
method of Dulong and Petit,11 the hot object was enclosed in an evac- 
uated and blackened chamber, losing its heat by radiation. The 
chamber was placed either in an ice bath or in a water bath of suffi- 
cient size to be unaffected by the heat given up by the cooling object. 
The relative temperatures of the hot object and its environment, and 


Ann. de Chim. et Ph., 3, 38, 437. 

Pogg. Ann., 136, 70, 235 (1869). 

Wien. Ber., 62, (2), 379 (1870). 

Arch. Gen., 2, 89, 217 (1870) ; 2, 55, 118 (1876). 

C. R., 90, 694 (1880). 

Thermochem. Untersuch., 1, 24 et seq. (1882); Pogg. Ann., 142, 387 (1871). 
9 Wien. Ber., 59, (2), 145 (1869) ; 100, (2a), 352 (1891). 

10 Phys. Rev., 9, 65 (1899) ; 13, 91 (1901) ; 14, 193 (1902) ; 17, 105 (1908). 

11 Ann. de Chim. et Ph., 2, 10, 395 (1819). 


ο “2 6 σ᾽ ὦ ὦ 


RICHARDS AND ROWE. — THE SPECIFIC HEATS OF LIQUIDS. 477 


the time required to secure thermal equilibrium, gave the necessary 
data. The uncertainty of the true law ot cooling is enough to seri- 
ously impair the accuracy of any results thus obtained, however. 

Quite a different procedure was adopted by Hesehus,12 who balanced 
the heating effect of the calorifer in a calorimeter at room temperature 
by the additions of successive portions of cold water. In this way 
he eliminated any cooling of the calorimeter. Waterman 15 improved 
this method, and made a series of apparently excellent determinations 
of the specific heats of metals. Using a Pfaundler resistance coil as a 
source of heat, Litch 14 has studied in this way the specific heat of 
water. Satisfactory as these methods may appear upon first sight to 
be, however, the unavoidable warming of the cold water during its 
transference to the warm calorimeter introduces an element of uncer- 
tainty just as great as the uncertainty in the ordinary cooling cor- 
rection ; hence no real gain was made. ‘The method is not really 
adiabatic. 

In 1905 a new method was described by Richards and Lamb,15 
eliminating most of the earlier sources of error while maintaining all 
the advantages of the older procedure except simplicity. Two por- 
tions of liquid — one hot, the other cold — were rapidly discharged 
from their respective containers and mixed in a calorimeter, the tem- 
perature of the mixture being that of the environment. Obviously, 
the cooling experienced by the warm liquid during transference is bal- 
anced by the warming of the cold liquid. The method involves a 
somewhat high degree of mechanical complexity, and is further com- 
plicated by the necessity of making supplementary determinations of 
the heats of solution or dilution where the two liquids possess any 
degree of mutual solubility. 

More recently a new method of calorimetry, by a strictly adiabatic 
procedure, has been described by Richards,16 and its applicability has 
been experimentally proved by the same investigator with the assist- 
ance of Forbes,17 Henderson,1® and Frevert.19 Here the environ- 
ment of the calorimeter is caused to increase in temperature as the 
calorimeter itself becomes warmer. ‘The studied transformation in the 
calorimeter thus takes place without interchange of heat with the sur- 
- roundings. Further, since both the initial and the final temperatures 
are stationary, the error due to the lag of the thermometer disappears. 


12 Jour. Soc. Ph. Chim. Russ., Nov., 1887; Jour. de Phys., 7, 489 (1888). 

13 Phys. Rev., 4, 161 (1896). 17 Thid., 41, 10 (1905). 

14 Tbid., 5, 182 (1897). 18 [bid., 41, 10 (1905); 42, 573 (1907). 
15 These Proceedings, 40, 659 (1905). 19 [bid.,42, 573 (1907). 

16 Tbid., 41, 8 (1905). 


478 PROCEEDINGS OF THE AMERICAN ACADEMY. 


The use of this method obviates at once the greatest source of error 
in calorimetric work of all kinds, namely, the correction for cooling. 
As the method may be employed in any kind of calorimetric work, 
there seemed to be no reason why it should not be applicable to work 
on specific heats; and the present paper will show that it is indeed 
of great service there. ‘The application is extremely simple: the 
substance to be studied should obviously be placed in a calorimeter 
surrounded on all sides by a jacket, the temperature of which can be 
changed to correspond exactly with the warming of the substance by 
some known source of heat. 

It was first necessary to decide upon the exactly quantitative source 
of energy to be used for heating the substance within the calorimeter. 
Some experimenters have used merely the heat of a warmer body ; 
others have used electrical heat ; and Thomsen availed himself of the 
heat of combustion of hydrogen. Of course many other chemical 
reactions might be employed for this purpose, as Ostwald and Luther 
have pointed out 2°; and after much consideration there was selected 
for this present work the heat of neutralization of pure sulphuric acid 
and sodic hydroxide as the most convenient, especially because it is 
not very changeable with the temperature. 

Definite amounts of acid and alkali were allowed to react in a 
platinum flask surrounded by the liquid in the calorimeter, and the 
rise of temperature in the whole system was carefully noted. By 
comparing the rise of temperature under these conditions with the 
rise shown when pure water is in the calorimeter, @ comparative 
measurement of the heat capacity of the liquid is made. A few words 
will suffice to explain the disposition of the apparatus and the method 
of its use. 

APPARATUS. 


A diagrammatic sketch of the apparatus in vertical section is seen in 
Figure 1. First, the environment of the calorimeter will be described. 
The jacket (A) was made of heavy sheet copper and was provided with 
an outflow cock (V’) for convenience in emptying. ‘The soldered joints 
were heavily coated with shellac to prevent corrosion by the alkaline 
solution with which it was filled. The capacity was 17.5 liters. A 
rotary, vaned stirrer (/?), with a speed of 145 turns per minute, insured 


thermal homogeneity in the contents of the jacket. ΤῸ raise the 


temperature, crude sulphuric acid was run into the jacket through 
the funnel (/’), into the alkali contained in the jacket, and the heat 
of neutralization thus liberated was rapidly disseminated throughout 


20 Ostwald-Luther, Phys. chem. Messungen (1902), p. 204. 


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Figure 1. 


480 PROCEEDINGS OF THE AMERICAN ACADEMY. 


the entire mass of liquid. The acid was contained in the burette (2) 
empirically graduated to give a rise of 0.1° for each scale division. 
The Beckmann thermometer (77, graduated in twentieths of a degree, 
indicated the temperature. ‘lhe cover (C) was similarly constructed, 
the capacity being 6 liters. It was furnished with an oscillating 
stirrer (S) with a speed of 45 strokes per minute, and the Beckmann 
thermometer (Q) similar to that in the jacket. In the same way acid 
was admitted from the burette (2), suitably graduated. Copper tubes, 
permitting the passage of those portions of the apparatus which pro- 
jected below the cover, were soldered to the bottom, and the joints 
were protected by a coating of shellac. The cover must fit tightly, 
otherwise evaporation will cause a slight cooling effect. The vessel 
was thoroughly cleaned at the end of each day’s work. The inner 
cylinder (Z) used to hold the calorimeter proper, was of sheet copper, 
nickel plated, and burnished on the inner surface. It was mounted on 
three legs, fitting into holders soldered to the bottom of the jacket, 
and was provided with the ring or apron (G), which prevented any 
portion of the liquid in the jacket from being thrown by the rapid 
stirring into its interior space. 

Inside this inner cylinder and separated from it by points of dry 
cork was the calorimeter proper (W). This was a platinum can of 
0.7 liter capacity, weighing 107 grams. During an experiment this 
was filled with water, or with the liquid the specific heat of which was 
to be measured. Thermal homogeneity of the calorimeter contents 
was secured by the two-stage perforated platinum stirrer (7) driven 
at a speed of 45 oscillations per minute. The temperature was accu- 
rately indicated by a large-bulbed, Beckmann thermometer (27), which 
was graduated in hundredths of a degree and capable of being read 
within yjoo. A small auxilliary thermometer (Z) gave the tempera- 
ture of the exposed stem. ‘Thus far the apparatus is essentially simi- 
lar to that used by Richards, Henderson, and Frevert. 

The heat-producing system presents the chief novelty. It was made 
up of two parts, a bottle (Y) and a burette (Z). The former was 
made of platinum, with a capacity of 0.17 liter and weighing 52.64 
grams. In this was placed a definite weight of a somewhat dilute, 
exactly known solution of sulphuric acid. The liquid was agitated 
by the platinum stirrer (./), alternating 145 times per minute. The 
bottle rested upon the glass triangle (/’), thus permitting a free circu- 
lation of the calorimeter liquid around the entire surface. Tightly 
fastened into the neck by a small rubber stopper was the tip of the 
burette (Z), which contained a concentrated solution of soda. The dis- 
charge of this solution into the acid, and the consequent heat evolved 


---- ea 


RICHARDS AND ROWE.— THE SPECIFIC HEATS OF LIQUIDS. 481 


by the reaction, formed the heat-producing action upon which the 
method is based. Since the alkali was the only part of the reacting 
system which, from its position, might, at the beginning of an experi- 
ment, have a different temperature than that of the remainder of -the 
system, one needed to measure its temperature accurately. To this 
end the thermometer (A’) 24 was immersed in the liquid, in which 
the stirrer (Q) oscillated 145 times per minute. Concentric layers of 
heavy white silk aided in protecting the liquid mass from outside 
fluctuations of temperature. ‘he drainings which collected in the 
lower end of the delivery tube after the admission of the soda to the 
bottle were expelled by blowing with a rubber bulb through the side 
tube (//). 

It is of the utmost importance that the stirring should be efficient. 
The entire system of stirrers was driven by a small electric motor, a 
system of wooden pulleys giving the 
required reductions in speed. ‘The 
stirrers of the bottle, jacket, and burette 
formed one system, and those of the 
calorimeter and cover, asecond. It was 
found advantageous to attach the vari- 
ous oscillating stirrers to metal rods 
working in sleeves and actuated by 
cords fastened eccentrically to the 
proper pulleys. In this way uniformity 
of travel and stroke were secured, the 
friction of the rods in the sleeves being 
reduced by good lubrication to a negli- 
gible quantity. 

As uniformity of composition in the 
acid used in the bottle within the 
inner vessel of the calorimeter is a 
frnndamental condition for the accuracy 
of the process, the familiar device 
shown diagrammatically in Figure 2 
was used for delivering it. ‘The acid 
was stored in the 2-litre Jena flask (A ) 
closed with a perforated rubber stopper. 
Through the siphon (S) the acid could ice uno: 
be drawn into the burette (2). ‘The 
auxiliary tube (7) equalized the pressure in the two containers. After 


21 The thermometer was a very accurate one, made especially for this purpose. 
It has a range of but 8 degrees, graduated in tenths. 
VOL. XLill. — 91 


482 PROCEEDINGS OF THE AMERICAN ACADEMY. 


filling the burette, the inflow cock (C’) was closed. When the acid was 
to be drawn from the burette, the cock (/’) connecting with the outside 
air through the wash bottle () was opened and the pressure thus 
equalized. As the wash bottle was filled with acid of the same con- 
centration as that in the reservoir, the tension of aqueous vapor of the 
air introduced was the same as that obtaining in the system. The 
flask was always shaken before anything was drawn from it. By this 
means an acid was secured of unvarying composition, as shown by 
numerous experiments. In a similar way, with the addition of a soda- 
lime tower for the removal of carbon dioxide, the alkaline solution was 
maintained at constant strength. 

It is needless to say that the thermometers were compared with 
Sevres standards with the greatest care, especially that designated 
M. Successive standardizations at different times were gratifyingly 
concordant. 


Conpuct oF AN EXPERIMENT. 


The calorimeter proper ( W, Figure 1) was partly filled with about 0.47 
litre of the desired liquid, — either pure water to serve as a standard, 
or a solution to be studied. It was then brought to the temperature 
selected for the experiment, accurately weighed, and placed inside the 
jacket (4, Figure 1). This latter contained its charge of dilute crude 
alkaline solution, and was also near the selected initial temperature. 
About 0.1 litre of pure acid (1.34 normal) was then run into the plati- 
num bottle (Y, igure 1), weighed carefully, and placed in a thermostat 
to bring it to the desired temperature. ‘lhe innermost short burette 
(Z) was filled to the mark with about 0.02 litre of pure alkaline solu- 
tion and brought near the required temperature. ‘The whole apparatus’ 
was then rapidly assembled in the form already described. A few 
minutes after the stirrers were put in operation, the whole system was 
in thermal equilibrium, as was shown by the constant readings of the 
various thermometers. ‘I'he temperatures of the calorimeter and the 
pure alkaline solution, indicated by the thermometers 27 and A’ re- 
spectively, were then carefully recorded, the stirrer in the bottle was 
disconnected, and the pure alkali discharged into the bottle as rapidly 
as possible. ‘I'he immediate temperature rise, as the heavy alkali sank 
through the acid, was paralleled outside by running acid into jacket 
and cover. The bottle-stirrer (7) was then agitated by hand, this 
permitting excellent control of the mixing of pure acid and alkali and 
the resulting rise in temperature. When the mixing was almost com- 
plete, as shown by the rise of the thermometer 7, the stirrer was 
reconnected with the motor and the final mixing done mechanically. 
The changes in the calorimeter throughout the experiment were care- 


RICHARDS AND ROWE. — THE SPECIFIC HEATS OF LIQUIDS. 483 


fully duplicated in the jacket and cover. At the end of some nine 
minutes the final equilibrium was attained, the thermometer readings 
becoming constant, at a temperature about four degrees above the 
initial temperature. 

The calculation was exceedingly simple except for two features, each 
of which concerned the sodic hydroxide. The first of these was a 
correction needed because the alkaline solution had not exactly the 
temperature of the calorimeter at the moment of delivery. If warmer, 
‘the alkali brought with it a slight excess of heat; if cooler, it caused 
a slight deficiency. ‘his correction was easily calculated by multiply- 
ing the water equivalent of the alkaline solution by the difference of 
temperature. When the alkali was too warm, this small product was 
subtracted from the total ; when too cold, added. ‘The other unusual 
feature involved not the total amount of alkali, but only the eacess of 
this solution over and above the constant amount (19.30 grams) needed 
to neutralize the acid. It was intended that the alkaline solution 
should be of such concentration as to evolve enough heat on dilution 
to raise itself through the range of temperature of the experiment. If 
this were the case, it would not be necessary to know very exactly the 
amount of the alkali; any excess would not affect the final temper- 
ature. The alkali was made up as nearly as was possible on the basis 
of the previously known data to accomplish this result, and was nearly 
enough so for the present purpose. Its concentration was 8.97 normal. 

The data and calculation of a specimen experiment may now be 
given without further preamble. 


SpEcIMEN EXPERIMENT WITH WATER IN CALORIMETER. 
No. 4, February 27, 1908. 


Data concerning temperature : 


Initial temperature of calorimeter. . . . . 16.489° 
Final temperature of calorimeter . . . . . 20.237° 
Rise of temperature during experiment. . . 3.748° 
Temperature of sodic hydroxide . . . . . 16.44° 


Difference between this and initial temperature 0.055 


Data concerning heat capacity, expressed in terms of the water-equivalent: 


Water incalorimeter. . ... . =. - 474.97 grm. 
Calorimeter and fittings, equivalent to . Wisp pe 
103.71 grm. of dilute acid (sp. ht. =0.94) . ΠΥ τς 
19.3 grm. alkaline solution needed to neu- 

tralize acid (sp. ht. ΞΞ 0.84). ... . 16:28: Ὁ 


Total heat capacity . . . . . . ~~ 600,02 grm. 


484 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Total heat observed = 600.02 X 3.748° . . . . 2248.87 cal. (18°) 
Correction for heat needed to warm 20.9 
grm. alkaline solution through 0.05°.. . +0.88 “ 
Total heat, corrected, from neutralization of 103.71 
grams Gd a a es SO ee oe Se ὍΒΙ. 


2249.75 


10371 2169.3 cal. 


Heat evolved from 100 grm. dilute acid = 


This process was repeated until there seemed to be no doubt as to 
the exact amount of heat evolved by the heat of neutralization of 
exactly 100 grams of this particular dilute acid by a slight excess of this 
particular alkaline solution under these perfectly definite conditions. 
The data and results of a series follow. 

In the following table, ΠῚ is the initial temperature of the system 
and 7’, — 7’, is the observed rise. ‘The other values are self-explanatory. 


Resutts with WATER. 


Total Water| NaOH Τ T,—T Corrected Heat per 
Value. Correction. ν᾿ 3 1° Heat. 100 grams. 


grams. calories. | Centigrade.) Centigrade. calories (18°) calories (18°) 


597.19 —4.74 10.089 3.7769 2250.3 2169.1 
597.19 —3.51 10.979 3.7749 2250.3 2169.1 


600.02 +7.02 10.209 8.1809 2248.7 2168.7 


599.98 +5.44 10.979 Ὁ. 1409 2249.4 2169.5 
600.02 +0.88 16.49° 3.7489 2249.8 2169.3 


2169.14 


The maximum variation from the mean here is only 8 parts in 22,000, 
or about 0.02 percent. As will be seen upon inspection, the correction 
for the difference in temperature of the alkali is sometimes additive 
and sometimes subtractive in the different experiments, hence the con- 
cordance of the observed results in connection with these values is 
excellent testimony as to the accuracy of the correction. 

The amount of heat evolved by the neutralization of 100 grams of 
sulphuric acid under these conditions was now used as the standard 
in warming various definite solutions through about the same range 
of temperature. In order to accomplish this purpose, the solutions 


RICHARDS AND ROWE. — THE SPECIFIC HEATS OF LIQUIDS. 485 


were successively placed in the calorimeter, and the flask for conduct- 
ing the heat-producing neutralization was immersed in each just as it 
had previously been immersed in the pure water. 

As an example, a series of results with a special solution of hydro- 
chloric acid may be given. This acid was chosen for determination 
because, being involved in another research, its specific heat was a 
matter of immediate interest. 

Below are given the data and method of calculating a single experi- 
ment, as well as the data of a series. 


SPECIMEN EXPERIMENT WITH A SOLUTION. 
No. 3, May, 1908. 
Weight of dilute sulphuric acid in platinum bottle . 103.72 grm. 


Data concerning temperature : 


Initial temperature . . . . . . . . . 16.236° 
Final temperature . . .... . . . 19.960° 
Temperature risO< . << τ. τὸν 5 πὸ 8. 1245 
Momperatureoialkaly.. . . + . 2. ς 16.13° 
Excess over initial temperature . . . . . —0.11° 


Heat, producing this effect : 
Calculated heat evolved by reaction = 


L012 xX 216914 . . « 2249.83 cal. (18°) 


Heat taken by alkali = 20.9 Χ 0.84 X 0.11 —1.93 “ 
Total heat actually available in process. . 2247.90 cal. 
Data concerning heat capacity, in terms of water equivalent : 2? 
Water value of calorimeter. . . . . . 10.87 grm. 
Water valueofacid . . τς 6 «5 «a8 Ὁ. Ὁ oy 
Water valueofalkali. . ..... - 16.2 
StH fore ars ae . ... τ... 1218 STM 


Heat used by system exclusive of solution = 124.58 X 
ee. ww ee te oe tO OL cali’) 


Heat needed to raise 488.35 grams of hydrochloric 
acid contained in calorimeter 
= 2247.90 — 463.94 = 1783.96 (18°) 


22 As these amounts are constant in all the determinations, slight constant 
errors in them would have only a vanishingly small pernicious effect upon the 
final results. The method is a comparative one, and small errors of this kind 
cancel out. 


486 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Hence, specific heat of hydrochloric acid of concen- 
γ Spect 2 ) 


: 784.0 
tration HCl 200.0 H,O = —11840_ 
488.35 X 3.724 


= 0.9809 


The experimental data for this series are found in the accompanying 
table. Several experiments where the manipulation was faulty were 
rejected, but if they had been included the average would have re- 
mained essentially unchanged. 


Tue Sreciric Heat or HCl 200 H,0. 


Correction Specific 
NaOH. 


Txwon 


calories, 


10.989 : 0.00 
16.14 : +2.63 
16.18 : —1.93 


16.30 A? —1.76 


As will be seen, the maximum variation from the mean is 0.03 
per cent. ‘This experimental error is as low as could possibly be 
expected. 


Heat or Ditvrion. 


It is obvious that this apparatus can be applied to the accurate de- 
termination of the heat of dilution of any solution put into the burette 
(Z), if water instead of sulphuric acid is placed inthe platinum flask 
(.\). The liquid to be diluted is run into the bottle as before, and there 
mixes with a weighed amount of pure water. A series of three experi- 
ments on the dilution of a concentrated solution of sodic hydroxide is 
given below. ‘The results are calculated in kilojoules, as the best 
standard for permanent record ; in the experiments previously recorded 
this was unnecessary because the method was a comparative one and 
the dimension of heat energy was eliminated in the result. 0.100 litre 
of pure water was contained in the platinum bottle. 


23 The corresponding values obtained from the results of Thomsen (loc. cit.) 
and Marignae (loc. cit.) are respectively 0.979 and 0.983. 


RICHARDS AND ROWE. —THE SPECIFIC HEATS OF LIQUIDS. 487 


Tne Heat oF DiLutTion or Sopic Hyproxipr NaOH: 5.85 H.O. 


Heat evolved b 
Water Value. δ 4 : Corr. (NaOH), Dilution to ᾿ 
NaOH °43.5 H,0. 


grams. grams. aC: calories. kilojoules. 


601.79 21.39 13% — 4.5 3.82 


601.86 21.43 Ἢ: — 8.2 
602.01 21.59 


The variation from the mean falls within the probable experimental 
error (0.001°). 

Obviously any thermochemical effect produced by the mixing of two 
liquids could be measured in the same way. It is to be noted that 
the method has a great advantage over other methods in that great 
speed in the execution of the experiment is not at all necessary. By 
the old methods, speed was essential because of the correction for 
cooling ; but here there is no correction for cooling because the per- 
formance is strictly adiabatic. The reaction may extend over hours, 
if necessary. 


It should be noted that the correction concerning the sodic hy- 
droxide could be wholly avoided if the pure alkaline liquid were con- 
tained in a receptacle within the calorimeter, instead of being held in 
a burette above it. Such a receptacle has been used successfully by 
Richards and Henderson 2* and was not introduced in these prelimi- 
nary experiments on account of its slightly greater complexity. In 
the future it will be adopted, and with it we hope to secure yet more 
accurate results. 

Experiments are now under way for the determination of the specific 
heats and heats of dilution of various solutions at different concentra- 
tions and at different temperatures, by the methods just described. 

It is a pleasure to acknowledge the generous aid of the Carnegie 
Institution of Washington, without which we should have been greatly 
hampered in this work. The present and future results of this investi- 
gation will be published in greater detail by that Institution, in one of 
its shortly forthcoming regular publications. 


24 These Proceedings 41, 11 (1905) ; Zeit. phys. Chem., 52, 551 (1809). 


488 PROCEEDINGS OF THE AMERICAN ACADEMY, 


SUMMARY. 


The results of this paper may be briefly summarized as follows : 

1. A new method for the accurate determination of the specific heats — 
of liquids has been described, using the adiabatic calorimeter and ἃ 
chemical source of heat. 

2. The heat capacity of a solution of hydrochloric acid of molal 
concentration HCl + 200 H.O has been measured. 

3. The method has been applied to the accurate determination of 
heats of dilution. 

4. A solution of alkali was used whose heat of dilution automat- 
ically compensates for any excess which might have been added. 


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Proceedings of the American Academy of Arts and Sciences. 


Vou. XLII. No. 19.— June, 1908. 


 PISISTRATUS AND HIS EDITION OF HOMER. 


By SAMUEL HART NEWHALL. 


Υ 
‘ey 
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= νος 
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PISISTRATUS AND HIS EDITION OF HOMER. 
By SAMUEL Hart NEWHALL. 
Presented by M. H. Morgan. Received May 13, 1908. 


In dealing with the life and works of any great character in history, 
especially a man whose figure in the world has conceivably been mag- 


 nified through the mists of distant time, it is essential carefully to 


discriminate between fact and fable, between a clear statement, how- 
ever incidental, found in any reliable writer, whether he makes the 
assertion on his own authority or on that of some author known to 
us, and a mere tradition to which the writer refers without stating his 
authority, however prevalent the story may have been in his own life- 
time, and even for many years previous. For it is possible, though 
not perhaps probable, that a tradition could be very old and very wide- 
spread without having the slightest foundation on fact. In dealing, 
then, with the literary work of Pisistratus, a prominent and influential 
person in the early days of Hellas, it is especially necessary to distin- 
guish between uncompromising statements made by authorities con- 
cerning his work, and mere references to a commonly accepted tradition 
introduced by such listless preludes as of παλαιοί φασιν and similar ex- 
pressions. In this article I shall try to make a satisfactory answer to 
two questions: first, did Pisistratus really do any literary work in 
connection with the Homeric poems? and, secondly, how thorough and, 
so to speak, professional were his services? that is, did he produce a 
text edition of the Iliad and the Odyssey? These questions are by 
no means new, but it is time that they were once more considered 


together, and perhaps something new may be brought forward in 


answering them. 
First, I desire to present a few passages from the ancient authors 
which point to a certain amount of literary activity on the part of 


Gc Pisistratus in connection with the Homeric poems, though they could 
ἘΞ not be considered indicative of anything so thorough and systematic 


crc 


as a regular edition. Strabo, the geographer, who manifests a wide 


Sp interest in literature, briefly tells the following story (IX, 394, 10): 


Ψ' > ~ ΄ 
καί φασιν οἱ μὲν Πεισίστρατον, οἱ δὲ Σόλωνα παρεγγράψαντα ἐν τῷ νεῶν κατα- 


a x ΓΚ] ΄ ” ΄ a een Fs 
=> λόγῳ μετὰ τὸ ἔπος τοῦτο, Αἴας δ᾽ ἐκ Σαλαμῖνος ἄγεν δυοκαίδεκα νῆας, ἑξῆς τοῦτο; 
τ 


" 


LIBRARY 
NEW γι 
BOTANICAL 

GARDBN, 


492 PROCEEDINGS OF THE AMERICAN ACADEMY. 


στῆσε δ᾽ ἄγων, ἵν᾽ ᾿Αθηναίων ἵσταντο φάλαγγες, μάρτυρι χρήσασθαι τῷ ποιητῇ τοῦ 
τὴν νῆσον ἐξ ἀρχῆς ᾿Αθηναίων ὑπάρξαι. ‘This bit of evidence, if true, though 
we must bear mm mind that it is based on tradition, and that, too, tra- 
dition which ascribes an act to either one of two men, points to an 
insertion which might more properly be called malicious than literary. 
This inserted line, popularly said to have been an interpolation, is 
verse 558 of the Iliad B, and stands in all known manuscripts, with 
the exception of seventeen.1_ But in the best manuscript it is lacking, 
as La Roche points out in his edition of the Iliad.2 By “the best 
manuscript ” I understand him to mean the Venetus A. Accordingly, 
in his text, he encloses this line in brackets. Aristotle also, in his 
Rhetoric,? makes Homer, as a writer of historical accuracy, the final 
court of appeal for the Athenians in their contest for the possession 
of the much-disputed Salamis, though unfortunately he does not men- 
tion the name of Pisistratus: περὶ δὲ μαρτύρων, μάρτυρές εἶσι διττοί, of μὲν 
παλαιοί, οἵ δὲ πρόσφατοι, καὶ τούτων οἵ μὲν μετέχοντες τοῦ κινδύνου, οἱ δ᾽ ἐκτός. 
λέγω δὲ παλαιοὺς μὲν τούς τε ποιητὰς καὶ ὅσων ἄλλων γνωρίμων εἰσὶ κρίσεις 
φανεραί, οἷον ᾿Αθηναῖοι ᾿Ομήρῳ μάρτυρι ἐχρήσαντο περὶ Σαλαμῖνος. 115 re- 
mark of Aristotle’s, of course, has no direct connection with Pisistratus. 
I quote it here merely to show that at least Strabo’s story of the use 
of Homer as a witness in the dispute about Salamis is true on the 
authority of Aristotle. In Quintilian (V, 11, 40) we have a slightly 
more pertinent reference to the same circumstance. His words are 
these : neque est ignobile exemplum (i. 6. of auctoritas) Megarios ab 
Atheniensibus, cum de Salamine contenderent, victos esse Homeri 
versu, qui tamen ipse non in omni editione reperitur, significans 
Aiacem naves suas Atheniensibus iunxisse. Here we 566 the verse in 
question is quoted in a translation with the added suggestion that per- 
haps it is not genuine from the fact that it is not contained in all the 
manuscripts. ‘This statement, however, about the use of Homer as 
historical testimony may very well have been made by Quintilian on 
the authority of Strabo, his predecessor, Quintilian’s own more inti- 
mate and critical literary knowledge prompting him to note the omis- 
sions in certain manuscripts, with which Strabo, very naturally, was 
unfamiliar. 

On the authority of Hereas, a Megarian writer of uncertain date, we 
are informed by Plutarch (Theseus, XX) that Pisistratus inserted verse 
630 of the eleventh book of the Odyssey: Δειδὸς γάρ μιν ἔτειρεν ἔρως Πανο- 
mnidos AlyAns. Τοῦτο yap τὸ ἔπος ἐκ τῶν Ἡσιόδου Πεισίστρατον ἐξελεῖν φησιν 


1 Cf. T. W. Allen in Class Rey., XV, p. 8 (1901). 
2 Footnote to 1]., 11, 658. 
3 1, p. 1875, 26. 


| 


NEWHALL. — PISISTRATUS AND HOMER. 493 


ἫἩρέας 6 Μεγαρεύς, ὥσπερ ad πάλιν ἐμβαλεῖν εἰς τὴν “Ounpov νεκυίαν τό, Θησέα 
Πειρίθοόν τε θεῶν ἀριδείκετα τέκνα, χαριζόμενον ᾿Αθηναίοις. "I'he manuscripts, 
according to La Roche,* read in this place, ἐρικυδέα for dpidetkera, which 
change he himself adopts in his edition, explaining the variation by 
the well warranted supposition that either Hereas or Plutarch, in ac- 
cordance with the prevailing custom of the ancients, was quoting from 
memory. ‘This passage shows that even before the time of Plutarch it 
was believed by one writer at least that Pisistratus inserted this verse 
in the Odyssey. Diintzer,> then, has some warrant for his supposition 
that in the time of Hereas credence was given to the story of the 
Pisistratean edition of the Homeric poems, provided we take it for 
granted that the poems did not exist in writing before the time of 
Pisistratus, —a point on which authorities differ. IPf they had previ- 
ously been reduced to manuscript form, then the insertion of a line by 
a ruler, merely to tickle the vanity of his subjects, can hardly be con- 
sidered indicative of an entire recension of the poems. 

Ascribed to Dieuchidas, the Megarian historian, we find a statement 
which, though vague, has reference, nevertheless, to an activity of some 
sort on the part of Pisistratus in connection with the Homeric poems. 
The exact date of Dieuchidas himself is a matter of some uncertainty, 
though he is confidently placed by Wilamowitz® in the fourth century 
B.c., and by W. Christ, who refers to Wilamowitz, among the earlier 
Atticists, which would make his sphere of activity fall in the first part 
of the third century B.c. The statement is contained in Diogenes 
Laertius (1, 57), and reads as follows: τά τε Ὁμήρου ἐξ ὑποβολῆς γέγραφε 
(i. e. Σόλων), ῥαψῳδεῖσθαι, οἷον ὅπου 6 πρῶτος ἔληξεν, ἐκεῖθεν ἄρχεσθαι τὸν 
ἐχόμενον. μᾶλλον οὖν Σόλων Ὅμηρον ἐφώτισεν i) Πεισίστρατος, ὥς φησι Διευχί- 
δας ἐν πέμπτῳ Μεγαρικῶν. It is obviously impossible to determine the 
exact nature of the services of Pisistratus to Homer as indicated by 
the word “ἐφώτισεν. Even the very reading of the text itself after 
the word “ Πεισίστρατος " has been questioned by scholars, not, however, 
because the manuscript is corrupt, but merely because the sequence of 
the next sentence is deemed too abrupt. Diintzer (ibid., p. 8), with 
Ritschl and Lehrs, finds himself compelled to indicate a lacuna after 
that word. ‘Two insertions into the text have accordingly been pro- 
posed, one by Diintzer himself and the other by Ritschl, both being 
relative clauses descriptive of the literary activity of Pisistratus. 
That the reputed collection of poems by Pisistratus can find no sup- 
port in this reference to Dieuchidas has already been pointed out by 


4 Hom. Textkritik, p. 18. 
5 Hom. Abhandlungen, p. 5. 
6 Hom. Untersuchungen, p. 241. 


494 PROCEEDINGS OF THE AMERICAN ACADEMY. 


Lang.?7 It does show, however, that Diogenes Laertius found a state- 
ment in Dieuchidas expressive of his belief in some service performed 
by Pisistratus for Homer. 

So far, the cited passages which attest a mere literary dabbling on 
the part of Pisistratus have been rather unsatisfactory ; they are, 
briefly, a reference by Strabo to a mere tradition which ascribed the 
insertion of a line either to Solon or Pisistratus ; second, the insertion 
by Pisistratus of another line in another place according to Plutarch, 
who is quoting from a writer about whose date we know only this, 
that, appearing in Plutarch, he must have written earlier than the 
year 80 A. D., which approximately marks the date of Plutarch’s ac- 
tivity ; third and last, the statement of Dieuchidas, as quoted by 
Diogenes Laertius, saying that Solon did more to elucidate Homer 
(if that is the best way to translate ἐφώτισεν) than did Pisistratus. 

Next, let us consider a few passages in authorities of the time of 
Cicero and later, who make definite statements about what might with 
fairness be called a Pisistratean edition of Homer. ‘The earliest refer- 
ence of this sort in any Latin author occurs in the De Oratore III, 
137, where Cicero says with reference to Pisistratus: qui primus 
Homeri libros, confusos antea, sic disposuisse dicitur ut nune habemus. 
The use of the word “‘dicitur” in this place is significant, showing, as 
it does, that Cicero is careful not to make the statement on his own 
authority, but introduces the story as one commonly believed in his 
own day or as transmitted by previous writers. It is reasonable to 
suppose that Cicero is indebted for his information on this point either 
to the Alexandrian scholars, or to some of the philosophers of Greece, 
or to the rhetoricians of the school of Pergamos, though such a state- 
ment is of course merely conjectural. 

More definite information about the edition of Pisistratus is pre- 
served to us in the scholia® of the Townley manuscript at the beginning 
of Book K of the Iliad. It runs thus: φασὶ τὴν ῥαψῳδίαν ὑφ᾽ Ὁμήρου 
ἰδίᾳ τετάχθαι καὶ μὴ εἶναι μέρος τῆς ᾿Ιλιάδος, ὑπὸ "δὲ Πεισιστράτου τετάχθαι εἰς 
τὴν ποίησιν. ‘This scholion is one of our most important bits of evidence 
and must be carefully considered. First we must note that no literary 
forgery on the part of Pisistratus is implied, but merely the assigning 
of a place in the Iliad to a poem which had been separately composed 
by Homer. Since the insertion of an entire book is a fundamental 
change to make in any piece of literary work, I think I am justified in 
considering this passage as pointing in the direction of an entire re- 
cension of Homer by Pisistratus. The use of the word “φασί in this 


7 Homer and his Age, London, 1906, p. 46. 
8 Ed. Maass, Ox. 1887, p. 841. 


NEWHALL. — PISISTRATUS AND HOMER. 495 


passage does not bring to the “source hunter” the despair which is usu- 
ally attendant on such expressions, because, in this case, it is possible 
with some degree of accuracy to determine the sources of the Townley 
scholia. Let us briefly consider this point. The codex Venetus A 
of the Iliad has the following subscription: παράκειται τὰ ᾿Αριστονίκου 
σημεῖα καὶ τὰ Διδύμου περὶ τῆς ᾿Αρισταρχείου διορθώσεως, τινὰ δὲ Kal ἐκ τῆς 
Ἰλιακῆς προσῳδίας “Hpwdiavod καὶ ἐκ τῶν Νικάνορος περὶ στιγμῆς. ‘The dates 
of these four men are as follows : Aristonicus, 60 B. 6.--19 Δ...» Didy- 
mus in the time of Augustus, Herodian under Marcus Aurelius, and 
Nicanor probably under Hadrian. Of their connection with the Town- 
ley scholia W. Christ 9 says that to ‘extracts from the works of these 
men the scholia of our manuscripts go back. Such are best preserved 
to us in Venetus, 454 (A); next in worth stand the Townley scholia. 
. . . To the works of these men there were added in later times also 
scholia from other grammarians, and especially from the Ζητήματα of 
Porphyrius.” Without doubt, therefore, our Townley scholia rest on 
really ancient authorities and have the same source as the scholia of 
Venetus A. {600 10 also agrees with Christ in deeming Aristonicus, 
Didymus, Herodian, and Nicanor, together with Porphyrius, the sources 
of our scholia.1+ 

A clear and valuable reference to the collection of the Homeric 
poems by Pisistratus or his associates is to be found in Pausanias 
(VII, 26, 6). When speaking of a certain city in Greece named 
Δονοῦσσα, he makes the remark: μνημονεύειν δὲ καὶ Ὅμηρον ἐν καταλόγῳ 
τῶν σὺν ᾿Αγαμέμνονί φασιν αὐτῆς ποιήσαντα ἔπος; 


Οἵ θ᾽ Ὑπερησίην τε καὶ αἰπεινὴν Δονόεσσαν, 


Πεισίστρατον δέ͵, ἡνίκα ἔπη τὰ Ὁμήρου διεσπασμένα τε καὶ ἄλλα ἀλλαχοῦ μνη- 
μονευόμενα ἠθροίζετο, ἢ αὐτὸν Πεισίστρατον, ἢ τῶν τινα ἑταίρων μεταποιῆσαι τὸ 
ὄνομα ὑπὸ ἀγνοίας. ‘Nhe word ““ ἠθροίζετο ᾿ in this passage must clearly 
refer to a writing down of the poems or to the collection of such por- 
tions as may have existed in writing before the time of Pisistratus. It 
is furthermore interesting to note that Pausanias is the earliest extant 


_ writer to mention anything like a school of revisors and collectors as- 


sociated with Pisistratus. Later we shall have other and more detailed 


references to such a body of coworkers. 
πα ἙέΠΠέΠπΠπΣςΞἙἋἝἣᾳὭὸξῤῤΠΠηΠ Ὃ ὋῸὋΘὋΘΦᾧ΄ὕ:.  ο -  --ς--ςςςς-ς-ς-ς-ς--ς-.---- 

9 Griesch. Lit. Gesch., ed. iv, Munich, 1905, p. 71. 

10 Homer, Glasgow, 1887, p. 100. 

11 It is obviously dangerous as well as unnecessary for our present purposes 
to make any one of these four or five authorities the ultimate source of this 
scholion. That is a point which cannot be definitely settled. Sufficient it is if 
I have merely hinted at the real antiquity and trustworthiness of our Townley 
scholia. 


496 PROCEEDINGS OF THE AMERICAN ACADEMY. 


As alone and unassisted in a similar literary undertaking, Pisistra- 
tus is described by Aelian (XIII, 14): ὕστερον δὲ (1. e., after Lycurgus, 
who had just been mentioned) Πεισίστρατος συναγαγὼν ἀπέφηνε τὴν ᾿Ιλιάδα 
καὶ ᾿Οδύσσειαν. The word “drépnve” without a context might be of doubt- 
ful significance, but when, as here, it is combined with “ συναγαγὼν," 
a word which can refer to nothing but a written collection, there can 
be little doubt that it means ‘‘publish” in the modern sense of the 
word. It should be noted, however, that nothing of the nature of a 
critical edition is here implied, merely a published collection. 

In a seventh 12 century scholion?* to the Τραμματική of Dionysius 
Thrax we have the following account of a Pisistratean school, which 
though interesting is not without obvious historical inaccuracies. It 
runs thus: ἐκήρυξεν ἐν πάσῃ τῇ Ἑλλάδι τὸν ἔχοντα ‘Ounptxols στίχους ἀγαγεῖν 
πρὸς αὐτὸν... καὶ μετὰ τὸ πάντας συναγαγεῖν, παρεκάλεσεν ἑβδομήκοντα δύο 
γραμματικοὺς συνθεῖναι τὰ τοῦ “Ομήρου ἕκαστον κατ᾽ ἰδίαν, ὅπως ἂν δόξῃ τῷ συντι- 
θέντι καλῶς ἔχειν . ~~ καὶ μετὰ τὸ ἕκαστον συνθεῖναι κατὰ τὴν ἑαυτοῦ γνώμην, 
εἰς ἕν συνήγαγε πάντας τοὺς προλεχθέντας γραμματικούς. . . . οὗτοι οὖν ἀκροασά- 
μένοι οὐ πρὸς ἔριν, ἀλλὰ πρὸς τὸ ἀληθὲς καὶ πᾶν τὸ τῇ τέχνῃ ἁρμόζον, ἔκριναν 
πάντες κοινῇ καὶ ὁμοφώνως, κρατῆσαι τὴν σύνθεσίν τε καὶ διόρθωσιν ᾿Ἀριστάρχον 
καὶ Ζηνοδότου. καὶ πάλιν ἔκριναν τῶν δύο συνθέσεών τε καὶ διορθώσεων βελτίονα 
τὴν ᾿Αριστάρχου. We shall later consider the glaring falsity of this last 
statement about Aristarchus and Zenodotus when we find a similar 
statement ridiculed by T'zetzes of the twelfth century. ‘The same 
scholia likewise contain an epigram on Pisistratus, which, as its date 
has never been determined, loses much of its importance for our pres- — 
ent investigation. The following is an extract: 


τὸν μέγαν ἐν βουλῇ Πεισίστρατον, ds τὸν Ὅμηρον 
ἤθροισα σποράδην τὸ πρὶν ἀειδόμενον. 


(ἐσ 


Suidas 14 also, the lexicographer, under the word “’Opnpos,” relates 
the story of the collection of poems made by Pisistratus. His words 
are these: ὕστερον δὲ συνετέθη καὶ συνετάχθη ὑπὸ πολλῶν, καὶ μάλιστα ὑπὸ 
Πεισιστράτου, τοῦ τῶν ᾿Αθηναίων τυράννου. Hor this statement Suidas may 
very well have had Pausanias as his authority. ‘This is not unlikely, 
inasmuch as the two accounts are substantially similar, that is, in both 
Pisistratus was only one of several who collected the Iliad and Odyssey. 


12 The principal commentators on Dionysius Thrax wrote in the sixth and 
seventh centuries. We probably have here a note by Heliodorus, who wrote in 
the seventh century, though we cannot determine with certainty the author of 
this scholion. 

13 In Bekker’s Anecdota, p. 767 ff. 

14 Ed. Bernhardy, Halle, 1853, 2, 1096. 


NEWHALL. — PISISTRATUS AND HOMER. 497 


By the use of the expression ὑπὸ πολλῶν Suidas rather implies different 
collections separated by considerable lapses of time, so that it seems to 
me very possible that, as Lachmann 15 suggests, he may have misin- 
terpreted his sources, misunderstanding a reference to the different 
collectors of the Pisistratean school as an allusion to compilers among 
the predecessors of Pisistratus. 

Coming now to T'zetzes, a commentator of the twelfth century, we 
find that at one time in his life he believed in a collection of Homer 
by a Pisistratean school of seventy-two, though, as will appear later, 
he subsequently rejected this theory, expressing the greatest disgust 
with Heliodorus,6 whom he had used as his authority. His first 
belief he expresses in the following words :17 Πεισίστρατος δὲ ὁ φιλολογώ- 
τατος, ἐν χρόνοις τοῦ Σόλωνος τυραννήσας ἐν ταῖς ᾿Αθήναις, κήρυγμα ἐξεκήρυξε τὸν 
ἔχοντα ἔπη ‘Opnpov, ἀποκομίζειν αὐτὰ πρὸς αὐτόν, καὶ ἕκαστον ἔπους χρυσοῦν 
ἀντιφορτίζεσθαι νόμισμα. οὕτω δὲ συναγείρας αὐτά, ἑβδομήκοντα καὶ δύο γραμμα- 
τικοῖς ἑνὶ ἑκάστῳ ἐπέδωκε κατ᾽ ἰδίαν τεθεωρικέναι καὶ συνθεῖναι αὐτά" ἐκεῖνος δὲ 
τὴν ἑνὸς ἑκάστου αὐτῶν σύνθεσιν ἀπεγράφετο. ὕστερον δὲ ὁμοῦ πάντας συναγαγὼν 
παρακλήσεσι, μεγάλαις τε δωρεαῖς ἐκείνους δεξιωσάμενος, ὑπέδειξε τὴν ἀπογραφὴν 
τῆς ἑνὸς ἑκάστου συνθήκης, καὶ ἠξίωσεν αὐτοὺς φιλαλήθως καὶ ἀφιλέχθρως εἰπεῖν, 
ὅτου ἄρα εἴη κρείττων ἡ σύνθεσις " καὶ πάντες τὴν ᾿Αριστάρχου καὶ Ζηνοδύτου ὑπερ- 
εξέκριναν. ἐκ δυεῖν δὲ πάλιν, τὴν ᾿Αριστάρχειον, καθ᾽ ἣν νῦν τὸ παρὸν τοῦ Ὁμήρου 
βιβλίον συντέθειται. Hvidently, at some later time, T'zetzes got new light 
on this subject, and realizing the absurdity of making the Alexandrian 
Aristarchus and Zenodotus the contemporaries of Pisistratus, and boil- 
ing with indignation when he reflected how he had been taken in, thus 
expressed his new belief, prefacing it with a brief note in which he 
makes poor Heliodorus the scapegoat of his disgust by the amusing 
epithet of opprobrium τῷ βδελυρῷς The passage runs thus: Πεισθεὶς 18 
᾿ἩἩλιοδώρῳ τῷ βδελυρῷ εἶπον συνθεῖναι τὸν Ὅμηρον ἐπὶ Πεισιστράτου ἑβδομήκοντα 
δύο σοφοὺς, ὧν ἑβδομήκοντα δύο εἶναι καὶ τὸν Ζηνόδοτον καὶ τὸν ᾿Αρίσταρχον. 
καίτοι τεσσάρων ἀνδρῶν ἐπὶ Πεισιστράτου συνθέντων τὸν Ὅμηρον. οἵτινές 
εἰσιν οὗτοι " ἐπικόγκυλος, ᾿Ονομάκριτος ᾿Αθηναῖος, Ζώπυρος Ἡρακλεώτης καὶ 
᾿Ορφεὺς Κροτωνιάτης. ‘This last statement I have found in no author 
before Tzetzes, so that I am at a loss to know his authority. In this 
passage the expression ἐπὶ Πεισιστράτου could be interpreted as meaning 


15 Betrachtung ii. Homers Ilias, Berlin, 1847, p. 82. 

16 This fact serves to strengthen my belief that Heliodorus was the composer 
of the cited scholion to Dionysius Thrax, since there he expounds at length the 
story of the school of seventy-two. 

17 Exegesis to Iliad, ed. G. Hermann. Leip., 1812, p. 45, 1. 27. 

18 See Ritschl’s Opuscula, I, 205, which contain Tzetzes’ Prolegomena to the 
scholia of Aristophanes. The word printed as ἐπικόγκυλος has been variously 
emended, but the MSS. are hopelessly defective at this point. 

VOL. XLIII. — 92 


498 PROCEEDINGS OF THE AMERICAN ACADEMY. 


merely that ‘in the time of Pisistratus ” this collection of Homer took 
place, did not T'zetzes elsewhere give us a more definite statement of 
his opinion. On page 207 of his prolegomena to the scholia of Aris- 
tophanes we find these words: τὰς ‘Ounpelous δὲ κατεξαίρετον mpd διακοσίων 
καὶ πλειόνων ἐνιαυτῶν Πτολεμαίου τοῦ Φιλαδέλῴφου καὶ τῆς διορθώσεως Zyvoddrov 
συντέθεικεν σπουδῇ Πεισίστρατος παρὰ τῶν τεσσάρων τούτων σοφῶν ἐπὶ Κογκύ- 
λου, ᾿᾽Ονομακρίτου τε ᾿Αθηναίου. Ζωπύρου τε Ἡρακλεώτου καὶ Κροτωνιάτου ᾿Ορφέως, 
Οὕτω μὲν ἐν χρόνοις τοῦ Πεισιστράτου τοῖς τέσσαρσι τουτοις σοφοῖς αἱ ‘Ounpixat 
συγγραφαὶ τεμαχίοις περιφερόμεναι συνετέθησαν καὶ βίβλοι ἐγένοντο. Hence 
we see that 'I'zetzes regarded Pisistratus as an active participant in 
the work of collection, though he was assisted by these four men. 
There can be little doubt, I think, that for these prolegomena he was 
drawing on the ancient scholia. John Williams White,1® in speaking 
of Tzetzes’ interlinear notes to the Aves in codex Urbinas, says: “ He 
was writing a brief commentary on the Aves based on the old scholia 
with additions ‘by the editor.’” By some scholars, however, Tzetzes 
is held in very low esteem as an authority. For example, Sandys 2° 
says of him: “ His inordinate self-esteem is only exceeded by his ex- 
traordinary carelessness. He calls Simonides of Amorgus the son of 
Amorgus, makes Naxos a town in Euboea, describes Servius Tullius as 
‘consul’ and ‘emperor’ of Rome, and confounds the Euphrates with 
the Nile. He is proud of his rapid pen and remarkable memory ; but 
his memory often plays him false, and he is for the most part dull as a 
writer and untrustworthy as an authority.” With regard to the pass- 
age already quoted from 'T'zetzes, Monro 21 writes: ‘“ Everything points 
to the conclusion that the story is a mere fabrication. He does not 
give his authority, and it can scarcely be imagined that he had access 
to sources unknown to the generality of Byzantine scholars.” But is 
not this unjustly making light of the character of Tzetzes? The worst 
that Sandys cares to say about him is that he was careless ; but is it 
carelessness that gives birth to such a circumstantial statement as this ? 
I cannot see how such a detailed story could have come full-grown like 
Minerva from the head of any writer unless his fault had been some- 
thing much more serious than carelessness ; but this no one would say 
of Tvetzes. I prefer then to follow Mr. White in believing Tzetzes to 
have based his prolegomena on the old scholia with some additions, 
and accordingly I think it most probable that for this statement he 
must have found some authority in the scholia. 


19 Harvard Studies, XII, 104. 
20 Hist. of Class. Scholarship, ed. ii, 419. 
21 Od., XIII-XXIV, ed. i, Ox., 1901, p. 406. 


NEWHALL. — PISISTRATUS AND HOMER. 499 


Let. us now briefly consider references to any of these four associates 
of Pisistratus in literature earlier than the time of Tzetzes. In Herod- 
otus (VII, 6) these words are applied to Onomacritus: ἄνδρα ᾿Αθηναῖον 
ema uOnGyov τε kat διαθέτην χρησμῶν τῶν Μουσαίου... ἐξηλάθη yap ὑπὸ 
Ἱππάρχου τοῦ Πεισιστράτου ὁ ᾿᾽Ονομάκριτος ἐξ ᾿Αθηνέων. Asa contemporary 
of Hipparchus, so, without doubt, he was also a contemporary of Pi- 
sistratus. ‘Thus Herodotus vouches for the chronology of 'T'zetzes so 
far as Onomacritus is concerned. But we must admit that in all 
probability the connection of Onomacritus with Pisistratus in the 
Homeric collection was unknown to Herodotus; hence his silence in 
this place. The only other of these four men to whom I have been 
able to find a reference in an ancient author is Orpheus, —not the great 
Orpheus, but one of Croton, who is referred to by Suidas (p. 1176), 
under the words Ὀρφεὺς Κροτωνιάτης in the following manner: ἐποποιός, 
ὃν Πεισιστράτῳ συνεῖναι τῷ τυράννῳ ᾿Ασκληπιάδης φησὶν ἐν τῷ ἕκτῳ βιβλίῳ τῶν 
Τραμματικῶν. ‘his writer Asclepiades was, according to Sandys (p. 160), 
a native of Myrleia in Bithynia, and was born at some period between 
130 and 180 B.c. As Orpheus was an epic poet and associated with 
the tyrant Pisistratus, according to Asclepiades, I think we are justi- 
fied in inferring that the connection was doubtless of a literary nature. 
This fact, of course, is not enough to vindicate the whole story of 
Tzetzes, but it shows that in the case of at least one of these four men, 
his connection with Pisistratus was known even before the beginning 
of our era, and that in this one regard the so-called fabrication of 
Tetzes shows a remarkable coincidence with the truth. 

In the commentary of Eustathius on the [liad and Odyssey, written 
about the year 1175 of our era, and shortly after the time of Tvetzes, 
are found two different accounts of the Pisistratean collection, obviously 
drawn from different sources. In the first, we are surprised to find 
him giving credence to the story we have met before of the Pisistratean 
school dominated by Aristarchus and Zenodotus. In the second, Pi- 
sistratus himself is mentioned as sole author of a probable recension. 
The passages are as follows, first from his commentary to the first book 
of the Iliad (p. 5, 1.28): of δὲ συνθέμενοι ταύτην (1. 6. Ἰλιάδα), κατ᾽ ἐπιταγὴν, 
ὥς φασι, Πεισιστράτου τοῦ τῶν ᾿Αθηναίων τυράννου, γραμματικοὶ καὶ διορθωσάμενοι 
κατὰ τὸ ἐκείνοις ἀρέσκον, ὧν κορυφαῖος ᾿Αρίσταρχος καὶ μετ᾽ ἐκεῖνον Ζηνόδοτος διὰ 
τὸ ἐπίμηκες καὶ δυσεξίτητον καὶ διατοῦτο προσκορὲς κατέτεμον αὐτὸ εἰς πολλά. 
This undoubtedly refers to a Pisistratean collection, but not one in 
which Pisistratus took a personal part. The second of these passages 
(Vol. II, p. 309, 1. 17) is identical in meaning with the Townley scho- 
lion already quoted, and almost identical in form. The source of both 
is doubtless the same: φασὶ de οἱ παλαιοὶ τὴν ῥαψῳδίαν ταύτην ὑφ᾽ ᾿᾽Ομήρου 


500 PROCEEDINGS OF THE AMERICAN ACADEMY, 


ἰδίᾳ τετάχθαι καὶ μὴ ἐγκαταλεγῆναι τοῖς μέρεσι τῆς Ἰλιάδος, ὑπὸ δὲ Πεισιστράτου 
τετάχθαι εἰς τὴν ποίησιν. 

It is necessary, I think, at this point to consider briefly from what 
authorities Eustathius drew his information. Diintzer?? seems ag- 
nostic on this point, though confident in the real antiquity of such 
sources. “It is difficult,” he writes, “to see whom Eustathius means 
by of παλαιοί in his note on the beginning of Iliad K. We cannot say 
that he means any particular scholar of the Alexandrian school. On 
the other hand, much less can we say that the supposition of the 
insertion of a book by Pisistratus was wholly unknown to the Alexan- 
drians. So the supposition of Lehrs, that the old Alexandrines had no 
knowledge of the especial critical significance of the arrangement of 
the Homeric poems by Pisistratus, is unfounded.” Eustathius, as we 
know,?3 further used as sources an epitome made from the commen- 
taries of the four men whom | have previously mentioned as probable 
sources of our Townley scholia, viz., Aristonicus, Didymus, Herodian, 
and Nicanor. Likewise the Λέξεις of Aristophanes, the rhetorical dic- 
tionary of Dionysius, the encyclopaedic lexicon of Apion, and Herod- 
orus and the Paralipomena of Porphyrius. Furthermore, I have noted 
at least one place in Eustathius (Vol. I, p. 230, 1. 46) where he quotes 
directly from Strabo (IX, 394, 10) in very nearly his exact words, 


Σόλων δὲ ἢ Πεισίστρατος παρενέγραψεν ἐνταῦθα μετὰ τὸν ‘Ounpov στίχον τὸ, 
στῆσε δ᾽ ἄγων, ἵν᾽ ᾿Αθηναίων ἵσταντο φάλαγγες 


καὶ οὕτω μάρτυρι τῷ ποιητῇ ἐχρήσατο τοῦ τὴν νῆσον ἐξ ἀρχῆς ᾿Αθηναίων ὑπάρξαι, 
ὡς ὁ γεωγράφος ἱστορεῖ. And finally Sengebusch,2* who refers in turn 
to the opinion of Lehrs, holds exactly the same view as Christ. Im- 
portant therefore are the statements of Eustathius, inasmuch as he 
himself, though a comparatively late writer, drew his information, so 
far as we can ascertain, from writers even as early as the Alexandrian 
school. 

In a document three centuries later than Eustathius, that is, in a fif- 
teenth century manuscript in the library of the Collegio Romano, con- 
taining fifteen plays of Plautus, is preserved a version of the Pisistratean 
story identical with the account of 'T'zetzes. Ritschl conjectures that 
these scholia are drawn from T'zetzes, as they are, without a doubt. The 
similarity is conclusive. ‘Towards the end of the Poenulus they run 


22 Hom, Abhandlungen, Leip., 1872, p. 4. 
23 See Christ, Griesch. lit. Gesch., ed. iv, p. 72. 
24 Homerica Dissertatio, I, Leip., 1870, p. 40. 


NEWHALL. — PISISTRATUS AND HOMER. 501 


thus :25 Ceterum Pisistratus sparsam prius Homeri poesim ante Ptol- 
emaeum Philadelphum annis ducentis et eo etiam amplius sollerti cura 
in ea quae nunc extant redegit volumina, usus ad hoc opus divinum 
industria quattuor celeberrimorum et eruditissimorum hominum, vide- 
licet, Concyli, Onomacriti Athenién. Zopyri Heracleotae et Orphei 
Crotoniatae. Nam carptim prius Homerus et non nisi difficillime 
legebatur. This of course is a quotation from the passage of Tzetzes 
written after he had revolted from Heliodorus and his belief in the 
school of seventy-two grammarians. ‘These scholia also contain a few 
sentences adapted from the Prolegomena of T'zetzes in the place where 
he applies to Heliodorus the epithet of τῷ βδελυρῷς They read as fol- 
lows : Quum etiam post Pisistrati curam et Ptolemaei diligentiam Ari- 
starchus adhue exactius in Homeri elimandum collectionem vigilavit. 
Heliodorus multa aliter nugatur quae longo convitio Cecius repre- 
hendit. Nam ol’ LXXII duobus doctis viris a Pisistrato huic negotio 
praepositis dicit Homerum ita fuisse compositum. Qui quidem Zenodoti 
et Aristarchi industria omifibus praelatam comprobarint, quod constat 
fuisse falsissimum. Quippe cum inter Pisistratum et Zenodotum fue- 
rint anni supra ducentos. Aristarchus autem quattuor annis minor 
fuerit ipso et Zenodoto atque Ptolemaeo. ‘his shows better than any- 
thing else the utter falsity of the account given in Bekker’s Anecdota 
(p. 767 ff.). By the clause ‘‘Quum etiam post Pisistrati, etc.” the text 
recension of Zenodotus and Aristarchus is unquestionably meant. But 
these are not quoted as the words of 'T'zetzes 26 but of Heliodorus, as 
the “ multa aliter” clearly indicates. Without doubt, “Nam ol’ LXXII, 
etc.,” down to ‘‘comprobarint” comes from Heliodorus, and ‘“ quod 
constat” to the end from Tzetzes. But these late scholia add no new 
testimony to that already given by 'T'zetzes himself. 

Our last and probably latest reference .to the collection of Homeric 
poems by Pisistratus is found in two lives 27 of Homer which were 
made from the collation of facts preserved in fourteenth and fifteenth 
century manuscripts. A passage from one of them reads: περιιὼν δὲ 
ras πόλεις ἦδε [Ὅμηρος] τὰ ποιήματα. ὕστερον δὲ Πεισίστρατος αὐτὰ συνήγαγεν» 


« A > , , ΄ 
ὡς τὸ ἐπίγραμμα τούτου δηλοῖ 


τὸν μέγαν ἐν βουλαῖς Πεισίστρατον, ὃς τὸν Ὅμηρον 
ἤθροισα σποράδην τὸ πρὶν ἀειδόμενον. 


25 These scholia were first published by F. W. Ritschl, and can be found in 
Vol. I of his Opuscula, p. 6, or in his Alexandrinische Bibliotheken, Breslau, 
1838, p. 4. 

26 See Ritschl, Op., I, 33. 

27 See Jahn’s Neue Jahrb. fiir Philologie u. Paedagogik, 9es Suppbd., p. 508. 


502 PROCEEDINGS OF THE AMERICAN ACADEMY. 


The second life draws its facts from practically the same manuscripts 
as the preceding, and in the following portion is very similar to it: 
τὰ δὲ ποιήματα αὐτοῦ τὰ ἀληθῆ σποράδην πρότερον ἀδόμενα Πεισίστρατος ᾿Αθηναῖος 
συνέταξεν, ὡς δηλοῖ τὸ φερόμενον ἐπίγραμμα ᾿Αθήνησιν ἐπιγεγραμμένον ἐν εἰκόνι 
αὐτοῦ Tov Πεισιστράτου. ἔχει δὲ ὧδε. .. and then follows the same epigram. 

Briefly summing up the testimony of such accounts as we may con- 
sider reliable for an Homeric edition by Pisistratus or Pisistratus and 
his associates, the result is as follows. ‘The accounts in Cicero, the 
Townley scholia, Aelian, Suidas, and Eustathius all point to a collec- 
tion of the poems by Pisistratus alone and unassisted. The accounts 
in Pausanias, 'I'zetzes, and, of course, the scholia to Plautus, are the 
only ones which indicate any kind of a Pisistratean school. I do not 
think, however, that we ought to consider this as strong evidence that 
Pisistratus was not assisted by a board of associates in his work of 
collecting. Naturally if he, a ruler in absolute authority and eager 
for fame in letters, chose to be the proud supervisor of such a literary 
undertaking, even .though his co-workers were ever so numerous, the 
edition which was produced would be called by subsequent writers 
“ Pisistratus’s Edition” and the ‘Collection which Pisistratus made,” 
while his helpers would be gradually disregarded, just as we, for in- 
stance, refer to our Bible as “King James’s Version.” 

The fact that the story of a collection of Homeric poems by Pisis- 
tratus, or Pisistratus and certain associates, was known by Cicero and 
several reputable writers after him is very significant. No one would 
presume to say that, as in the case of T'zetzes, so also in the case of 
Cicero, this story is a fabrication. In fact, he himself uses the word 
“dicitur,” which we may translate “we are told.” What, then, was 
his authority and the authority of these subsequent writers? It seems 
at least probable that the Alexandrian School, for instance, must have 
played a part in handing down the tradition. The most that can be 
said against this is that neitber Aristarchus nor any ‘of his successors 
in any of their writings which are extant in whole or in part mention 
the connection of Pisistratus with Homer as a collector or reviser ; but 
this is obviously an unfair objection because, without doubt, only small 
portions of all their writings have come down to us. And yet Flach 28 
derives especial satisfaction from the contemplation of such facts as, 
for instance, that Aristarchus never so much as implies that the inser- 
tions into the text of Homer especially complimentary to the Athenians 
were found only in the manuscripts that came from Athens, although, 
if this were the state of things, we should expect him to mention it. 


28 Peisistratus u. seine Lit. Tatigkeit, Tiibingen, 1885, p. 89. 


NEWHALL. — PISISTRATUS AND HOMER. 503 


As to whether Homer had existed in writing before the time of 
Pisistratus or not, that is not so important a question, and with regard 
to it only general inferences can be drawn from the statements of the 
ancients themselves. ‘he testimony of Pausanias 29 and the first 39 
and second 51 lives of Homer tend to show that until the time of 
Pisistratus, at least, oral tradition was the medium of transmission. 
Cicero,?2 however, the Townley scholia,3? and Suidas%* give evidence 
which is more definite and points directly to a written tradition. The 
evidence then is quite fairly divided ; but on the whole I feel safer in 
favoring a written Iliad and Odyssey before the days of Pisistratus, 
since the tradition recorded by Cicero is likely to have been older and 
more reliable than the one mentioned by Pausanias, and especially be- 
cause the Townley scholia ought to outweigh any evidence contained 
in the lines of Homer based merely on manuscripts which are them- 
selves inferior to the 'lownley. Furthermore, in addition to Suidas, 
there are several other authors whose testimony in favor of a written 
Homer before Pisistratus is sure. Plutarch says in his life of Lycur- 
gus,?° when referring to the state of the Homeric poems in Greece in 
the time of the great lawgiver [οἱ Ἕλληνες] ἐκέκτηντο δὲ οὐ πολλοὶ μέρη τινά 
[τοῦ “ομήρου], where it seems that a word like ἐκέκτηντο must refer to ἃ 
tangible written copy. Aelian also (XIII, 14) in speaking of Lycurgus 
writes : πρῶτος ἐς τὴν Ἑλλάδα ἐκόμισε τὴν “Ounpov ποίησιν. Here again the 
supposition of a manuscript seems imperative. Plutarch likewise, 
in his life of Solon (X, 1), referring to his insertion of a verse, says: 
ἐμβαλόντα yap αὐτὸν ἔπος εἰς νεῶν κατάλογον ἐπὶ τῆς δίκης ἀναγνῶναι, where this 
last word cannot leave us in a moment's doubt. Here δίκης refers to 
the trial in which the Lacedaemonians were made arbiters between the 
_ Athenians and Megarians. Diogenes Laertius (1, 2, 48), with reference 
to this same performance of Solon’s, uses the word ἐγγράψαι, prefacing 
it however by ἔνιοι δέ φισιν. I therefore cannot agree with these words 
of Bonitz,36 “that this was the first time that the whole of the poems 
was written down may be clearly inferred from the form and character 
of the numerous statements in regard to it.” Christ and Jebb, both on 
grounds other than I have taken, favor the theory of a written trans- 


29 Poems said to have been μνημονευόμενα. 

30 ["Ounpos] ἦδε τὰ ποιήματα. 

31 Poems said to have been πρότερον ἀδόμενα. 

32 “ Libros” of Homer referred to. 

33 T]. K said to have been τετάχθαι ὑφ᾽ ‘Ounpov. 
34 eypadpe“Ounpos. 

35 Plutarch I, p. 82, |. 9, ed. Sintenis, Leip., 1884. 
36 Origin of Homeric Poems, N. Y., 1880, p. 27. 


504 PROCEEDINGS OF THE AMERICAN ACADEMY. 


mission. {60} 57 is of the opinion that “it cannot be proved that the 
Homeric poems were not committed to writing either when originally 
composed or soon afterwards. For centuries they were known to the 
Greek world at large chiefly through the mouth of rhapsodes. But that 
fact is not inconsistent with the fact that the rhapsodes possessed writ- 
ten copies. On the other hand, a purely oral transmission is hardly 
conceivable.’ The judgment of Christ (p. 65) is thus expressed: 
“Fully one hundred years before the Athenian 'l'yrants, the Ionic 
books were reduced to writing, and it would truly be strange if the 
honor of a written copy should have fallen to the lot of an iambic or 
elegiac poet sooner than to the great national poet. Also the testi- 
mony shows that Pisistratus made nothing more than a complete Iliad 
and Odyssey. Probably before that time certain parts had been re- 
duced to writing to aid the memory, as, for example, the Catalogue of 
Ships.” 

Perhaps at this point it would not be out of place to make a brief 
excursus on stories which, for the most part, without mentioning the 
name of Pisistratus, tell us of other men who are reported to have done 
work of some kind in connection with the Homeric poems. Since in 
making this excursus a chronological arrangement of evidence by 
authors (the system I have adopted up to this point) does not seem 
necessary or even advisable inasmuch as it would cause confusion 
through the separation of all passages by different authors, though 
referring to the same historical personage, I have thought it best to 
arrange the following passages in the chronological order of the differ- 
ent persons whose activity is described therein. In La Roche’s Homer- 
ische 'l'extkritik im Altertum (p. 7) there is published an interesting 
fragment of Heraclides who lived at about the middle of the second 
century B.C. Δυκοῦργος ἐν Σάμῳ ἐτελεύτησε" καὶ τὴν Ὁμήρου ποίησιν παρὰ 
τῶν ἀπογόνων Κρεωφύλου λαβὼν πρῶτος διεκόμισεν εἰς Πελοπόννησον. ‘This, of 
course, is another story entirely, and, even if true, is nothing to influ- 
ence our belief in the nature of the services that Pisistratus may have 
performed for Homer at a much later date.88 Similar also is a state- 
ment made about Lycurgus by a much later writer in the second half 
of the first century a. p. Plutarch (Vol. I, p. 82, 1. 2) tells how 
Lycurgus, when he was in Asia, realizing that the Homeric poems con- 
tained educational elements as well as political qualities, determined 
to bring them ‘to Athens. Then comes the significant part: ἦν γάρ 
τις ἤδη δόξα τῶν ἐπῶν ἀμαυρὰ παρὰ τοῖς Ἕλλησιν, ἐκέκτηντο δὲ οὐ πολλοὶ μέρη 


37 Homer, Boston, 1887, Ῥ. 114, 
38 This fragment is additional evidence for a written Homer before the days 
of Pisistratus. 


NEWHALL. — PISISTRATUS AND HOMER. 505 


τινά, σποράδην τῆς ποιήσεως, ὡς ἔτυχε, διαφερομένης. γνωρίμην δὲ αὐτὴν καὶ 
μάλιστα πρῶτος ἐποίησε Λυκοῦργος. ‘This again 15 interesting as throwing 
light on the life of Lycurgus and the early history of the Homeric 
poems, though it is not of a nature to influence our judgment as to 
the truth or falsity of the Pisistratean story. And lastly Aelian (XIII, 
14) makes substantially the same statement about Lycurgus when he 
writes : ὀψὲ δὲ Δυκοῦργος 6 Λακεδαιμόνιος ἀθρόαν πρῶτος ἐς τὴν Ἑλλάδα ἐκόμισε 
τὴν Ὁμήρου ποίησιν. So much for Lycurgus. 

We have already seen that the insertion of verse 558 of Iliad B was 
said by Strabo to have been ascribed by one tradition to Pisistratus 
and by another to Solon. ‘To this I can add two accounts by some- 
what later writers who, from hearsay or report, make Solon the author 
of the same interpolation without any mention of Pisistratus. 'The 
first of these is from Plutarch’s life of Solon (X, 1): od μὴν ἀλλὰ τῶν 
Μεγαρέων ἐπιμενόντων πολλὰ κακὰ καὶ δρῶντες ἐν τῷ πολέμῳ καὶ πάσχοντες ἐποιή- 
σαντο Λακεδαιμονίους διαλλακτὰς καὶ δικαστάς. Οἱ μὲν οὖν πολλοὶ τῷ Σόλωνι 
συναγωνίσασθαι λέγουσι τὴν “Ομήρου δόξαν" ἐμβαλόντα γὰρ αὐτὸν ἔπος εἰς νεῶν 
κατάλογον ἐπὶ τῆς δίκης ἀναγνῶναι; ---- then follow verses 557 and 558 of 
Iliad B. Diogenes Laertius (1, 2, 48) also writes with regard to Solon: 
ἔνιοι δέ φασι καὶ ἐγγράψαι αὐτὸν εἰς τὸν κατάλογον τοῦ “Ομήρου μετὰ τὸν (v. Dod, 
v. 558). And, to end the discussion of Solon, we have in Diogenes 
Laertius still another passage already quoted (1, 57) which bears 
testimony merely to a certain literary activity in connection with 
Homer on the part of Solon, earlier of course than the time of Pi- 
sistratus. In a certain respect, expressed by ἐφώτισεν, according to 
Dieuchidas the Megarian, Solon is said to have surpassed Pisistratus : 
τά τε Ὁμήρου ἐξ ὑποβολῆς γέγραφε ῥαψῳδεῖσθαι, οἷον ὅπου ὃ πρῶτος ἔληξεν, 
ἐκεῖθεν ἄρχεσθαι τὸν ἐχόμενον. μᾶλλον οὖν Σόλων Ὅμηρον ἐφώτισεν ἢ Πεισί- 
στρατος, ὥς φησι Διευχίδας ἐν πέμπτῳ Μεγαρικῶν. 

Hipparchus, the elder of the sons of Pisistratus, is the only other 
man to. whom I have found activity in connection with the Homeric 
poems ascribed. In one account he is said to have brought them to 
Greece, in the other, to Athens, and in both to have ordered the rhap- 
sodes to sing them at the Panathenaic festival. The first account, 
contained in the pseudo-Platonic dialogue Hipparchus (228 B) runs 
as follows: Ἱππάρχῳ, ὃς τῶν Πεισιστράτου παίδων ἦν πρεσβύτατος καὶ σοφώ- 
τατος, ὕς ἄλλα τε πολλὰ καὶ καλὰ ἔργα σοφίας ἀπεδείξατο, καὶ τὰ ὋὉμήρου ἔπη 
πρῶτος ἐκόμισεν εἰς τὴν γῆν ταυτηνί, καὶ ἠνάγκασε τοὺς ῥαψῳδοὺς Παναθηναίοις 
ἐξ ὑπολήψεως ἐφεξῆς αὐτὰ διιέναι, ὥσπερ νῦν ἔτι οἵδε ποιοῦσι. Now the 
question whether Plato or somebody else wrote the dialogue which 
contains this information is not essential to this investigation. But it 
is necessary for us to ascertain as nearly as may be when it was writ- 


506 PROCEEDINGS OF THE AMERICAN ACADEMY. 


ten, and something, if possible, about the writer. Accordingly a slight 
digression on its authenticity will not be out of place. 

That the genuineness of this dialogue was doubted, even in antiquity, 
has been maintained by some, notably Wolf, on the authority of the 
following passage in Aelian (VIII, 2): οὐκ ᾧετο yap δεῖν οὐδενὶ φθονεῖν 
σοφίας, dre ὧν καλὸς καὶ ἀγαθός, λέγει δὲ Πλάτων ταῦτα, εἰ δὴ ὁ Ἵππαρχος Πλά- 
rovds ἐστι τῷ ὄντι. But this contains, at the very end, as Grote 39 points 
out, a conjectural emendation. Hercher in his edition ascribes the 
reading ὄντε with no following word to the emendation of Perizonius, 
doubtless in his edition of 1701.49 But the manuscripts read τῷ ὄντι 
μαθητής. Grote’s contention is that “if you construe the passage as it 
stands without such conjectural alteration, it does not justify Wolf's 
inference ‘that the genuineness of the Hipparchus was doubted in 
antiquity.’” But if we do not emend with Perizonius we have an his- 
torical error, the suggestion that Hipparchus might have been the 
pupil of Plato, a mistake which Mr. Grote probably with perfect justice 
considers “ nowise impossible in the case of Aelian.” But if we do not 
emend, I fail to see the connection of the statement ‘if Hipparchus is 
really a pupil of Plato” with the preceding. It is entirely lacking in 
logical sequence. 

There is also another argument, which, so far as I can discover, has 
not been adduced by any one as yet, but which to me is conclusive in 
favor of adopting the emendation of Perizonius. Aelian, in the same 
book, and only a few lines before the disputed passage, has these words 
(VIII, 2): Ἵππαρχος ὃ Πεισιστράτου παῖς πρεσβύτατος ὧν τῶν Πεισιστράτου 
καὶ σοφώτατος ἢν ᾿Αθηναίων. οὗτος καὶ τὰ “Opnpov ἔπη πρῶτος ἐκόμισεν ἐς τὰς 
᾿Αθήνας, καὶ ἠνάγκασε τοὺς ῥαψῳδοὺς τοῖς Παναθηναίοις αὐτὰ ἄδειν. Now, after 
a comparison of this with the passage from the Hipparchus (228 B) which 
I have just quoted, I do not think that there can be any doubt that 
Aelian was quoting outright from pseudo-Plato. What could be more 
natural then that a few lines later he should make a reference to the 
book Hipparchus from which he had just quoted and which was still 
running in his mind, and probably to our very passage containing the 
words, ὃς ἄλλα τε πολλὰ καὶ καλὰ ἔργα σοφίας ἀπεδείξατο, which would make 
a very tolerable precedent for ΑΘ] 1818, --- οὐκ ᾧετο γὰρ δεῖν οὐδενὶ φθονεῖν 
σοφίας, ἅτε ὧν καλὸς καὶ ἀγαθός. It therefore seems to me-by all means 
preferable and even necessary to adopt the emendation of Perizonius 
and to agree with Wolf that the authenticity of the Hipparchus was 
doubted even as early as Aelian (fl. 130). 

Diogenes Laertius, who flourished at some time near the beginning 


39 Plato, London, 1888, II, 865. 40 See Christ, p. 762. 


NEWHALL. — PISISTRATUS AND HOMER. 507 


of the third century, contains the following very possible reference to 
the dialogue under consideration and to the man whom he supposed 
to be the author (2, 122): Σίμων ᾿Αθηναῖος, oxvtorépos* οὗτος ἐρχομένου 
Σωκράτους ἐπὶ τὸ ἐργαστήριον καὶ διαλεγομένου τινά, ὧν ἐμνημόνευεν ὑποσημειώσεις 
ἐποιεῖτο" ὅθεν σκυτικοὺς αὐτοῦ τοὺς διαλόγους καλοῦσιν. εἰσὶ δὲ τρεῖς καὶ τριά- 
κοντα ἐν ἑνὶ φερόμενοι βιβλίῳ, ---- then follows a list of thirty-one titles, 
among which is the title περὶ φιλοκερδοῦς, which is the subject under dis- 
cussion in the pseudo-Platonic Hipparchus. In order to fix the date 
of this Simon I must quote another passage from Diogenes Laertius’ 
life of Simon (2, 123), which reads as follows: οὗτος, φασί, πρῶτος διελέχθη 
τοὺς λόγους τοὺς Σωκρατικούς, ἐπαγγειλαμένου δὲ Περικλέους θρέψειν αὐτὸν καὶ 
κελεύοντος ἀπιέναι πρὸς αὐτόν, οὐκ ἂν ἔφη τὴν παρρησίαν ἀποδόσθαι. This 
then places his sphere of activity in the age of Pericles, making him a 
little older than Plato himself. Accordingly Boeckh, connecting the 
Hipparchus and the Minos, as works by the same author (basing his 
decision on evidences of style, apart from the statement of Diogenes to 
the same effect), published at Heidelberg in 1810 these two dialogues 
and two others in a separate edition which he called “ Simonis Socra- 
tici, ut videtur, dialogi quattuor.” Grote, as I have already implied 
from my previous quotation of his opinion, considers the Hipparchus 
one of the inferior works of Plato. Steinhart as quoted by Fritzsche 44 
dates the composition of the Hipparchus in the Macedonian Age (say 
from 350-320 B. c.) deducing his opinion from internal evidence. 
First, Hipparchus is lauded, whereas the murderers fail in the common 
meed of praise, two things which would be more in accord with the 
spirit of the Macedonian Age than that of the Periclean, for instance ; 
and secondly, the ratio of gold to silver is mentioned as twelve to one 
(231 D), facts which he considers significant enough to warrant his 
conclusion. This, of course, if true, would place its composition slightly 
after the death of Plato. All testimony, therefore, which can be ad- 
duced tends to show that if not by Plato himself it was composed by 
some author almost contemporaneous with him. 

I might mention here again, for the sake of completeness, the refer- 
ence in Aelian to the literary importation by Hipparchus, but as Aeli- 
an’s sole authority for this story is doubtless the pseudo-Plato, it really 
has no important evidence to add. 

To summarize, then, briefly, this little excursus, the accounts of 
Lycurgus given by Heraclides, Plutarch, and Aelian contain abso- 
lutely nothing to influence our belief as to the activity of Pisistratus. 
The only story about Solon which seems to concern Pisistratus at all 


41 Stallbaum, Plato, ed. ii, Leip., 1885, b. II, 304. 


508 PROCEEDINGS OF THE AMERICAN ACADEMY. 


is the account of Dieuchidas which, we must remember, is quoted at 
second hand, and contains those words, μᾶλλον ἐφώτισεν κτὰ, Which seem 
too vague and doubtful in their significance to be given very much 
weight. ‘lhe only account, therefore, which conflicts with the suppo- 
sition of a Pisistratean edition is contained in the pseudo-Plato. This 
story I hesitate to reject hastily because of its antiquity. But yet 
there are several facts in connection with it which we must face: 
first, the author is doubtful, practically unknown ; second, the story 
is found nowhere else except in Aelian, so far as I can discover ; third, 
it is practically contradictory to the statements I have quoted about 
Lycurgus, to say nothing of the accounts of Pisistratus,42 which are 
based on good authority. How such a plausible story, if true, could 
have been so nearly forgotten, or how so disregarded by subsequent 
writers, had the pseudo-Plato possessed a good reputation for histor- 
ical accuracy, is past understanding. Very plausible is the supposition 
that it may have been a confusion of two or more stories. This opin- 
ion is favored by Flach when he writes (p. 21): ‘The author of pseudo- 
Plato was not reliable in comparison with Dieuchidas,*? he makes 
noticeable historical blunders, and was probably lightly recording some 
local tradition. This tradition arose from an analogy with Solon and 
from the fact that Hipparchus was a patron of literature, as shown by 
his calling over Anacreon from Samos in 522 8 C., after the death of 
Polycrates.” On the whole I am forced to admit this rather plausible 
explanation of the practically unique account in the pseudo-Plato. 
Finally, then, what inference are we justified in deducing with 
regard to the literary activity of Pisistratus in connection with the 
Homeric poems? We must endeavor to avoid any conclusions which, 
however plausible, are not fully justified by our evidence. For ex- 
ample, Monro says (p. 406): “The Pisistratean edition is excluded by 
the account adopted in the pseudo-Platonie Hipparchus, which leaves 
no room for a collection of Homeric verses.” But it is not just that 
the authority of this one anonymous writing should outweigh all other 
passages which testify to a collection of Homeric poems by Pisistratus, 
and are drawn from such reliable sources as Cicero, Aelian, Pausanias, 
and the scholia of our second best manuscript. Neither can I agree 


#2 The only way in which I can reconcile this with the accounts about Pisis- 
tratus is by supposing that Hipparchus introduced the Homeric poems into Greece 
a good many years prior to the death of Pisistratus his father. But this suppo- 
sition seems rather improbable. 

43 Flach gives no credence to the stories about Pisistratus, but believes in the 
greater Homeric activity of Solon. Hence the mention of Dieuchidas, who says 
Σόλων μᾶλλον ἐφώτισεν κτλ. 


NEWHALL. — PISISTRATUS AND HOMER. 509 


with Monro in any such statement as that such a collection “may be 
shown to be unknown to the Alexandrian grammarians,” for their 
works are preserved to us in such an incomplete state that it is abso- 
lutely impossible to say exactly what they did mention and what not. 
T. W. Allen, in the Classical Review,** assuming the reality of this 
silence, has an explanation which is possible. He writes: “If Pisis- 
tratus were the reputed father of the κοινή, it is natural that we find 
no mention of him in the scholia. The grammarians ignore the κοινή 
because it was in every one’s hands, and because it had suffered by 
transmission. ‘I'he same account explains the absence of reference to 
the Athenian edition.” 

The explanation of the sources of the so-called Pisistratean legend 
by those who disbelieve in it has afforded critics the exercise of much 
originality and ingenuity, but it is based for the most part on merest 
conjecture. Flach (p. 41) is of the opinion that the story of Pisistra- 
tus’s edition came from Megarian historians of little scientific impor- 
tance, and was “boomed” by the scholars of the Pergamean school 
that they might find a great literary man to belittle the Homeric 
scholars of their rival school, the Alexandrian. Likewise Nutzhorn,4® 
who disbelieves in the Pisistratean recension, makes light of the testi- 
mony of Cicero, saying that Cicero drags in Pisistratus here merely as 
an added example of the point he is trying to establish, — how neces- 
sary it is for the great statesman to be a learned man as well. How- 
ever that may be, unless Nutzhorn is willing to admit that Cicero in 
this place is deliberately falsifying evidence (i. e., the tradition which 
he cites), I fail to see that his remark has any point. Desire on the 
part of Cicero to illustrate a principle aptly cannot be said to imply 
the use of fictitious examples. Interesting also, and more probable, 
is the conjecture of Diintzer (p. 17), who makes Dicaearchus in his 
Bios ‘EAddos the authority for the statement of Cicero. ‘This opinion 
is based on the fact that Dicaearchus was an author of general popu- 
larity with Cicero, as shown by his references to him on several occa- 
sions, his work being of great importance in the literary history of 
Greece. 

After such a discussion of conjectures we are reminded of the words 
of Wolf: 46 “Nunc vero nihil opus est coniecturas capere. Historia 
loquitur. Nam vox totius antiquitatis et, si summam spectes, consen- 
tiens fama testatur Pisistratum carmina Homeri primum consignavisse 
litteris, et in eum ordinem redegisse quo nune leguntur. Hoe pos- 


44 XV, p. 8 (1901). 
45 Die Entstehungsweise der Hom. Gedichte, Leip., 1869, p. 48. 
46 Prolegomena ad Homerum, ed. ii (posthumous), Berlin, 1876, c. xxxiii. 


510 PROCEEDINGS OF THE AMERICAN ACADEMY. 


terius Cicero, Pausanias et reliqui omnes qui mentionem rei faciunt, 
iisdem prope verbis et ut vulgo notissimum perhibent.’” At first 
thought this statement seems too sweeping to be literally true, but 
when one bears in mind that the only statement by an ancient au- 
thority really contradictory to the idea of a Pisistratean edition of 
Homer is contained in the pseudo-Plato of doubtful authority, and 
when one remembers that the accounts, even as old as Cicero, were, as 
is most probable, drawn from much older authorities which are now 
lost, then one can see that this statement, though framed in bold lan- 
guage, was not made without due deliberation. The statement, “ pri- 
mum consignavisse litteris,’” however, does not seem to have equal 
justification. On the contrary, available evidence seems to indicate 
that even before the time of Pisistratus the Homeric poems, at least 
large portions of them, already existed in writing. 

All our testimony clearly shows, I think, that Pisistratus, who was 
a τύραννος interested in literature, with the help, as is most likely, of 
several poets or literary men of his court, was the first to make a 
careful collection or edition (though in no sense of the word a critical 
edition) of the Iliad and Odyssey, on the basis of what scattered writ- 
ten copies were available, filling in the gaps (if there were any) in the 
written Homer from the mouths of the rhapsodes. That this collee- 
tion was more or less for private use and convenience it is reasonable to 
suppose, and that it showed no accuracy of critical discrimination is a 
necessary supposition in consideration of its early date. 


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New Fixed Point in Thermometry, pp. 341-350, November, 1907. 200, 
Kent, N. A., and Avery, A. H. — Difference in Wave-Lengths of Titanium AA 3900 and 8018 
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ary, 1908. 15c. = 
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1908. 15c. ΤᾺ 
Parker, G. H. —The Sensory Reactions of Amphioxus. pp. 413-455. April, 1908. 4δο. 
Dickey, W. P. — On Delays before ἀναγνωρίσεις in Greek Tragedy. pp. 457-471. May, 1908. 
De. 
Ricuarps, T. W., and Rowe, A. W. —A New Method for the Determination of the Specifid 
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Newnaut, 8. H. — Pisistratus and His Edition of Homer. pp. 489-510. June, 1908. 45e. 
Trowsrinee, J. — Positive Rays. pp. 511-517. June, 1908. 1δο, 
RicnhArvs, Τὶ W., and MatHews, J. H — Concerning the Use of Electrical Heating in Fractional μ΄ 
Distillation, pp, 519-524. June, 1908, 1δο, ? 4 


Proceedings of the American Academy of Arts and Sciences. 


Vou. XLIII. No. 20.— June, 1908. 


CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY, 
HARVARD UNIVERSITY. 


POSITIVE RAYS. 


By JoHN TROWBRIDGE. 


¥ 
ea oe , ψλγχλδον τὸ δος κυ 
aa 4 ἴα δ, “4.1 ba αἰ icy he Oe hs See ΚΟΡΥς 


oO 
(> 


JUN 30 190 


CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY, 
HARVARD UNIVERSITY. 


POSITIVE RAYS. 


By JOHN TROWBRIDGE. 


Presented May 13, 1908. Received May 18, 1908. 


My intention in undertaking this investigation was to endeavor to 
measure the group velocity of the positive rays by producing a stand- 
ing wave, or a stratum of maximum collisions in an exhausted tube in 
the space between the anode and the cathode. In the case of an oscil- 
lating circuit, if we call A the wave length, » the velocity of light, ¢ the 
time of a half oscillation, s the distance between the anode and the 
cathode, v! the velocity of the positive rays, we have 


Kq. 1, A= vt 
Kq. 2, s= vt 


== y= — 


If, by tuning a circuit containing a condenser, self-induction, and 
the exhausted tube, the strata of maximum collisions could be formed 
at the orifice in the cathode, it was thought that none of the positive 
rays would enter the canal region ; if, on the other hand, the positive 
rays swung, so to speak, with the oscillations of the circuit, a maxi- 
mum fluorescence could be obtained on a suitably placed willemite 
screen. 

The circuit was arranged as follows: A Leyden jar, L, Figure 1, was 
charged by a storage battery of ten thousand cells, through a large 
resistance of running water, B. he discharging circuit included an 
adjustable self-induction, I, a tube filled with rarefied hydrogen, T, 
and a spark, 8S. K was an iron electrode, with an orifice two milli- 
meters in diameter at its centre. A glass tube welded to the sides of 
the tube C entered this orifice. The end of the tube C was coated 


with willemite. 
VOL. XLIII. — 33 


LIBRARY 
NEW YORK 
BOTANICAL 

GARDEN. 


514 PROCEEDINGS OF THE AMERICAN ACADEMY. 


At first I studied the effect of increasing the self-induction on the 
admittance of the mixture of anode and cathode rays to the region C. 


Figure 1. 


The phosphorescence on the screen at the end of the tube was ob- 
served with a spectrophotometer, and also with a photometer consisting 
of crossed nichol prisms. 

In Figure 2 the intensity of light is plotted along the axis of Y, 
and the wave lengths of the circuit along X. The phosphorescence 


400 500 600 


Ficure 2. 


appeared suddenly at wave length 380 meters, and increased to a 
maximum at wave length 620. he curve then continued parallel to 
the axis of X. In determining the wave lengths I employed the ad- 


TROWBRIDGE. — POSITIVE RAYS. 515 
mirable wave metre of Professor G. W. Pierce.1 This instrument ena- 
bled me to make measurements in a few moments which otherwise would 
have required days of labor. 

On placing the tube C between 
the poles of an electromagnet, 
which produced a field just suf- 
ficient to divert the cathode rays 
from the screen, I found that the 
changes in the phosphorescence 
represented in Figure 2 were 
produced by the cathode rays, for 
the phosphorescence due to the 
positive rays remained constant 
through the range measured. he 
positive rays were deflected in Rianne. 
the direction opposite to that in 
which the cathode rays were thrown, by a field of 530 lines to the 
centimeter, and produced a narrow band on the willemite screen, 
which showed a slight discontinuity (Figure 3), although the pressure 
did not exceed 51; mm. I was surprised to find that 
the group of positive rays was so readily deflected by 
a comparatively weak magnetic field. The length of 
the band of phosphorescence was 1.5 cm. It is to be 
noted that the band occurred only on one side of the 
middle point of the phosphorescent screen. 

On discovering that changes in self-induction had 
no effect upon the intensity of the phosphorescence 
produced by this group of positive rays, I resolved 
to damp out all oscillations by introducing a large 
water resistance in the oscillating circuit. While the 
dimensions of the discharge tube between the anode 
and the cathode remained the same as in the experi- 
ments described above, the canal region was changed 
from a circular tube of 3 cm. diameter to the form 
shown in Figure 4 in plan P and end section E. The 
width of the cross-section was 3.5 cm. It will be 

Ἐν ἢ, noticed that it had a flattened egg-shaped section, to 
enable me to place it between the poles of an elec- 

tromagnet. When all oscillations were damped, and a magnetic field 
of 500 lines to the centimeter was excited, the positive rays produced 


1 Contributions from the Jefferson Physical Laboratory, 4 (1907). 


516 PROCEEDINGS OF THE AMERICAN ACADEMY. 


a narrow, sharply defined band of fluorescence, which is represented in 
the photograph, Figure 5. ‘The middle of the end of the tube is indi- 
cated by the sharp pointers on the photograph, and it will be seen that 
the phosphorescent band extends to approximately equal distances on 
both sides of the middle of the screen. At first I thought that I was 
dealing with a mixture of positive and negative rays, and various the- 
ories of molecular attraction occurred to me; but experiment showed 
that all negative rays had been driven out of the field. Moreover, by 
producing a difference of electrostatic potential, the entire phospho- 
rescent band, or magnetic spectrum, moved in the direction the positive 


Figure 65. 


rays should move. In Figure 5 it will be noticed that the band moved 
to the smaller pointer; whereas, if the portion of the band to the right 
of the pointers was made up of negative rays, and that to the left of 
positive rays, the band would not have moved parallel to its original 
position. 

In order to ascertain why the band spread to the right and left of 
the middle of the screen I introduced a septum of glass in the middle 
of the tube constituting the canal region (Figure 6). ‘This septum was 
welded to the end of the tube and was coated on both sides with 
willemite. ‘The band of phosphorescence now appeared mainly on one 
side of the partition. By greatly weakening the magnetic field the 
negative rays were brought upon the screen to the left of the partition, 
while the positive rays appeared on the right of this partition, thus 


TROWBRIDGE. — POSITIVE RAYS, 517 


proving again that the band (Figure 5) was made up of positive 
rays. A large storage battery proved the best means of studying 
the positive band, for the phenomenon was 
not confused by the make and break of 
mechanical or electrolytic interrupters. It 
was soon discovered that a narrow phospho- 
rescent band was formed on the side of the 
septum which shielded the end of the tube. 
The explanation of the band in the tube 
without the septum was evidently this: the 
pilot spark produces a number of positive 
rays of different velocities which spread out 
in the form of a cone, of which the apex is 
the narrow orifice in the cathode terminal. 
Under the influence of the magnetic field 
these rays whirl around in the field somewhat 
in the manner indicated by the dotted lines (Figure 6). 
ev! 


Figure 6. 


———.—. p can have many values, dependin 
mH sini ? y pee δ 


upon the values of ο΄. The narrowness of the band results from the 
electrodynamic attraction of the whirls in a manner similar to the at- 
traction of electrical currents all moving in the same direction. The 
band may be called a magnetic spectrum, since it is produced by many 
rays of different velocities. 

W. Wien 2 has shown that positive rays emanate from the anode, and 
that these rays can be diverted by an ordinary horseshoe magnet. 
The rays which I have investigated are undoubtedly of the same na- 
ture as those studied by Wien. ‘heir connection, however, with the 
pilot discharge from a condenser is an added point of interest. 


In the expression p = 


JEFFERSON PHysIcaAL LABORATORY, 
Harvarp UNIVERsITY. 


2 Wien, Ann., 65, 449-450 (1898). 


ae = 
aa ahs. dies : 
πο τ τ pl ena ae 
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ἦς PEIRCE, B. On On the Permeability and the Retentiveness of a Mass of Fine Iron Particles, 
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‘Manx, E. L., and Copenanp, M.—Some Stages in the Spermatogenesis of the Honey Bee. 
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Peirce, B. O. — On the Correction for the Effect of the Counter Electromotive Force induced 
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11, Kent, N. A., and Avery, A. H. — Difference in Wave-Lengths of Titanium AA 3900 and 3918. ὴΣ 
in Arc and Spark. pp. 351-361, November, 1807. 250, 

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13. Prerce, G. W. —A Simple Method of Measuring the ais of Sound, pp. 375-395. Febru- | ; 
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14. TROWBRIDGE, J. — Longitudinal Magnetic Field and the Cathode Rays. pp. 397-404. Februe- 
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᾽ 15. Beri, L.— Note on Some Meteorological Uses of the Polariscope. pp. 405-412. Marek “- 
1908, 15c. —, 


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17. Dickey, W. P. — On Delays before ἀναγνωρίσεις in Greek Tragedy. pp. 457-471. May, 1908, - 
25e. ᾿ 


18. RicHarps, T. W., and Rowe, A. W.— A New Method for the Determination of the Specifle | ᾿ 
Heats of Liquids, pp. 473-488. June, 1908. 25c. - 
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20, Trowsriper, J. — Positive Rays. pp. 511-517. June, 1908. be. ; 
21, Ricnarps, Τὶ W., and Maruews, J. H — Concerning the Use of Electrical Heating in Fractional : 
Distillation. pp. 519-524. June, 1908. 180, 


as 


Proceedings of the American Academy of Arts and Sciences. 


Vou. XLIII. No. 21.— Junz, 1908. 


CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF 
HARVARD COLLEGE. 


CONCERNING THE USE OF ELECTRICAL HEATING © 
IN FRACTIONAL DISTILLATION. 


By THEropore W. RicHARDS AND J. HowArp MATHEWSs. 


INVESTIGATIONS ON LIGHT AND HEAT MADE AND PUBLISHED, WHOLLY OR IN PART, WITH APPROPRIATION | 
FROM THE RumFORD FUND. 


JUN 30 1908 


CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF 
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LIBRARY 
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CONCERNING THE USE OF ELECTRICAL HEATING IN BOTANICA! 


FRACTIONAL DISTILLATION. 


By THEODORE WILLIAM RICHARDS AND JosePpH HOWARD MATHEWS. 


Received May 18, 1908. 


In the course of a research? now in progress in this laboratory it 
became necessary to fractionate a number of organic liquids in order 
to prepare them in a state sufficiently pure for investigation. 'The 
process of distillation was at first carried out in the usual manner, but 
some of the substances required very many successive systematic dis- 
tillations in order to furnish enough material boiling within a reason- 
able limit of temperature, and, indeed, in more than one case the task 
seemed hopeless. 

A part of the research in question involved the determination of the 
latent heat of vaporization of the various substances by means of a 


- modification of Kahlenberg’s method,? to be described later. In the 


course of these experiments it was noticed that each organic liquid 
boiled at a much more constant temperature when heated electrically 
by the platinum coil of this apparatus than it had during its previous 
fractional distillations in an ordinary boiling flask. This led to the 
use of the hot platinum coil instead of the gas burner as a source of 
heat in the preliminary fractional distillation, with a very great gain 
in the efficiency of this process. 

Probably the reason for this difference in efficiency between the two 
methods lies in the difference in the extent of superheating. The suc- 
cess of fractional distillation might be supposed to be impaired when 
superheating occurs, for in this case the higher boiling fractions would 
naturally have more tendency to come over with those of lower boiling 
point. In-order that the most effective separation may be made, the 


1 J. Am. Chem. Soc., 30, 8 (1908); also Z. phys. Chem., 61, 449 (1908). 
2 Kahlenberg, Journ. Phys. Chem., 5, 215 (1895). 


GARDEN. 


522 PROCEEDINGS OF THE AMERICAN ACADEMY. 


temperature of the liquid should never exceed the true boiling point of 
the mixture. 

Very considerable superheating occurs when a liquid is boiled in 
a glass flask by the application of heat from outside. On the other 
hand, we found that very little superheating of a liquid occurs when 
the liquid is heated by means of an electric current passing through a 
suitable resistance wholly immersed in the liquid. S. Lawrence Bige- 
low has suggested this method of heating in the determination of the 
molecular weights of a substance in solution by measuring the eleva- 
tion in boiling points; its satisfactory application to this problem is 
an indication of its efficiency in obviating superheating. It is clear, 
therefore, that the electrical method of heating might be expected to 
give more complete separation during the process of practical distilla- 
tion than the ordinary method. 

The matter is so obvious that probably others have thought of this 
before ; but because we have never seen the method in use, nor have 
been able to find a reference to it in chemical literature, we venture to 
call attention to it in this brief paper. 

The extent of the increased efficiency is best indicated by two par- 
allel experiments, alike in every essential respect except the difference 
in the source of heat, and the fact that into the ordinary boiling flask 
Markovnikov capillary tubes were placed to relieve the superheating 
to some extent. Even with this precaution added to the old way, the 
difference in result was very marked, as the following figures show. 

0.1 liter of a specimen of normal butyl alcohol, dried with anhydrous 
copper sulphate, needed szz distillations in order to secure 75 milli- 
liters of liquid boiling within the limits of 1 degree (117.0°-118.0° at 
759 mm.), using the ordinary method of outside heating by a gas 
flame. 

The same volume of the original liquid by only ¢wo fractional distil- 
lations with electrical heat yielded the same volume of distillate of a 
much higher grade of purity, having boiling-point limits only 0.6 apart 
(117.3°-117.9°). 

Similarly, 120 milliliters of ortho cresol which in one distillation 
gave 100 milliliters within 0.8° (190.0°-190.8° at 765.0 mm.) gave an 
equal amount boiling within 0.3° (189.9°-190.2° at 758.5 mm.) by the 
new method. Numerous other examples might be cited, but these 
are sufficient to show the great advantage to be derived from electrical 
heating. 

A word concerning an advantageous form of apparatus is not out of 
place, although a heating resistance-coil may be immersed under the 
liquid in any ordinary distilling apparatus. In order to economize 


RICHARDS AND MATHEWS. — ELECTRICAL HEATING. ou 


material, a narrow cistern was blown into the bottom of a common 
stout distilling flask. Into this depression the heating coil was placed. 
The coil consisted of about 40 centimeters of platinum wire having a 
resistance of about 0.7 ohms. A 


current of from ten to fifteen am- : 
peres was led to the resistance wire | 
from above by heavy copper wires ἢ 


encased in glass tubes, into the ends 
of which the ends of the platinum 
wire were sealed, contact being made 
by adrop of mercury. It is necessary 
that these copper wires be heavy 
(about 2.5-3.0 mm. in diameter), so 
that they may not become heated 
by the current and thus superheat 
the vapor coming into contact with 
the glass tubes encasing them. For 
this reason it might be well to intro- 
duce the electrical connection from 
below, through the glass walls of the 
cistern ; but obviously the present 
arrangement can be most easily 
made. It is necessary that the coil 
and mercury contacts be entirely 
covered by the liquid at all times. 
The diagram illustrates the arrange- 
ment. ‘The coil was more compact 
than that represented in the figure, 
so that it was possible to distil all 
but four or five milliliters without 
uncovering the resistance. 

It is almost needless to call attention to the fact that short-cireuit- 
ing through the liquid may cause slight decomposition when electro- 
lytes are thus heated ; hence the method is not well applicable to 
liquids of this class. 

Because the bubbles of vapor arise only from the small area of the 
hot resistance wire, ebullition proceeds quietly, and there is never any 
tendency to “bump.” This method of heating is therefore especially 
applicable to fractional distillations under reduced pressure, where so 
much trouble is usually experienced from the explosive formation of 
vapor. Concentrated sulphuric acid, for example, boils as quietly 
under greatly reduced pressure when so heated as does water or 


§24 PROCEEDINGS OF THE AMERICAN ACADEMY. 


alcohol under ordinary pressures. ‘The method of heating dispenses 
entirely with the necessity of passing air through the liquid in vacuum 
distillations, and heavy viscous liquids may be advantageously dis- 
tilled in this way. By combining this method of heating with the 
Hempel, Wurtz, Linnemann, or other fractionating towers, great effi- 
ciency may be expected. However, where the amount of material is 
small, the towers cannot be advantageously used, because of the loss 
of material required to wet the considerable area of their condensing 
surfaces ; and it is very convenient to have at hand an economical 
method fully as efficient as the ordinary method where the tower is 
used. 

The method may also find successful application in the distillation 
of inflammable liquids, and may therefore be of some industrial impor- 
tance where power may be obtained cheaply. Moreover, low boiling 
liquids, ordinarily requiring special precautions, can be distilled as 
expeditiously as those of high boiling point, since superheating is 
impossible. 

In brief, this article describes experiments showing the great gain 
in the efficiency of separation obtainable by the use of electricity as a 
source of heat in fractional distillation. An advantageous form of 
apparatus for this purpose is described. 


Toe CuemicAL LABORATORY OF HarvVARD COLLEGE. 


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VOLUME 42. 


Rosrnson, B. L.— Studies in the Eupatorieae: (I.) Revision of the Genus Pigueria; (IT.}. 


Revision of the Genus Ophryosporus ; (III.) The Genus Helogyne and its Synonyms ; (IV.) 
Diagnoses and Synonymy of Eupatorieae and of Certain Other Compositae which have been 
Classed with them. pp. 148. May, 1906. 50c. 

Sapine, W. C. — Architectural Acoustics: (I.) Introduction; (II.) The Accuracy of Musical 
Taste in regard to Architectural Acoustics; (III.) Variation in Reverberation with Varia- 
tion in Pitch. pp. 49-84. June, 1906. 45c. : 


Peirce, Β. 0. — On the Permeability and the Retentiveness of a Mass of Fine Iron Particles, 


pp. 85-91. June, 1906. 15c. 

Peirce, Β. Ο. --- On the Length of the Time of Contact in the Case of a Quick Tap on a Tele- 
graph Key. pp. 93-100. June, 1906. 15c. 

Mark, E. L., and Copetanp, M.—Some Stages in the Spermatogenesis of the Honey Bee. 
pp. 101-111. 1pl. June, 1906. 20c, 

Hoee, J. L. — Friction and Force due to Transpiration as Dependent on Pressure in Gases. 
pp. 113-146. July, 1906. 45c. ‘ 

Peirce, B. O. — On the Conditions to be Satisfied if the Sums of the Corresponding Members 
of Two Pairs of Orthogonal Functions of Two Variables are to be Themselves Orthogonal. 
pp. 147-157. July, 1906. 165c. 

Peirce, B. O. — On the Correction for the Effect of the Counter Electromotive Force induced 
in a Moving Coil Galvyanometer when the Instrument is used Ballistically. pp. 159-169. 
July, 1906. 15c. 

Perce, B. O. —A Simple Device for Measuring the Deflections of a Mirror Galvanometer. 
pp. 171-174. 1lpl. July, 1906. 15c. 

Rippie, L. W. —On the Cytology of the Entomophthoraceae. pp. 175-197. 3 pls. August, 
1906. 40c. 

Baxter, G. P. — A Revision of the Atomic Weight of Bromine. pp. 199-214. August, 1906. 
250. 

LARRABEE, A. P, —The Optic Chiasma of Teleosts: A Study of Inheritance. pp. 215-231. 
October, 1906. 25c. 5 

Woop, R. W. — Fluorescence and Magnetic Rotation Spectra of Sodium Vapor, and their Analy- 
sis. pp. 233-260. 5 pls. November, 1906. 65c. 

Rorcn, A. L. — Results of the Franco-American Expedition to Explore the Atmosphere in the 
Tropics. pp. 261-272. December, 1906. 20c. 

Kennetiy, A. E.— An Approximate Law of Fatigue in the Speeds of Racing Animals. 
pp. 273-331. December, 1906. $1.15. 

Cote, Τῷ, J. — An Experimental Study of the Image-Forming Powers of Various Types of Eyes. 
pp. 333-417. January, 1907. $1.10. 

Smrra, A. W. — Expansion and Compressibility of Ether and of Alcohol in the Neighborhood 
of their Boiling Points. pp. 419-460. January, 1907. 60c. 

Conepon, E. D.— The Hydroids of Bermuda. pp. 461-485. January, 1907. 40c. 

BiackmAN, M. W. — The Spermatogenesis of the Myriapods. (V.) On the Spermatocytes of 
Lithobius. pp. 487-518. 2pls. February, 1907. 50c. : ἢ 

ΜΌΟΒΕΕ, A. H. — Revision of the Genus Spilanthes. pp. 519-569. March, 1907. 60c. 

RicHarps, Τὶ W., and Messrs. HENDERSON and FREvERT. — Concerning the Adiabatic Deter- 
mination of the Heats of Combustion of Organic Substances, especially Sugar and Benzol. 
pp. 571-593. March, 1907. 35c. 

Hatt, E. H., and Messrs. Camprety, Serviss, and CuurcHiir.—On the Thomson Effect and 
the Temperature Coefficient of Thermal Conductivity in Soft Iron between 115° and 204° C. 
pp. 595-626. March, 1907. 40c. 

Mark, E. L.— An Electric Wax-Cutter for Use in Reconstructions. pp. 627-636. March, 1907. 
20e. 

HeEnpERsoN, L. J. — Concerning Position Isomerism and Heats of Combustion. pp. 637-647. 

March, 1907. 206. ; 

Lowet, Ρ. --- Temperature of Mars, A Determination of the Solar Heat Received. pp. 649- 
667. March, 1907. 25c. f 

Apams, J. M. —The Transmission of Réntgen Rays through Metallic Sheets. pp. 669-697. 
April, 1907. 45c. 


KeEnneLLy, A. E.— The Process of Building up the Voltage and Current in a Long Alternating- 


Current Cireuit. pp. 699-715. May, 1907. 256. 

SanGer, C. R., and Gipson, J. A. — The Determination of Small Amounts of Antimony by the 
Berzelius-Marsh Process. pp. 717-733. 1 pl. May, 1907. 806. 

Records of Meetings; Biographical Notices; Officers and Committees; List of Fellows and 
Foreign Honorary Members ; Statutes and Standing Votes, ete. 60c. 


(Continued on page 2 of Cover. ) 


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PUBL 5 A LU x πον 


AMERICAN ACADEMY OF ARTS AND SOIENC ES. 


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Proceedings of the American Academy of Arts and Sciences 


‘Vou. XLIII. No. 22.— Jury, 1908. 


᾿Ξ “RECORDS. OF MEETINGS, 1907-1908. 
- REPORT OF THE COUNCIL: BIOGRAPHICAL NOTICE. 


‘SAMUEL Casot. By CHARLES LORING JACKSON. 


OFFICERS AND COMMITTEES FOR 1908-1909. 


LIS? OF THE FELLOWS AND FOREIGN HONORARY — 
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STATUTES“ AND STANDING VOTES. 
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ae 


~ ies Spe ᾿ ν ΡΟ Ὡς τῷ : 2 : 
Sia ee tes a - 
τα ον Pap pe 
(Continued from age 3 of C0 wget ee 

>t 


VOLUME 8 ne ae 


Morse, H. W. —Studies on Fluorite: (IV. ) The Keble Sarmiseacbebe ck Fluorite. me .ι 
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Rickarps, Τὶ W., and Wreve, F.— The Transition Temperature of Manganous Chloride 
New Fixed Point i in Thermometry. pp. 341-350, November, 1907. 200. 
Kent, N. A., and Avery, A. H. — Difference in Wave-Lengths of Titanium AA 3900 and; 
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Proceedings of the American Academy of Arts and Sciences. 


Vou. XLIII. No. 22. — Jury, 1908. 


RECORDS OF MEETINGS, 1907-1908. 
REPORT OF THE COUNCIL: BIOGRAPHICAL NOTICE. 


SAMUEL CABOT. By CHARLES LORING JACKSON. 


OFFICERS AND COMMITTEES FOR 1908-1909. 


LIST OF THE FELLOWS AND FOREIGN HONORARY 
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STATUTES AND STANDING VOTES. 
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INDEX. 


(Tirte Pace anp TABLE oF CONTENTS). 


ae. CN, + Pt, eRe ΡΟ τ ge ee kp eee ee eer re στ eee a eAy?. Τἢ 


24 “tere a 


RECORDS OF MEETINGS. 
: LIBR ARY 
NEW YORK 


ROTA 


Nine hundred seventy-fifth Meeting. : 
OcTOBER 9, 1907. — STATED MEETING. 


The PRESIDENT in the chair. 

There were present twenty-four Fellows. 

The Corresponding Secretary, pro tempore, read letters from 
G. W. Pierce, accepting Fellowship; from the California Acad- 
emy of Sciences, thanking the Academy for the contribution of 
its publications; from Arthur McDonald, asking the Academy 
to form resolutions regarding the establishment of laboratories 
for the study of the criminal, pauper, and defective classes, and 
transmitting a pamphlet on the subject; from C. van Over- 
bergh, Directeur général de 1 Administration de l’Ensignment 
Supérieur des Sciences et des Lettres, enclosing a copy of the 
report of the International Congress for the Study of the Polar 
Regions, and requesting the publications of the Academy; from 
St. C. Hepites and I. St. Murat, notifying the Academy of their 
appointment as Directors of the Roumanian Meteorological In- 
stitute and Service Central des Poids et Mesures; from Vilh. 
Thomsen, President of the International Congress of Orien- 
talists, inviting the Academy to send delegates to the Fifteenth 
Congress, in August, 1908; from President Capellini, two com- 
munications relative to the celebration of the anniversary of the 
death of Aldrovandi; from the Société Géologique de Belgique, 
notifying the Academy of the death of its Secretary, Henri- 
Joseph Fourir; from the Astrophysical Observatory, Potsdam, 
notifying the Academy of the death of H. C. Vogel; from the 
Kon. bohmische Gesellschaft der Wissenschaften, notifying the 
Academy of the death of Johann Gebauer, and also of the death 
of J. Bohuslav, Freih. v. Rieger. 


528 PROCEEDINGS OF THE AMERICAN ACADEMY. 


The Chair announced the following deaths : — 

Charles Εἰ, Folsom, Resident Fellow, of Class II, Section 4; 
H. C. Vogel, Foreign Honorary Member of Class I, Section 1; 
and of Henry G. Denny, a former Resident Fellow. 

On the recommendation of Professor Webster, it was 

Voted, That an unexpended balance of $93.46 from the in- 
come of the Rumford Fund, returned by Professor Edwin H. 
Hall, be reappropriated to the use of the Rumford Committee. 

The following gentlemen were elected Resident Fellows of 
the Academy : — 

James Flack Norris, of Boston, in Class I, Section 3 (Chem- 
istry). 

William Hultz Walker, of Newton, in Class I, Section 3 
(Chemistry). 

Mr. A. T. Thompson showed the use of his reflectoscope in 
projecting photographs and opaque objects upon the screen. 

On motion of the Recording Secretary, it was 

Voted, That the thanks of the Academy be tendered to Mr. 
Thompson for his interesting exhibition of the reflectoscope. 

Dr. Theodore Lyman gave a paper entitled “ The Absorp- 
tion of the Air for Light of very Short Wave Lengths.” 

The following paper was presented by title : — 

“ Difference in Wave Lengths of Titanium AXA 3900 and 3913 
in Arc and Spark.” By Norton A. Kent and Alfred H. Avery. 
Presented by John Trowbridge. 


Nine hundred seventy-sixth Meeting. 
NOVEMBER 13, 1907. 


VicE-PRESIDENT WALCOTT in the chair. 

There were present twenty-seven Fellows. 

The following letters were read : — 

From Wm. H. Walker, accepting Fellowship; from Dr. G. 
Hellman, announcing his appointment as Director of the Kin. 
Preuss. Meteorologisches Institute of Berlin; from the Verein 
fiir Naturwissenschaft in Braunschweig, announcing the death 
of Professor Dr. Rudolf Blasius. 

The Chair announced the following deaths: — 

Edward G. Gardiner, Resident Fellow in Class IT, Section 3. 


4 


RECORDS OF MEETINGS. 529 


Sir Benjamin Baker, Foreign Honorary Member in Class I, 
Section 4. 

The following communications were given : — 

“The Volcanoes of the Azores.” By Professor W. H. 
Pickering. 

“The Linnaean Celebration at Upsala, Sweden.” By Pro- 
fessor W. G. Farlow. 

The following paper was read by title: — 

“A Revision of the Atomic Weight of Lead. Preliminary 
Paper: The Analysis of Lead Chloride.” By Gregory Paul 
Baxter and John Hunt Wilson. 


Nine hundred seventy-seventh Meeting. 


DECEMBER 11, 1907. 


The PRESIDENT in the Chair. 

There were present seventeen Fellows. 

Letters were read from Arthur I. Davenport, announcing the 
death of his father, George E. Davenport; from the Sixteenth 
International Congress of Americanists, inviting the Academy 
to send delegates. 

The Chair announced the death of George E, Davenport, 
Resident Fellow in Class II, Section 2, and also of Professor 
Minton Warren, whose nomination had been read to the Acad- 
emy at its last meeting. 

On motion of Professor Davis, it was 

Voted, That in reference to the death of Professor Warren 
the President be authorized to take such action as he thinks 
proper. 

On motion of Professor Davis, it was 

Voted, That the House Committee be authorized to provide 
a simple collation for the Members at the meetings of the 
Academy. 

The following communications were given : — 

“The Most Recent Exploration in Palestine.” By Professor 
D. G. Lyon. 

“The Centenary Celebration of the Geological Society of 
London.” By Professor W. M. Davis. 

The following papers were presented by title: — 


VOL. ΧΙ1Π — 34 


530 PROCEEDINGS OF THE AMERICAN ACADEMY. 


“ The Influence of Hysteresis upon the Manner of Establish- 
ment of a Steady Current in the Primary Circuit of an Induc- 
tion Coil.” By B. O. Peirce. 

“Some Effects of Heavy Pressure on Arc Spectra.” By W. 
J. Humphreys. Presented by C. R. Cross. 

“ The Effect of a Magnetic Field on the Cathode Rays.” By 
John Trowbridge. 


Nine hundred seventy-eighth Meeting. 
JANUARY 8, 1908.—STATED MEETING. 


The PRESIDENT in the chair. 

There were present twenty Fellows. 

Letters were read from the Secretaries of the Third Inter- 
national Congress for the History of Religions, enclosing the 
first announcement of the Meeting to take place at Oxford in 
September, 1908, and inviting the Academy to send a Repre- 
sentative; from the Physikalische Verein of Frankfort, inform- 
ing the Academy of the opening of the new Institute Building, 
and inviting the Academy to send Delegates; from the Com- 
mittee of Organization, informing the Academy of the First 
Congress of Chemistry and Physies to be held at St. Petersburg 
in January, in memory of D. I. Mendéléeff. 

The following deaths were announced by the Chair : — 

Lord Kelvin, Foreign Honorary Member in Class I, Sec- 
tion 4; Charles A. Young, Associate Fellow in Class I, Sec- 
tion 1; Thomas D. Seymour, Associate Fellow in Class III, 
Section 2. 

The following Delegates were appointed to represent the 
Academy at the Fifteenth International Congress of Oriental- 
ists, to be held at Copenhagen in August, 1908: — 

Charles R. Lanman, George F. Moore. 

In answer to an inquiry by Professor Webster, on motion of 
Colonel Livermore, it was 

Voted, That the Corresponding Secretary be requested to 
ascertain and report to the Academy on the measures to be 
taken in reference to the Nobel Prizes. 

Le Baron Russell Briggs was elected a Resident Fellow in 
Class III, Section 4 (Literature and the Fine Arts). 


RECORDS OF MEETINGS. 531 


The following communications were presented : — 

* Cretan Chronology.” By President W. W. Goodwin. 

“ The Polariscope and the Weather.’ By Dr. Louis Bell. 

The following paper was read by title: — 

‘A Simple Method of Measuring the Intensity of Sound.” 
By George W. Pierce. 


Nine hundred seventy-ninth Meeting. 


FEBRUARY 12, 1908. 


The CORRESPONDING SECRETARY pro ¢empore in the chair. 

There were present twenty-four Fellows, 

Letters were read from the Sub-director of the Museo Nacio- 
nal, Mexico, felicitating the Academy on the New Year; from 
the Committee of the Fourth International Congress of Mathe- 
maticians to be held at Rome, April 6-11, 1908. 

The death of Edward H. Strobel, Resident Fellow in Class ITI, 
Section 1, was announced. 

The following report of the House Committee was read and 
accepted : — 


“ At the meeting of the Academy held on the eleventh of Decem- 
ber, the House Committee were instructed to consider and report 
whether it would be advisable for the Academy to provide a light re- 
past, consisting of crackers, ale, and cheese, at the conclusion of the 
meetings. 

“We find that the expense involved would be about twenty-five 
dollars for tables and dishes, and an annual outlay of about twenty- 
five dollars. After consulting the ‘Treasurer, we recommend that these 
sums be expended, the initial outlay being paid by the appropriation 
for House expenses, and the current expense charged to the appropria- 
tion for the expense of meetings. 

‘‘The Committee have, as has been announced, provided a ventilator 
in the meeting-room, with an air-shaft reaching above the roof, which 
it is hoped will prove effective. If not, it can be made more so by 
putting an electric fan into the air-shaft. 

‘Meanwhile it has been urged upon them that the present meeting- 
room shall be given up, and a larger and pleasanter one be constructed 
in the front of the house in the third story. A room could be made 
covering about six hundred and fifteen square feet, about a third more 


532 PROCEEDINGS OF THE AMERICAN ACADEMY. 

than the area of the present room, which covers four hundred and 
sixty-five square feet. The cost would be about thirteen hundred 
dollars ($1300), a larger sum, considerably, than the means at the 
Treasurer's command can supply. But if the ventilation now pro- 
posed proves on trial unsatisfactory, and it is found that the cost of 
these changes can be raised, as has been suggested, by subscription, 
and, at the close of the season, the Academy so vote, the alteration can 
be made in the course of the summer.” 


On motion of Professor Webster, and seconded by Professor 
Kinnicutt, it was 

Voted, That the House Committee be requested to consider 
the question of raising funds for the carrying out of the plans 
for a meeting-room on the third floor. 

Professor George F. Moore was appointed a Delegate to the 
Third International Congress for the History of Religions, to be 
held at Oxford in September, 1908. 

Professor Jaggar informed the Academy that there was a bill 
pending in the Legislature for a new topographical survey of 
the State. 

Professor Τὶ A. Jaggar gave the following communication : — 

« Volcanoes of the Aleutian Islands,” 

The following papers were read by title : — 

“ Measurements of the Internal Temperature Gradient in 
Common Materials.” By Charles B. Thwing. Presented by 
C. R. Cross. 

“The Variation of the Thermomagnetic Effect in Soft Iron 
with Strength of the Magnetic Field and Temperature Gra- 
dient.” By L. L. Campbell. Presented by John Trowbridge. 


Nine hundred eightieth Meeting. 


Marcu 11, 1908.—StatepD MEETING. 


VicE-PRESIDENT TROWBRIDGE in the chair, 

There were present twelve Fellows. 

Letters were read from L. B. R. Briggs, accepting Fellow- 
ship; from William W. Goodwin, declining re-election as Presi- 
dent of the Academy; from the Geological Society of London, 
thanking the Academy for delegating Professor W. M. Davis 


RECORDS OF MEETINGS. 583 


to attend its centenary, and presenting to the Academy the 
volume, “The History of the Geological Society of London” ; 
from the Académie des Sciences, Agriculture, Arts et Belles- 
Lettres, of Aix, requesting delegates from the Academy to 
attend the celebration of the centenary of its Reconstitution ; 
from the Gesellschaft von Freunden der Naturwissenschaften, 
notifying the Academy of its fiftieth anniversary. 

The Chair announced the following deaths : — 

Asaph Hall, Class I, Section 1; Israel C. Russell, Class IT, 
Section 1; Augustus St. Gaudens, Class III, Section 4; E. C. 
Stedman, Class III, Section 4, Associate Fellows. 

The Chair appointed for Nominating Committee : — 

Charles R. Cross, of Class I. 

Charles 5. Minot, of Class IT. 

Morris H. Morgan, of Class III. 

It was 

Voted, To meet on adjournment on the second Wednesday in 
April. 

Dr. G. H. Parker presented the communication : — 

“ The Influence of Light on the Daily Activities of Animals.” 

The following papers were read by title : — 

‘The Damping of the Quick Oscillations of a Twisted Fibre 
by the Resistance of the Air and by the Torsional Forces.” By 
B. O. Peirce. 

« Notes on Superheated Steam: I, Its Specific Heat; 11, Its 
Total Heat; 111, Its Joule-Thomson Effect.” By Harvey N. 
Davis. Presented by W. C. Sabine. 

“ The Sensory Reactions of Amphioxus.” By ἃ. H. Parker. 

“On Delays before ἀναγνωρίσεις in Greek Tragedy.” By 
W.P. Dickey. Presented by M. H. Morgan. 


Nine hundred eighty-first Meeting. 


APRIL 8, 1908.— ADJOURNED STATED MEETING. 


The Academy met by invitation of Professor Elihu Thomson 
at the Algonquin Club, 217 Commonwealth Avenue. 

Vick-PRESIDENT TROWBRIDGE in the chair. 

There were present forty-nine Fellows and four guests. 


534 PROCEEDINGS OF THE AMERICAN ACADEMY. 


The following gentlemen were elected members of the 
Academy : — 

Louis Derr, of Brookline, as Resident Fellow in Class I, Sec- 
tion 2 (Physics). 

John Ulric Nef, of Chicago, as Associate Fellow in Class I, 
Section 3 (Chemistry). 

On the recommendations of the Recording Secretary, the 
Chairman of the Rumford Committee, and the Chairman of the 
Publishing Committee, it was 

Voted, To make the following appropriations: From the in- 
come of the General Fund, for House expenses, $3425; for 
Books and binding, $340; for Meeting expenses, $35; from the 
income of the Rumford Fund, for the furtherance of research, 
$141.90 (the unexpended balance of a previous grant) ; from the 
income of the Publication Fund for publication, $800. 

Vice-President Trowbridge announced that the Rumford 
Premium had been awarded to Mr. Edward Goodrich Acheson 
for the application of heat in the electric furnace to the indus- 
trial production of carborundum, graphite, and other new and 
useful substances. He then called upon the chairman of the 
Rumford Committee, Professor Charles R. Cross, who gave a 
short account of the previous awards of the Rumford Medal, 
followed by a brief analysis of Mr. Acheson’s work and the 
circumstances which influenced the Committee to recommend 
the award to him. 

Vice-President Trowbridge then presented the medal in the 
name of the Academy to Mr. Acheson, who expressed his ap- 
preciation of the honor conferred upon him, saying: ‘ The 
medal has been a great incentive to me from boyhood, and I 
had hoped sometime to attain it. To-night my dream has come 
true.” 

On the invitation of the Chair he then gave an account in 
detail of his discoveries, illustrated by a number of interesting 
demonstrations. 

The following papers were presented by title : — 

“The Invariants of Linear Differential Expressions.” By 
Frank Irwin. Presented by Maxime Bécher. 

“Contributions toward a Monograph of the Laboulbeniaceae. 
Part 11." By Roland Thaxter. 


RECORDS OF MEETINGS. 


Nine hundred eighty-second Meeting. 


May 18, 1908.— ANNUAL MEETING. 


VICE-PRESIDENT WALCOTT in the chair. 


There were present twenty-eight Fellows. 
Letters were read from Thomas Dwight, Theodore Hough, 
and Arthur Michael, resigning Fellowship; from Louis Derr, 
accepting Fellowship; from the Third International Congress 
of Botany, two circulars referring to the Congress. 
The death of Gustavus Hay, Resident Fellow in Class I, 


Section 1, was announced by the Chair. 


The annual report of the Council was read.1 
The annual report of the Treasurer was read, of which the 


following is an abstract: — 


GENERAL Funp. 


Receipts. 
Investments . $2,833.37 
Assessments . 1,830.00 
Admission fees 70.00 
Rent of offices 1,204.00 
Expenditures. 
General expenses $3,034.25 
Library OR ea πον ἢ- 1,759.67 
Income transferred to principal 758.49 
Balance, April 30, 1908 . 
Rumrorp Funp. 
Receipts. 
$ 186.86 


Balance, April 30, 1907 
Investments . . 


1 See p. 547. 


3,027.90 


535 


$5,933.41 


$5,552.41 
381.00 


$5,933.41 


$3,214.76 


PROCEEDINGS OF THE AMERICAN ACADEMY. 


or 
i) 
συ 


Expenditures. 
Research $1,200.00 
Publication 571.99 
Library 222.74 
Medal . ee Pee 341.50 
Income transferred to principal 127.35 
Balance, April 30, 1908 . 

C. M. Warren Funp. 
Receipts. 

Balance, April 30,1907... . -; <. «al seeps ow ene 
Investments . Fat Mee abe : 700.33 

Expenditures. 
Research το Seis Ae Ge es ΠΟ nee 
Vault rent ΣΟ τ. ΤΟ τ 4.00 
Premium on bonds charged off . 90.00 
Income transferred to principal 241.37 
Balance, April 30, 1908 

Pusiication Funp. 
Receipts. 

Balance, April 30, 1907 $ 212.84 
Investments . 3,179.02 
Sale of publications 148.20 

Expenditures. 
Publication : $3,046.55 
Yaultvent. τς ον 12.80 
Income transferred to principal 136.71 


Balance, April 30, 1908 . 


$2,463.58 
751.18 
$3,214.76 


$1,463.30 


$ 485.37 
977.93 


$1,463.30 


RECORDS OF MEETINGS. dot 


The following reports were also presented : — 


REPORT OF THE LIBRARIAN. 


Of the library catalogue there remains to be done the serial publi- 
cations on general science, comprising the two lower floors of the stack 
building, and the few books on literature, the fine arts, and religion. 
The Academy is fortunate in having this work done by so accomplished 
a cataloguer as Miss Wyman, and at such a moderate cost, the last 
advantage resulting from the fact that Miss Wyman gives only a por- 
tion of her time to the Academy. 

The Assistant Librarian is endeavoring to complete the sets of Soci- 
ety publications now in the library by sending to the various societies a 
request for each missing number, and offering in return to complete their 
sets of the Academy’s publications. In a great many cases the request 
is complied with, in others the numbers requested are scarce or out of 
print. These could perhaps be purchased of second-hand booksellers 
were money available for the purpose. ‘This lack of money is much to 
be regretted, as in time it will be practically impossible to purchase 
them. 

The accessions during the year have been as follows : — 


Vols. Partsof Vols. Pams. Maps. Total. 

By gift and exchange . . . 234 2076 76 5 2391 
By purchase — General Fund 12 538 550 
By purchase — iumford Fund ὅ 327 eo 332 
Doteasy ee es | 2 2941 76 5) 3273 


The bound volumes in the library have been counted since the last 
report, and there are now 29,089 volumes. Hereafter in this report 
the accessions will be given in volumes, and not by parts, as heretofore, 
and will represent the volumes placed on the shelves during the pre- 
ceding year. 

80 books have been borrowed from the library by 24 persons, includ- 
ing 13 Fellows, and two libraries (Clark University and the University 
of Cincinnati). 

All books borrowed during the year have been returned for the 
annual examination. Of the books reported as still out a year ago, 
all have been returned. 

The expenses charged to the library are as follows: Miscellaneous, 
$519.67 (which includes $175.93 for cataloguing) ; Binding, $585.55 
General, and $56.35 Rumford, Funds ; Subscriptions, $654.45 General, 
and $142.75 Rumford, Funds; making a total of $1240.00 for the 


538 PROCEEDINGS OF THE AMERICAN ACADEMY. 


General, and $199.10 for the Rumford, Funds, as the cost of subscrip- 
tions and binding. Of the appropriation of $50.00 from the Rumford 
Fund for books, five have been purchased at a cost of $23.64. 
Although $585.55 from the income of the General Fund was spent 
for binding, there are still 400 volumes waiting to be bound. There 
has never been an adequate amount appropriated for binding, and we 
are now exchanging with more societies and universities than ever 
before. Societies are now publishing more volumes, and these contain 
more plates than formerly, which makes the binding more expensive. 


A. Lawrence Rortcu, Librarian. 
May 18, 1908. 


ReporT OF THE RumMFOoRD CoMMITTEE. 


From the amount available for the purpose, the Committee during 
the year 1907-08 has made grants as follows, for the furtherance of 
researches in light and heat : — 

June 12, 1907. P. W. Bridgman, of the Jefferson Physical 
Laboratory, for the continuation of his work on the optical and 
thermal properties of bodies under extreme pressure . . . $400 

Oct. 9, 1907. P. W. Bridgman, in addition to the above ap- 
propriation, for the same purpose. 400 

Jan. 8, 1908. Dr. L. J. Henderson, of the Harvard Medical 
School, in aid of his research on a new method for the direct 


determination of physiological heats of reaction . . . . 200 
Feb. 12, 1908. Professor Joel Stebbins, of the University of 

Illinois, for his research on the use of selenium in photometry . [100 
Feb. 12, 1908. Mr. Willard J. Fisher, of Cornell aise 

for his research on the viscosity of gases. . ἐν a ee 


Reports stating the progress of their Ἔπειτ: inv estigations have 
been received ΕΠ Messrs. P. W. Bridgman, A. L. Clark, E. B. Frost, 
L. J. Henderson, L. R. Ingersoll, N. A. Kent, F. E. Kester, H. W. 
Morse, E. F. Nichols, A. A. Noyes, J. A. Parkhurst, T. W. Richards, 
R. W. Wood. 

Since the last annual meeting the following papers have been pub- 
lished at the expense of the Rumford Fund, the first-mentioned in the 
Memoirs, the others in the Proceedings : — 

“High Electromotive Foree.” John Trowbridge, May, 1907. 

“Studies on Fluorite: ΓΚ, The Kathodo-Luminescence of Fluorite.” 
H. W. Morse. June, 1907. 

“The Physiological Basis of Illumination.” L. Bell. September, 
1907. 


RECORDS OF MEETINGS. 539 


“The Transition Temperature of Manganous Chloride: A New 
Fixed Point in Thermometry.” 1). W. Richards and F. Wrede. No- 
vember, 1907. 

“Difference in Wave-Lengths of Titanium AA 3900 and 3913 in 
Are and Spark.” N. A. Kent and A. H. Avery. November, 1907. 

““Note on Some Meteorological Uses of the Polariscope.” LL. Bell. 
March, 1908. 

At its meeting of Jan. 8, 1908, the Committee, at the request of the 
Librarian, voted an appropriation of $50 for the binding of books and 
periodicals relating to light and heat. 

The Committee is endeavoring to make a complete list of all appa- 
ratus purchased in past years through appropriations from the Rum- 
ford Fund, and hence at present the property of the Academy, to the 
end that such apparatus, if suitable, may be available for purposes of 
research in the future. 


CHARLES R. Cross, Chairman. 
May 13, 1908. 


Report oF THE C. M. Warren CoMMITTEE. 


The C. M. Warren Committee beg leave to report that grants have 
been made during the past year to the following persons, in aid of the 
researches specified : — 

Dr. Frederic Bonnet, Jr., Worcester Polytechnic Institute . $150 

“The Effect of Lanthanum, Cerium, and Neodymium Oxides 
upon Porcelain Glazes, especially as regards their Electrical 
Conductivity.” 

Professor James F. Norris, Simmons College. . . . . . 250 

“A Study of the Structure of T'riphenyl Methyl.” 

The work of Professor J. Bishop Tingle on the “Study of the Action 
of Certain Secondary Amines on Camphoroxalic Acid,” to aid which 
research a grant of $50 was made by the Warren Committee in 1907, 
has been published in the American Chemical Journal, and acknowl- 
edgment made in the paper for the grant received from the Warren 
Committee. 

A report of the progress made has also been received from Dr. Fred- 
eric Bonnet, Jr., and the result of his investigations will, it is hoped, 
be published the coming year. 


LeonarD P. Krynicutt, Chairman. 
May 19, 1908. 


540 PROCEEDINGS OF THE AMERICAN ACADEMY, 


REPORT OF THE PUBLICATION COMMITTEE. 


Between May 1, 1907, and May 1, 1908, there were published of the 
Proceedings, three numbers of Volume XLII (Nos. 27-29), and six- 
teen numbers of Volume XLIII; also one biographical notice, —in all 
567 + v pages and four plates. Five numbers of Volume XLIII 
(Nos. 1, 4, 19, 11, and 15) were paid for from the income of the Rum- 
ford Fund. 

There has also been published, at the expense of the Rumford Fund, 
one Memoir (Volume XIII, No. 5, pp. 188-215, plates xxv—xxvii). 

There are in press two numbers of the Proceedings ; and an exten- 
sive Memoir of some three hundred pages, illustrated with forty-four 
plates, isin type. ‘This will complete Volume XIII of the Memoirs. 

The Academy placed at the disposal of the Publication Committee, 
from the income of the Publication Fund, $3200. Of this amount, 
$3046.55 have been paid by the Treasurer on bills approved by the 
chairman of the Committee, leaving a balance of $153.45. 

Bills aggregating $473.51 incurred in publishing Rumford papers 
have been forwarded to the chairman of the Rumford Committee for 
approval. 


Report oF House ΟὈΜΜΊΤΤΕΕ. 


During the last year the lower story of the Academy’s House has 
been occupied by the three physicians to whom it has been leased ; 
the second story by the Academy itself, the Meeting Room being in 
the rear, and the Reception Room and the Librarian’s Office being 
in the front ; the third story by the dwelling rooms of the Assistant 
Librarian, and the fourth story by storerooms and workroom, and a 
bedroom for the Janitor. Under this arrangement the building has 
been almost constantly occupied in one part or another, and its con- 
tents have been properly guarded. 

The bills approved by the Secretary of the Academy and the Chair- 
man of this Committee, and paid by the Treasurer, have amounted to 
$1624.62, of which $1200 was especially appropriated at the begin- 
ning of the year, and the balance, amounting to $414.62, was made up 
from unappropriated funds in the hands of the ‘Treasurer by a subse- 
quent vote of the Academy. These amounts include $11.50 spent for 
the tables and dishes used for the slight repasts which have been fur- 
nished to the members at the close of the meetings. The sum of $16.02, 
which has been the total cost of five such entertainments, coming to 
about $3.30 apiece, has been charged to the expense of the meetings. 


RECORDS OF MEETINGS. 541 


The Committee have spent $163.77 in improving the ventilation of 
the Meeting Room, an amount included in the previous statement. 

The ventilation will probably be still further improved by the change 
recently made in the seating, which will enable the southern windows 
to be opened. ‘This will, we expect, make the ventilation entirely 
satisfactory. 

But some objection has also been made to the general aspects of the 
Meeting Room and its somewhat contracted appearance. The Acad- 
emy accordingly at the February meeting directed this Committee to 
consider and report upon the practicability of building a somewhat 
larger Meeting Room in the front of the third story, over the present 
Reception Room. We find that this could be done at a cost of between 
$1200 and $1500, the new room promising to be about one-third 
larger than the present one. 

But as the Academy has not this amount of money in hand, and, as 
the leases of the first floor will expire within a reasonable time, we 
think that it would be better for the Academy to try meanwhile to 
raise money enough to enable it to dispense with the leasing of the 
first floor and to fit up a commodious meeting room there, and we 
recommend that steps be taken towards this end. 

Witiiam R. Warez, Chairman. 


May 13, 1908. 
FINANCIAL REPORT OF THE COUNCIL. 


The income for the year 1908-09, as estimated by the Treasurer, is 
as follows : — 


pe cnnents io eae AO BITS G97 
GENERAL FunD Assessments . .. . - 1800.00 
| Rent Ol Ομ. 900.00 $4486.97 


fAppleton Fund investments $ 559.52 
Pe OnON UND (Centennial Fund investments 2236.75 $2796.27 


Rumrorp Funp Investments . . «2. « « « 4 $2698.04 


WarRREN FunpD Investments: π΄. sy)... hae ae 0559 


The above estimates, less 5 per cent to be added to the capital, 
leaves an income available for appropriation as follows :— 


Ponta. hs sh: aly os ein ae π᾿ ΟΡ) 
UD WGa OMe UNG! 60 co.) 4. uct es sw ales @ ep ot Προ 
ἘΠ τ πη. =. i » « «Some 8 ee 25634 


ἀρ tee Sg. a’ eos care, οὖς 601.19 


542 PROCEEDINGS OF THE AMERICAN ACADEMY. 


The following appropriations are recommended : — 


GENERAL Funp. 


House expenses 4° 6% si us sre) Ba aL eee et me 
Library expenses. . re ee ee ra 
Books, periodicals, and binding ον mrp perc. 900 
Expenses Of meetings a. Ὁ we <) sim Soke woe 250 
Treasurers OMCs τὰ Las sells eee ee 150 


PUBLICATION FUND. 
Pablicahion τὸν geo ake oe ee eee eee 


Rumrorp Funp. 


Research . Ὄντων τ eee setae 
Periodicals and binding: ΣΑΣ ores 150 
Books-and ‘bmaing: Gu) ae oS See δ0 
Publication. . . Seal ae Sipe 700 
To be used at ἘΞ τ of Games! are are ς 663 


C. M. Warren Founp. 
Research 


$4100 


In accordance with he recommendations in ne foregoing 


report it was 


Voted, To appropriate for the purposes named the following 


sums : — 


From the income of the General Fund . . . $4100 
From the income of the Publication Fund . . 2400 
From the income of the Rumford Fund . . . 256: 
From the income of the C. M. Warren Fund . 500 


On the motion of the Treasurer, it was 


Voted, That the assessment for the ensuing year be ten dol- 


lars ($10). 


The annual election resulted in the choice of the following 


officers and committees : — 


JOHN TROWBRIDGE, President. 

Exuinu THomson, Vice-President for Class I. 
Henry Ρ. Waucort, Vice-President for Class 1]. 
Joun ©. Gray, Vice-President for Class II. 
Epwin H. HALL, Corresponding Secretary. 


RECORDS OF MEETINGS. 548 


WixtiiaAMm Watson, Recording Secretary. 
CHARLES P, BowpitcH, Treasurer. 
A. LAWRENCE Rotca, Librarian. 
Councillors for Three Years. 
WiuuiAM L. Hooper, of Class I. 
HAROLD C. Ernst, of Class II. 
FREDERIC J. STIMSON, of Class III. 
Finance Committee. 
JOHN TROWBRIDGE, 
EviotT ὦ. CLARKE, 
FRANCIS BARTLETT. 
Rumford Committee. 
CHARLES R. Cross, ARTHUR G. WEBSTER, 
EDWARD C. PICKERING, ELIHU THOMSON, 
Erasmus D. LEAVITT, THEODORE W. RICHARDS, 
Louis: BELL. 
C. M. Warren Committee. 
LEONARD P. KINNICUTT, CHARLES R. SANGER, 
Ropert H. RIcHArRDs, ARTHUR A. Noygs, 


Henry P. TALBOT, THEODORE W. RICHARDS, 
GEORGE D. Moore, 


The following standing committees were chosen: — 
Publication Committee. 
WALLACE C. SABINE, of Class 1, Eowarp L. MARK, of Class 11, 
CRAWFORD H. Toy, of Class III. 
Library Committee. 
Harry M. Goopwin,of ClassI, SamMvuEL HENSHAW, of Class IT, 
Henry W. Haynss, of Class 11]. 
Auditing Committee. 
A. LAWRENCE LOWELL, FREDERIC J. STIMSON. 
House Committee. 


WILLIAM R. WARE, A. LAWRENCE Rotca, 
Morris H. Morean. 


544 PROCEEDINGS OF THE AMERICAN ACADEMY. 


On motion of the Recording Secretary, the following Resolu- 
tion was unanimously adopted : — 

Ltesolved, That the Fellows of the American Academy desire 
to place upon record their grateful appreciation of the services 
of their retiring President, William W. Goodwin, during the 
five years in which he has presided over their deliberations. 

The following gentlemen were elected members of the 
Academy: 

Douglas Wilson Johnson, of Cambridge, as Resident Fellow 
in Class II., Section 1 (Mathematics and Astronomy), 

Charles Hyde Warren, of Auburndale, as Resident Fellow in 
Class II., Section 1. 

Emil Fischer, of Berlin, as Foreign Honorary Member in 
Class I., Section 3 (Chemistry), in place of the late D. 
Mendeleeff. 

Professor A. G. Webster gave a communication entitled: 
‘* Absolute Measurements of Sound.” 

The following papers were presented by title : — 

‘*A new Method of Determining the Specific Heats of Solu- 
tions. By T. W. Richards and A. W. Rowe. 

“ Positive Rays.” By John Trowbridge. 

“Variation of the Thermomagnetie Effect in Soft Iron.” 
By L. L. Campbell. Presented by John Trowbridge. 

“The Latent Heat of Fusion and the Specific Heat in the 
Solid and Liquid State of Salts Melting below 600°C.” By 
H. M. Goodwin and Η. T. Kalmus. 

“ Pisistratus and his Edition of Homer.” By Samuel Hart 
Newhall. Presented by M. H. Morgan. 


AMERICAN ACADEMY OF ARTS AND SCIENCES, 


Report oF THE Councit. — PRESENTED May 13, 1908. 


BIOGRAPHICAL NOTICE. 


GaAMUEL CABOT .. . . τ + - . + By CHanrtes Lorine JACKSON. 


i) 


REPORT OF THE COUNCHE 


The Academy has lost fourteen members by death since the 
last report of the Council, — five Resident Fellows, Charles F. 
Folsom, Edward G. Gardiner, George E. Davenport, Edward 
H. Strobel, Gustavus Hay; six Associate Fellows, Τ᾿. D. Sey- 
mour, C. A. Young, Asaph Hall, I. C. Russell, A. St. Gaudens, 
E. C. Stedman; three Foreign Honorary Members, H. C. Vogel, 
Sir Benjamin Baker, Lord Kelvin. 

Three Resident Fellows have resigned. 

Seven Resident Fellows have been elected. 

One Resident Fellow has been elected to Associate Fellow- 
ship. 

The roll of the Academy now includes 187 Resident Fellows, 
92 Associate Fellows, and 65 Foreign Honorary Members. 


SAMUEL CABOT. 


SamuEL Cazort, the fourth of the name, was born February 18, 
1850, in Boston, where his father was an eminent surgeon. His grand- 
father, a successful East India merchant in the days before commercial 
supremacy had left New England, married Elizabeth Perkins, the daugh- 
ter of Thomas Handasyd Perkins, founder of the Perkins Institution 
for the Blind. His mother, Hannah Lowell Cabot, was the daughter 
of Patrick Tracy Jackson, of Boston, celebrated for the introduction 
of the manufacture of cotton goods into America at Waltham and 
Lowell, and of Lydia Cabot, of Beverly. He was therefore descended 
on each side from a family noted for rugged independence, sturdy hon- 
esty, and devotion to high ideals. 

He was the oldest son but second child in a numerous family domi- 
nated by the high ideals of which I have just spoken, as his father was 
one of the most vigorous supporters of the antislavery cause when 
this could not be done without sacrifice, and in this and all other mat- 
ters the pursuit of the highest at any cost was impressed on the chil- 
dren by the precept and example of both parents. The life in his 
earlier days in Boston, and in the summer at Canton, was of necessity 
simple ; those were the days of small fees, when a surgeon, even of his 
father’s eminence, gained an income barely sufficient for the support of 


548 SAMUEL CABOT. 


a large family. In fact, it was characteristic of Dr. Cabot that even to 
the day of his death he remained an uncompromising opponent to the 
high charges for surgical work which had already appeared. But if 
the life was simple, it was very full and happy; the family circle was 
bound together by a warm, almost passionate affection, and was sur- 
rounded by troops of friends both in Boston and in the country. All 
the burning questions of the day were discussed continually with great 
energy by the brothers and sisters, each one of whom was thoroughly 
convinced of the truth of his or her opinion and never backward in 
proclaiming it. The home atmosphere was therefore stimulating, both 
morally and mentally. 

He was educated in the public schools, finally at the Boston Latin 
School, from which he graduated in 1866. Here he proved himself a 
painstaking but not brilliant scholar, as, like so many healthy boys, 
his interests were in athletic sports, especially baseball and football, 
rather than in his books. 

On leaving the Latin Schooi he was naturally attracted by the Mas- 
sachusetts Institute of Technology, then in its infancy, since he in- 
herited strong scientific tastes from his father, who was an excellent 
ornithologist and in his younger days had made scientific journeys. 
It is probable, however, that the impulse to chemistry came from the 
Jacksons, as his contemporaries in this family included nine profes- 
sional chemists divided among three branches of the family, which had 
separated in the seventeenth century. If this does not indicate a 
strong family taste for chemistry, but is a mere coincidence, it is cer- 
tainly a strange one, as chemistry is distinctly an unusual profession. 
Accordingly he entered the Institute in the third class received by it, 
and devoted his attention to chemistry principally under the direction 
of Professor F. H. Storer. 

In 1870 he became chemist of the Merrimack Print Works at Lowell, 
and, while holding this position, introduced successfully a process for 
recovering alizarine from the spent residues of the madder root by the 
use of sulphuric acid, which was new to this country, —a remarkable 
achievement for a young man of twenty-two. It is striking to note 
that even as a beginner he was not content with the mere routine work 
of his position, but entered at once the field in which he was destined 
to reap such abundant harvests, for his principal merit lies in making 
effective, on a commercial scale, new processes, whether of his own in- 
vention or foreign ones as yet unknown in America. This adaptation 
of foreign processes is not by any means the simple matter which it 
might appear at first sight; great judgment is necessary in selecting 
the one best fitted to the needs of this country, and, after this is done. 


SAMUEL CABOT. 549 


the details must in many cases be reinvented, or, when not carefully 
guarded secrets, they usually need extensive modifications to fit them 
to American conditions, which differ in many and unexpected ways 
from those abroad. It would be a mistake, however, to suppose from 
this early success that he was a precocious genius, who leaped to results 
by some intuitive process; on the contrary, his mind moved rather 
slowly, and his early successes were obtained by patient, well-directed, 
persistent labor. 

In 1873 he went to Europe to complete his chemical education, and 
studied for the first half year with Emil Kopp, in the Ziirich Polytech- 
nicum, where he gave part of his time to the analysis of aniline black, 
a dyestuff then recently introduced. ‘The second half of the year was 
devoted to travel, and especially to visits to laboratories and chemical 
works. At this time he was only twenty-four years old, but it was 
striking to see the most eminent chemists receiving him as a fellow- 
chemist, and discussing scientific matters with him as with a contem- 
porary. The acquaintanceships made at this time, and the practical 
knowledge acquired, were of life-long value to him. 

In 1874, after his return to America with greater attainments and 
enlarged horizons, he attempted to establish at the Lowell Bleachery 
the Solvay process for making sodic carbonate, then only eleven years 
old, but without success. This is an excellent example of the difficul- 
ties in introducing foreign manufacturing processes. There was no 
lack of judgment in the selection of the process, as is shown by the 
enormous development of it at Syracuse, where it was started under 
the auspices of the mother company in Belgium ten years later ; the 
details also seemed to be sufficiently well known, but the working out 
of these details so as to secure success needed not only the highest 
ability of the technical chemist, but also mechanical engineering of a 
most difficult and unusual sort, which at that time was beyond him. 
His failure, therefore, was not surprising or mortifying, and he had the 
happy faculty of learning from his failures, and, like Peter the Great, 
making them the school for later victories. After this he spent a 
short time in the office of his uncle, Henry Lee, learning business 
methods. 

His only chemical papers date from this period, 1872-1877. They 
are seven in number and of good quality for a beginner, but he evi- 
dently soon realized that the publication of original researches was not 
his line of work, since he could be employed much more usefully for 
the community and himself in perfecting chemical manufactures. With 
this end in view he became the most expert consulting chemist for in- 
dustrial work in this part of the country, and continued to give advice 


550 SAMUEL CABOT. 


of this sort, as he could find time, until his own manufactures absorbed 
his whole attention. 

It was in 1877 that he began business on his own account in part- 
nership with Frederick Nourse. They established a coal-tar distillery 
at Chelsea, from which he hoped to develop an industry in fine organic 
chemicals similar to that which was then showing such wonderful 
growth in Germany, but the time was not ripe for such a growth in 
America ; in fact, even now, thirty years afterward, this industry has 
not yet emerged from its infancy. Accordingly he turned his attention 
to the less varied list of products for which he found a demand. 
Among these, lampblack was the most important, and he at once im- 
proved the apparatus for its manufacture in his usual thorough, pains- 
taking way. Mr. Nourse retired from the partnership in the autumn 
of 1878, and after this he had sole charge of the business, keeping 
himself a firm grasp on all departments of it, with the assistance of a 
series of able managers, — his brother-in-law, Mr. C. P. Nichols, 
Mr. Edward Cunningham, Mr. W. R. Cabot, and Mr. M. G. Bennett. 

Always on the lookout for new fields of work, his attention was 
called at an early day to the gas region of Pennsylvania, in which he 
hoped to find mineral wealth similar to that of the Midland region of 
England. Although these hopes were not fulfilled, the investigation 
led him to the establishment in 1882-1883 of a plant at Worthington, 
Pennsylvania, for making carbon black by burning natural gas against 
a cast-iron plate beneath which the burner and black-box revolved. 
This method, which was in part, perhaps wholly, original with him, is 
still in use in the largest factory for this product. After a few years, 
however (in 1888), his brother, Godfrey L. Cabot, who had worked 
with him for a short time, took this business off his hands, and has car- 
ried it on successfully ever since. 

At about the same time he began the manufacture of sulpho-naphthol 
—one of the most excellent disinfectants known ; and another profit- 
able new industry, rendered effective by him somewhat later, was the 
preparation of creosote shingle stains. Many attempts had been 
made in foreign countries to use creosote as a basis for paint, but none 
of these had been crowned with success. He, however, had the pene- 
tration to see that such a paint or stain would be specially adapted for 
use with shingles, which were essentially unknown abroad, and after 
this a painstaking study of the details and great care and thorough- 
ness in the manufacture led to a complete victory over the difficulties, 
which had proved too much for his predecessors. His insulating felt 
for deadening sound, keeping out cold, and fireproofing, was an en- 
tirely original idea. It consisted of eel-grass quilted between two 


SAMUEL CABOT. DDL 


layers of asbestos or felting, and proved especially well adapted for 
these purposes, thus furnishing a use for a very cheap and hitherto 
worthless material. 

Not every experiment was a success, however ; as with all inventors, 
his path was strewn with failures, for it was not enough to make a 
process work, but it must also pay. Thus, for instance, he invented a 
set of stains on a creosote basis for interior use in houses, but, although 
admirable from the technical and artistic standpoints, the demand for 
them was so small that it was not worth while to manufacture them. 

At the time of his death his principal products were shingle-stains, 
lampblack, deadening-felt, sulpho-naphthol, benzol, naphtha, brick pre- 
servative, sheep dip, mortar colors, black varnish, and coal-tar pitch. I 
give this list to show how far he had departed from his original plan of 
establishing a varied manufacture of fine chemicals, as it seems to me 
a remarkable proof of his sagacity that he was able to select products 
for which there was a demand, instead of wasting his energies on lines 
of work for which the country was not prepared. 

One of his most interesting achievements was the successful estab- 
lishment of a system of profit-sharing with the operatives of his fac- 
tory. Iam fortunately able to give an account of it in his own words, 
taken from an address on the subject delivered a few years ago before 
the American Social Science Association. 

“At a very early period in my business experience it appeared to 
me that the rewards ordinarily offered to the wage-earner were not 
such as to stimulate him to the best exertion nor foster in him the best 
and kindest feelings toward his employer. 

“Even to-day is it not true that in the great majority of cases the 
wage-earner’s only stimulus is the desire to hold his job? In fact, is 
not the fear of discharge the only incentive to exertion in a large ma- 
jority of cases ? 

“Feeling as I did, and still do, that men can always be led more 
successfully than they can be driven, that Hope as leader and captain 
can accomplish more than Fear as tyrant and slave-driver, I set myself 
—ignorantly and crudely to be sure, but earnestly — to try to do bet- 
ter things. My method has grown to be essentially as follows : 

“Every man who enters my employ is given the current rate of 
wages for similar work. If he desires also to participate in the profit- 
sharing, he is required to sign a paper in which he promises to do his 
work as quickly and carefully as possible, remembering that the greater 
the yield the larger the profits, and to give me sixty days’ notice before 
leaving me. 

“On my part, I promise to divide, at the expiration of each six 


vox SAMUEL CABOT. 


months, a certain fraction of the profits among the participants, strictly 
in proportion to the wages of each during that period. This sum in 
each ease is divided into two equal parts, one of which is given in cash 
to the employee and the other is deposited in a savings-bank by me as 
his trustee. 

“This fund in the bank is in the nature of an insurance upon the 
life of the employee, and is given over with interest to his executors, 
if he dies. It, however, does not come back into my hands. If he 
should, for instance, refuse to give me sixty days’ notice on leaving 
me, although he had already received an equal amount in cash upon 
the promise to give me such notice, the money would not come back 
to me, but would simply be distributed among the other participants 
at the next division. 

“The same is true in case of his discharge for cause. 

“Tn case of sickness 1 am empowered at my discretion to draw upon 
his fund, though in temporary cases I always put sick men on half- 
pay for a considerable time without recourse to their fund. I also 
have the right to lend him money upon it to build a house. And now 
let me give you a few figures. 

“The system was begun a little over seventeen years ago, and has 
gone on uninterrupted up to the present time. The profit-sharers at 
the outset numbered 21, and to-day number 42. The total amount paid 
out by me has been $40,464 during that period. Now the natural 
question which you all will ask, I think, is, Has this been a good bar- 
gain? I think you will all agree that in the ultimate analysis no bar- 


gain isa good bargain that is not profitable to both sides. Well, there . 


will, I think, be no dispute that from the workman’s point of view the 
bargain has been a good one, as he has a very considerable addition to 
his wages, which were as high as other labor of the same kind; and 1 
may say that the average wages have steadily advanced as the effi- 
ciency and skill increased. 

“But now comes the question of my own investment: What 
means have I of knowing that the efficiency of the workmen has been 
increased to an amount equivalent to the $40,464 which I have 
expended ? 

“J will now give you a few more statistics which bear upon this 
question. Let me remind you that the same proportion of the profit 
was paid to the 21 men who first entered the agreement that is now 
paid to the 42 men who compose the present corps. But now note this 
very significant fact. While the first payments averaged about 10 per 
cent upon the wages of each man, the last payment — which was larger 
than usual, to be sure — was exactly 21,3; per cent of their wages. 


4 
᾿ 


SAMUEL CABOT. 0. 


“Tt seems to me obvious that, if we can draw any inference from 
these facts, it is that, inasmuch as my profit compared to the wages 
paid has increased, the efficiency of my workmen has improved. 

“But, above all, my own observation has convinced me that the 
morale of my employees is much superior to the average, and that they 
are more contented and willing by far than is usual in similar establish- 
ments. In fact, I am satisfied that this bargain has been a good bar- 
gain, a good one for both parties to it, and that the extra money I have 
laid out has been well and profitably invested. 

“T have, for obvious reasons, not laid any emphasis upon the philan- 
thropic side of this enterprise, especially as 1 am sure it can be recom- 
mended to many, if not to most, manufacturers, and to their employees, 
purely upon its utilitarian advantages ; but it is obvious that it stimu- 
lates both sobriety and thrift in workmen, and that it can be made to 
assist men of family to build homes for themselves, thus surrounding 
the factory with the homesteads of men who are interested in its 
success and that of the neighborhood. 

“From my seventeen years’ experience, therefore, gentlemen, I can 
cordially recommend profit-sharing on this or a similar plan as of 
marked advantage to both employer and employed.” 

I have quoted this paper almost entire, because it seems to me to 
show the man —his desire for the good of others, joined to sound busi- 
ness common sense, and the practical wisdom needed to make the 
scheme effective. That it was effective is shown by the fact that, 
when a new hand was inclined to be indolent, the other workmen 
insisted on vigorous work from him if he was to stay in the factory, 
for, said they, “ We will not have our profits cut down by the lazy or 
inefficient.” It will be observed that the success of this system de- 
pended on an absolute trust on the part of the men in the upright- 
ness of their employer. The slightest suspicion that it would not be 
carried out equitably, or that in some underhand way it would redound 
to the profit of the chief, would have wrecked it at once. And here 
the comparatively small number of men was a potent factor, as they 
were all able to know Mr. Cabot personally, and to realize his absolute 
honesty and fairness. That they also learned to love him appeared 
from the impressive sorrow with which they attended his funeral. 

This absolute honesty and fairness was also conspicuous in his busi- 
ness relations. He would often make concessions beyond what could 
be justly demanded, if he thought the claim was made in good faith, 
while, on the other hand, he would not yield an inch when this was 
not the case, but proved a dangerous and pertinacious adversary. In 
one case at a very early stage in his career a man who had circulated 


554 SAMUEL CABOT. 


malicious stories about his goods was forced to sign a written retrac- 
tion couched in the most abject terms. 

His business activities would have been enough to exhaust the 
energy of most men, but he found time and strength for the enthu- 
siastic pursuit of many other interests. He was a most devoted son 
of the Institute of Technology, always ready with advice or more 
material help. In 1889 he was elected to the Corporation intrusted 
with its government, and in spite of his strong opinions and fighting 
blood won and kept the respect and affection of all his fellow-members. 
He was a member of the executive committee for many years, and very 
active on committees in charge of special departments, serving at various 
times on those on chemistry, chemical engineering, physics, botany, 
biology, modern languages, and English. His principal interest was 
naturally in the Chemical Department, which he watched over with 
unceasing care. He even induced Professor Lunge to come to Boston 
from Ziirich to examine it, and make suggestions in regard to the best 
methods for teaching industrial chemistry. 

Nor did he confine his attention to the Institute of Technology, as 
for many years he was a member of the “Committee to visit the 
Chemical Laboratory ” of Harvard University, and in this capacity 
gave much useful advice about the organization of the course in indus- 
trial chemistry, in which he advocated the teaching of broad general 
principles rather than instruction in details, showing in this way a 
power of rising above the narrowing tendency of the highly specialized 
work by which alone a chemical manufacturer attains success. 

He was devoted to athletics throughout his life, telling with gusto 
in one of his last years how he had beaten a much younger man at 
tennis, and about the same time causing the publication of a delight- 
ful volume of reminiscences by the idol of his boyhood, Lovett, the 
pitcher of the Lowells. This interest influenced his relations with the 
Institute of Technology, as he was a member of the Advisory Council 
on Athletics, and gave a tract of land in Brookline for a playground. 
He also established an annual prize for the greatest improvement in 
athletics, and gave a silver cup, on which the names of the victors 
were inscribed each year. It is almost needless to add that his influ- 
ence was always used in maintaining the highest ideal of sportsmanship. 
In addition to these gifts for athletics he gave his house in Brookline 
for a dormitory, and was always ready to answer any pressing need. 

He threw himself with the same enthusiasm into other recreations. 
Thus he made a careful study of the theory and construction of aero- 
planes, for many years carrying on experiments in the summer on kites, 
studying especially the resistance of the air to various forms, and the 


SAMUEL CABOT. 55D 


effect of atmospheric currents. While in Europe in 1896 he saw 
Maxim and Lilienthal, and provided the latter with money to carry on 
his work; and in this country he stood ready to help the Wright 
brothers, when the time should come to make their experiments 
public. 

Another engrossing pursuit was the study of the authorship of the 
plays of Shakespeare. He espoused the Baconian theory with great 
vigor, and defended his position by elaborate and costly investigations. 
_ His fine taste for art made him an authority on this subject also, and 
proved of great use to him in some of the branches of his business. 

He was elected a fellow of our Academy in 1893, and served on the 
C. M. Warren Committee from its establishment in the same year until 
his death. That he held no other office was from his own choice, since 
he was at one time elected treasurer of the Academy, but declined to 
serve. He was also a member of the Society for Chemical Industry. 

In 1878 he married Helen Augusta Nichols, of Lowell, and they had 
two children, a daughter and a son. In his family and society his 
genial, affectionate nature won all hearts. It made one happier for the 
whole day simply to exchange a few words with him in the street. 

This life, so full of various beneficent activities, was brought to an 
end by a sudden attack of pneumonia, November 26, 1906. 

In looking back at his life the most striking characteristic was, ! 
think, his very high standards. It was not enough that he should be 
successful from a worldly point of view, but in all his undertakings 
the good of the country was a prime consideration ; the introduction 
of new and useful processes, the utilization of waste materials, were his 
objects quite as much as his own personal advantage. Further, all his 
products must be of the highest quality, all his processes brought to 
the highest perfection. His probity was without a flaw, and anything 
mean or underhanded aroused in him a scorching, disdainful wrath, — for 
he was always a fighter, never afraid of an outspoken expression of his 
opinion ; yet even in his more vehement controversies his antagonists 
could never lose sight of his sincerity of purpose and his large, warm 
heart. With all his vehemence of opinion his character was a singu- 
larly gentle and affectionate one, so that his genial nature won the love 
of all who knew him well. His thoroughness in all his pursuits, and 
the good judgement with which he selected or abandoned his manu- 
facturing experiments, have been dwelt on sufficiently in the narrative 
of his life ; but not enough has been said there of his generosity — always 
on the watch to help the deserving, yet concealed so carefully that in 
one case at least even the person benefited did not know from whom 
the help had come. ΤῸ these he added a modesty and humility which 


556 SAMUEL CABOT. 


led him always to undervalue his ability and attainments, a purity so 
feminine that it was respected even by the wilder men whom he 
chanced to encounter in his youth, and a strong and vivid imagination 
both in his experiments and recreations. 

His ruddy face under a mass of curly hair always beamed with a 
genial light; and he seemed to glow with exuberant life and enthu- 
siasm while he discussed some important subject in a slow rather 
hesitating manner, as if his abundant ideas found difficulty in gaining 
utterance. It seems impossible to believe that this overflowing vitality 
is no longer with us. 

CuarLes Lorine Jackson. 


American Academy of Arts and Sciences 
OFFICERS AND COMMITTEES FOR 1908-09. 


PRESIDENT. 
JOHN TROWBRIDGE. 


VICE-PRESIDENT. 

Class I. Class II. Class III. 
ELIHU THOMSON, Henry P. WALCOTT, JoHN C. GRAY. 
CORRESPONDING SECRETARY. 

Epwin H. HALL. 


RECORDING SECRETARY. 
WILLIAM WATSON. 
TREASURER. 
CHARLES P. BOWDITCH. 


ξ LIBRARIAN. 
A. LAWRENCE ROTCH. 


COUNCILLORS. 
Class I. Class II. Class III, 
IrA N. HOLLIs, JaMEs C. WHITE, WILLIAM R. WARE. 
Terms expire 1909. 
HeEnryY P. TALBOT, Joun E. WoLrFr, GEORGE L. KITTREDGE. 
Terms expire 1910. 
WILLIAM L. HOOPER, HAROLD C. ERNST, FREDERIC J. STIMSON. 


Terms expire 1911. 


COMMITTEE OF FINANCE. 
JoHN TROWBRIDGE, Enior ‘Cy CLarkKE, FRANCIS BARTLETT. 


RUMFORD COMMITTEE. 
: CHARLES R. Cross, Chazrman, 
ErAsMus Ὁ. LEAVITT, EDWARD Ὁ. PICKERING, ELInu THOMSON. 
ARTHUR G. WEBSTER, THEODORE W. RICHARDS, Louris BELL. 


Cc. M. WARREN COMMITTEE. 
LEONARD P. KINNICUTT, Chairman, 
ROBERT H. RICHARDS, CHARLES R. SANGER, ARTHUR A. NOYES. 
HENRY P. TALBOT, THEODORE W. RICHARDS, GEORGE D. MOOLE. 


COMMITTEE OF PUBLICATION. 
EDWARD L. MARK, of Class II, Chairman, 
WALLACE C. SABINE, of Class I, CRAWFORD H. Toy, of Class III. 


COMMITTEE ON THE LIBRARY. 
A. LAWRENCE RotcH, Chairman, 

Harry M. Goopwin, of Class I, SAMUEL HENSHAW, of Class II, 
HENRY W. Haynes, of Class III. 


AUDITING COMMITTEE. 
A. LAWRENCE LOWELL, FREDERICK J. STIMSON. 


HOUSE COMMITTEE. 
WILLIAM ΚΕ. WARE, Chazrman. 
A. LAWRENCE ROTCH, Morris H. MorGAn: 


ΤΌΤ ΝΣ 


OF THE 


FELLOWS AND FOREIGN HONORARY MEMBERS. 


(Corrected to June 1, 1908.) 


RESIDENT FELLOWS.—189. 


(Number limited to two hundred.) 


Crass I.— Mathematical and Physical Sciences. — 78. 


Section I. —14. 


Mathematics and Astronomy. 


Solon I. Bailey, 
Maxime Bocher, 
William E. Byerly, 
Seth C. Chandler, 
Percival Lowell, 
Edward C. Pickering, 
William H. Pickering, 
John Ritchie, Jr., 
Arthur Searle, 
William E. Story, 
Henry Taber, 

Harry W. Tyler, 

O. C. Wendell, 

P. S. Yendell, 


Section II. 
Physics. 


A. Graham Bell, 
Louis Bell, 
Clarence J. Blake, 
Francis Blake, 
George A. Campbell, 
Harry E. Clifford, 
Charles R. Cross, 
Louis Derr, 


Cambridge. 
Cambridge. 
Cambridge. 


Wellesley Hills. 


Boston. 
Cambridge. 
Cambridge. 
Dorchester. 
Cambridge. 
Worcester. 
Worcester. 
Boston. 
Cambridge. 
Dorchester. 


— 27. 


Washington, D.C. 


Boston. 
Boston. 
Weston. 
New York. 
Newton. 
Brookline. 
Brookline. 


A.W. Duit, 

H. M. Goodwin, 
Edwin H. Hall, 
Hammond V. Hayes, 
William L. Hooper, 
William W. Jacques, 
Frank A. Laws, 
Henry Letavour, 
Theodore Lyman, 
Charles L. Norton, 
Benjamin O. Peirce, 
George W. Pierce, 
A. Lawrence Rotch, 
Wallace C. Sabine, 
John S. Stone, 
Elihu Thomson, 
John Trowbridge, 

A. G. Webster, 
Robert W. Willson, 


Worcester. 
Roxbury. 
Cambridge. 
Cambridge. 
Somerville. 
Newton. 
Boston. 
Boston. 
Brookline. 
Boston. 
Cambridge. 
Cambridge. 
Boston. 
Boston. 
Boston. 
Swampscott. 
Cambridge. 
Worcester. 
Cambridge. 


Section III. —19. 


Chemistry. 


Gregory Paul Baxter, 
Arthur M. Comey, 
James M. Crafts, 
Charles W. Eliot, 
Charles L. Jackson, 
Walter L. Jennings, 


Cambridge. 
Cambridge. 
Boston. 
Cambridge. 
Cambridge. 
Worcester. 


560 


Leonard P. Kinnicutt, 
Charles F. Mabery, 
George D. Moore, 
James F. Norris, 
Arthur A. Noyes, 
Robert H. Richards, 


RESIDENT FELLOWS. 


Worcester. 


Cleveland, O. 


Worcester. 


Boston. 


Boston. 


Theodore W. Richards, Cambridge. 


Charles R. Sanger, 
Stephen P. Sharples, 
Francis H. Storer, 
Henry P. Talbot, 
William H. Walker, 
Charles H. Wing, 


Cambridge. 
Cambridge. 
Boston. 


Newton. 


Newton. 


Boston. 


Section IV. —18. 


Technology and Engineering. 


Comfort A. Adams, 


Cambridge. 


Jamaica Plain. 


Alfred E. Burton, 
Eliot C. Clarke, 
Heinrich O. Hofman, 
Ira N. Hollis, 

L. J. Johnson, 
Arthur E. Kennelly, 
| Gaetano Lanza, 

Ἑ. D. Leavitt, 


Hiram F. Mills, 
Cecil H. Peabody, 
Andrew H. Russell, 
Albert Sauveur, 
Peter Schwamb, 

H. L. Smyth, 
George F. Swain, 
William Watson, 


Boston. 
Boston. 


Jamaica Plain. 


Cambridge. 
Cambridge. 
Cambridge. 
Boston. 

Cambridge. 


William R. Livermore, New York. 


Lowell. 
Brookline. 
Paris. 
Cambridge. 
Arlington. 
Cambridge. 
Boston. 
Boston. 


Crass II.— Natural and Physiological Sciences. — 59. 


SEcTION 1. —16. 


Geology, Mineralogy, and Physics of 


the Globe. 


H. H. Clayton, 
Algernon Coolidge, 
William O. Crosby, 
William M. Davis, 
Benj. K. Emerson, 
O. W. Huntington, 
Robert T. Jackson, 
T. A. Jaggar, Jr., 
Douglas W. Johnson, 
William H. Niles, 
Charles Palache, 
John E. Pillsbury, 
Robert DeC. Ward, 
Charles H. Warren, 
John E. Wolff, 

J. B. Woodworth, 


Milton. 
Boston. 


Cambridge. 
Amherst. 

Newport, R. 
Cambridge. 
Cambridge. 
Cambridge. 
Cambridge. 
Cambridge. 


I. 


Washington. 


Cambridge. 


Auburndale. 


Cambridge. 


Cambridge. 


Section II. —1J1. 


F. S. Collins, 
William G. Farlow, 
Charles E. Faxon, 


Jamaica Plain. | Merritt L. Fernald, 


George L. Goodale, 
John G. Jack, 
Edward C. Jeffrey, 
B. L. Robinson, 
Charles S. Sargent, 
Arthur B. Seymour, 
Roland Thaxter, 


Botany. 


Malden. 
Cambridge. 


Jamaica Plain. 


Cambridge. 
Cambridge. 


Jamaica Plain, 


Cambridge. 
Cambridge. 
Brookline. 

Cambridge. 
Cambridge. 


Section III. —21. 


Zovlogy and Physiology. 


Alexander Agassiz, 
Robert Amory, 


Cambridge. 
Boston. 


Henry P. Bowditch, 
William Brewster, 
Louis Cabot, 
Walter B. Cannon, 
William E. Castle, 
Samuel F. Clarke, 
W. T. Councilman, 
Harold C. Ernst, 
Samuel Henshaw, 
Edward L. Mark, 
Charles ὃ. Minot, 
Edward 5. Morse, 
George H. Parker, 
William T. Porter, 
James J. Putnam, 
Samuel H. Scudder, 


RESIDENT 


Jamaica Plain. 
Cambridge. 
Brookline. 
Cambridge. 
Cambridge. 
Williamstown. 
Boston. 
Jamaica Plain. 
Cambridge. 
Cambridge. 


Milton. 
Salem. 
Cambridge. 
Boston. 


Boston. 
Cambridge. 


William T. Sedgwick, Boston. 


FELLOWS. 


James C. White, 


561 


Boston. 


William M. Woodworth, Cambridge. 


SECTION [Ve — ie 


Medicine and Surgery. 


Edward H. Bradford, 


Arthur T. Cabot, 
Reginald H. Fitz, 


| Frederick 1. Knight, 
| Samuel J, Mixter, 


W. L. Richardson, 
Theobald Smith, 
O. F. Wadsworth, 
Henry P. Walcott, 
John C. Warren, 


Francis H. Williams, 


Boston. 
Boston. 
Boston. 
Boston. 
Boston. 
Boston. 
Jamaica Plain. 
Boston. 


Cambridge. 
Boston. 
Boston. 


Crass Π]|.--- Moral and Political Sciences. — 52. 


SEcTIon I. --- 8. 


Philosophy and Jurisprudence. 


James B. Ames, 


Joseph H. Beale, Jr., 


John C. Gray, 
Francis C. Lowell, 
Hugo Miinsterberg, 
Josiah Royce, 
Irederic J. Stimson, 
Samuel Williston, 


Cambridge. 
Cambridge. 
Boston. 
Boston. 
Cambridge. 
Cambridge. 
Dedham. 
3elmont. 


Section II. —19. 


Philology and Archeology. 


Charles P. Bowditch, 
Lucien Carr, 
VOL. XLIII. — 36 


Jamaica Plain. 
Cambridge. 


Franklin Carter, 
J. W. Fewkes, 


Williamstown. 
Washington, 


William W. Goodwin, Cambridge. 


Henry W. Haynes, 
Albert A. Howard, 
Charles R. Lanman, 
David G. Lyon, 
George F. Moore, 


| Morris H. Morgan, 
Frederick W. Putnam, Cambridge. 


Edward Robinson, 
Edward 5. Sheldon, 


Herbert Weir Smyth, 


F. B. Stephenson, 
Crawford H. Toy, 


| John W. White, 
| John H. Wright, 


Boston. 

Cambridge. 
Cambridge. 
Cambridge. 
Cambridge. 
Cambridge. 


New York. 
Cambridge. 
Cambridge. 
Boston. 

Cambridge. 
Cambridge. 
Cambridge. 


562 RESIDENT FELLOWS. 


Section III.—12. Section IV.—13. 
᾿ Literature and the Fine Arts. 

Political Economy and History. Wants Βα ξεν meee 
Charles F. Adams, Lincoln. Arlo Bates, Boston. 
Thomas N. Carver, Cambridge. L. B. R. Briggs, Cambridge. 
Andrew McF. Davis, Cambridge. Kuno Francke, Cambridge. 
Ephraim Emerton, Cambridge. | Edward H. Hall, Cambridge. 
A. C. Goodell, Salem. T. W. Higginson, Cambridge. 
Charles Gross, Cambridge. | George L. Kittredge, Cambridge. 
Henry C. Lodge, Nahant. William C. Lane, Cambridge, 
A. Lawrence Lowell, Boston. Charles Eliot Norton, Cambridge. 
James F. Rhodes, Boston. Denman W. Ross, Cambridge. 
William Z. Ripley, | Newton. William R. Ware, Milton. | 
Charles C. Smith, Boston. Herbert L. Warren, Cambridge. 


F. W. Taussig, Cambridge. Barrett Wendell, Boston. 


ASSOCIATE FELLOWS. 


563 


ASSOCIATE FELLOWS. — 92. 


(Number limited to one hundred. Elected as vacancies occur.) 


Crass I.— Mathematical and Ph ysical Sevences. — 36, 
Section IIT. —10. 


Section 1. --- 12. 
Mathematics and Astronomy. 
Edward E. Barnard, Williams Bay, 
Wis. 
S. W. Burnham, Williams Bay, Wis. 
George Davidson, San Francisco. 


Fabian Franklin, Baltimore. 
George W. Hill, W. Nyack, N.Y. 
E. S. Holden, New York. 
Emory McClintock, Morristown,N.J. 
E. H. Moore, Chicago. 

Simon Newcomb, Washington. 
Charles L. Poor, New York. 
George M. Searle, Washington. 


J. N. Stockwell, Cleveland, O. 


Section II.—6. 
Physics. 
Carl Barus, Providence, R.I. 
G. E. Hale, Williams Bay, Wis. 
T. C. Mendenhall, Worcester. 
A. A. Michelson, Chicago. 


E. L. Nichols, Ithaca, N. Y. 
ΜῈ Pupin, New York. 


Chemistry. 


Wolcott Gibbs, 
Frank A. Gooch, 


Newport, R.I. 
New Haven. 


Eugene W. Hilgard, Berkeley, Cal. 


S. W. Johnson, 
J. W. Mallet, 
E. W. Morley, 


New Haven. 


Charlottesville, Va. 
W. Hartford, Conn. 


Charles E. Munroe, Washington. 


John U. Nef, 
J. M. Ordway, 
Ira Remsen, 


Chicago, Il. 
New Orleans. 
Baltimore. 


Section IV.—8. 


Technology and Engineering. 


Henry L. Abbot, 


Cyrus B. Comstock, 


W. P. Craighill, 
John Fritz, 
James D. Hague, 
F. R. Hutton, 
William Sellers, 


Cambridge. 
New York. [Va. 
Charlestown, W. 
Bethlehem, Pa. 
New York. 
New York. 
Edge Moor, Del. 


Robt. 5. Woodward, Washington. 


Crass Il. — Natural and Physiological Sciences. — 32. 


Section I.—9. 
Geology, Mineralogy, and Physics of 
the Globe. 


Cleveland Abbe, 
George J. Brush, 


Washington. 
New Haven. 


T. C. Chamberlin, 
Edward 5. Dana, 


Walter G. Davis, 


Chicago. 
New Haven. 
Cordova, Arg. 


Samuel F. Emmons, Washington. 


G. K. Gilbert, 
hk. Pumpelly, 


Washington. 
Newport, R.I. 


Charles 1), Walcott, Washington. 


564 


Section II. —6. 
Botany. 


Ithaca, N. Y. 
Palo Alto, Cal. 


L. H. Bailey, 
1). H. Campbell, 


J. M. Coulter, Chicago. 

C. G. Pringle, Charlotte, Vt. 
John D. Smith, Baltimore. 
W. Trelease, St. Louis. 


Section III.—9. 
Zoology and Physiology. 


Joel A. Allen, New York. 
W. Καὶ. Brooks, Lake Roland, Md. 
C. B. Davenport, 

Cold Spring Harbor, N, Y. 
F. P. Mall, Baltimore. 


ASSOCIATE FELLOWS. 


5. Weir Mitchell, 
H. F. Osborn, 
A. E. Verrill, 

C. O. Whitman, 
E. B. Wilson, 


Philadelphia. 
New York. 
New Haven. 
Chicago. 
New York. 


Section IV. —8. 


Medicine and Surgery. 


John S. Billings, 
W.S. Halsted, 
Abraham Jacobi, 
W. W. Keen, 
William Osler, 


New York. 
Baltimore. 
New York. 
Philadelphia. 
Baltimore. 


T. Mitchell Prudden, New York. 


Wm. H. Welch, 
H. C. Wood, 


Baltimore. 
Philadelphia. 


Crass II.— Moral and Political Sciences. — 24. 


Section I. —6. 


Philosophy and Jurisprudence. 


Joseph H. Choate, New York. 
Melville W. Fuller, Washington. 
William W. Howe, New Orleans. 
Charles 5. Peirce, Milford, Pa. 

G. W. Pepper, Philadelphia. 
T. R. Pynchon, Hartford, Conn. 


Section II. —6. 

Philology and Archeology. 
Timothy Dwight, 
B. L. Gildersleeye, 
D. C. Gilman, Baltimore. 
T. R. Lounsbury, New Haven. 
{ufus B. Richardson, New York. 
A. D. White, Ithaca, N.Y. 


New Haven. 
Baltimore. 


SECTION 


Ill. —7. 


Political Economy and History. 


Henry Adams, 
G. P. Fisher, 


Washington. 
New Haven. 


Arthur T. Hadley, New Haven. 


Henry C. Lea, 
Alfred Τὶ Mahan, 


Philadelphia. 
New York. 


H. Morse Stephens, Ithaca. 


W. G. Sumner, 


New Haven. 


͵ 


Section IV. —5. 


Literature and 


James B. Angell, 
H. H. Furness, 

R. 5. Greenough, 
Herbert Putnam, 
John S. Sargent, 


the Fine Arts. 


Ann Arbor, Mich. 
Wallingford, Pa. 
Florence. 
Washington. 
London. 


FOREIGN HONORARY MEMBERS. 


FOREIGN 


(Number limited to seventy-five. 


HONORARY 


MEMBERS.—65. 


Elected as vacancies occur.) 


Crass I.— Mathematical and Physical Sciences. — 20. 


Srecrion I. — 6. 
Mathematics and Astronomy. 


Arthur Auwers, 3erlin. 
George H. Darwin, Cambridge. 
Sir William Huggins, London. 


Felix Klein, Gottingen. 
Emile Picard, Paris. 
H. Poincaré, Paris. 


Section II. —5. 
Physics. 


Oliver Heaviside, 


F. Kohlrausch, Marburg. 
Joseph Larmor, Cambridge. 
Lord Rayleigh, Witham. 
Joseph J. Thomson, Cambridge. 


Newton Abbot. 


Srcrion III.—6. 


Chemistry. 


Adolf Ritter von Baeyer, Munich. 


Emil Fischer, Berlin. 

J. H. van’t Hoff, Berlin. 
Wilhelm Ostwald, Leipsic. 

Sir H. E. Roscoe, London. 
Julius Thomsen, Copenhagen. 


Section IV. —3. 
Technology and Engineering. 


Maurice Lévy, Paris. 
H. Muller-Breslau, Berlin. 
W.Cawthorne Unwin, London. 


Crass 11.-- Natural and Physiological Sciences. — 22. 


SecTIon J. —4. 


Geology, Mineralogy, and Physics of | EK. Bornet, 


the Globe. 


Sir Archibald Geikie, London. 


Julius Hann, Vienna. 
Albert Heim, Zurich. 
Sir John Murray, Edinburgh. 


Section II. —6. 
Botany. 


Paris. 
A. Engler, Berlin. 
Sir Joseph D. Hooker, Sunningdale. 


ἣν Pfefter, Leipsic. 
H. Graf zu Solms- 

Laubach, Strassburg. 
Eduard Strasburger, Bonn. 


FOREIGN 


Section III. —5. 


Zoblogy and Physiology. 


Ludimar Hermann, 


II. Kronecker, Bern. 

FE. Ray Lankester, London, 
Elias Metschnikoff, Paris. 

M. Gustav Retzius, Stockholm. 


HONORARY 


Konigsberg. | A. Celli, 


MEMBERS. 


Section IV.—7. 


Medicine and Surgery. 


Emil von Behring, Marburg. 
Sir T. L. Brunton, London. 
Rome. 
Sir V. A. H. Horsley, London. 
R. Koch, Berlin. 
Lord Lister, London. 


F. v. Recklinghausen, Strassburg. 


Crass ITI.— Moral and Political Sciences. — 23. 


Secrion I. —5. 


Philosophy and Jurisprudence. 


Section III.—5. 


Political Economy and History. 


A. J. Balfour, Prestonkirk. | James Bryce, London. 

Heinrich Brunner, Berlin. Adolf Harnack, Berlin. 

A. V. Dicey, Oxford. Sir G. O. Trevelyan, 

F. W. Maitland, Cambridge. Bart., London. 

Sir Frederick Pollock, John Morley, London. 
Bart., London. Pasquale Villari, Florence. 


Secrion Il. —7. 


Section IV.—6. 


Philology and Archeology. 


Ingram Bywater, 
F. Delitzsch, 
Hermann Diels, 
W. Dorpfeld, 

Sir John Evans, 
H. Jackson, 

G. C. C. Maspero, 


Literature and the Fine Arts. 


Oxford. 

Berlin. FE. de Amicis, Turin. 

Berlin. Gaston Boissier, Paris. 

Athens. Georg Brandes, Copenhagen. 
Berkhampsted. |S. H. Butcher, London. 

Cambridge. Jean Léon Géréme, Paris. 

Paris. | Rudyard Kipling, Burwash. 


STATUTES AND STANDING VOTES. 


SLATUTES: 


Adopted May 30,1854: amended September 8, 1857, November 12, 1862, 
May 24, 1864, November 9, 1870, May 27, 1878, January 26, 1876, 
June 16, 1886, October 8, 1890, January 11, and May 10, 1893, May 
9, and October 10, 1894, March 18, April 10, and May 8, 1895, May 
8, 1901, January 8, 1902, May 10, 1905, February 14 and March 14, 
1906, 


AL RR A 
Or FELLOWS AND FOREIGN HONORARY MEMBERS. 


1. The Academy consists of Resident Fellows, Associate Fellows, and 
Foreign Honorary Members. They are arranged in three Classes, ac- 
cording to the Arts and Sciences in which they are severally proficient, 
viz.: Class I. The Mathematical and Physical Sciences ;— Class II. 
The Natural and Physiological Sciences ;— Class III. The Moral and 
Political Sciences. Each Class is divided into four Sections, viz. : 
Class I., Section 1. Mathematics and Astronomy ;— Section 2. Physics ; 
—Section ὃ. Chemistry ;— Section 4. Technology and Engineering. 
Class II., Section 1. Geology, Mineralogy, and Physics of the Globe ;— 
Section 2. Botany; Section ὃ. Zodlogy and Physiology ;— Section 4. 
Medicine and Surgery. Class III., Section 1. Theology, Philosophy, 
and Jurisprudence ; — Section 2. Philology and Archeology; — Sec- 
tion 3. Political Economy and History ;— Section 4. Literature and 
the Fine Arts. 

2. The number of Resident Fellows residing in the Commonwealth 
of Massachusetts shall not exceed two hundred, of whom there shall not 
be more than eighty in any one of the three classes. Only residents in 
the Commonwealth of Massachusetts shall be eligible to election as Resi- 
dent Fellows, but resident fellowship may be retained after removal from 


568 STATUTES OF THE AMERICAN ACADEMY 


the Commonwealth. Each Resident Fellow shall pay an admission fee 
of ten dollars and such annual assessment, not exceeding ten dollars, 
as shall be voted by the Academy at each annual meeting. Resident 
Fellows only may vote at the meetings of the Academy. 

3. The number of Associate Fellows shall not exceed one hundred, 
of whom there shall not be more than forty in either of the three classes 
of the Academy. Associate Fellows shall be chosen from persons resid- 
ing outside of the Commonwealth of Massachusetts. They shall not be 
liable to the payment of any fees or annual dues, but on removing within 
the Commonwealth they may be transferred by the Council to resident 
fellowship as vacancies there occur. 

4. The number of Foreign Honorary Members shall not exceed 
seventy-five; and they shall be chosen from among persons most eminent 
in foreign countries for their discoveries and attainments in either of the 
three departments of knowledge above enumerated. There shall not be 
more than thirty Foreign Members in either of these departments. 


CHAPTER II. 
OF OFFICERS. 


1. There shall be a President, three Vice-Presidents, one for each 
Class, a Corresponding Secretary, a Recording Secretary, a Treasurer, 
and a Librarian, which officers shall be annually elected, by ballot, at 
the annual meeting, on the second Wednesday in May. 

2. There shall be nine Councillors, chosen from the Resident Fellows. 
At each annual meeting, three Councillors shall be chosen, by ballot, 
one from each Class, to serve for three years; but the same Fellow shall 
not be eligible for two successive terms. The nine Councillors, with the 
President, the three Vice- Presidents, the two Secretaries, the Treasurer, 
and the Librarian, shall constitute the Council. Five members shall 
constitute a quorum. It shall be the duty of this Council to exercise a 
discreet supervision over all nominations and elections. With the con- 
sent of the Fellow interested, they shall have power to make transfers 
between the several sections of the same Class, reporting their action to 
the Academy. 

3. The Council shall at its March Meeting receive reports from the 
Rumford Committee, the C. M. Warren Committee, the Committee on 
Publication, the Committee on the Library, the President and Record- 


OF ARTS AND SCIENCES. 569 


ing Secretary, and the Treasurer, proposing the appropriations for their 
work during the year beginning the following May. The Treasurer at 
the same meeting shall report on the income which will probably be 
received on account of the various Funds during the same year. 

At the Annual Meeting, the Council shall submit to the Academy, 
for its action, a report recommending the appropriations which in the 
opinion of the Council should be made for the various purposes of the 
Academy. 

4. If any office shall become vacant during the year, the vacancy shall 
be filled by a new election, at the next stated meeting, or at a meeting 
called for this purpose. 


GHAPT ER, Lik 
Or NOMINATIONS OF OFFICERS. 


1. At the stated meeting in March, the President shall appoint a 
Nominating Committee of three Resident Fellows, one for each Class. 

2. It shall be the duty of this Nominating Committee to prepare a list 
of candidates for the offices of President, Vice- Presidents, Corresponding 
Secretary, Recording Secretary, Treasurer, Librarian, Councillors, and 
the Standing Committees which are chosen by ballot; and to cause this 
list to be sent by mail to all the Resident Fellows of the Academy not 
later than four weeks before the Annual Meeting. 

3. Independent nominatidns for any office, signed by at least five 
Resident Fellows, and received by the Recording Secretary not less than 
ten days before the Annual Meeting, shall be inserted in the call for the 
Annual Meeting, which shall then be issued not later than one week 
before that meeting. 

4. The Recording Secretary shall prepare for use, in voting at the 
Annual Meeting, a ballot containing the names of all persons nominated 
for office under the conditions given above. 

5. When an office is to be filled at any other time than at the Annual 
Meeting, the President shall appoint a Nominating Committee in accord- 
ance with the provisions of Section 1, which shall announce its nomina- 
tion in the manner prescribed in Section 2 at least two weeks before 
the time of election. Independent nominations, signed by at least five 
Resident Fellows and received by the Recording Secretary not later 
than one week before the meeting for election, shall be inserted in the 
call for that meeting. 


τυ STATUTES OF THE AMERICAN ACADEMY 


CHAPTER IV. 
Or THE PRESIDENT, 


1. It shall be the duty of the President, and, in his absence, of the 
senior Vice-President present, or next officer in order as above enumer- 
ated, to preside at the meetings of the Academy; to direct the Recording 
Secretary to call special meetings ; and to execute or to see to the execu- 
tion of the Statutes of the Academy. Length of continuous membership 
in the Academy shall determine the seniority of the Vice-Presidents. 

2. The President, or, in his absence, the next officer as above enumer- 
ated, shall nominate members to serve on the different committees of the 
Academy which are not chosen by ballot. 

3. Any deed or writing to which the common seal is to be affixed 
shall be signed and sealed by the President, when thereto authorized 
by the Academy. 


CHAPTER V. 
Or STANDING COMMITTEES. 


1, At the Annual Meeting there shall be chosen the following Stand- 
ing Committees, to serve for the year ensuing, viz. : — 

2. The Committee on Finance to consist of three Fellows to be 
chosen by ballot, who shall have, through the Treasurer, full control and 
management of the funds and trusts of the Academy, with the power of 
investing and of changing the investment of the same at their discretion. 

3. The Rumford Committee, to consist of seven Fellows to be chosen 
by ballot, who shall consider and report to the Academy on all applica- 
tions and claims for the Rumford premium. They shall also report to 
the Council in March of each year on all appropriations of the income of 
the Rumford Fund needed for the coming year, and shall generally see 
to the due and proper execution of the trust. All bills incurred on ac- 
count of the Rumford Fund, within the limits of the appropriation made 
by the Academy, shall be approved by the Chairman of the Rumford 
Committee. 

4. The C. M. Warren Committee, to consist of seven Fellows to be 
chosen by ballot, who shall consider and report to the Council in March 
of each year on all applications for appropriations from the income of the 
C. M. Warren Fund for the coming year, and shall generally see to the due 


OF ARTS AND SCIENCES. ayia 


and proper execution of the trust. All bills incurred on account of the 
C. M. Warren Fund, within the limits of the appropriations made by the 
Academy, shall be approved by the Chairman of the C. M. Warren 
Committee. 

5. The Committee on Publication, to consist of three Fellows, one 
from each class, to whom all communications submitted to the Acad- 
emy for publication shall be referred, and to whom the printing of the 
Proceedings and Memoirs shall be entrusted. This Committee shall re- 
port to the Council in March of each year on the appropriations needed 
for the coming year. ΑἹ] bills incurred on account of publications, within 
the limits of the appropriations made by the Academy, shall be approved 
by the Chairman of the Committee on Publication. 

6. The Committee on the Library, to consist of the Librarian ex 
officio, and three other Fellows, one from each class, who shall examine 
the Library and make an annual report on its condition and management. 
This Committee, through the Librarian, shall report to the Council in 
March of each year, on the appropriations needed for the Library for the 
coming year. All] bills incurred on account of the Library, within the 
limits of the appropriations made by the Academy, shall be approved by 
the Librarian. 

7. The President and Recording Secretary shall be a Committee on 
the general expenditures of the Academy. This Committee shall report 
to the Council in March of each year on the appropriations needed for 
the general expenditures for the coming year, and either member of the 
Committee may approve bills incurred on this account within the limits 
of the appropriations made by the Academy. 

8. An auditing Committee, to consist of two Fellows, for auditing the 
accounts of the Treasurer, with power to employ an expert and to ap- 
prove his bill. 

9. In the absence of the Chairman of any Committee, bills may be 
approved by a member of the Committee designated by the Chairman 
for the purpose. 


CHAPTER VI. 


OF THE SECRETARIES. 


1. The Corresponding Secretary shall conduct the correspondence of 
the Academy, recording or making an entry of all letters written in its 
name, and preserving on file all letters which are received; and at each 


572 STATUTES OF THE AMERICAN ACADEMY 


meeting he shall present the letters which have been addressed to the 
Academy since the last meeting. Under the direction of the Council, 
he shall keep a list of the Resident Fellows, Associate Fellows, and 
Foreign Honorary Members, arranged in their Classes and in Sections 
in respect to the special sciences in which they are severally proficient ; 
and he shall act as secretary to the Council. 

2. The Recording Secretary shall have charge of the Charter and 
Statute-book, journals, and all literary papers belonging to the Academy. 
He shall record the proceedings of the Academy at its meetings; and 
after each meeting is duly opened, he shall read the record of the pre- 
ceding meeting. He shall notify the meetings of the Academy, apprise 
officers and committees of their election or appointment, and inform the 
Treasurer of appropriations of money voted by the Academy. He shall 
post up in the Hall a list of the persons nominated for election into the 
Academy ; and when any individual is chosen, he shall insert in the 
record the names of the Fellows by whom he was nominated. 

3. The two Secretaries, with the Chairman of the Committee of 
Publication, shall have authority to publish such of the records of the 
meetings of the Academy as may seem to them calculated to promote 
its interests. 

4. Every person taking any books, papers, or documents belonging to 
the Academy and in the custody of the Recording Secretary, shall give a 
receipt for the same to the Recording Secretary. 


CHAPTER VII. 
Or THE TREASURER. 


1. The Treasurer shall give such security for the trust reposed in 
him as the Academy shall require. 

2. He shall receive all moneys due or payable to the Academy and 
all bequests and donations made to the Academy. He shall pay all bills 
due by the Academy, when approved by the proper officers (except those 
of the Treasurer’s office, which may be paid without such approval). 
He shall sign all leases of real estate in the name of the Academy. All 
transfers of stocks, bonds, and other securities belonging to the Academy 
shall be made by the Treasurer with the written consent of one member 
of the Committee of Finance. He shall keep an account of all receipts 
and expenditures, shall submit his accounts annually to the Auditing 


~ 


OF ARTS AND SCIENCES, Die 


Committee, and shall report the same at the expiration of his term of 
office or whenever called on so to do by the Academy or Council. 

3. The Treasurer shall keep separate accounts of the income and 
appropriation of the Rumford Fund and of other special funds, and 
report the same annually. 

4. The Treasurer may appoint an Assistant Treasurer to perform his 
duties, for whose acts, as such assistant, the Treasurer shall be responsi- 
ble ; or the Treasurer may employ any Trust Company, doing business 
in Boston, as agent to perform his duties, the compensation of such As- 
sistant ‘Treasurer or agent to be paid from the funds of the Academy. 


CHAPTER VIII. 
Or THE LIBRARIAN AND LIBRARY. 


1. Τὸ shall be the duty of the Librarian to take charge of the books, 
to keep a correct catalogue of them, to provide for the delivery of books 
from the Library, and to appoint such agents for these purposes as he 
may think necessary. He shall make an annual report on the condition 
of the Library. 

2. The Librarian, in conjunction with the Committee on the Library, 
shall have authority to expend such sums as may be appropriated, either 
from the General, Rumford, or other special Funds of the Academy, for 
the purchase of books, periodicals, etc., and for defraying other necessary 
expenses connected with the Library. 

3. To all books in the Library procured from the income of the 
Rumford Fund, or other special funds, the Librarian shall cause a stamp 
or label to be affixed, expressing the fact that they were so procured. 

4. Every person who takes a book from the Library shall give a 
receipt for the same to the Librarian or his assistant. 

5. Every book shall be returned in good order, regard being had to 
the necessary wear of the book with good usage. If any book shall 
be lost or injured, the person to whom it stands charged shall replace 
it by a new volume or set, if it belongs to a set, or pay the current 
price of the volume or set to the Librarian; and thereupon the remain- 
der of the set, if the volume belonged to a set, shall be delivered to the 
person so paying for the same. 

6. All books shall be returned to the Library for examination at 
least one week before the Annual Meeting. 


574 STATUTES OF THE AMERICAN ACADEMY 


7. The Librarian shall have custody of the Publications of the 
Academy. With the advice and consent of the President, he may effect 
exchanges with other associations. 


CHAPTER IX. 


Or MEETINGS. 


1. There shall be annually four stated meetings of the Academy ; 
namely, on the second Wednesday in May (the Annual Meeting), on 
the second Wednesday in October, on the second Wednesday in January, 
and on the second Wednesday in March. At these meetings, only, or at 
meetings adjourned from these and regularly notified, or at special meet- 
ings called for the purpose, shall appropriations of money be made, or al- 
terations of the statutes or standing votes of the Academy be effected. 

Special meetings shall be called by the Recording Secretary at the re- 
quest of the President or of a Vice-President or of five Fellows. Notifi- 
cations of the special meetings shall contain a statement of the purpose 
for which the meeting is called. 

2. Fifteen Resident Fellows shall constitute a quorum for the trans- 
action of business at a stated or special meeting. Seven Fellows shall 
be sufficient to constitute a meeting for scientific communications and 
discussions. 

3. The Recording Secretary shall notify the meetings of the Academy 
to each Resident Fellow; and he may cause the meetings to be adver- 
tised, whenever he deems such further notice to be needful. 


CHAPTER. xX; 
Or THE ELECTION oF FELLOWS AND Honorary MEMBERS. 


1. Elections shall be made by ballot, and only at stated meetings. 

2. Candidates for election as Resident Fellows must be proposed by 
two Resident Fellows of the section to which the proposal is made, in 
a recommendation signed by them; and this recommendation shall be 
transmitted to the Corresponding Secretary, and by him referred to the 
Council. No person recommended shall be reported by the Council as a 


OF ARTS AND SCIENCES. 575 


candidate for election, unless he shall have received the approval of at 
least five members of the Council present at a meeting. All nominations 
thus approved shall be read to the Academy at any meeting, and shall 
then stand on the nomination list until the next stated meeting, and until 
the balloting. No person shall be elected a Resident Fellow, unless he 
shall have been resident in this Commonwealth one year next preceding 
his election. If any person elected a Resident Fellow shall neglect for 
one year to pay his admission fee, his election shall be void; and if any 
Resident Fellow shall neglect to pay his annual assessments for two 
years, provided that his attention shall have been called to this article, 
he shall be deemed to have abandoned his Fellowship ; but it shall be in 
the power of the Treasurer, with the consent of the Council, to dispense 
(sub silentio) with the payment both of the admission fee and of the 
assessments, whenever in any special instance he shall think it advisable 
so to do. 

3. The nomination and election of Associate Fellows shall take place 
in the manner prescribed in reference to Resident Fellows. 

4. The nomination and election of Foreign Honorary Members shall 
take place in the manner prescribed for Resident Fellows, except that 
the nomination papers shall be signed by at least seven members of the 
Council before being presented to the Academy. 

5. Three-fourths of the ballots cast must be affirmative, and the 
number of affirmative ballots must amount to eleven to effect an elec- 
tion of Fellows or Foreign Honorary Members. 

6. If, in the opinion of a majority of the entire Council, any Fellow — 
Resident or Associate — shall have rendered himself unworthy of a 
place in the Academy, the Council shall recommend to the Academy 
the termination of his Fellowship; and provided that a majority of two- 
thirds of the Fellows at a stated meeting, consisting of not less than 
fifty Fellows, shall adopt this recommendation, his name shall be stricken 
off the roll of Fellows. 


CHAPTBR: XE 
Or AMENDMENTS OF THE STATUTES. 


1. All proposed alterations of the Statutes, or additions to them, shall 
be referred to a committee, and, on their report at a subsequent stated 
meeting or a special meeting called for the purpose, shall require for 


O76 STATUTES OF THE AMERICAN ACADEMY 


enactment a majority of two-thirds of the members present, and at least 
eighteen affirmative votes. 

2. Stauding votes may be passed, amended, or rescinded at a stated 
meeting, or a special meeting called for the purpose by a majority of two- 
thirds of the members present. ‘They may be suspended by a unanimous 
vote. 


CHAPTER XII. 


Or Literary PERFORMANCES, 


1. The Academy will not express its judgment on literary or 
scientific memoirs or performances submitted to it, or included in its 
publications. 


OF ARTS AND SCIENCES, ΠΤ 


STANDING VOTES. 


1. Communications of which notice has been given to the Secretary 
shall take precedence of those not so notified. 

2. Associate Fellows, Foreign Honorary Members, and Resident 
Fellows, who have paid all fees and dues chargeable to them, are en- 
titled to receive one copy of each volume or article printed by the 
Academy on application to the Librarian personally or by written order 
within two years of the date of publication. Exceptions to this rule 
may be made in special cases by vote of the Academy. 

3. The Committee of Publication shall fix from time to time the price 
at which the publications of the Academy may be sold. But members 
may be supplied at half this price with volumes which they are not 
entitled to receive free, and which are needed to complete their sets. 

4, Two hundred extra copies of each paper accepted for publication 
in the Memoirs or Proceedings of the Academy shall be placed at the 
disposal of the author, free of charge. 

5. Resident Fellows may borrow and have out from the Library six 
volumes at any one time, and may retain the same for three months, and 
no longer. 

6. Upon special application, and for adequate reasons assigned, the 
Librarian may permit a larger number of volumes, not exceeding twelve, 
to be drawn from the Library for a limited period. 

7. Works published in numbers, when unbound, shall not be 
taken from the Hall of the Academy, except by special leave of the 
Librarian. 

8. Books, publications, or apparatus shall be procured from the 
income of the Rumford Fund only on the certificate of the Rumford 
Committee that they, in their opinion, will best facilitate and encourage 
the making of discoveries and improvements which may merit the Rum- 
ford Premium; and the approval of a bill incurred for such purposes 
by the Chairman shall be accepted by the Treasurer as proof that such 
certificate has been given. 

9. A meeting for receiving and discussing scientific communications 
may be held on the second Wednesday of each month not appointed for 
stated meetings, excepting July, August, and September. 


VOL, ΧΙ.111.--- 37 


σι 
«ι 
io 6) 


STATUTES OF THE AMERICAN ACADEMY. 


RUMFORD PREMIUM. 


In conformity with the terms of the gift of Benjamin, Count Rumford, 
granting a certain fund to the American Academy of Arts and Sciences, 
and with a decree of the Supreme Judicial Court for carrying into effect 
the general charitable intent and purpose of Count Rumford, as ex- 
pressed in his letter of gift, the Academy is empowered to make from 
the income of said fund, as it now exists, at any Annual Meeting, an 
award of a gold and a silver medal, being together of the intrinsic value 
of three hundred dollars, as a premium to the author of any important 
discovery or useful improvement in light or in heat, which shall have 
been made and published by printing, or in any way made known to 
the public, in any part of the continent of America, or any of the 
American islands; preference being always given to such discoveries 
as shall, in the opinion of the Academy, tend most to promote the good 
of mankind; and to add to such medals, as a further premium for such 
discovery and improvement, if the Academy see fit so to do, a sum of 
money not exceeding three hundred dollars. 


INDEX. 


Académie des Sciences, Agriculture, 
Arts et Belles-Lettres, of Aix, 
Letter from, 533. 

Acheson, E. G., receives Rumford 
Medal, 534. 

Activities of Animals, The Influence 
of Light on the Daily, 533. 

Air, The Absorption of the, for Light 
of very Short Wave-Lengths, 528. 

Air, Damping of the Quick Oscilla- 
tions of a Twisted Fibre by the 
Resistance of the, and by the 
Torsional Forces, 533. 

Aldrovandi, Anniversary of Death 
ΟΥ̓ ΟΣ: 

Aleutian Islands, Volcanoes of, 532. 

Amphioxus, The Sensory Reactions 
of, 413, 533. 

Animals, The Influence of Light on 
the Daily Activities of, 533. 
Are and Spark, Difference in Wave- 
Lengths of Titanium AA 3900 and 

3913 in, 351, 528. 

Are Spectra, Some Effects of Heavy 
Pressure on, 530. 

Arsenic in Urine, The Determina- 
tion of, 325. 

Arsenic, The Quantitative Determina- 
tion of, by the Gutzeit Method, 
295. 

Assessment, Annual, Amount of, 542. 

Atomic Weight of Lead, A Revision 
of, 363, 529. 

Avery, A. H. See Kent, N. A., and 
Avery, A. H. 

Azores, Voleanoes of the, 529. 


Baker, Sir Benjamin, Death of, 529. 
Bartlett, H. H. See Robinson, B. L., 
and Bartlett, H. H. 


Baxter, G. P., and Wilson, J. H., A 
Revision of the Atomic Weight 
of Lead. Preliminary Paper. — 
The Analysis of Lead Chloride, 
363-373, 529. 

Bell, Louis, Note on Some Meteoro- 
logical Uses of the Polariscope, 
405-412, 531; The Physiological 
Basis of Hlumination, 75-96. 

Black, O. F. See Sanger, C. R., and 
Black, O. F. 

Blasius, R., Death of, 528. 

Bohuslav, J., Death of, 527. 

Bowditch, C. P., Report of Treasurer, 
Dav: : , 

Briggs, L. B. R., elected Resident 
Fellow, 530; accepts Fellowship, 


532. 

Cabot, Samuel, Biographical Notice 
of, 547. 

California Academy of Sciences, 


Letter from, 527. 

Campbell, L. L., The Variation of 
the Thermomagnetic Effect in 
Soft Iron with Strength of the 
Magnetic Field and Temperature 
Gradient, 532, 544. 

Cathode Rays, Longitudinal Magnetic 
Field and the, 397, 530. 

Chemical Laboratory of Harvard 
College, Contributions from, 295, 
395, 363, 473, 519. 

Chemistry, Thermodynamic, Outlines 
of a New System of, 257. 

Chloride, Manganous, Transition Tem- 
perature of, 341. 

Coil, An Induction, The Influence of 
Hysteresis upon the Manner of 
Establishment of a Steady Cur- 


580 


rent in the Primary Circuit of, 
530. 

Committees, Standing, 
543; List of, 557. 

Congress of Chemistry and Physics, 
Letter from, 530. 

Copeland, Manton. See Mark, E. L., 
and Copeland, Manton. 

Council, Report of, 547; 
Report of, 541. 

Cretan Chronology, 531. 

Cross, C. R., Report of the Rumford 
Committee, 538. 

Current, Steady, The Influence of 
Hysteresis upon the Manner of 
Establishment of a, in the Pri- 
mary Circuit of an Induction 
Coil, 530. 


appointed, 


Financial 


Damping of the Quick Oscillations of 
a Twisted Fibre by the Resistance 
of the Air and by the Torsional 
Forces, 533. 

Davenport, A. I., Letter from, 529. 

Davenport, G. E., Death of, 529. 

Davis, H. N., Notes on Superheated 
Steam: I. Its Specific Heat; 11. 
Its Total Heat; III. Its Joule- 
Thomson Effect, 533. 

Davis, W. M., The Centenary Cele- 
bration of the Geological Society 
of London, 529. 

Deam, C. C., New Plants from Gaute- 
mala and Mexico, collected by, 
48. 

Demagnetizing Factors for Cylindri- 
eal Iron Rods, 183. 

Denny, Henry G., Death of, 528. 
Derr, Louis, elected Resident Fellow, 
534; accepts Fellowship, 535. 
Dickey, W. P., On Delays before 
ἀναγνὼρίσεις in Greck Tragedy, 

457-471, 533. 

Differential Expressions, Invariants 
of Linear, 534. 

Distillation, Fractional, Concerning 
the Use of Electrical Heating in, 
519. 

Dwight, Thomas, resigns Fellowship, 
535. 


INDEX. 


Electrical Heating, concerning the 
Use of, in Fractional Distilla- 
tion, 519. 

Electromagnet, Magnetic Behavior 
of the Finely Divided Core of an, 
while a Steady Current is being 
established in the Exciting Coil, 
97. 


Farlow, W. G., The Linnaean Celebra- 
tion at Upsala, Sweden, 529. 

Fellows, Associate, deceased, — 

Hall, Asaph, 533. 
Russell, I. C., 533. 
St. Gaudens, A., 533. 
Seymour, T. D., 530. 
Stedman, E. C., 533. 
Young, C. A., 530. 

Fellows, Associate, elected, — 
Nef, J. U., 534. 

Fellows, Associate, List of, 563. 

Fellows, Resident, deceased, — 

Davenport, G. E., 529. 
Folsom, C. F., 528. 
Gardiner, E. G., 528. 
Hay, G., 535. 
Strobel, E. H., 531. 

Fellows, Resident, elected, — 
Briggs, L. B. R., 530. 
Derr, Louis, 534. 
Johnson, D. W., 544. 
Norris, J. F., 528. 
Walker, W. H., 528.. 
Warren, C. H., 544. 

Fellows, Resident, List of, 559. 

Fernald, M. L., Diagnoses of New 
Spermatophytes from Mexico, 
61-68. 

First Chemical Institute of the Royal 
Friedrich-Wilhelm University of 
Berlin, Contributions from, 341. 

Fischer, Emil, elected Foreign Hon- 
orary Members, 544. 

Fluorite, Studies on, 1; The Kathodo- 
Luminescence of, 1. 

Folsom, C. F., Death of, 528. 

Foreign Honorary Members, de- 

ceased, — 
Baker, Sir Benjamin, 529. 
Kelvin, Lord, 530. 
Vogel, H. C., 528. 


INDEX. 


581 


Foreign Honorary Members, elected,— | Heat, Specific, in the Solid and Liquid 


Fischer, Emil, 544. 

Foreign Honorary Members, List of, 
565. 

Fourir, Joseph, Death of, 527. 

Fractional Distillation, Concerning the 
Use of Electrical Heating in, 519. 


Gardiner, E. G., Death of, 528. 

Gebauer, Johann, Death of, 527. 

General Fund, 535, 541; Appropria- 
tions from the Income of, 534, 
542. 

Geological Society of London, Cen- 
tenary Celebration of the, 529; 
Letter from, 532. 

Gesellschaft von Freunden der Natur- 
wissenschaften, Anniversary of, 
533. 

Goodwin, H. M., and Kalmus, H. T., 
The Latent Heat of Fusion and 
the Specific Heat in the Solid 
and Liquid State of Salts melt- 
ing Below 600° C., 544. 

Goodwin, W. W., Cretan Chronology, 
531; Letter from, 552. 

Gray Herbarium of Harvard Uni- 
versity, Contributions from, 17. 


Greek Tragedy, On Delays before 
ἀναγνωρίσεις (Recognitions) in, 
457, 533. 


Greenman, J. M., New species of 
Senecio and Schoenocaulon from 
Mexico, 17-21. 

Guatemala, New Plants from, 48. 

Gutzeit Method, The Quantitative 
Determination of Arsenic by the, 
295. 


Hall, Asaph, Death of, 533. 
Harvard College. See Harvard Uni- 


versity. 
Harvard University. See Chemical 
Laboratory, Gray Herbarium, 


Jefferson Physical Laboratory, 
and Zodlogical Laboratory. 

Hay, G., Death of, 535. 

Heat, Latent, of Fusion, and the 
Specific Heat in the Solid and 
Liquid State of Salts melting 
Below 600° C., 544. 


State of Salts melting Below 
600° C., 544. 

Heating, Electrical, Concerning the 
Use of, in Fractional Distilla- 
tion, 519. 

Heats of Liquids, Specific, A New 
Method for the Determination 
of the, 473, 544. 

Hellman, G., Announcement from, 
528. 

Hepites, St. C., Letter from, 527. 
Homer, Pisistratus and his Edition 
of, 489, 544. 
Hough, Theodore, 
ship, 535. 
House Committee, Report of, 531, 

540. 

Humphreys, W. J., Some «Effects of 
Heavy Pressure on Arc Spectra, 
530. 

Hysteresis, The Influence of, upon 
the Manner of Establishment of 
a Steady Current in the Primary 
Circuit of an Induction Coil, 
530. 


resigns Fellow- 


Illumination, The Physiological Basis 
OL; 10: 

Intensity of Sound, A Simple Method 
of Measuring the, 375, 531. 

International Congress for the History 
of Religions, Letter from, 530. 

International Congress for the Study 
of the Polar Regions, Report of, 
527. 

International Congress of American- 
ists, Letter from, 529. 

International Congress of Botany, 
Circulars from, 535. 

International Congress of Mathe- 
maticians, Letter from, 531. 

International Congress of Orientalists, 
Invitation from, 527. 

Invariants of Linear Differential Ex- 
pressions, 534. 

Iron Rods, Cylindrical, Demagnetiz- 
ing Factors for, 183. 

Iron, Soft, The Variation of the Ther- 
momagnetic Effect in, with 
Strength of the Magnetic Field 


582 


INDEX. 


and Temperature Gradient, 532,| Luminescence, Kathodo-, of Fluorite, 


O44. 


1 


Irwin, Frank, The Invariants of Linear} Lyman, Theodore, The Absorption 


Differential Expressions, 534. 


Jackson, Charles Loring, Biographical 
Notice of Samuel Cabot, 547. 
Jagger, T. A., Voleanoes of the Aleu- 

tian Islands, 532. 

Jefferson Physical Laboratory, Con- 
tributions from, 1, 97, 183, 375, 
397, 511. 

Johnson, D. W., elected Resident 
Fellow, 544. 


Kalmus, H. T. See Goodwin, H. M., 
and Kalmus, H. T. 

Kathodo-Luminescence of Flourite, 1. 

Kelvin, Lord, Death of, 530. 

Kent, N. A., and Avery, A. H., Differ- 
ence in Wave-Lengths of Tita- 
nium AA 3900 and 3913 in Are 
and Spark, 351-361, 528. 

Kinnicutt, L. P., Report of C. M. 
Warren Committee, 539. 


Laboulbeniaceae, Contributions 
toward a Monograph of, 534. 
Lanman, ©. R., appointed Dele- 

gate, 530. 

Lead, A Revision of the Atomic 
Weight of, 363, 529. 

Lead Chloride, The Analysis of, 363, 
529. 

Lewis, G. N., Outlines of a New Sys- 
tem of Thermodynamic Chemis- 
try, 257-293. 

Librarian, Report of, 537. 

Library, Appropriations for, 542. 

Light, The Influence of, on the Daily 
Activities of Animals, 533. 

Light of very Short Wave-Lengths, 
The Absorption of the Air for, 
528. 

Linear Differential Expressions, In- 
variants of, 534. 

Linnaean Celebration 
Sweden, 529. 

Liquids, A New Method for the De- 
termination of the Specific Heats 
of, 473, 544. 


at Upsala, 


of the Air for Light of very Short 
Wave-Lengths, 528. 

Lyon, D. G., The Most Recent Ex- 
ploration in Palestine, 529. 


Magnetic Behavior of the Finely Di- 
vided Core of an Electromagnet 
while a Steady Current is being 
established in the Exciting Coil, 
97. 

Magnetic Field and Temperature 
Gradient, The Variation of the 
Thermomagnetic Effect in Soft 
Iron with Strength of the, 532, 
544. 

Magnetic Field, Longitudinal, and the 
Cathode Rays, 397, 530. 

Manganous Chloride, Transition Tem- 
perature of, 341. 

Mark, E. L., Report of the Council, 
547; Report of the Publication 
Committee. See Zodlogical Lab- 
oratory of the Museum of Com- 
parative Zodlogy at Harvard 
College, Contributions from. 

Mark, E. L., and Copeland, Manton, 
Maturation Stages in the Sper- 
matogenesis of Vespa maculata 
Linn., 69-74. 

Massachusetts Institute of Tech- 
nology. See Research Laboratory 
of Physical Chemistry. 

Mathews, J. H. See Richards, T. W., 
and Mathews, J. H. 

Maturation Stages in the Spermato- 
genesis of Vespa maculata Linn., 
69. 

McDonald, Arthur, Letter from, 527. 

Measurements, Absolute, of Sound, 
544. 

Measurements of the Internal Tem- 
perature Gradient in Common 
Materials, 532. 

Meteorological Uses of the Polari- 
scope, Note on Some, 405, 531. 

Mexico, Diagnoses of New Sper- 
matophytes from, 61. 


Mexico, New and Otherwise Note- 


INDEX. 


worthy Spermatophytes, Chiefly 
fromm 212 

Mexico, New Plants from, 48. 

Mexico, New species of Senecio and 
Schoenocaulon from, 17. 

Michael, Arthur, resigns Fellowship, 


535. 
Moore, G. F., appointed Delegate, 
SB), Gey. 


Morse, H. W., Studies on Fluorite: 
(1V.) The Kathodo-Lumines- 
cence of Fluorite, 1-16. 

Museo Nacional, Mexico, Letter from, 
531. 

Museum of Comparative Zoédlogy at 
Harvard College. See Zodlogical 
Laboratory. 


Nef, J. U., elected Associate Fellow, 
534. 

Newhall, S. H., Pisistratus and his 
Edition of Homer, 489-510, 544. 

Norris, J. F., elected Resident Fellow, 
528. 


Officers, elected, 542; List of, 557. 

Oscillations, The Quick, of a Twisted 
Fibre, Damping of, by the Re- 
sistance of the Air and by the 
Torsional Forces, 533. 

Overbergh, C. van, Letter from, 527. 


Palestine, The Most Recent Explora- 
tion in, 529. 

Parker, G. H., The Influence of Light 
on the Daily Activities of Ani- 


mals, 533; The Sensory Reac- 
tions of Amphioxus, 413-455, 
533. 


Peirce, B. O., The Damping of the 
Quick Oscillations of a Twisted 
Fibre by the Resistance of the Air 
and by the Torsional Forces, 533; 
The Influence of Hysteresis upon 
the Manner of Establishment of 
a Steady Current in the Primary 
Circuit of an Induction Coil, 530; 
On the Determination of the 
Magnetic Behavior of the Finely 
Divided Core of an Electromagnet 


583 


while a Steady Current is being 
established in the Exciting Coil, 
97-182. 

Physikalische Verein, Frankfort, Let- 
ter from, 530. 

Physiological Basis of Dlumination, 
The, 75. 

Pickering, W. H., The Volcanoes of 
the Azores, 529. 

Pierce, G. W., accepts Fellowship, 

A Simple Method οἵ 
Measuring the Intensity of Sound, 
375-395, 531. 

Pisistratus and his Edition of Homer, 
489, 544. 

Plants, New, from Guatemala and 
Mexico, 48. 

Polariscope, Note on Some Meteoro- 
logical Uses of the, 405, 531. 

Positive Rays, 511, 544. 

Pressure, Heavy, Some Effects of, 
on Are Spectra, 530. 

Publication, Appropriation for, 534, 
542. 

Publication Committee, 543; Report 
of, 540. 

Publication Fund, 536. 


627; 


Rays, Positive, 511, 544. 

Reactions, The Sensory, of Amphi- 
oxus, 413, 533. 

Recognitions, On Delays before, in 
Greek Tragedy, 457, 533. 

Records of Meetings, 527. 

Research Laboratory of Physical 
Chemistry of the Massaehusetts 
Institute of Technology, Con- 
tributions from, 257. 

Richards, T. W., and Mathews, J. H., 
Concerning the Use of Electrical 
Heating in Fractional Distilla- 
tion, 519-524. 

Richards, T. W., and Rowe, A. W., 
A New Method for the Determi- 
nation of the Specific Heats of 
Liquids, 473-488, 544. 

Richards, T. W., and Wrede, Franz, 
The Transition Temperature of 


Manganous Chloride: A New 
Fixed Point in Thermometry, 
341-350. 


584 


Robinson, B. L., New or Otherwise 
Noteworthy Spermatophytes, 
Chiefly from Mexico, 21-48. 

Robinson, B. L., and Bartlett, H. H., 
New Plants from Guatemala and 
Mexico collected Chiefly by C. C. 
Deam, 48-60. 

Rods, Cylindrical Iron, Demagnetiz- 
ing Factors for, 183. 

Rotch, A. L., Report of Librarian, 
537. 

Rowe, A. W. See Richards, T. W., 
and Rowe, A. W. 

Royal Friedrich-Wilhelm University 
of Berlin. See First Chemical 
Institute of the Royal Friedrich- 
Wilhelm University of Berlin. 

Rumford Committee, Report of, 538; 
Reports of Progress to, 538. 

Rumford Fund, 535; Appropriations 
from the Income of, 534, 542; 
Papers published by Aid of, 1, 75, 
341, 351, 405, 478, 511. 

Rumford Premium, 578; Presenta- 
tion of, 534. 

Russell, 1. C., Death of, 533. 


St. Gaudens, A., Death of, 533. 

St. Murat, I., Letter from, 527. 

Salts Melting below 600° C., The 
Latent Heat of Fusion and the 
Specific Heat in the Solid and 
Liquid State of, 544. 

Sanger, C. R., and Black, O. F., The 
Quantitative Determination οἵ 
Arsenic by the Gutzeit Method, 
295-324; The Determination of 
Arsenic in Urine, 325-340. 


Schoenocaulon from Mexico, New 
Species of, 17. 

Senecio and Schoenocaulon from 
Mexico, New Species of, 17. 
Sensory Reactions of Amphioxus, 

The, 413, 533. 


Seymour, T. D., Death of, 530. 

Shuddemagen, C. L. B., The Demag- 
netizing Factors for Cylindrical 
Iron Rods, 183-256. 

Solutions, A New Method of Deter- 
mining the Specific Heats of, 
473, 544. 


INDEX. 


Sound, Absolute Measurements of, 
544. 

Sound, A Simple Method of Measur- 
ing the Intensity of, 375, 531. 
Specific Heats of Solutions, A New 
Method of Determining the, 473, 

544, 

Spectra, Arc, Some Effects of Heavy 
Pressure on, 530. 

Spermatogenesis of Vespa maculata 
Linn., Maturation Stages in the, 
69. 

Spermatophytes, Chiefly from Mexico, 
New and Otherwise Noteworthy, 
mis 

Spermatophytes from Mexico, Diag- 
noses of New, 61. 

Standing Committees, appointed, 543; 
List of, 557. 

Standing Votes, 567. 

Statutes, 567. 

Steam, Notes on Superheated, 533. 

Stedman, E. C., Death of, 533. 


Temperature, Transition, of Manga- 
nous Chloride, 341. 

Temperature Gradient, The Internal, 
in Common Materials, Measure- 
ments of, 532. 

Temperature Gradient, The Variation 
of the Thermomagnetic Effect 
in Soft Iron with Strength of the 
Magnetic Field and, 532, 544. 

Thaxter, Roland, Contributions 
toward a Monograph of the La- 
boulbeniaceae. Part II., 534. 

Thermodynamic Chemistry, Outlines 
of a New System of, 257. 

Thermomagnetic Effect in Soft Iron, 


The Variation of the, with 
Strength of the Magnetic Field 
and Temperature Gradient, 532, 
544. 

Thermometry, A New Fixed Point 
in, 341. 


Thwing, C. B., Measurements of the 
Internal Temperature Gradient 
in Common Materials, 532. 

Titanium AA 3900 and 3913 in Are 
and Spark, Difference in Wave- 
Lengths of, 351, 528. 


——— ον νου 


INDEX. 


Torsional Forces, The Damping of the 
Quick Oscillations of a Twisted 
Vibre by the Resistance of the 
Air and by the, 533. 

Transition Temperature of Manga- 
nous Chloride; A New Fixed 
Point in Thermometry, 341. 

Treasurer, Report of, 535. 

Trowbridge, John, Longitudinal Mag- 
netic Field and the Cathode Rays, 
397-404, 530; Positive Rays, 
511-517, 544. 


Urine, The Determination of Arsenic 
Ibo 595. 

Upsala, Sweden, The Linnaean Cele- 
bration at, 529. 


Vespa maculata Linn., Maturation 
Stages in the Spermatogenesis 
of, 69. 

Vogel, H. C.; Death of, 528. 

Voleanoes of the Aleutian 
532. 

Volcanoes of the Azores, 529. 


Islands, 


Resident 
Fellow- 


Walker, W. 
Fellow, 
ship, 528. 


EH; 


528; 


elected 
accepts 


585 

Warren, C. H., elected Resident 
Fellow, 544. 

Warren (C. M.) Committee, Report 
of, 539. 

Warren (C. M.) Fund, 536; Appro- 
priation from the Income of, 
542. 

Warren, Minton, Death of, 529. 

Wave-Lengths, Difference in, οἵ 
Titanium dA 3900 and 3913 in 
Arce and Spark, 351, 528. 

Wave-Lengths, very Short, The Ab- 
sorption of the Air for Light of, 
528. 

Webster, A. G., Absolute Measure- 
ments of Sound, 544. 

Wilson, J. H. See Baxter, G. P., and 
Wilson, J. H. 

Wrede, Franz. See Richards, T. W., 

and Wrede, Franz. 


Young, C. A., Death of, 530. 


Zoélogical Laboratory of the Museum 
of Comparative Zodlogy at Har- 
vard College, E. L. Mark, 
Director, Contributions from, 69, 
413. 


si Sli 


22. 


25. 


26. 


x 


VOLUME 42. 


Rozrson, B. L.— Studies in the Eupatorieae: (I.) Revision of the Genus P‘queria; (11. 
Revision of the Genus OpAryosporus ; (III.) The Genus Helogyne and its Synonyms ; (IV.) 
Diagnoses and Synonymy of Eupatorieae and of Certain Other Compositae which have been 
Classed with them. pp. 1-48. May, 1906. 50c. 

Sapine, W. C. — Architectural Acoustics: (I.) Introduction; (II.) The Accuracy of Musical 
Taste in regard to Architectural Acoustics; (III.) Variation in Reverberation with Varia- 
tion in Pitch. pp. 49-84. June, 1906. 45c. 

Peirce, Β. O. — On the Permeability and the Retentiveness of a Mass of Fine Iron Particles, 
pp. 85-91. June, 1906. 15c. 

Perce, B. 0. — On the Length of the Time of Contact in the Case of a Quick Tap on a Tele- 
graph Key. pp. 93-100. June, 1906. 15c. 

Makzx, E. L., and CopeLanp, M.—Some Stages in the Spermatogenesis of the Honey Bee. 
pp. 101-111. 1pl. June, 1906, 20c. 

Hoga, J. L. — Friction and Force due to Transpiration as Dependent on Pressure in Gases. . 
pp. 113-146. July, 1906. 45c. ; 
Perce, B. 0. — On the Conditions to be Satisfied if the Sums of the Corresponding Members 
of Two Pairs of Orthogonal Functions of Two Variables are to be Themselves: Orthogonal. 

pp. 147-157. July, 1906. 156. 

Peirce, B. O. — On the Correction for the Effect of the Counter Electromotive Force induced 
in a Moving Coil Galvanometer when the Instrument is used Ballistically. pp. 159-169, 
July, 1906. 15e. : 

Peirce, Β. 0. --- A Simple Device for Measuring the Deflections of a Mirror Galvanometer. 
pp. 171-174. 1pl. July, 1906. 156. : 

Rippiz, L. W. —On the Cytology of the Entomophthoraceae. pp. 175-197. 3 pls. August, 
1906. 40c. 

Baxter, G. P. — A Revision of the Atomic Weight of Bromine. pp. 199-214. August, 1906. 
250. 

LARRABEE, A. P. —The Optic Chiasma of Teleosts: A Study of Inheritance. pp. 215-231. 
October, 1906. 256. : 

Woop, R. W. — Fluorescence and Magnetic Rotation Spectra of Sodium Vapor, and their Analy- 
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