, then S,v)=0; and ifr=n,
Sn(z)=(—1)" | 1 Lume ak
Ss Sp+1 Sp+2 «+ + Sptn
Spt+n—1 Spin Sptn+1 + « « Sp+2n-1
=(ayay. . . An)?&(ay. . « An)(X—a,)(H@—ay) . . . (W—an)
= (aay «08 an)’ Kay aes an) (a" + pa"! + pv"? + m Te) +),) 5
A SPECIAL CLASS OF STURMIANS. 1638
if a, a... . ad be the roots of
B+ pe i+... +p,=0.
3. When z=a,
= becomes (ayaz.. . An)?E(a, . . « An) (a1 —A2) » . « (1 — Gn)
and
Sn—1(%) becomes (agaz . . . an)’E(az. . . An)(ay—az) .. . (ay —aan).
Hence, when v=a,
Bol) / $,_1(2) =a? {(1—as) ras)» « (@h—a)}®.
Now, if a, be real, and p be an even positive or negative integer, this ratio will
be real and positive ; for a, a,... a, being by supposition the root of an equa-
tion with real coefficients, for every imaginary in the series a, — a,, a, —a3...4,— On,
there will occur a corresponding conjugate imaginary so that the product of them
all will be real.
It follows that S,_,(v) and S,(v) have opposite signs when 2 is just less than
any real root of
SZ) = 0,
which is the second characteristic of the first two functions of a Sturmian
series.
The restriction as to p being even may be removed if positive and negative
roots be considered separately; but for simplicity I shall suppose p to be
always even.
4, If we take the determinantal expression for S,, multiply each column
by 2, and subtract the next following, leaving of course the last column
unchanged, we get, denoting for brevity s,v—s,,, by (p), Spu:%—Sp4. by
(p+1), &e.,
S,(”) =| (p) Ga Oe... Kp +n—-1)
GE) (Oreo) = = En)
@Gr2) . @E3prs) .-. (p+n+1)
| (p+n—1)(p+n)(p+n+l1) ... (p+2n—2)
which it will be observed is a symmetrical determinant. S,_:(z), similarly trans-
formed, becomes the first principal minor of this obtained by deleting the last row
and the last column, and so on. Hence, by (1), S,(), S,-1 (7)... S,(z) S,(z),
164 PROFESSOR CHRYSTAL ON
the last being any positive constant, have the property that, when any one
of the series vanishes, the next higher and the next lower have opposite
signs.
5. It has now been shown that 8,(z), S,_:(z), ...8,(z), S,(z) form a
Sturmian series. By giving particular even values to p, we get of course an
infinite number of such series.
If it were desirable to employ these functions for the purposes of root
discrimination, s,, s,-1, &c., could be calculated by Newron’s method, and by
giving a proper negative value to p, the labour could be diminished by nearly
half in the most general case.
For example, if we take the cubic equation
a+petq=0,
and put p= —2, the Sturmian’s are
S=—-|1 ¢@ 2¢@2@/,S=+12 « #/,8,==—|1 2 |,8=+1.
G5 5.1 8p a een Sasa
S_1 So Sy So S-1 So Sy Sj So
So) Si Sada SSS Sh
6. If we wish simply to find how many real roots there are, then we have
simply to consider the signs of the coefficients of the highest powers of # in
the Sturmians. This gives us the following theorem :—
There are as many pairs of imaginary roots of the equation
B+ pe + ... +p,=0
as there are variations of sign in the series
+1, 5, | S S41 |5| S Sp4i Spre |, &e.
Sp+1 Sp+2 Sp+1 Sp+2 Sp+s
Sp+2 Sp43 Sp44
when p=0 this gives a well-known theorem (see Satmon, “ Higher Algebra,”
p. 49).
If we put p=0, the series for the cubic
e+ pat+q=0,
neglecting certain positive multipliers, is
rh Ly +31, —6p, — (4p? + 279") .
A SPECIAL CLASS OF STURMIANS. 165
If we put p= —2, we get
eee ap) (4p +279") .
Each of these leads to the well-known condition for the reality of the roots
of the cubic.
7. It follows at once from (2) that, if two roots of the equation be equal,
then S,(z) vanishes identically, and 8,_,(z), S,_,(z), . . . S,(z), form a Stur-
mian series for the roots all supposed single. If three roots be equal to one
another, or if two pairs be equal, then §,(z) and S,_,(z) vanish identically, and
the rest form a Sturmian series for all the roots supposed single ; and so on.
The present class of Sturmians present therefore an instructive contrast to the
ordinary series obtained by the method of the greatest common measure.
VOL. XXX. PART I. 25
eumer ss
VII.—On the Cranial Osteology of Rhizodopsis. By Ramsay H. Traquair,
M.D., F.R.S., Keeper of the Natural History Collections in the Museum
of Science and Art, Edinburgh.
(Read May 21, 1877. Received for Press July 22, 1881, Abstract in ‘‘ Proceedings,” vol. ix. p. 444.)
In a paper by Mr E. W. Binney on the Fossil Fishes of the Pendleton Coal
Field, published in 1841, the dentary bone of Rhizodopsis is figured as the
“upper jaw of a new species of Holoptychius,” to which, however, he did not
attach any specific name. In the same paper its scales are also figured and
referred to the same genus.* Scales belonging to the same fish were after-
wards figured by Professor WILLIAMSON under the name of WHoloptychius
sauroides,t and again by Mr Satter, as those of Rhizodus granulatus.{ Both
of these specific names occur under Holoptychius in AGassiz’s general list of
Ganoids published in 1843, but as they were unaccompanied either by figures
or descriptions, it is really immaterial which of them, if indeed either, was
applied by him to the fish in question. The authority for the term “sauroides”
as applied to the common species of Ahizodopsis, the only species of the genus
which is as yet known with certainty, must therefore remain with Professor
Wiuiamson. Holoptychius sauroides of Binney § and of Messrs Kirkby and
Atthey || is quite another fish, now also distinguished generically as Strepsodus,
and for it the specific name “ sawrozdes” is therefore equally valid.
In 1866 Professor Younc published a description of the entire fish, under
the name of Rhizodopsis sauroides, Williamson, sp., the authorship of the new
generic title being attributed to Professor Huxtey.' From Professor Youna’s
description, we learn that the position of Ahizodopsis, in Professor Hux ry’s
classification of the Ganoids, is in the cycliferous division of the Glyptodipterine
family of the suborder Crossopterygide, and that it possesses subacutely lobate
pectoral fins, two dorsals, and a heterocercal tail. Some of the bones of the
head are noticed, such as the parietals, the three dermal plates of the occipital
region, the opercular bones, the maxilla, and the mandible. No preemaxilla
* Trans. Geol. Soc. Manchester, vol. i. (1841), pp. 153-178, pl. v. figs. 6, 8, and 10.
+ “On the Microscopic Structure of the Scales and Dermal Teeth of some Ganoid and Placoid Fish,’
Phil. Trans., 1849, p. 457, pl. xlii. figs, 21-23.
t “Tron Ores of Great Britain,” Mem. Geol. Survey, 1861, p. 223, pl. i. figs. 4-6.
§ Op. cit., pl. v. fig. 7.
|| Trans. Tyneside Nat, Field Club, vol. vi. (1863-64), p. 234, pl. vi. figs. 5 and 6,
{1 “Notice of New Genera of Carboniferous Glyptodipterines,” Quart. Journ. Geol. Soc., 1866,
pp. 596-598.
VOL, XXX. PART I. 2c
168 RAMSAY H. TRAQUAIR ON
was, however, observed by Professor Youne, and he states that the jugular
plates are “in two pairs, principal and posterior,” and that there is no trace of
median or lateral plates. The characters of the scales and of the vertebre,
whose centra are in the form of osseous rings, are described as well as the
dentition ; the teeth of the maxilla being fine, equal, and conical, while those of
the mandible are of two sizes. The non-trenchant character of the mandibular
laniaries distinguishes the genus from &/izodus, while as separating it from
Holoptychius, Professor Youne gives the thinness of the scales, the nature of
their ornament, and the presence of teeth of two sizes.
Two years later a notice of this fish was published by Messrs Hancock and
ATTHEY, from specimens found in the shales of the Northumberland Coal Field,*
in which the authors state that in all respects their specimens “agree well with
Dr Youne’s description of the species.” Their description contains, however,
two points specially worthy of notice, viz., the detection, on the anterior
margins of some of the fins, of peculiar fulcral scales similar to those which
occur in Megalichthys and other Saurodipterines, and the determination of a
peculiarly shaped dentigerous bone as “pramazilla.” Moreover, according to
Messrs Hancock and ATTHEY, the piscine genera and species Dittodus parallelus,
Ganolodus Craggesii, and Characodus confertus, and the supposed Amphibian
Gastrodus, all founded by Professor OWEN on specimens of teeth from the same
coal-field, are only synonyms of Rhizodopsis sauroides.
Rhizodopsis is also noticed by Mr T. P. Barxas,t who accepts Messrs
Hancock and ATTHEY’s interpretation of the bone supposed by them to be a
premaxilla. So also does Mr J. W. Barxkas,{ who solves the problem
regarding the specific nomenclature of the fish by quoting Rhizodopsis sauroides
and granulatus as distinct species, without, however, giving any reasons in
support of the supposed distinction.
Being struck by the total dissimilarity of form presented by the bone
interpreted by Messrs Hancock and ATTHEy as the preemaxilla of Rhizodopsis,
when compared with that element in other Crossopterygii, I carefully examined
the subject with the aid of a beautiful series of specimens from North Stafford-
shire, kindly lent me by my friend Mr Joun Warp, F.G.S., and with the result
of finding that the reputed premaxilla is in reality the dentary element of the
mandible. Moreover, the mandible of &hizodopsis is of a very complex
structure, and that structure finds itself in all essential respects repeated and
explained in the mandible of the much more bulky Rhizodus Hibbert.
These observations were published in the ‘“ Annals and Magazine of Natural
* “Note on the Remains of some Reptiles and Fishes from the Shales of the Northumberland
Coal Field,” Ann. Nat. Hist. (4), vol. i. (1868), pp. 346-378.
+ “Manual of Coal Measure Palontology,” London, 1873, pp. 23-25, Atlas, figs. 59-66.
t Monthly Review of Dental Surgery, vol. iv. No. x., March 1876.
— ea
a
a coir regeg,
THE CRANIAL OSTEOLOGY OF RHIZODOPSIS. 169
History” for April of the present year (1877). ‘In the present communication I
propose, with the aid of a few restored outline drawings, to consider the entire
subject of the cranial osteology of Rhizodopsis, the greater part of the material
for which belongs to the collection of Mr Warp. My thanks are also due to
Mr Joun Puant of Salford, for the loan of a number of shale specimens, showing
isolated bones, from the Manchester coal-field.
Rhizodopsis sauroides, Williamson, sp.
Cranium proper.—The cranial roof bones form a “buckler,” which in its
configuration and composition is very similar to that in Osteolepis, Megalichthys,
&c. As in these forms it falls into two principal parts, anterior and posterior,
of which the posterior, or parietal portion, is slightly longer than the anterior
or fronto-ethmoidal. The parietal portion is
about twice as broad posteriorly as it is in front,
each external margin passing, a little behind
the middle, first inwards at an obtuse angle and
then nearly straight forwards; the anterior and
posterior margins are nearly straight. This
portion of the buckler is composed of six paired
ossifications, two of which (pa. fig. 1) extend
along its whole length, articulating with each
other in the middle line; their form is rather
narrow and elongated, and they are also broader
behind than in front. These two plates may
very safely be reckoned as the parietals; as
such the corresponding plates have been, in
Ostevlepis and Megalichthys, designated by Pan-
Fic. 1.—Upper Surface of the Head of
DER, by HUXLEY in Glyptolemus, and by AGASSIZ Rhizodopsis swuroides.
F 5 s.¢. supratemporal ; pa. parietal; sq. squa-
nN Osteolepis, although the last-named author has peal : Df. réatauioe Aéagal ; frontal
or. orbit ; p.mex. premaxilla.
marked the very same bones in MMegalichthys
as “frontals.” Along the outer edge of each parietal are two smaller plates,
anterior (pf) and posterior (sq.), regarding the signification of which, in
allied forms, some pretty serious difference of opinion is found in the works
of different writers. By Agassiz the anterior one was, in Osteolepis, con-
sidered to be the post-frontal, the posterior to be the “mastoid,” while
in Megalichthys, he considered the very same plates to be equivalent to
the chain of intercalary ossicles placed along the external margins of
the cranial shield in Polypterus. By PanpeEr the latter interpretation is
accepted both for Osteolepis and Megalchthys; while by Professor Hux ey,
these two plates, anterior and posterior, are in Glyptolemus respectively termed
170 RAMSAY H. TRAQUAIR ON
‘ post-frontal” and ‘squamosal.” Now, as the bones of the skull of Teleostean
fishes, known in the Cuvierian system of nomenclature as “ post-frontal” and
“mastoid,” are ossifications in the periotic portion of the primoidial cranium
(sphenotic and pterotic of Parker), and as the disputed bones in the cranial
buckler of the Crossopterygian Ganoids above referred to are evidently dermal
in their nature, the latter may be considered as really partaking more of
the nature of the ossa intercalaria in Polypterus. But as to their being
considered exactly the equivalents of those little plates in Polypterus, there are
some pretty serious, and to my mind fatal objections. They are firmly united
by suture to the outer margin of each parietal, with which they form an integral
part of the cranial buckler. In the Lepidosteoid Ganoids (Lepidosteus,
Lepidotus, &c.), there is, external to each parietal, a plate (sgwamosal) evidently
corresponding to the posterior of the two in Rhizodopsis, &c., and which no
one has ever thought of considering homologous with the Polypterine inter-
calaries. The same plate is found in Ama, and there is in addition another
smaller one in front of it corresponding to the anterior of the two in Rhizodopsis,
but which, from the relatively greater shortness of the parietal, and the corre-
sponding greater extension backwards of the frontal, comes to lie external to
the posterior part of the outer margin of the latter. In the Paleeoniscidee there
are also two corresponding plates, but the anterior of these, which I have
lettered as post-frontal in my memoir on the structure of this family,* is placed
relatively to the frontal still further forwards, owing to the greater proportional
length of the squamosal behind it. In Acipenser there is also, external to
the plates which seem to represent the parietals and frontals of other fishes, a
chain of two or more smaller plates, which apparently represent those in
question, and which, firmly articulated with the others covering the cranial
cartilage, lie zms¢de the position of the spiracle. There is no spiracle in
Lepidosteus or Amia, and no evidence of it in the Paloniscide, or in either the
Rhombo- or Cyclodipterine Crossopterygii, but in Polypterus there is, and the
chain of intercalary ossicles, loosely articulated to the margin of the cranial shield,
lies external to the spiracular slit, which passes down between two of them
and the side of the cranium proper. It therefore seems to me inappropriate
to consider the bones p.f. and sg. of the cranial shield of Rhizodopsis and allied
forms to be the homologues of the intercalary ossicles in Polypterus, and better
to follow Professor Huxtey in designating them respectively as post-/rontal and
squamosal, always bearing in mind, however, that the former has nothing to
do with the post-frontal of Cuvier, for which it is better to adopt the term
“ sphenotic”” as proposed by Parker. In Ama, in fact, a well-developed
sphenotic coexists with the more superficial plate to which I have referred as
“ post-frontal.”
* “Carboniferous Ganoids,” Paleontographical Society, 1877.
THE CRANIAL OSTEOLOGY OF RHIZODOPSIS. 171
The anterior, or fronto-ethmoidal division of the cranial shield is not so
well preserved, so that it is not possible to map out its constituent ossifications
with completeness ; in no case are its external or orbital margins well defined,
and its upper surface is more or less broken and crushed. Nevertheless, the
form and constitution of its anterior margin are unmistakeable. This is
crescentically expanded, forming the rounded depressed snout ; and to the two
dentigerous bones, the premazille forming its oral edge, we shall presently
return in describing the bones of the jaws. I have not been able to detect the
nasal openings.
The external surfaces of these cranial plates are ornamented with minute
tubercles and short ridges, frequently arranged in lines radiating from the
centres of ossification.
Facial Bones.—Immediately behind the posterior margin of the cranial
shield are the usual three plates (s.¢., fig. 1), one median and two lateral, which
are of such constant occurrence in fishes of the Rhombo- and Cyclodipterine
families. I have already, in my memoir on the structure of Tristichopterus
alatus,* expressed my opinion that these are equivalent to the transverse chain
of supra-temporal ossicles in Polypterus, Lepidosteus, &c.
The hyomandibular is a somewhat elongated bone, extending downwards
with a slightly backward inclination from below the squamosal to just behind
the articulation of the lower jaw; it is also slightly curved, the concavity being
directed forwards. Above, where it articulates with the cranium, it is flattened
for about a little less than one-third of its length; this flattened portion, to
which the superior anterior angle of the operculum is articulated, becomes very
suddenly cut away on the posterior aspect, below which the bone becomes
slender and cylindrical, expanding, however, in thickness in its lower half.
Remains of a powerfully developed palato-quadrate apparatus are seen in several
specimens, but not exposed with sufficient completeness to admit of any de-
scription of its component elements ; its outer margin is for some distance
articulated with the inner aspect of the maxilla, behind which it recedes a little
inwards to admit of the passage of the masticatory muscles to the coronoid
part of the lower jaw. |
By reason of the slightly backward slope of the hyomandibular, the gape is
wide, and in three specimens, it is exposed all round the head, so that the
bones forming the edges of the mouth are very completely seen. In nearly all
the heads preserved in nodules the upper margin of the mawilla (mz. fig. 2) is
injured, but its complete contour is well exhibited in detached shale specimens.
In shape it resembles very closely the maxilla of Megalichthys, being of an
elongated triangular form, broadest about the junction of its posterior and
middle thirds, and narrowly tapering anteriorly. Its posterior extremity forms
* Trans. Roy. Soc. Edinburgh, vol. xxvii. (1874) p. 386.
Lrg RAMSAY H. TRAQUAIR ON
a tolerably acute angle, from which the inferior margin slopes first a little
downwards and forwards, and then passes nearly straight forwards; the short
posterior margin slopes gently upwards and forwards to the very obtuse and
usually more or less truncated superior angle, from which the superior margin
then slopes downwards and forwards
to the anterior extremity, just before
attaining which it sends off a small
articular process directed obliquely
upwards and forwards. The external
surface is ornamented with minute
pits and delicate reticulating ridges ;
the inner surface shows a delicate
ledge running longitudinally a little
above the inferior margin and nearly
parallel with it. The inferior margin
of the maxilla is set with a single row
Fic. 2.—Lateral View of the Head of Rhizodopsis sawroides.
op. operculum ; s.op. suboperculum ; p.op. preoperculum ; : ;
az.z. plates on the cheek; j. principal jugular; 1.7. of small teeth, cylindro-conical, acutely
lateral jugular; m.j. median jugular; mz. maxilla; ’ : :
d. dentary ; ag. angular; 7.d. infradentary ; or. orbit ; pointed, slightly incurved, and of
s.o. suborbital; s.f. supratemporal; pa. parietal; sq.
squamosal; p.f. posterior frontal; 7 frontal; p.ma. equal size. Their external surfaces
premaxilla.
are quite smooth and glistening under
an ordinary lens ; they are usually placed pretty closely together, though some
irregularity in their distances from each other is not unfrequently observed.
Each of these teeth measures about ,j, inch from base to apex in a maxilla of
11 inch in length.
In several specimens are seen the sharp imprints of two small dentigerous
bones (p.ma.) forming the front edge of the mouth below the snout, and placed
between and articulating with the anterior extremities of the right and left
maxilla, while they are joined with each other in the middle le. Each of
these two bones is nearly as high as long; they are firmly fixed to each other,
and also to the front of the cranial shield ; the posterior extremity of each fits
into the angle between the anterior extremity of the maxilla and the little arti-
cular process already mentioned in the description of the last-named bone ; the
attached teeth, seen in impression and in section, resemble those of the maxilla.
That we have here the true premazxille cannot for a moment be doubted ; it
is therefore abundantly clear that this element in Rhizodopsis does not in the
least resemble the bone interpreted as such by Messrs Hancock and ATTHEY,
but that on the other hand it is quite conformable to the type of premaxilla
found in other Crossopterygii, as indeed in the Ganoids generally.
The mandible is longer than both premaxilla and maxilla put together,
reaching, as it does, a little further back than the posterior extremity of the
latter. Its depth is contained about four times in its length, its upper and
THE CRANIAL OSTEOLOGY OF RHIZODOPSIS. 173
lower margins are tolerably parallel save just at the anterior extremity, where
the upper one bulges a little upwards in a slight convexity, and at the posterior
extremity where the same margin suddenly slopes downwards and backwards
at an obtuse angle, meeting the lower one, which likewise curves upwards
towards it, in a posteriorly directed point. Nothing has been said in the works
of previous writers concerning the constitution of the mandible, though it
might be inferred to be a composite structure, as it is in all fishes with ossified
skeleton, and more especially in the Ganoidei. In one specimen we find that
over a considerable area the bony matter of the outer aspect has flaked off,
leaving behind it a pretty sharp cast with sutural lines. On close examination
a suture is seen commencing near the posterior extremity of the upper margin
of the jaw, which, passing gradually downwards and forwards, marks off as
dentary (d. fig. 2) an element precisely the counterpart in shape of the bone
reckoned by Messrs Hancock and ArrTuey “ preemaxilla,” but here placed with
its toothed margin wpwards instead of downwards as supposed by them. These
two bones, right and left, are in many specimens indisputably seen forming the
lower margin of the mouth and meeting each other at the symphysis. Each
dentary bone is of a somewhat narrow and elongated form, truncated and some-
what expanded at the anterior or symphyseal extremity, and pointed at the other
or posterior. The upper margin, nearly straight, save just in front where it shows
a slight convexity, is set with a single row of small pointed teeth of nearly uniform
size, but the anterior extremity bears in addition a single more or less incurved
laniary tooth, much larger than the others, and also more internal in its
position; the opposite margin, thin and sharp, displays a gently flexuous
contour. Seen from the inner aspect, the anterior extremity of the bone
presents a conspicuous thickening, in which the large laniary tooth is socketed,
and which at the dental margin passes into a delicate ledge, which runs back
for some distance along the roots of the smaller teeth. The teeth borne by
this bone are round in transverse section, slender-conical in shape, brilliantly
polished, and apparently smooth externally, but under a lens the surface is seen
to be delicately fretted with minute longitudinal groovings, disappearing
towards the point ; the large laniary is also very distinctly fluted or plicate at
its base.
The rest of the outer surface of the mandible is composed of at least three
additional bony plates, separated from each other by sutures which pass
obliquely forwards and upwards. The posterior and largest of these (ag. fig. 2)
covering over the articular region, may be considered as equivalent to the
angular element, though it also occupies very much the place of a supra-
angular ; the other two (d.) in front of the latter and below the dentary,
may be called infradentary. The presence and contour of these large infra-
dentary plates is perfectly clear, the evidence as to additional ones is obscure.
174 RAMSAY H. TRAQUAIR ON
From the appearance presented by one specially large mandible, I rather
suspect there is a third small one, as there is in Rhizodus, just below the
symphyseal extremity of the dentary, and I have in my paper in the “ Annals”
referred to some doubtful evidence of still another, situated posteriorly on the
lower margin of the jaw, and here separating the angular from the first infra-
dentary for a little distance, but on this I am not prepared to insist.
We have as yet accounted for the attachment of one laniary tooth, the one
at the symphysis. But the mandible of Rhizodopsis, when perfect, shows not
merely one large tooth in front, but several additional ones (usually three in
number) behind it and internal to the series of smaller teeth. What has
become of these in the dentary bone when disarticulated and detached ?
A ready explanation of this is found in the structure of the lower jaw of
certain Old Red Sandstone “Dendrodonts” in which the laniary teeth are not
attached to the dentary bone proper,-but to a series of accessory “internal
dentary ” pieces articulated to its inner side.* Should this also be the case
with the posterior laniaries of the mandible of Ahzzodopsis, then in cases where
its elements are broken up and separated, these additional pieces will also get
detached, and the absence of all but the anterior laniary in the isolated dentary
bone will thus be amply accounted for.
At the time I wrote the notice in the ‘‘ Annals,” already quoted, I had not
obtained a clear view of the ossicles supporting the posterior laniaries in
Rhizodopsis, and consequently referred to the analogy of the structure of the
lower jaw in Ahizodus, in which I had most certainly found them, as amounting
to a moral certainty of their existence also in the former genus. My attention
has subsequently been directed to a specimen in the Edinburgh Museum of
Science and Art, which completely confirms the view I then took.
This is a slab of shale, not localitated, but probably from the Edinburgh
Coal Field, over which scales of Rhizodopsis of large size lie thickly scattered,
some of which are over 1 inch in length and nearly ? in breadth. ‘This is
indeed an unusually large size, but is by no means an isolated example of the
bulk which Rhizodopsis must sometimes have attained, and the form and
sculpture of the scales here exhibited unmistakeably demonstrate the genus
to which they belong. Lying in the midst of the scales is a mandible,
evidently belonging to the same fish, and seen from the internal aspect.
The splenial is gone, as is likewise the bony substance of the symphyseal part
of the entire mandible, though a rough impression of it remains on the stone ;
the hinder extremity is also injured, as well as the posterior part of the lower
margin ; such impressions of the external surface, as remain when the bone has
splintered off, indicate a sculpture of the usual minutely pitted-rugose character
* See Panper’s “ Saurodipterinen, Dendrodonten, &c., des devonischen Systems,” pp. 41-43,
tab. x. figs. 2, 3, 4, 14, 22,
.
|
j
THE CRANIAL OSTEOLOGY OF RHIZODOPSIS. 175
of the mandibular elements of this genus. The depth of this jaw is 1,3,
inch ; its entire length, including the impressions of its anterior and posterior
extremities, is 54 inches. The upper edge of the dentary element is seen
extending from the obtuse angle of the posterior extremity of the upper aspect
of the jaw to where it is broken off, apparently 14 inch from its symphyseal
termination, as indicated by the impression, and is set with a single row of small
conical teeth, placed on an average at distances from each other of + inch,
though they are more closely set anteriorly, where a few empty sockets are also
seen. Some of the hinder ones are entire, and measure 3} inch in length; they
are sharp, slightly incurved, their bases plicate, the surface fretted with very
minute striz, visible only under a strong lens. Anteriorly they are all broken
off at various heights, the sections showing a large internal pulp cavity, the
walls of which become very simply plicate at the base. Now, articulated just
below this dentary margin is a longitudinal chain of two separate ossicles and
the hinder part of a third. Each of these (én. d.) is of an oblong shape, con-
tracted at the extremities, and in the middle showing first an empty socket, and,
immediately in front of this, the broken off root of a large laniary tooth, at once
recognisable by the complex folded structure of its constituent dentine. The
anterior of these ossicles is obliquely broken off right through the empty
socket, at the bottom of which are the remains of dentinal plice, showing how
here too a large tooth had once existed and had been broken off; and in front
of this, and just above where the root of the actual laniary had been, is a part
of the impression, upon the matrix, of the very tooth itself. Nothing can be
more distinct than the sutures which separate these accessory or internal
dentary ossicles from each other, and from the contiguous dentary element
proper—the remaining bony matter beneath, consisting of the plates previously
referred to as angular and infradentary, is thin and traversed by numerous
cracks and fractures, so that very careful examination is here required for
the determination of sutures. Nevertheless, with due attention, the lines
of demarcation between the angular and the two large infradentaries may
be made out, and just behind the position of the symphysis there is an
indication of another suture passing upwards and forwards from the lower
margin of the jaw, and separating off the third and smaller infradentary
already alluded to. Lying on the margin of the slab, 24 inches from the above-
described jaw, is a broken-off piece of bone having a large tooth attached to
it, the latter measuring 2 inch in length by 1 inch in diameter at the base. Its
length was originally in all probability greater, as it is obliquely fractured, and
the fractured surfaces ride over each other a little. Its base is plicate, above
which the surface of the tooth is very minutely and delicately striated up to 4
inch from the point, which is perfectly smooth. Close beside this large tooth,
and apparently attached to the same piece of bone, are two smaller ones, each
VOL. XXX. PART I. 2D
176 RAMSAY H. TRAQUAIR ON
about 4 inch in length, so that I rather think we have here a fragment of the
anterior extremity of the dentary bone of the other side of the head, with the
sympbyseal laniary.
Returning to the examination of the smaller specimens, a portion of the
splenial element is seen in one specimen, exposed by the breaking out of a
portion of the middle of the mandible. The articular element, which was
doubtless also present, is not exhibited in any specimen I have seen.
The opercular bones are largely developed. The operculwm (op. fig. 2) is a
large, somewhat square-shaped plate, though broader above than below, and
behind than in front. Its posterior-superior angle is rounded off; its inferior
margin overlaps another plate, which may be considered to be the suboperculum
(s. op.). This is somewhat narrower, and has its posterior-inferior angle much
rounded off; its upper and lower margins are nearly parallel, and from the
former, just at the anterior-superior angle of the bone, there projects a short
pointed process, producing the anterior margin a little way upwards.
In front of the operculum, and covering a large part of the cheek, is a plate
(x) of a somewhat oval shape, and somewhat obliquely placed, so that its long
axis runs from below upwards and forwards. Above, it is in contact with the
outer edge of the cranial shield; its posterior margin is separated from the
operculum by a smaller plate (p.op.). The latter is of a narrower shape, rather
pointed above and a little less so below ; its long axis is pretty parallel to the
direction of the hyomandibular which it covers ; its posterior margin, in contact
with the operculum, is gently convex ; its anterior one, somewhat angulated,
articulates with the large plate 2, and below also with the smailer one wa’.
This third plate z lies immediately above the articular extremity of the
mandible ; its posterior margin, covering the lower extremity of the hyoman-
dibular, is in contact with the suboperculum below, touching also the plate
p.op. above ; its upper margin is articulated with the plate 2, while in front it
comes into relation with the oblique posterior margin of the maxilla. As
figured by Acassiz, three precisely similar plates occur in the same position in
Megalichthys,* of which he compares both the upper and posterior to the
so-called pree-operculum of Polypterus, while the lower one he compares to the
little bone fixed above the posterior edge of the maxilla in the Salmonide, &c.,
and which by Mr Parker is considered to be the homologue of the malar bone of
other vertebrata.t In Osteolepis, according to PANDER, the corresponding space
on the cheek is occupied by one large plate, denominated by him “ preeo-
perculum,” on which, however, lines are visible indicating a division into three
similar component parts. On comparing the arrangement with what is seen in
* “ Poisson’s Fossiles,” vol. ii, part 2, p. 92; ‘ Atlas,” vol. ii. pl. Ixiii.a, figs. 1 and 3, 7, &, J.
+ “On the Structure and Development of the Skull inthe Salmon” (Salmo salar, L.), Phil. Trans.,
1872, p. 100.
THE CRANIAL OSTEOLOGY OF RHIZODOPSIS. 177
Polypterus, it is, I think, pretty evident that the bone p.op., together with the
one 2 in Lhizodopsis, corresponds to the large cheek plate in the former genus,
considered by Acassiz to consist of the equivalents of the cheek cuirass in
Lepidosteus united with the preeoperculum, while the lower one (2’) apparently
corresponds to the posterior of the two small plates, which in Polypterus are
placed below the inferior margin of the large one and behind the maxilla. The
bone p.op. in Rhizodopsis may then be considered as the prwoperculum, the
~ two others, x and a’, as equivalent to the cheek cuirass in Lepidosteus, or to
the posterior set of sub-orbitals in other Lepidosteids (e.g., Lepidotus), and in
the Paleoniscide.
In front of the bone 2, and above the maxilla, there are in some specimens
evident enough remains of the proper sub-orbitals, which seem to have cor-
responded in number and position pretty closely to those in Osteolepis. Two
of them (s.o. fig. 2)), corresponding respectively to the posterior-inferior and
anterior-inferior parts of the boundary of the orbit, are clearly seen in many
specimens, but the unfortunate manner in which the heads are crushed renders
any further description hardly possible.
The space between the right and left mandibular rami is occupied by a set
of jugular plates. Professor YouNG
has described these as consisting of
“two pairs, principal and posterior,”
and has also stated that there is ‘no
trace of median or lateral plates.” *
The specimens before me, however, do
not corroborate the views above quoted.
I find two principal jugulars (7. figs. 2
and 3) occupying almost the whole of
the space. Each of these is of the
usual oblong shape, and broader behind
than in front. The short and rounded
posterior margin passes uninterruptedly
into the internal one, which is more
convex than the external for the Fic. 3.—Under Surface of the Head of Rhizodopsis sawroides.
greater part of its length ; near the mn. mandible pe principal jugular ; 7.7. lateral jugular ;
; . m.j. median jugular ; s.op. suboperculum,
front, however, the internal and ex-
ternal margins converge and meet in an acute angle. What Professor Youne
means by a “posterior” jugular I am unable to determine, unless he
has mistaken for such a plate the broad infra-clavicular element of the
shoulder girdle, which, as in the recent Polypterus, is overlapped by the
posterior margin of the principal jugular. The presence of lateral jugulars
2 Op. cil.. 9p. 596,
178 RAMSAY H. TRAQUAIR
(7.7.) is clearly shown in several specimens, and are at least five in number on
each side. Of these, the hindermost is also the largest, and is situated below
the lower margin of the suboperculum, extending also beyond the posterior
margin of the principal jugular; the remaining four are placed between the
last-named plate and the mandible, and diminish in size regularly from behind
forwards. There is also the clearest possible evidence of a median jugular
(mj.), of a somewhat oval-acuminate form, placed immediately behind the
symphysis of the mandible, and overlapping to some extent the anterior
extremities of the principal jugulars. That the lateral and median jugular
plates were not noticed by Professor Youne, is clearly due to the more
imperfect material then at his command.
CONCLUSION.
The foregoing investigation into the osteology of the head of Rhizodopsis,
deficient as it is with regard to the more internally situated parts, nevertheless
brings out, in a very striking manner, the affinity of that genus to the rhombic-
scaled Saurodipterini, and supplies further evidence, were that now required,
of the comparatively small value of the mere external forms of scales as
indicating the natural affinities of ganoid fishes.
No one acquainted with the structure of Megalichthys can fail to be struck
with the extreme resemblance which its cranial osteology bears to that of
Rhizodopsis, not only in general arrangement but in the shapes of individual
bones,—a resemblance shared in as well by the teeth with their labyrinthically
plicated bases, by the shoulder bones, by the fins in their structure and position,
and by the vertebral column with its ring-shaped centra. Beyond a doubt, the
affinities of Rhizodopsis are much more with the rhombiferous Saurodipterini
than with the cycliferous Holoptychiide, although, on account of the form of
the scales, both Rhizodopsis and Rhizodus were once included in the genus
Holoptychius.
Very distinct family characters are, however, presented by the Saurodipte-
rini in the scales having assumed a sharply rhombic contour, in their free
surfaces, as well as those of the cranial bones and fin rays, being covered with
a layer of brilliant ganoine, and in the tendency of many of the bones of the
head to fusion with each other. In Megalichthys, for example, the mandible
though closely resembling that of Rhizodopsis in external contour and in the
form and arrangement of its teeth, has the elements—which in the latter genus I
have designated as angular, dentary, infradentary, and internal dentary—all
fused into one piece, an oblique line on the outside of the jaw usually indicating
the original separation of the dentary. In some Old Red Sandstone Sauro-
dipterini the original separation of the parietal, sguamosal, and posterior frontal
ON THE CRANIAL OSTEOLOGY OF RHIZODOPSIS. 179
elements of the cranial buckler, is on the surface almost entirely obliterated.
These circumstances would lead us to the conclusion that the Saurodipterini
constitute a more specialised type than the Cyclodipteride, in which, in a
previous essay,* I have included the genera Rhizodus, Rhizodopsis, Strepsodus,
Archichthys, and Tristichopterus, the Glyptolemini being probably intermediate.
Note added July 20, 1881.—For the term “ Cyclodipteride,” which I have
hitherto used for the family to which Rhizodopsis, Rhizodus, &c., belong, and
which I borrowed from Dr LitrTxen (“ Begrenzung und Eintheilung der
Ganoiden,” German edition, p. 47), though excluding the Holoptychii, which
were also here placed by him, I propose in future to substitute “ Rhizodon-
tide,” as being in every way more appropriate.
* “On the Structure and Affinities of Tristichopterus alatus,” Trans. Roy. Soc. Ed., 1874.
VOL. XXX. PART I. DE
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VIII.—On the Action of Phosphide of Sodium on Haloid Ethers and on the Salts
of Tetrabenzyl-Phosphonium. By Professor Letts and N. CoLiz, Esq.
The phosphines, or substances derived from phosphuretted hydrogen by
the partial or complete replacement of its hydrogen by hydrocarbon radicals,
have formed the subject of many valuable researches; but although their
discovery was anterior to that of the compound ammonias, their study has made
comparatively little progress. This is no doubt mainly due to the difficulty
attending their preparation, a fact which is immediately forced upon the notice
of any one who wishes to investigate them.
In spite of the undoubted analogies existing between phosphines and
amines, the methods employed for obtaining the former are, with one excep-
tion, different from those by which the latter are usually prepared. The
reason for this we may find in the great differences between the elements
phosphorus and nitrogen—differences which are in many cases still apparent
in their compounds. Thus, phosphorus forms no compound with carbon
analogous to cyanogen ;-nor have any phosphorised bodies been obtained
up to the present time analogous to the cyanides of hydrocarbon radicals.
Neither has a phosphorised cyanic acid, (HCPO), nor its hydrocarbon salts
been obtained.
And we have another link wanting in the chain of analogies existing
between nitrogen and phosphorus, in the absence of compounds of the latter
element analogous to the nitro-bodies. Now, the amines are usually prepared
by one or other of the four following processes :—
1. Action of nascent hydrogen on the cyanide of a hydrocarbon radical.
2. Action of caustic potash on the cyanate of a hydrocarbon radical.
3. Action of nascent hydrogen on a nitro-body.
4, Action of ammonia on a compound of a hydrocarbon radical with a
halogen.
For the reasons given above, the phosphines cannot be prepared by pro-
cesses corresponding with the first three of these methods; but Hormann,
in his masterly researches on these bodies, has shown that it is possible
to directly replace hydrogen in phosphuretted hydrogen by hydrocarbon
radicals, in a manner similar to that employed in the fourth of the above
processes,
But this is not the only process we possess for obtaining the phosphines,
VOL. XXX. PART I. 2F
182 PROFESSOR LETTS AND N. COLLIE ON THE
altheugh it is the only one analogous to any of those employed for preparing
amines ; and we shall give a short sketch of the other methods by which, from
time to time, the phosphines have been prepared.
Paut THENARD was the discoverer of the first organic phosphorus com-
pounds.* In the year 1843 he investigated the action of chloride of methyl on
phosphide of calcium ; and in 1847 he communicated to the Academy further
results as to the nature of the bodies obtained in the reaction. The investiga-
tion was attended with great difficulties, owing to the labour involved in
separating the different products, and in obtaining them in the pure state ; also,
on account of their explosive and inflammable nature, and their poisonous
properties.
In spite, however, of these difficulties, THENARD appears to have isolated
trimethyl-phosphine; a substance analogous to kakodyle, P,(CH;),; and
a substance analogous to solid phosphide of hydrogen, P,(CH;).. The
last he describes as an inert solid body; but the second, as a spontane-
ously inflammable liquid boiling at 250° C.—very explosive, poisonous, and
unstable.
THENARD recognised the relations existing between trimethyl-phosphine
and ammonia, and predicted the existence of the then undiscovered organic
compounds of nitrogen, arsenic, and antimony. In the meantime, Wirtz and
HornmaNnNn had verified THENARD’s predictions, having discovered the compound
ammonias ; and Lorwie and ScHWEITZER had obtained stib-ethyl.
HorMann and Canourst turned their attention in 1855 to the study of the
phosphines, and repeated THENARD’S experiments, with this difference, however,
that they substituted phosphide of sodium for phosphide of calcium. They
obtained trimethyl-phosphine, THENARD’s phosphorus kakodyle and iodide of
tetramethyl-phosphonium—but only after great difficulty. Speaking of the action
of phosphide of sodium on iodide of methyl, they say,—‘“ The action is very
energetic when the two are heated together (@ chaud). Moreover, inflammable
and detonating substances are formed, so that this method of preparation is
not without danger, and exposes the fruit of one’s labour to loss ...... It
is unreliable (trop pew sir), and furnishes mixtures, of which the separation
presents enormous difficulties.” For these reasons, they sought for a simpler
and more certain process. This they found in the action of zinc ethers
on terchloride of phosphorus, which gives a compound of chloride of zine
and the tertiary phosphine, from which potash separates the latter in a state
of purity.
By means of this reaction, HorMANN and Canours prepared the tertiary
phosphines of methyl, ethyl, and amyl. They determined some of their most
* Comptes Rendus, vols. xxi. and xxv.
+ Comptes Rendus, xli.
ACTION OF PHOSPHIDE OF SODIUM ON HALOID ETHERS. 183
important properties, and showed that in many respects they resemble the
tertiary amines, especially in the readiness with which they combine with
iodides of hydrocarbon radicals to give quaternary compounds. They found,
however, that, unlike amines, tertiary phosphines are capable of directly
combining with oxygen.
HorFMANN continued the study of the tertiary phosphines, and communi-
cated the results of his experiments to the Royal Society* in 1860. He
confined his experiments chiefly to triethyl-phosphine, and, in his lengthy
memoir, describes accurately its properties and reactions. He prepared
and analysed oxide of triethyl-phosphine and the characteristic red com-
pound which bisulphide of carbon forms with the phosphine itself, and he
investigated the action of the latter on a considerable number of organic
compounds.
BERLEt attempted to obtain triethyl-phosphine by the action of phosphide
of sodium on iodide of ethyl. The phosphide of sodium he prepared by the
heating sodium and phosphorus together in rock oil. Iodide of ethyl only
acted upon this at a high temperature, and he obtained only very small quantities
of the tertiary phosphine. Berit next attempted to prepare the tertiary
phosphine by heating sodium, phosphorus, and iodide of ethyl together in a
sealed tube; but although the bodies reacted, he does not seem to have
obtained any very satisfactory results.
Canours, in 1859, prepared iodide of tetrethyl-phosphonium by the action of
iodide of ethyl, on crystallised phosphide of zinc (prepared by heating the
metal in phosphorus vapour) at 180° C. The next experiments on the pre-
paration of phosphines are very interesting and important.
Previous to these only tertiary and quaternary compounds had been
obtained, but Hormann§ showed in an elegant manner that the primary and
secondary bases may be formed by the action of phosphuretted hydrogen on
the iodides of hydrocarbon radicals—a process exactly analogous to that
employed by him for preparing the corresponding amines. Phosphuretted
hydrogen, however, does not behave in exactly the same manner as ammonia
in this reaction, for HormMAnn found that the replacement of hydrogen does
not proceed further than the second atom; whereas with ammonia all the
hydrogen is replaced step by step, and even quaternary compounds are
formed.
Moreover, ammonia acts on the iodides of hydrocarbon radicals much more
readily than phosphuretted hydrogen, and at lower temperatures.
* Transactions Royal Society, London, vol. cl. p. 409.
¢ Journ. fiir. prac. Chem., lxvi. p. 73.
{ Comptes Rendus, xlix.
§ Berichte der. deutsch. chem. Ges., iv. pp. 205, 372; v. p. 100.
184 PROFESSOR LETTS AND N. COLLIE ON THE
Hormann’s process for obtaining primary and secondary: phosphines—
which he employed successfully in the methyl, ethyl, and benzyl series
—consists in heating a mixture of phosphonium iodide, zine white, and the
hydrocarbon iodide, in sealed tubes for some hours at a temperature of
160°-180°. The tubes are then found to contain a white crystalline mass,
consisting of compounds of the hydriodates of the primary and secondary bases
with zinc iodide.
The reactions which occur are represented by the equations,
2C,H,I +2PH,I + ZnO =2[(C,H,)H,P,HI}, ZnI, +H,0.
2C,H,I+PH,I +Zn0=(C,H,),HP, HI, ZnI,+H,0.
The separation of the primary from the secondary compound is accom-
plished with the greatest ease. It is only necessary to add water to the con
tents of the sealed tubes when the compound of the primary base is decom-
posed and the base itself set at liberty. When it has been distilled off, the
addition of potash to the residue separates the secondary base.
Hormann also studied the action of phosphuretted hydrogen on the alcohols
at a high temperature, and with a singularly interesting result.
Not only does phosphuretted hydrogen act on the alcohol, but the bodies
produced consist entirely of tertiary and quaternary compounds, no primary |
or secondary compounds being formed at all. Thus the action of phos-
phuretted hydrogen on an iodide of a hydrocarbon radical is exactly comple-
mentary to its action on an alcohol.
In employing the action of phosphuretted hydrogen on ordinary alcohol
for the preparation of the tertiary and quaternary phosphines, Hormann places
iodide of phosphonium at the bottom of a sealed tube, and above it the
alcohol in a smaller tube. The vapour of the phosphonium iodide thus comes
in contact gradually with the alcohol. The reaction is complete after six to
eight hours digestion at 180°. The tubes are then found to be full of a white
crystalline mass, from which caustic potash liberates the tertiary phosphine,
whilst the iodide of the phosphonium remains in solution.
The reactions which occur are represented by the equations
3(C,H,OH) + PH,I=P(C,H,),HI + 3H,0.
4(C,H,OH) +PH,I=P(C,H,),1 +4H,0.
MicHAELIS* has comparatively recently added to our knowledge of the
phosphines, and to the methods of preparing them.
By passing the mixed vapours of terchloride of phosphorus and _ benzol
through a red hot tube he obtained phosphenyl-chloride,
PCl, + CsH,=(C,H;)PCl, + HCl.
* Liebig’s Annalen, 181, p. 280.
|
ACTION OF PHOSPHIDE OF SODIUM ON HALOID ETHERS. 185
a substance which he also prepared by the action of terchloride of phos-
phorus on mercury di-phenyl,
PCl, + Hg(C,H;).=(C,H;)PCl, + HgCl(C,H,) .
By the action of water on this body, phosphenylous acid is produced,
(C,H;)PCl, + 2H,O =(C,H;)PO,H, +2HCl,
and this when destructively distilled yields phenyl-phosphine—the phosphorus
analogue of aniline,
3 {(C,H);PO,H,} =(C,H,)PH,+2C;H, + 2HPO,.
The same body results when hydriodate of phosphenyl-iodide (obtained by
the action of hydriodic acid on phosphenyl-chloride) is decomposed with
alcohol.
We were led in the first instance to the experiments to be presently
described by the difficulty which one of us had experienced in preparing
triethyl-phosphine on the large scale. Hormann’s later method had been at
first resorted to, but in spite of numerous experiments, it had led to no satis-
factory results. The pressure produced when alcohol and iodide of phos-
phonium are heated together is enormous, especially at the high temperature
(180° C.) at which they react, and in almost nine cases out of ten it was found
that the sealed tubes burst. ,
Nor is the other process for preparing triethyl-phosphine, viz., by treating
zinc-ethyl with terchloride of phosphorus, a simple operation. The preparation
of zinc-ethyl is expensive and troublesome, and although it reacts readily with
the terchloride, the reaction is not so simple as might be expected. Scarcely
50 per cent. of the theoretical quantity of crude phosphine can be obtained,
and this crude product contains impurities in considerable quantities, which
are very difficult to remove. The preparation of triethyl-phosphine is in fact
an expensive, uncertain, and troublesome operation.
Such being the case, and one of us requiring large quantities of it, the
question naturally presented itself—Is there no simpler and less expensive
process for preparing a tertiary phosphine? It seemed to us that one of the
processes—and in fact the earliest—for preparing these bodies ought to be an
extremely good one, if the difficulties attending its general application could be
removed. The process to which we allude depends upon the ease with which
metallic phosphides can be formed, and the readiness with which haloid ethers
act on them. As before stated, THENARD, Beruz, Canours, HOFMANN and
others, have worked with this process, but it has not met with great favour,
and was abandoned by Hormann (who employed phosphide of sodium) on
186 PROFESSOR LETTS AND N. COLLIE ON THE
account of the uncertainty of the reaction, the frequent explosions, and the
great difficulties in separating the resulting phosphines from each other,—“ not
to speak of the difficulty of obtaining the phosphide of sodium fit for the
reaction.”
It seemed to us, however, that in phosphide of sodium an admirable reagent
was at hand for the preparation of tertiary phosphines—provided only, to quote
again Hormann’s words, that it can be obtained in a state “fit for the
reaction.”
This conclusion has been borne out by our experiments. With proper
precaution, phosphide of sodium may be obtained in any quantity, and in a
perfectly safe condition. It reacts with haloid ethers in a perfectly smooth
manner, nor have we ever had an explosion, nor remarked the production of
explosive bodies.
Our first experiments were made with iodide of ethyl. The reaction occurs
at ordinary temperatures with ease, the iodide of ethyl boils violently, and the
chief product of the reaction appears to be the iodide of tetrethyl-phosphonium.
We have not as yet, however, brought these experiments to a conclusion,
because of the difficulties which we experienced in separating the phosphines
and phosphonium salt from the iodide of sodium produced along with them in
the reaction.
Our next experiments were made in the benzyl series, which we chose
partly because neither tribenzyl-phosphine nor tetrabenzyl-phosphonium salts
have hitherto been obtained, and partly because no deliquescent or volatile
bodies were likely to be formed, thus rendering the investigation free from
those difficulties which cause experiments in the methyl and ethyl series to be
so troublesome and laborious. To these reasons for our choice of benzyl must
be added its similarity to fatty radicals and the well-known ease with which its
compounds react.
Before proceeding to describe our experiments on the preparation of phos-
phide of sodium, and on its action on chloride of benzyl, we consider it
necessary to give a short account of Hormann’s researches on monobenzyl-
and dibenzyl-phosphine, which we believe to be the only ones that have been
made on benzyl-phosphines.
Benzyl-Phosphines.
The following is an abstract of Hormann’s paper on “ Aromatic Phos-
phines” :*—
He was induced to experiment on the aromatic series, in consequence of the
readiness with which, by the use of iodide of phosphonium, he had obtained
* Hormann, Ber. d. deutsch. chem, Ges., iv. p. 100.
ACTION OF PHOSPHIDE OF SODIUM ON HALOID ETHERS, 187
methyl- and ethyl-phosphines. His first attempts were made with the view of
obtaining a phenyl-phosphine analogous to aniline, a substance highly interest-
ing from a theoretical point of view.
To obtain this body he heated, under varying conditions, phenyl-chloride
and iodide of phosphonium ; but the experiments did not lead to a successful
result, the phenyl-chloride becoming reduced to benzol, which even at high
temperatures was not further acted upon. ‘That the reaction did not proceed in
the desired manner was, as he says, not surprising, considering the inertness of
chloride of phenyl and the fact that aniline cannot be obtained by acting
on it with ammonia.
Equally unsuccessful were his efforts to obtain the tertiary phosphine and
the quaternary compound by the action of phenol upon iodide of phosphonium,
though phosphorised bodies resulted, the nature of which he did not ascertain.
Experiments to obtain a phosphorised toluidine led to no successful
issue ; but, on the other hand, the preparation of a phosphorus analogue of
benzylamine presented no difficulty, as indeed he did not doubt, considering
the readiness with which chloride of benzyl reacts with ammonia.
Benzyl Phosphine, C,H,PH,.—This body is formed when chloride of
benzyl (which may be employed in the crude condition) is heated for six hours
at a temperature of 160° with a mixture of phosphonium iodide and zinc
oxide. The substances are taken in the proportions of 2 molecules benzyl
chloride, 2 of phosphonium iodide, and 1 of zinc oxide.
When complete reaction has occurred the sealed tubes in which the mixture
has been heated contain a white crystalline mass. On opening them a large
quantity of phosphuretted hydrogen is evolved. On distilling the product of
the reaction with water a heavy, oily liquid passes over of highly characteristic
odour. This is separated, dried with caustic potash, and distilled in hydrogen.
The thermometer rises to 180°, and then remains stationary, whilst a considerable
quantity of a colourless, highly refractive liquid distils. | This is monobenzyl-
phosphine, whilst the lower boiling fraction consists mainly of toluol, and the
residue in the retort contains dibenzyl-phosphine and other products. ' (CAH,) PO... (C,H) FHP:
Carbon, 1 .%ea 2 OG tat .' 18°9
Hydrogen, . : 661), GG 5 | 66
We did not think it likely that dibenzyl-phosphine had been formed in the
reaction, as we could not account for the hydrogen atom which it requires ;
but bearing in mind the results of our experiments on the action of baryta on
the acid sulphate of tetrabenzyl-phosphonium, it did not appear impossible
that oxide of tribenzyl-phosphine had been formed ; for, by the action of phos-
phide of sodium on water, caustic soda is produced: this might react on
chloride of tetrabenzyl-phosphonium, and give rise to oxide of tribenzyl-phos-
phine and toluol.
At first sight, such a supposition may not appear probable, as haloid salts
of methyl- and ethyl-phosphonium are not changed by caustic alkalies; but we
have shown that corresponding salts of benzyl-phosphonium possess very
different properties from these bodies. On treating the product of the action
of phosphide of sodium on chloride of benzyl with water, abundance of phos-
phuretted-hydrogen was evolved, showing that a considerable quantity of
phosphide of sodium had remained unacted on. The solution was boiled; and
thus, if alkalies really act on chloride of tetrabenzyl-phosphonium in the manner
we have indicated, we have the necessary conditions for the production of oxide
of tribenzyl phosphine.*
As a further argument for supposing that the oxide had really been
obtained, and not the cacodyl, it will be noticed that, although the percentage
of carbon calculated for the two bodies varies by only 0°8 per cent., the results
of our analyses are more favourable to the supposition that the body is the
oxide, and not the cacodyl. For we obtained 0°3 per cent. too much carbon
for the cacodyl, and therefore 0°5 per cent. too little for the oxide; and in
carefully conducted organic analyses the carbon is often too low, but seldom
too high.
We had noticed that oxide of tribenzyl-phosphine (obtained as described
at p. 198) combines with iodide of zinc to form a compound (analogous
to Hormann’s zinc iodide compound of triethyl-phosphine oxide) of charac-
teristic crystalline form. If, then, the substance were the phosphine oxide, the
* We have since proved that alkalies act very readily on chloride of tetrabenzyl-phosphonium, On
boiling a solution of the chloride in alcohol with potash or soda for a few minutes, decomposition occurs,
chloride of the alkaline metal is precipitated and the solution contains oxide of tribenzyl-phosphine,
which is easily identified by its insolubility in water and other characteristic properties.
ACTION OF PHOSPHIDE OF SODIUM ON HALOID ETHERS, 205
production of this salt would be an almost crucial test. We therefore proceeded
with the supposed cacodyl as we had done with the oxide of tribenzyl-phosphine,
and operating under exactly the same conditions, obtained a double salt with
zinc iodide, which could not be distinguished rie that of the oxide, either in
crystalline form or in composition.
We have further verified the identity of the supposed cacodyl with oxide
of tribenzyl-phosphine, by processes which we may consider along with the
properties of that substance.
Since writing the above, we have noticed that oxide of tribenzyl-phosphine
has been obtained by F. FLEISsNER,* by the action of benzal chloride on iodide
. of phosphonium. The results of FLEISSNER’s investigations on the properties of
the oxide, so far as they go, are in accordance with our own.
Oxide of Tribenzyl-Phosphine.—Subjoined are the results of the analysis of
the oxide prepared by three different methods :-—
I. Obtained as just described from the residues.
II. and III. Obtained by the action of caustic baryta on chloride of tetra-
benzyl-phosphonium.
IV. Obtained during experiments on the action of sodium on chloride of
tetrabenzyl-phosphonium (see p. 211).
Obtained. Calculated for
P(C,H;)30
I. Il. Ill. IV.
Carbon, . . ; Seb ise 79:2 788 78:3 78°75
Hydrogen, . Ss) 6°8 6'8 67 6°56
=~
Phosphorus, . : . 85 88 — — 8:4 9°68
Oxygen, : : oo _ i 5°01
100-00
The three specimens were quite different in appearance.
I. Crystallised in thick needles of great refractive power, and quite trans-
parent.
II. and III. In opaque plates of indefinite form.
IV. In very bulky, silky needles.
We could not at first reconcile ourselves to the belief that they were one
and the same body.
The following carefully conducted experiments, however, appear to prove
beyond doubt that they were so :—
Melting Point.—This was determined in the whee manner, by heating the
carefully dried and pulverised substance in a capillary tube tied to a thermo-
* Ber. d. deutsch. chem. Ges., xiii, 1665.
VOL. XXX. PART I. 21
206 ‘ PROFESSOR LETTS AND N. COLLIE ON THE
meter, both thermometer* and capillary tube being placed in a beaker con-
taining sulphuric acid.
in I... snd 00, LY,
—_—_—_———"
(@) PLE Gianks uncrt boda i ee ions
(6) 212° ; : ; 212° 5 , : 210-212°
The temperature is uncorrected.
Double Salt with Zine Todide—This compound was formed easily with
any of the three specimens, by adding to its alcoholic solution an alcoholic
solution of zinc iodide, and evaporating to small bulk. The double compound
separates in thin transparent plates of characteristic form.
Examined under the microscope no difference could be detected in the
crystalline form of the double salt prepared with any of the three specimens of
the oxide.
The salt was analysed by volumetric determinationt of iodine in specimens
of Nos. I. and of II. and III.—
I. 0:606 grm. required 12°4 cc. decinormal AgNO,=0'15748= 26:0 per cent, iodine.
II. and III. 0-232 _,, - 47 ,, 3 5) = 005969259 2 5
Calculated for {P(C;H,),0},ZnI, . : : ; : ‘ : . 26-4
»”
» »
Chloroplatinate.—This salt is characteristic, and is formed with ease on
mixing dilute alcoholic solutions of the oxide and chloride of platinum. It
separates almost immediately as a light orange-coloured granular powder-—
which, under the microscope, is seen to consist of groups of needles, thick,
four-sided, and with blunt ends. Very commonly two needles form a cross,
at other times several radiate from a common centre. No difference could be
detected in the crystalline form of the chloroplatinate prepared with any of the
specimens.
The salt was analysed by determination of carbon, hydrogen, and in one
specimen of chlorine also :—
I,
Chlorine.
0:4356 grm. required 15:3 ce, decinormal AgNO,='054315 Cl=12'4 per cent.
0-4605__,, » 26"4.c¢, » =05822 ,, =12°6 per cent.§
IV.
Carbon and Hydrogen.
(A) 0°3932 grm. gave 0°8497 CO, = 0:25491 C = 58:9 per cent.
03932 ,, _, 01874 BO = 002082 = 5:3 5;
(B)-0:2738- ;, ,, 05975 CO, = 016295 C = 594. |,
O2788 , » 01350 0,0 = 0015" d= 76%) Is;
* One of CasELua's.
+ VorHarpt’s method.
+ Hormann’s method.
§ By precipitating the platinum with sulphuretted hydrogen and titrating the filtered solution.
ACTION OF PHOSPHIDE OF SODIUM ON HALOID ETHERS. 207
iE, IV.
ee _
Carbon, tela . ‘ , : 58°9 59-4
Hydrogen, . : ‘ ‘ ; : 53 54
4 —_—
Chlorine, 12°4 Poy ase , ; —— —
Platinum, ——— — —_——
The formula which HormMann~* gives for the chloroplatinate of the oxide of
triethyl-phosphine is 3(Ft,PO), Et,PCl,, PtCl,; but this formula does not
appear to be a very probable one. It seems to us to be more likely that
the chloroplatinate is a compound of the phosphine oxide with hydrochloric
acid and chloride of platinum, and we find that the numbers calculated for such
a formula, viz., 4(Et,PO), 2HCl, PtCl,, agree as closely with those obtained by
HorMann in the analysis of the chloroplatinate, as do those calculated from his
formula, thus—
Calculated for
Obtained. 3(Et. oi (Et,PCl,),PtCl,. 4(Et,PO),2HCl, PtCl,.
Carbon, 30°17 5 : 30°9 : ? 30°4
Hydrogen, 6°75 F ; ; 6:4 ' , ; 63
Platinum, 21:06 : : : 21°2 : ; : : 20°8
Chlorine, 22°93 : . ’ 22:9 , F ; 22:5
It will be seen that the only difference Peiven these two formule is that
the one on the right hand contains an atom more oxygen and two atoms more
hydrogen than the one on the left ; that is to say, a difference of 18 as regards
molecular weight. As the latter amounts to 930 in Hormann’s formula, the differ-
ence in the calculated percentage of each element is very slight, and this is still
more the case with the chloroplatinate of the benzyl compound—the molecular
weight of which with Hormann’s formula is 1674, and with our formula 1692.
But, on the other hand, the proportion of carbon is so large that the percen-
tage of that element is perceptibly different with the two formule, and it will
be seen that this difference is decidedly in favour of the formula which we
propose.
We may add that it appears to us to be highly improbable that O should be
replaced by Cl,, by simply mixing at ordinary temperatures chloride of plati-
num and the phosphine oxide.t
The results of our analysis, compared with the numbers calculated for the
two formule are—
Calculated for Calculated for
eS ee eT LES
Obtained. 3{ oR ets { eee te e PtCl, 4{(C,H,),PO}2HCLPtCl,.
Carbon, 59:2 ; : ; 595
Hydrogen, 5:3 é : : os ; : : : 50
Platinum, —— : ; 2 lly, : : ; : . ai alorA
Chlorine, 12°5 s : ; 12°7 : : ‘ , ; 12'5
* Trans. Roy. Soc. Lond., 1860, p. 418.
+ The experiments of Crarts and Srtva (Joc. ct.) show that this replacement does not occur.
208 PROFESSOR LETTS AND N. COLLIE ON THE
Brominated Compound.—This is a very characteristic substance, and its
production, with all of the specimens of the supposed oxide, we considered to
be a strong proof of their identity. .
It is formed by dissolving the phosphine ais in Siarel acetic acid (boiling),
and adding bromine in excess. No visible reaction occurs, except that the
bromine is at first decolorised. On cooling, the compound is precipitated as a
granular crystalline powder of bright yellow colour. Sometimes needles are
observed ; but these are found, when examined under the microscope, to con-
sist of cubical or rhombohedral crystals united ; the crystalline powder consist-
ing of the same forms isolated.
For analysis, the compound was simply dried 72 vacuo for some time, and
was not recrystallised.
Carbon and Hydrogen. *
0:4746 orm. gave 0'9915 CO, = 0:2704C = 56:9 per cent.
O4746''., ,, 02117 0: ="0'02330 49 ,,
Phosphorus. + , ;
06777 required 16:1 cc. uranium solution =0-0368 P = 5:2 per cent.
Bromine. }
0:1685 required 6:0 ce. silver solution= 0°048 Br=28-4 per cent.
0:2128 RO TD O MCE ass ; = 0060 Br=23:3 ,,
0:3498 plerlieai tema res; fim a D009 BuiPaisiaim 5
These numbers agree closely with the rather curious formula,
4 {(C,H,),POBr,} ,(C,H,),PO, or 5 {(C,H,),PO}, 4Br, ,
but with no other that appeared probable.
Obtained. Calculated. ©
1. Il. Ul.
Carbon, : ; 56°9 — — i : 563
Hydrogen, . 4 4:9 — — ; ; 4-7
Phosphorus, : 52 — — i : 69
Bromine, . b 28-4 28:3 ~~ 283 ; , 28°5
The bromine compound when treated with acetic acid loses bromine. It
cannot, therefore, be readily recrystallised. Heated by itself it fuses, but at no
definite temperature, to a deep yellow liquid. Hydrobromic acid is then given
off, and later bromide of benzyl (2) distills. Heated with alcohol it dissolves,
and the solution (at first yellow) gradually becomes colourless, and the odour of
bromide of benzyl is apparent ; but a considerable quantity of bromine may be
precipitated by nitrate of silver from the alcoholic solution. When boiled with
water it decomposes, and bromine is evolved.
* By combustion with oxide of copper and chromate of lead.
+ Fused in a silver dish with caustic potash and nitrate of potash, and subsequently titrated with
uranium solution.
{ Fused in a silver dish with caustic potash, and subsequently titrated by VorHarpt’s method,
ACTION OF PHOSPHIDE OF SODIUM ON HALOID ETHERS. 209
Sulphuretted Compound.—When the phosphine oxide is fused with sulphur
a reaction occurs, which apparently varies with the temperature and with
the quantity of sulphur employed. Jf much sulphur is taken and the mixture
heated to a high temperature, sulphuretted hydrogen is evolved, the mass
becomes dark coloured, and resinous products are formed.
But if the proportion of sulphur is low (P(C,H,),0 :S,) and the temperature
is kept at the melting point of the oxide or rather higher (240°), the sulphur
dissolves, no gas is evolved, and the product dissolves completely in a large
quantity of boiling alcohol. The solution on cooling deposits beautiful silky
needles of a light buff colour, which do not readily change in appearance (nor
alter in their melting point) by recrystallisation. That the new substance
contains sulphur is shown by burning it on platinum foil, when a strong odour
of sulphurous anhydride is at once observed.
The substance fuses at 211°-212° (uncorrected). It is insoluble in water,
and sparingly soluble in alcohol. The only determinations made were of the
carbon and hydrogen which it contains.
0:2103 gave 0:597 CO, =0:16254 C =77°3 per cent.
02103 ,, 0132 H,O=0:01466 H= 6:9 *
These numbers do not agree with any simple addition product. The only
probable formula which agrees with the numbers obtained is,
4 {(C;H;)sPO}, (C;H;);,POS=5 {(C;H,),PO},S.
Thus—
Obtained. Calculated.
Carbon, ; : ; (TS ; : : To
Hydrogen, . _ ‘ 6:9 4 : ‘ 6-4
Examination of Residue, soluble in Chloroform and Alcohol only.
This portion of the residue was contained in the dark brown mother liquors
of the crystalline substance, which the preceding experiments have shown was
oxide of tribenzyl-phosphine.
On evaporating off the alcohol a dark brown syrupy mass remained, which
solidified on cooling to a resin. This contained some crystalline matter, which
we could not succeed in separating. We have subjected the resin to many
experiments with the view of obtaining definite products, only, however, with
partial success.
In one of our earlier experiments we subjected it to the action of heat. 55
grms. were heated in a distilling flask. The thermometer rose rapidly to
380°, and a small quantity of a solid substance distilled. The temperature
then fell suddenly, and a liquid distillate was obtained. After some time the
temperature again rose above the boiling point of mercury, and the residue
began to char. The products of this distillation were collected together and
210 PROFESSOR LETTS AND N. COLLIE ON THE
redistilled. They began to boil a little above 100° C. The distillate was
divided into two fractions, viz., from 100°-200° C., and from 200°-3820° C.
The first of these was liquid, and on redistillation passed almost entirely
between 110°-114° C. (chiefly at 112° C.), and had all the properties of toluol. The
second was solid, and contained a large quantity of free phosphorus. As
its fractional distillation did not give satisfactory results it was dissolved in
boiling alcohol. Free phosphorus in some quantity remained undissolved,
and on filtering and cooling the solution, colourless crystals separated. They
were collected and recrystallised until their melting point was constant, viz.,
118° C. |
This is the melting point given by Laurent for stilbene, and the crystalline
habit which is so characteristic was exactly the same as that of the substance
under examination. On combustion we obtained numbers agreeing fairly well
with those calculated for that hydrocarbon.
0:3135 gave 1-0815 carbonic anhydride=0:29495 carbon =94'1 per cent.
03135 ,, 0°1965 water =0°02183 hydrogen=6°9 a
Obtained. Calculated.
Carbon, , ; ; 94:1 : : : 93:3
Hydrogen, . : : 6°9 . : : 66
The mother liquors from which it had been separated were concentrated, and
yielded a batch of colourless crystals, which were not examined. The mother
liquors from them were considerably concentrated, and yielded another crop of
colourless crystals, which, after repeated recrystallisation, ceased to alter in
melting point. This was 51° C, which is that of dibenzyl. We have not
analysed the substance, as we considered its identity with dibenzyl proved by
its melting point and characteristic odour.
We had thus proved that the resin split up on heating into free phosphorus,
stilbene, dibenzyl, and toluol—a result which might occur supposing it to
have consisted of tribenzyl-phosphine. The equation,
Stilbene. Dibenzyl. Toluol.
—s es ——
2(C,H,);P=2P+C,,Hi, + CyHy + 20H.
shows this.
This supposition is strengthened by the fact that sulphide of benzyl yields
stilbene when heated; and one of us has shown that organic compounds of
phosphorus and sulphur often behave in a similar manner.
Moreover, subsequent experiments showed that chloride of tetrabenzyl-
phosphonium is decomposed by heat into hydrochloric acid, and the same pro-
ducts as we obtained on heating the resin. We also heated the resin with
chloride of benzyl in a sealed tube for some time at 180°-190°C. Nothing par-
ACTION OF PHOSPHIDE OF SODIUM ON HALOID ETHERS, yal
ticular appeared to have occurred, the contents of the tube consisting of a brown
viscous mass. But on boiling this with water, and cooling the solution, chloride
of tetrabenzyl-phosphonium crystallised out, and was proved to be pure by a
determination of chlorine.
0°656 required 13°5 cc. decinormal AgNO,=7°3 per cent. Cl.
(C,H,),PC1,2H,O requires : : Paro Ate .
This experiment would have definitely proved the resin to consist of tribenzyl-
phosphine, had the phosphonium chloride been produced in large quantity ; but
such was not the case, for about 20 grms. of resin only gave about 2 grms. of
the chloride ; still it shows that the resin contained the phosphine.
As Hormann (loc. cit.) has found that dibenzyl-phosphine does not combine
with acids, we could scarcely expect to obtain salts of the tertiary-phosphine.
We, however, heated the resin with fuming hydrochloric acid, but, as we
expected, obtained no salt. We have also tried to obtain the well characterised
oxide of tribenzyl-phosphine, by treating the resin with various oxidising
agents, but without success. Nor could we obtain any definite compounds on
treating the resin with bromine, chloride of platinum, or iodide of zinc. We
therefore abandoned its further investigation,
Attempts to prepare Tribenzyl-Phosphine.
So far as we are aware, no method has been discovered for converting
the oxide of a tertiary-phosphine or a salt of a compound phosphonium into a
tertiary-phosphine itself.
Considering the remarkable stability of the former class of bodies, and the
tenacity with which the oxygen adheres to the phosphorus, we scarcely expected
to effect the reduction of the oxide of tribenzyl-phosphine. We, however, sub-
jected it to the action of potassium, of sodium, and of zinc dust, but, as we
expected, it either remained unchanged, or suffered complete decomposition.
We hoped, however, to meet with better success in attempting to obtain
tribenzyl-phosphine from chloride of tetrabenzyl-phosphonium. Two methods
suggested themselves to us, the first being to act on the chloride with sodium,
which we anticipated would give chloride of sodium, dibenzyl, and the
phosphine,
2[ (C,H,),PCl] + Na,=2NaCl+C,,H,,+2(C,H,)sP.
A preliminary experiment showed that when chloride of tetrabenzyl-
phosphonium is boiled for some hours with xylol and sodium, chloride of
’ sodium is produced,
We therefore made a carefully conducted experiment as follows :—
24 orms. of the pure chloride were carefully dried and introduced into a
212 PROFESSOR LETTS AND N. COLLIE ON THE
flask connected with a reversed condenser. 100 grms. of redistilled xylol
(boiling point 135°-137° C.) were then added together with 1°3 grm. of sodium.
A current of hydrogen was then passed through the apparatus, and the mixture
kept gently boiling. When most of the sodium had been acted on (which
required some days’ digestion), the xylol was poured off and filtered. On
cooling, it deposited an abundance of crystalline matter. This was collected
on a cloth filter, well squeezed to free it from adhering xylol, and dissolved in
boiling alcohol. On cooling, crystals separated having the appearance of oxide
of tribenzyl-phosphine, and which were proved to consist of that body. The
xylol from which this oxide had separated was distilled to dryness, and the
residue taken up with boiling alcohol. The solution on cooling deposited beau-
tiful silky needles, which were recrystallised twice from alcohol. In spite of
their very different appearance from other specimens of oxide of tribenzyl-
phosphine, a most careful examination showed that they consisted of that body
' (see p. 205). We are completely unable to account for the difference in appear-
ance of the two quantities of the oxide obtained in this experiment. No one
would imagine that they were the same body. We could not obtain any other
definite products from this experiment.
Now the production of the oxide may be accounted for in two ways—(1)
the chloride of tetrabenzyl phosphonium was not perfectly dry, and caustic
soda was formed, which then acted upon it (as we have already shown), to give
toluol, common salt, and the oxide; (2) tribenzyl-phosphine was formed, and
absorbed oxygen from the air during the subsequent processes to which the pro-
duct of the reaction was submitted. We have repeated the experiment several
times, using every precaution to prevent water or oxygen from coming in con-
tact with the mixture of sodium, xylol, and the phosphonium chloride, but
always with the same result—viz., production of large quantities of the oxide.
At present we do not know which of the two explanations we have given of its
production is the correct one.
We may mention that finely divided silver acts on the chloride of tetra-
benzyl-phosphonium when the two are heated together ; the action, however,
only occurs to a slight extent, and we were not successful in obtaining any
definite product.
The other method that occurred to us for obtaining tribenzyl-phosphine
from the chloride of tetrabenzyl-phosphonium was to treat the latter with
phosphide of sodium, which we hoped would react so as to give tribenzyl.
phosphine and chloride of sodium,
3(C,H,),PCl+ Na,P =3NaCl+4(C,H,),P.
The following experiment was made :—3 grms. of phosphide of sodium and a
little xylol were heated in a sealed tube, with 13 grms. of chloride of tetrabenzyl-
ACTION OF PHOSPHIDE OF SODIUM ON HALOID ETHERS. 213
phosphonium. After three days’ heating at a temperature of 180°-190° most of
the phosphide was acted on. The tube was then opened and repeatedly extracted
with dry chloroform. The extract was distilled to dryness, and the residue
treated with ether, which dissolved most of it, but left a small quantity of the
oxide of tribenzyl-phosphine. The ethereal extract was evaporated to dry-
ness, and left a light-coloured soft resin, which partly crystallised. A phos-
phorus determination showed that this contained the quantity of that element
calculated for tribenzyl phosphine,
0-651 required* 29-1 cc. uranium solution = 9:9 per cent. P
(C,H,),P requires NO Bre
The quantity, however, of the resin at our disposal was so small that we could
not make a thorough investigation of it. But we are inclined to the belief that
both it and the resin obtained as a bye product in the preparation of the chloride
of tetrabenzyl-phosphonium consisted mainly of tribenzyl-phosphine (see p. 209).
Action of Heat on the Salts of Tetrabenzyl-Phosphonium.
During the experiments we have described, we obtained on heating several
of the salts of tetrabenzyl-phosphonium, results which invited a closer investiga-
tion. Partly on this account, and partly from the interesting results which Drs
Crum Brown and Buatkret have obtained by the action of heat on the salts of
trimethyl-sulphine, we determined to study the behaviour of one or two of the
compounds of tetrabenzyl-phosphonium when heated.
Action of Heat on Chloride of Tetrabenzyl-Phosphonium—We hoped that
the salt would dissociate when submitted to the action of heat into chloride of
benzyl and tribenzyl-phosphine.
A considerable quantity of the chloride previously dried and fused was
placed in a small distilling flask and heated in an air bath. Nothing particular
occurred until the temperature had risen to about 300° C., when the fused salt
began to grow brown, and a colourless liquid distilled. When a considerable
quantity of this had passed over, hydrochloric acid was evolved, and later the
distillate was yellow, and contained an abundance of free phosphorus. The
heating was continued until nothing further distilled. There remained a con-
siderable residue, consisting chiefly of charcoal.
The whole of the distillate was fractionated. Hydrochloric acid was evolved
in abundance; the thermometer then rose to 109°, and by far the larger quantity
of the product passed over between that temperature and 115°. This fraction
on redistillation boiled constantly at 110°-113°, and had the odour of toluol.
_ It was not further examined, and was considered to be that substance.
* After fusion with a mixture of nitrate of potash and caustic potash.
+ Proceedings Roy. Soc., Edin.
VOL. XXX. PART I.
i)
A
214 ‘PROFESSOR LETTS AND N. COLLIE ON THE
The higher boiling residue passed between 280°-300°, and solidified in the
condenser. It was dissolved in alcohol, and recrystallised several times. The
recrystallised substance had the characteristic form and melting point (118° C.)
of stilbene.
In the mother liquors there remained a solid of lower melting point, and
having the odour of dibenzyl; but its quantity was too small to enable us to
identify it absolutely. We think that there can be but little doubt that
it consisted of that body.
No chloride of benzyl could be found, although the liquid product certainly
smelt of it. Its quantity was therefore insignificant. 2
This experiment shows that the phosphonium chloride is not dissociated by
heat, but splits up in a somewhat complicated manner. Very possibly the first
action of heat is to give stilbene, hydrochloric acid, and tribenzyl-phosphine.
C H,) — X = = = = a
F Oe Mote P01) = 2C;Hy)gP + OyH,—CH=CH-O,H, + 2HCl.
5
The phosphine splitting up later into toluol, stilbene, and dibenzy].
C,H,—CH:H C,H,—Ca—Ch CG He 4 C,H Ore
2(C,H;-OHH —SP} = ‘
C,H,—CHH: +C,H;—CH,—CH,—C,H; + 2P.
It is however quite possible, considering the large quantity of toluol which
is formed in proportion to the stilbene, and also considering the considerable
amount of charred matter which remains, that the tribenzyl-phosphine splits up
into toluol, and the residue C,H;—C,] only, the latter becoming carbonised.
cath = c= + 2C,H,—CH,.
Action of Heat on the Acid Sulphate.—8 grms. of the acid sulphate were
carefully dried, and heated in a small retort connected with a wide con-
densing tube. The salt fused, then effervesced violently, and a colourless liquid
distilled which solidified in the condenser. Sulphurous anhydride was given
off at the end of the operation, and a slight residue of syrupy consistency
and of a dark brown colour remained in the retort. The crystalline product
was washed with alcohol until quite colourless, and then recrystallised several
times from the same liquid, in which it was not very soluble. It crystallised
in very thin needles of considerable length. These melted at 205°-206° C.
It did not precipitate chloride of barium, but contained sulphur, as it gave
the sulphuric acid reaction after it had been oxidised with a mixture of
a
ACTION OF PHOSPHIDE OF SODIUM ON HALOID ETHERS. 215
nitric acid and chlorate of potash; and molybdate of ammonia showed that
phosphoric acid was also present in the substance thus oxidised. No chloro-
platinate could be obtained, but on mixing alcoholic solutions of the substance
and of chloride of platinum a black precipitate was produced, consisting either
of reduced platinum or of its sulphide.
The substance was burnt with chromate of lead and oxide of copper, and
gave numbers agreeing with those required for the sulphide of tribenzyl-
phosphine.
0:3567 gave 1:0097 CO, = 0:27587 C = 74:4 per cent.
- 03567 ,, 0:2114 H,O = 0:02348H= 66
»
Calculated for
Obtained. (C,H,), PS.
Carbon, , F 744, ; ; , f 75:0
Hydrogen, . : Gh. 3 P ; 6:2
The compound was not further examined.
Action of Heat on the Hydrate.—From the experiments described at p. 196
on the action of caustic baryta on the acid sulphate, we were led to think that
the latter would easily split up into toluol and oxide of tribenzyl-phosphine,
and we therefore determined to ascertain if this supposition were correct.
A quantity of the hydrate crystallised from alcohol was placed in a distilling
flask and heated in an oil bath. The alcohol of crystallisation first passed off,
and at 250° C. the compound melted, and immediately a colourless liquid began
to distil, which ceased to pass over at 260° C. The liquid was redistilled and
boiled constantly at 111°-112° C. It consisted therefore of toluol.
The residue in the distilling flask crystallised on cooling, was insoluble in
water (whereas the hydrate readily dissolves), but was soluble in alcohol, and
crystallised in the characteristic form of the oxide. Its melting point was
found to be 212° C., and it gave the characteristic brominated compound and
chloroplatinate of the oxide.
The decomposition which the hydrate suffers when heated may therefore be
expressed by the equation—
(C,H,),P(OH) =(C,H,),P0 + C,Hg.
Action of Heat on Oxide of Tribenzyl-Phosphine.—The oxide partly volatilises
unchanged when it is heated, and partly decomposes into toluol, free phosphorus,
charred matters, and other substances obtained in too small quantity to be
investigated.
(217 )
IX. —On the Geology of the Ferée Islands.
F.R.S. L. & E. (Plates XIII, XIV., XV., XVI)
(Read March 15, 1880.)
By James Gerke, LL.D.,
CONTENTS.
, PAGE
I. IntTRopucTION 218 3. Miocene Age of the Strata:
Physical Conditions, ete.
II, Paysican FEATURES OF THE 4, Position of old Volcanic Centre
IsLANDS.
1. Extent, Form, and Trend of = aaa aga Ae
the Islands and Fiords 220 Stns
2. Configuration and Height of 1. Early Notices of Glacial Phe-
the Land 221 nomena 5 ;
3. Valleys 222 2. Glaciation
4, Lakes and Streams 222 3. Till or Boulder-clay
4, Erratics and Morainic Débris .
III. Grotocican STRUCTURE OF THE 5. Lake-Basins
ISLANDS.
i Genel Din or the Strata 993 VI. OricIN oF THE V ALLEYS AND Fiorps:
2. Contemporaneous or Bedded SUBAERIAL AND GLactaL ERo-
Basalt-rocks of Suderée 223 Suen
3. Bedded Tuffs of Suderée 226 1. Forms of Valleys
4, Coal and Coal-bearing Beds of 2. Fiords ;
Suderde 227 3. Trend of Valleys ead Biords
5. Coal, &c. of Asean ead Main Water-parting
Tindholm ‘ 229 4, Origin of Main Water-parting
6. Subsequent or Intrusive Basalts 5. ioangesieete Erosion :
of Suderée . 230 6. Former Greater Rainfall
7. Contemporaneous or Bedded 7. Glacial Erosion of Valleys
Basalt-rocks of Northern 8. Weathering of Glaciated Sur-
Islands ; 231 face :
8. Bedded Tuffs of N Mtoe 9, Limited Necaraelelizoh of Till
Islands 235 on Land c
9. Subsequent or meaetve Tei 10. Direction of Jce-flow and
of Northern Islands. 235 Extent of Ice-sheet .
11. Origin of Erratics and Morainic
IV. THicknEss OF THE STRATA: Con- Débris
DITIONS UNDER WHICH THEY
WERE AMASSED. VII. Marine Eroston
1. Thickness of the Strata 237 VIIL Peat anp Buriep TREES
2. Igneous Rocks of Subaerial
Origin : . 237 TX. Expanation oF Puates
VOL. XXX, PART I.
Dawe
PAGE
240
242
243
244
249
250
251
218 DR JAMES GEIKIE ON
I. InTRODUCTION.
In this paper I give an account of observations made during a visit in 1879
to the Ferée Islands in company with my friend Mr Amunp HELLAnD of
Christiania. The principal object of our journey was to examine the glacial
phenomena of the islands, but we studied so far as we could the various rock-
masses of which the group is composed, and constructed a geological sketch-
map to show the line of outcrop of coal, the disposition of the strata, the
direction of dykes, and the trend of the glaciation. I have only to add, that
all the obseryations recorded in the followmg pages were made in concert with
my friend, and I am glad to say that we were quite at one in our general
conclusions.”*
The earliest references to the geology of the Ferde Islands are met with in
a general description of the group by Lucas Jacosson Dersest (1673), but, as
might have been expected, they are of no scientific value. He makes brief
reference to the occurrence of coal in Suderée, stating that it is found in only
one place “ to which one can with difficulty come ;” from which it is probable
that he had in view some of the outcrops in the precipitous sea-cliffs.
In 1800 appeared a general account of the islands by Jorgen LANpT, a
resident Danish clergyman, in which the physical features of the islands are
well described.{ The author was no geologist, but he notes some of the more
characteristic aspects of the rocks, and was clearly of opinion that some of
these at least had been in a state of fusion. He also gives some account of
the many large angular perched blocks which are so plentifully sprinkled over
the islands. It was LANpT’s description of the igneous rocks which induced
Sir Gzorce MackenziE to visit the islands. Sir GrorGE was accompanied by
Mr Tuomas ALLAN, and each subsequently gave an account of his own obser-
vations; the papers appearing in an early volume of the Transactions of this
Society.§
Sir GEORGE MACKENZIE limits his remarks on the “trap” of the Ferées to
such characters as seemed to him to demonstrate the igneous origin of that
class of rocks. He distinguishes between the “tuff” or “tuffa” and the
“trap ;” shows how they are interbedded; and gives the general inclination of
* Mr Hewwann’s paper has been published since the present memoir was read, See ‘‘Om Fero-
ernes Geologi,” in the Danish Geografisk Tidskrift, 1881.
+ Feroz et Feroa Reserata, &c., Kiobenhafn, 1673.
+ Forsog tilen Beskrivelse over Feroerne, Kiobenhavn, 1800. An English translation of Lanpt’s
work appeared in 1810.
§ “An Account of some Geological Facts observed in the Farée Islands” (Macxenzin), Trans.
Roy. Soc. Edin., vol. vii. p, 213; and “ An Account of the Mineralogy of the Farée Islands” (ALLAN),
op. cit. p. 229.
THE GEOLOGY OF THE FAROE ISLANDS, 219
the strata as towards south-east at an angle of about 4° or 5°. He was of
opinion that the bedded traps had been ejected from submarine volcanoes.
Mr ALLAn’s paper is chiefly mineralogical, but he also gives some geological
details. Both he and Mackenziz noticed the dykes that here and there inter-
sect the strata, but only Mr AuiAn describes the irregular masses of “green-
stone ” which are unconformable to the regular bedded trappean rocks among
which they occur. He also insists upon the igneous formation of all the traps,
but does not commit himself to MACKENzIr’s submarine-volcano theory. The
circumstances under which the traps were formed seem to him as inexplicable
as ever, but he evidently leans to the view of their subaerial origin. He
describes the smoothed appearance of the sides of the mountains, and particu-
larly refers to a place at Eide in Osterde where “the rock is scooped and
scratched in a very wonderful degree, not only on the horizontal surface, but
also on a vertical one of 30 to 40 feet high, which had been opposed to the
current, and presented the same scooped and polished appearance with the
rest of the rock, both above and below.” These phenomena he recognises to
be the same as the smoothed and dressed rocks near Edinburgh.
MackeEnziz’s and ALLAN’s papers were supplemented by Mr W. C. TrEvEL-
YAN, who, in a letter to Dr BrewstTer,* gives descriptions of the geology of
Myggenes and Suderde—two of the islands which Mackenzie and ALLAN
were unable to visit. His short description of the coal-beds of Suderée is
correct so far as it goes, but, curiously enough, he says the beds dip south-
east, while the section given by him shows them dipping to the north. The
letter is accompanied by some excellent sketch-sections, exhibiting the
appearances presented by certain irregular masses of basalt.
A few years later Dr ForcHHAMMER, who does not appear to have known of
MAckenziz’s and ALLAN’s papers, visited the islands at the instance of the
Danish Government, and afterwards published a very able description of their
geognosy,t accompanied by an admirable geological map. His observations
and views, however, I shall refer to more particularly in the sequel. He makes
no reference to the phenomena of smoothed rocks which so impressed ALLAN.
The next geological notice of the Feerde Islands occurs in a series of articles
by Ropert CuHampBers, entitled “Tracings in Iceland and the Ferée Islands.” f
He spent only some two or three days among the group, but recognised marks
of glaciation at various places, as I shall afterwards point out.
Since the date of his visit, the islands have frequently been referred to in
books of travel, but none of these has added anything to what was already
* “On the Mineralogy of the Farée Islands” Trans. Roy. Soc. Edin., vol. ix. p. 461.
+ “Om Ferjernes geognostiske Beskaffenhed,” Det kongl. danske Vidensk. Selsk. Skrifter, 1824.
See also Karsten’s Archiv. fiir Mineralogie ; vol. ii. p. 197.
+ Chambers’s Edinburgh Journal, 1855.
220 é DR JAMES GEIKIE ON
known. In 1873, however, appeared an excellent paper by Professor JoHN-
STRUP, in which he gives a detailed account of the coal-beds of Suderée. *
This, I believe, is the most recent addition to our knowledge of the geology of
the Feerde Islands. It is referred to in my description of Suderée.t
II. PaysicAL FEATURES OF THE ISLANDS.
1. Extent, Form, and Trend of the Islands and Fiords.—The Ferée Islands {
are upwards of twenty in number, and nearly all are inhabited. They extend
over an area of about seventy miles in length from north to south, and nearly
fifty miles in breadth from west to east. The two largest islands are Stromde
and Osterée, which closely adjoin and contain together upwards of 250 square
miles, an area which is nearly equal to that of all the other members of the
group. The extent of land in this little archipelago may therefore be roughly
estimated at about 500 square miles. Nearly all the islands have an elongated
form, and are drawn out ina N.N.W.and §.8S.E. direction. This is the direction
also of the more or less narrow sounds or open fiords that separate the islands
in the northern part of the archipelago ; and the wider belts of water in the
south, such as Suderde Fiord, Skuée Fiord, and Skaapen Fiord, have the same
general trend. A glance at the accompanying map (Plate XVI.) will show that
many of the closed fiords which penetrate the islands extend in a similar direc-
tion throughout the whole or a large part of their course. There are no great
depths in the immediate vicinity of the islands. None of the closed fiords is so
deep as many of the Scottish and Norwegian sea-lochs, the deepest soundings
indicated upon the charts never exceeding 65 fathoms. The soundings, how-
ever, are few in number, and we were told by the fishermen of considerably
greater depths in some places than are shown on the chart. Thus we were
assured that Skaalefiord is 40 or 50 fathoms deep. Immediately outside of the
islands the sea-bottom appears to slope away somewhat gradually in all
directions until a depth of upwards of 100 fathoms is reached at a distance of
15 or 20 miles, more or less, from the nearest coast-line.
* “Om Kullagene paa Feerderne samt Analyser af de i Danmark og de nordiske Bilande forekom-
mende Kul,” K. D, Vidsk. Selsk. Oversigt, 1873, p. 147.
+ Since the above was written, I have met with another paper referring to Suderée, by A. H. Stoxns,
H.M. Inspector of Mines, in ‘Trans. Chesterfield and Derbyshire Institute of Mining, Civil, and
Mechanical Engineers,” vol, ii. p. 320. The author seems to have examined only the mines and outcrops
in the Trangjisvaag district, and he gives the average thickness of the coal seen by him, together with
the heights above the sea-level of the various points at which the seam crops. He gives also analyses of
the coal. He upholds the submarine origin of the volcanic rocks, and thinks the coal may be the
remains of driftwood floated from America.
t For the spelling of place-names, I have followed the Danish Chart, although the orthography
differs from that used in other Danish works. Some of the places I refer to are not given on the chart,
and for the spelling of these I am indebted to my colleague Mr Hetuanp. A number of the place-
names in Suderée, I have taken from the map accompanying Professor Jounsrrur’s paper.
THE GEOLOGY OF THE FZROE ISLANDS, aya k
2. Configuration and Height of the Land.—-The islands are for the most part
high and steep, many of them being mere narrow mountain-ridges that sink
abruptly on one or both sides into the sea. The larger ones, such as Stromée,
Osterée, and Suderée, show more diversity of surface, but they possess very
little level land. All the islands have a mountainous character—the hills,
owing to the similarity of their geological structure, exhibiting little variety of
feature. These high grounds form as a rule straggling, irregular, flat-topped
masses, and sharper ridges which are notched or broken here and there into a
series of more or less isolated peaks and truncated pyramids. Sometimes the
mountains rise in gentle acclivities, but more generally they show steep and
abrupt slopes, which in several instances are found to have inclinations of 25°
to 27°, and even 30°. In many places they are still steeper, their upper
portions especially becoming quite precipitous. They everywhere exhibit the
well-known terraced character which is so common a feature of trappean masses,
Precipices and long cliffs or walls of bare rock rise one above another, like the
tiers of some cyclopean masonry, and are separated by usually short intervening
slopes, which are sparsely clothed with grass and moss, and sprinkled with
tumbled blocks and débris. The greatest elevations are reached in the two
largest islands, Osterde and Stromée, Slattaretind in the former attaining an
elevation of 2852 feet, and Skiellinge Field in the latter of 2502 feet.* Many
other hills in these two islands are over 2000 feet in height, and some approach
within 200 or 300 feet of the dominating point. Indeed, the average elevation
of Osterée and Stromée can hardly be less, and is probably more than 1000 feet.
The other islands are equally steep and mountainous, but in none do the hills
seem to attain a greater elevation than 2000 feet. Thus Stoiatind in Waagiée
is probably not over 2000 feet in height; Kalsée in the north-east is 1817
English feet, Kunde 2000 feet, and NaalsGe opposite Thorshavn 1276 feet. In
SuderGde some of the hills are more than 1700 feet high—one of them, Kvanna-
field, we found to be 5389 metres=1786 feet. The mean elevation of all the
islands (exclusive of Stromée and Osterde) must exceed 800 feet, and is
probably not less than 900 feet.
The coasts are usually precipitous, many of the islands having only a very
few places where a landing can be effected. Store Dimon, for example,
possesses but one landing-place, and even that is accessible only in calm weather.
The west coasts that face the open sea are as a rule the most precipitous—the
* The height of Slattaretind is given in some Danish geographies which I consulted in the islands,
as 2710 feet (Danish) =2789 feet English; Forcnuammer makes it 2816 French feet; and another
authority gives it at 882 metres = 2894 English feet. The height adopted in the text is that obtained
by Mackenziz and Auuan. There is a similar uncertainty as to the exact height of Skiellinge Field ;
some Danish geographies and gazetteers giving it as 2350 feet = 2418 English feet. The height
mentioned above is taken from the Danish Chart, which in Danish feet is 2431 feet or 2502 English
feet. This corresponds with the height of 763 métres given by some writers.
222 DR JAMES GEIKIE ON
finest mural cliffs occurring in Stromée, between Westmannshayn Fiord and
Stakken. These cliffs range in height between 900 and 2000 feet, and at
Mvling the nearly vertical walls of rock are even 2277 feet high. Osterde and
the north-east islands show sea-cliffs which exceed 1000 feet in height,
and similar lofty cliffs occur in Waagée, Sandée, Suderée, and all the other
islets.
3. Character of Valleys—The best defined valleys are often comparatively
broad in proportion to their length. Followed upwards from the head of a
fiord, they rise sometimes with a gentle slope until in the distance of two or
three miles they suddenly terminate in a broad amphitheatre-like cirque. In
many cases, however, they ascend to the water-parting in successive broad
steps or terraces (Plate XITI. figs, 2 and 3),—each terrace being cirque-shaped,
and framed in by a wall of rock, the upper surface of which stretches back to
form the next cirque-like terrace, and so on in succession until the series
abruptly terminates at the base, it may be, of some precipitous mountain,
Occasionally the col between two valleys is so low and level that it is with some
difficulty that the actual water-parting can be fixed. Such is the case with
Kolfaredal between H6i and Leinum-mjavatn in Stromée, where a well-defined
hollow passes right through the hills, leading from the head of Kollefiord to
the sea at Leinum. The height of the flattened co/ in this hollow is only 259
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( 271 )
X.— Researches in Contact Electricity: Thesis for the Degree of Doctor of
Science. By Careitt G. Knorr, D.Sc. Communicated by Professor
Tair. (Plate X VIL.)
(Received July 23d ; revised October 27th, 1879).
At the surface of separation of any two. different substances in contact,
there exists in general an electromotive force tending to maintain a certain
difference of potential between them. This principle, established for metals by
VotTA in 1796, has been extended by later investigators to other substances,
including liquids and gases. From these early researches of Vouita,* and the
later more elaborate inquiries of KonirAuscu,t HANKEL,{ and GERLAND, §
there have been deduced certain fundamental laws, which have been fully
corroborated by the recent work of CuiFrTon, || and Ayrron and Perry. If,
of a number of conductors set serially in contact, the difference of potential
between each successive pair is quantitatively estimated and reckoned positive
or negative, according as the first member of the pair is at a higher or lower
potential than its successor, then the difference of potential between the first
and last members of the chain is equal to the algebraic sum of the potential
differences between the successive contiguous pairs. Should the series be made
up of simple conductors, the potential difference between the extremities is
quite independent of the nature, number, and order of the intervening com-
ponents, and is, indeed, equal to the difference obtained by direct contact of
these extreme members. Hence, in a circuit composed of such substances
(metals for example) and kept at a uniform temperature throughout, the sum
of the differences of potential existing at the various surfaces of contact taken
in order all round the circuit is zero. The resultant electromotive force is
therefore also nz/, and no current can exist. This result of experiment is in full
- accordance with the recognised principle of the conservation of energy, there
being in these circumstances no source from which the current could derive its
energy. Should the contact-chain, however, consist partly of compound or
chemically decomposable: conductors, the potential difference between the
* Annales de Chimie, vol. xl. p. 225 (1801); also WiepEmann’s “ Galvanismus,” vol. i. §§ 1-7
and 14.
; + Poggendorff’s Annalen, vol. Ixxxii. p. 1 (1851), and vol. Ixxxviii, p. 465 (1853).
t Ibid., vol. exv. p. 57 (1862), and vol. exxvi. p. 286 (1865).
§ Ibid., vol. exxxiii. p. 513 (1868).
|| Proceedings of the Royal Society (London), vol. xxvi. (1877).
Jbid., vols. xxvii. (1878), and xxviii. (1879).
VOL. XXX. PART I, 25
272 DR CARGILL G. KNOTT ON
extremities may, and frequently does, become a function of the intermediate
structure, and is then no longer equal to the direct contact-difference between
the extreme members.* With a circuit including such materials in its com-
position, the resultant total electromotive force does not in general vanish, so
that the existence of a current is possible and necessary; and the energy of this
current is derived from the energy of chemical combination, which is the one
aspect of the accompanying action, whose other aspect is the decomposition
of the compound conductor. Except such chemical action were possible no
current could be generated; so that, probably, the possibility of chemical
action, and the non-vanishing character of the resultant electromotive force in
the circuit, are necessarily co-existent phenomena. Such, at present, seems to
be the most complete theory of the voltaic cell.
Although no current exists in a circuit of simple conductors maintained at
a uniform temperature because of the mutual balancing of the contact forces,
it is possible to cause a current to flow by heating or cooling one of the
junctions, and thereby destroying the equilibrium of the contact forces. The
energy of the thermo-electric current so obtained is a partial transformation of
the energy which was originally expended in unequalizing the temperature of
the system. Apparently, then, the contact-difference of potential between two
metals or other simple conductors depends upon the temperature—a conclusion
verified in a very remarkable way by consideration of the Peltier effect, or
reversible thermal effect, produced by the passage of a current across the
junction of two different metals. By an application of the dynamical theory of
heat, Sir W1LL1AmM Tuomsont proved that this evolution or absorption of heat at
the junction, according as the current flowed in one ‘or other direction, indicated
an electromotive contact force, acting against the current when heat was
evolved, with the current when heat was absorbed. In other words, because of
the difference of potential at the junction, the current has to do work when
passing in one direction, and has work done upon it when passing in the other—
giving rise respectively to an evolution and absorption of heat. From considera-
tion of the principle of dissipation of energy, Professor Tarir{ has developed a
formula for this electromotive contact force, expressing it as a parabolic
function of the temperature ; and this theory has been indirectly verified by a
long series of experiments upon the thermo-electric properties of metals,
With a view of testing by direct contact experiments the variation with
temperature of the contact-difference of potential between dissimilar metals, I
undertook the experiments whose results form the subject of this thesis, It
must be premised, however, that any positive result cannot be regarded as due
* See the papers of KonLrauscn, Hanken, Crirron, and Ayrton and Perry, cited above,
+ Transactions of the Royal Society of Edinburgh (1851).
{ Ibid, (1870-71).
RESEARCHES IN CONTACT ELECTRICITY. 273
only to the metals ; for, as pointed out by Professor CLERK MAXwWELL,* VoLta’s
electromotive force of contact is in general greater than that indicated by the
Peltier effect, and sometimes of opposite sign—a discrepancy to be accounted
for by the fact that in direct contact experiments there is always a film of con-
densed air or other gas between the metals when they are in so-called contact,
and that possibly the chief effect ‘must be sought for, not at the junction of
the two metals, but at one or both of the surfaces which separate the metals
from the air or other medium which forms the third element of the circuit.”
After a few preliminary experiments I concluded that direct contact of the
surfaces under investigation was a sufficiently accurate and constant method
for indicating any appreciable change which might occur. It was found neces-
sary, however, to keep the surfaces continually polished in a particular manner,
since they gradually altered their surface condition when exposed to the action
of the air—a fact formerly established by HANKEL.+ Previous to any discus-
sion of the results obtained, it is advisable first to give a description of the
apparatus and method of experiment.
Of the two metallic surfaces which were the subject of experiment the
lower was the upper surface of a flat cylindrical flask-shaped vessel, which
rested on an insulated stand in electric connection with one pair of opposite
quadrants of a THomson Quadrant Electrometer. The temperature of this
surface was determined by the temperature of the water contained in the flask.
Three such flasks were used—one of iron, one of zinc, and the third with the
one flat surface copper and the other tin. The diameters of the plane faces,
the thicknesses of the flasks, and their volume capacities, are as follows :—
Flask Diameter in | Thickness in | Volume in Cubic
ee Millimetres. | Millimetres. | Millimetres.
ron ater, f : 128 uy 198,000
Zin 0 ‘ ‘ 131 16 168,000
Copper and Tin, . 129 16 196,000
The upper plate of the condenser was a disk of approximately the same
area as the lower, on which it pressed during contact by its own weight. It
could be readily adjusted by screws to a practically accurate parallelism with
the lower plate, and had only one degree of freedom—an up-and-down motion
directed by a pin and guiding slot. It depended from the brass top of a
cylindrical glass case which surrounded the insulated stand and flask on all
sides, if we except the small aperture through which the internal arrangement
was put in connection with the electrometer. Great care was necessary in dry
* Electricity and Magnetism, vol. i. § 249.
+ Pogg. Ann., vol. exxvi. p. 286 (1865),
274 DR CARGILL G. KNOTT ON
weather to avoid rubbing, and thereby electrifying this glass case, which during ©
the experiments had to be repeatedly removed, so that the temperature inside
might be observed and the surfaces repolished. The upper and movable plate
of the condenser was connected with the other pair of electrometer quadrants,
which were put to earth and kept constantly at zero potential. In all cases
the plates were brought into direct surface contact, and the deflection on the
electrometer scale caused by the charge left on the msulated flask and the
connected quadrants, when the upper plate was withdrawn to a height of five
inches, was taken as the quantitative estimate of the difference of potential due
to the contact of the surfaces. These opposed surfaces were polished with
emery paper, and dusted with dry chamois skin. The polishing was effected
manually, the surface to be polished being held for the time in one hand, and
the emery paper in the other, and the two rubbed vigorously together for a
quarter of a minute or so. After being thus polished the surfaces were dusted
and reset in as short a time as possible, an interval of about fifteen seconds
elapsing between the polishing of the second surface and the first contact of
the two plates.
In the first series of experiments the condenser-plates remained almost
always in contact, being separated only when a reading was to be taken, or
when the surfaces had to be repolished and the temperature of the water in
the flask observed. The upper disk was then virtually at the same temperature
as the lower. Readings were taken in groups of five at a time, the interval
between each reading being conditioned by the swing of the electrometer
mirror, which, under the action of the bifilar suspension, had of course to come
to rest, or nearly so, before its dications could be of any value. After each
group of readings the surrounding glass case was removed, the temperature of
the cooling water observed, the surfaces repolished, and the whole arrangement
re-adjusted precisely as before. On the whole, the five consecutive readings
of any group were very consistent considering the difficulties besetting elec-
trometer measurements of contact forces, and were sufficiently so in all but
a few very exceptional cases to warrant the belief that, during the two or three
minutes necessary to make the complete set of readings, comparatively little
change took place on the surfaces. From theoretical considerations I was led
to try iron and copper as likely metals to give positive results. In this I was
not disappointed ; but the difficulty of drawing any sure conclusion from the
indications so obtained, or in any way deciding between the claims of the
various possible explanations which might be given to account for the facts,
induced me, after four months experimenting, to conduct the inquiry on a
different, and what turned out to be an improved, principle. In these earlier
experiments it is to be particularly observed that the two surfaces were at any
instant both at the same temperature; in the later experiments the tempera-
qn &
Cage akan SPV
reactant alga edi
nena
RESEARCHES IN CONTACT ELECTRICITY. 275
ture of the lower surface only was made to vary, so that the surfaces were
generally at different temperatures. By the former method it was found that
the difference of potential between polished iron and polished copper fell off
by at least 45th of its original value for a rise in temperature of 1° C. Many
series of experiments were made with these two metals, and each day’s results
gave the same general indication ; although, as might have been expected from
the nature of the inquiry, it is hardly possible to deduce from them any definite
quantitative law.
The general results of eleven series of experiments are given in the follow-
ing table. The first column represents the lowest temperature for which
readings were taken ; the second gives the electrometer deflection for that
temperature due to the electrification by contact of the lower surface ; the
third indicates the like deflection for the higher temperature; the fourth
registers that higher temperature ; and the fifth notes the percentage average
decrease of the deflection for unit increase of temperature.
T Lower _ Deflection. Deflection. eres Eezcanlage
emperature. | Temperature. | Decrease.
Tee 70 50 30°C. 1:32
14 60 35 40 1:60
13 78 58 45 83
10 ie 56 45 78
18 110 80 50 85
20 93 76 41 87
23 110 85 50 84
16 110 60 48 1:42
16 110 85 35 1:22
20 112 91 38 1:04
16 . 112 90 36 98
The first four experiments give smaller readings than the last seven—a
discrepancy easily accounted for by the change of circumstances occasioned by
removal to another room, and a refitting of the surfaces. Yet, that in such
altered circumstances the average percentage temperature-variation of the
deflection should be so consistent throughout, argues strongly in favour of the
reality of such a variation. A like series of experiments was commenced with
a zine surface substituted for the copper or under surface ; but, though there
were indications of a somewhat similar variation, these were too vague to
admit of any definite deductions being made. The same was true of the
aluminium-zine pair. In this mode of experimenting, however, it was impos-
sible to determine how much of the resultant variation of a given pair was due
to the action of a particular component, or how far this variation depended
directly upon the change of temperature, or indirectly through consequent
material alteration of the surfaces—through oxidation, for example.
276 DR CARGILL G. KNOTT ON
These considerations led me to abandon my first method of experimenting ;
and in the modified method finally adopted, the temperature of the upper plate
of the condenser was kept constant, while the temperature of the lower was
made to vary. This required the contact to be instantaneous, so that only one
reading could be taken between each preparation of the surfaces and observa-
tion of the variable temperature. During this interval the upper plate was
laid upon an iron slab, and thus kept at the temperature of the room; and
just before the apparatus was reset for observation the temperature of the
lower surface was noted, and both surfaces were polished and dusted as usual.
The first experiments were made with two iron surfaces, which, after sufficient.
polishing at the ordinary temperature of the air, gave no deflection on separa-
tion after contact. The lower surface was then heated up to 70° or 80° C. in
the manner formerly described, and then allowed to cool, while at rapid
intervals instantaneous contacts were made with the upper surface, each
contact being made as soon after polishing as possible. In this way I found
that iron hot was strongly negative to iron cold, and apparently more negative
the higher its temperature—in other words, the difference of potential between
iron and iron increases with the difference of temperature, being zero when
the temperature difference is zero. A glance at the representative curve
(Diagram, fig. 2) shows the nature of this change. The six different symbols
represent six different curves, five of which give the results of as many
independent experiments, while the sixth (represented by the circle and dot)
is the average curve formed by the combination of the others. Each point on
any one of the five primary curves, is, as far as possible, the mean of five
consecutive readings—a method of reduction which recommended itself as
giving the most probable value for the mean contact. Each point of the
final mean curve is obtained by taking the average of all such points as lie in
the same temperature decade. Subjoined are the tabulated results of these
experiments, the upper row of each of which gives the temperature of the
lower condenser plate, and the lower the corresponding deflection on the
electrometer scale.
EXPERIMENT I, (February 27, 1879).
(Curve symbol -),
Temperature (in degrees C.),. . : 53°8 49 +4 45:4 31 23°1
Deflection, . . : ° ' ; 21'8 21 17-4 10:8 72
EXPERIMENT IT. (February 28).
(Curve symbol +).
Temperature, : : : ; : t aa 3 40°7 31°6 224
Deflection, . : : é : : Ly 252 14:7 fia’
RESEARCHES IN CONTACT ELECIRICITY, 277
EXPERIMENT III. (March 5).
(Curve symbol x),
Temperature, ; : 5 : 64:6 473 31 22°2
Deflection, . 5 ; ; : oe 26 15'2 12
EXPERIMENT IV. (March 6).
(Curve symbol \ ).
Temperature, ‘ : 4 ; 66°5 36°7 34:2 25
Deflection, . J : i : 47°5 di 16 3
EXPERIMENT V. (March 13).
(Curve symbol A).
Temperature, . : , 60°4 5d'd 38 30 23:°2
Deflection, ; ; } 37 36 20 9°3 6
The reduced means for curve VI. (symbol ©) are as follows :—
Temperature, . : ; 63:1 54°6 45-7 33°4 23°2
Deflection, ; ; : 38°5 28°9 22°4 149 72
The temperature of the room, and therefore of the upper surface, was
12°C., at which point then the curve should. meet the line of temperatures.
The mean curve is obviously best represented by a straight line, whose tangent
of inclination to the temperature line is—°76, expressed in diagram units.
In seeking for an explanation of the results of these experiments, we
must not neglect the possible effects due to surface oxidation, or to the
change in density of the gas condensed upon the metallic surface. If the
negative character of heated iron to cold iron disappeared on the cooling of
the former, then the effect must be the result of some temporary change
accompanying the heating—such for example as the mere change of temper-
ature, or the driving off of the condensed gases at the higher temperature,
or of both causes combined. Experiment, however, clearly proved that
the originally heated surface, when cooled to the temperature of the colder
surface, retained its strong negative characteristics with no appreciable diminu-
tion; from which it would appear that the observed phenomena are to be
attributed mainly to a permanent change of surface condition depending upon
the temperature to which that surface has for a brief period been subjected—
probably to oxidation, It was also found by trial that no appreciable increase
in the deflection corresponding to a given temperature resulted when a
considerable interval of time was suffered to elapse between the polishing
of the heated surface and the making of contact between it and the upper
and colder surface. Whether the instantaneous contact was made fifteen
minutes (the usual interval) forty minutes, or sixty minutes after polishing,
278 : DR CARGILL G. KNOTT ON
the electrometer deflection was, as far as the method admitted of judg-
ing, the same. Probably after a longer lapse of time than that here speci-
fied, a change might become manifest—such a change as HANKEL long ago
established for iron and other metals at the ordinary temperature of the
air. In order to compare this time-variation of surface condition with the
temperature-variation established above, I made a series of observations,
at sufficiently distant intervals of time, of the deflections produced by con-
tact and separation of two iron surfaces, one of which was kept constant
by polishing, while the other was permitted to vary, by being simply left to
itself. Both were initially polished to be the same electrically—a state of
affairs evidenced by the absence of any effect on the electrometer when the
two plates were separated after contact. Readings were first taken at intervals
of five minutes, then at intervals of ten minutes, fifteen minutes, and finally
at half hour intervals. Each number in the following table is the mean of
five readings taken in rapid succession within the lapse of one minute.
EXPERIMENT X. (May 20).
(Fig. 1, 0).
Time (in minutes), Deflection (iron against iron).
0 0
5 —11
10 —14
15 —15
20 —16
30 —18
45 —19°4
75 —20
The curve corresponding to these numbers is given in the diagram (fig. 1, 0).
In its main characteristics it is very similar to an ordinary curve of cooling,
and is markedly dissimilar to the curve which represents the temperature-
variation of surface condition, Curves @ and ¢ on the same diagram indicate
the corresponding variations for copper and aluminium respectively. The
copper was electrified by contact with iron, both surfaces being allowed to
vary; and the real time-variation of the copper was obtained by properly
introducing the ‘nown time-variation of the iron. The aluminium was elec-
trified by contact with polished zine, to which it was originally positive, but in
the course of half an hour became as strongly negative. The contacts were
instantaneous, and except immediately before the taking of a reading the
surfaces were kept far apart. The tabulated values for these metals are given
below, the chemical symbol for each metal being employed to represent the
corresponding surface, and the suffix p signifying that the surface to which it
is suffixed was kept polished and therefore constant.
’
RESEARCHES IN CONTACT ELECTRICITY.
EXPERIMENT XI. (May 21).
279
(Fig. 1, a).
Time (in minutes). Cu | Fe Cu | Fe, * Cu | Cu,
(=Cu | Fe+Fe | Fe,).
0 —63 —63 0
2 —61 —67 — 4
7 —58 a0 — 7
Li. —57 —13'7 —10°7
47 —55 —75'5 —12°5
EXPERIMENT XII. (May 9).
(Fig. 1, ¢).
Time (in minutes). Al | Zn, Al| Al,
0 +18 0
10 — 74 —25°4
20 —146 —32°6
30 —16-2 —342
45 — 24:2 —42°2
60 — 24 —42
90 —36 —54
1350 (observed next morning) —47 —65
In experiment XI., the second column contains the observed values; the
third is calculated from it by adding to each number the corresponding number
from the iron curve; and the numbers of the fourth column are obtained from
those of the third by subtracting from each the first number, which gives the
deflection due to polished copper and polished iron. In experiment XII. there
is no column corresponding to the second column of experiment XI., since the
zinc surface employed for comparison was kept constant throughout the
experiment. The corresponding curves for zinc and tin are not represented on
the diagram because of their great proximity to the iron curve. In the course
of an hour the change on the zinc was only 6 per cent. greater than the
corresponding change on the iron ; while in forty minutes there was no appre-
ciable difference in the changes on the tin and iron surfaces.
The gradual character of the change here indicated is of special value in the
present inquiry, as I hope to bring out in the final conclusions to which I have
been led. Meanwhile it is advisable to give the results of the experiments on
the temperature-variation of the other metals which I investigated. Though
not so full and satisfactory as the results for iron, these later researches all
indicate the same general facts—as may be gathered from the following tables
for copper hot against iron cold, both surfaces being polished with emery paper
immediately before contact.
VOL. XXX. PART I. 2U
280 DR CARGILL G. KNOTT ON
EXPERIMENT VI. (March 24).
(Fig. 3; symbol . ).
Temperature, Deflection (Cu, | Fe,)
62° C. —66°6
57 — 68:2
52 — 64:5
48 —61°5
44 —573
32 —54
24 —52
12 —50
EXPERIMENT VII. (March 25).
(Fig. 3; symbol x ).
Temperature, Deflection (Cu, | Fe,)
70° C. —69
55 —65
43 —62
30 —52
23 —47
12 —47
The conditions under which these experiments were made were the very same
as those under which the temperature-variation of the iron was investigated.
The representative curve is shown in fig. 3, all the points clustering approxi-
mately round a straight line whose tangent of inclination to the temperature
axis is—'39, measured in diagram units. Hence it appears that the tempera-
ture-variation of copper is smaller than that of iron, and that consequently,
since the iron is the more positive metal, the difference of potential between
iron and copper falls off as the temperature of both is raised—a result already
obtained in the earlier experiments (see page 275).
Zine was the next metal which came under investigation. At first it was
electrified by contact with aluminium, kept polished at a constant temperature.
This latter metal, however, is not very suitable, on account of its proneness to
rapid change in time as evidenced by its curve on the diagram (fig. 1, c).
Nevertheless the same negative growth of the heated metal was indicated, and
more self-consistent results were obtained by contact of zinc hot with zinc cold,
both polished as usual. The numbers are as follows :—
EXPERIMENT VIII. (March 28).
(Fig. 4; symbol - ).
Temperature, Deflection (Zn, | Al,)
63°°8 C. —78
46°5 —66
34 — 64
21'8 —56°3
10 —40
RESEARCHES IN CONTACT ELECTRICITY. 281
EXPERIMENT IX. (April 4).
(Fig. 4; symbol x ).
Temperature. Deflection (Zn, | Zn,)
65° C. —42
45 —22°5
42:7 —19°2
40°6 —17°7
38°8 —18°5
28°6 —8
In the diagram (fig. 4), two lines are drawn, each representing one of the
above experiments. The dotted line is that which best agrees with the readings
of experiment VIII., the points on the curve of which are represented on the
diagram as “dots.” The curve-points of experiment IX. are entered as crosses,
and they all lie very near the continuous line drawn on the diagram. The
tangent of inclination of this line is—‘9, expressed in diagram units.
Apparently, then, zinc varies more rapidly with temperature than iron ; and
hence, since zinc is the more positive, the contact difference of potential between
zinc and iron falls off, as both are simultaneously raised in temperature ;
a result in accordance with the indications of the earlier experiments with
zinc and iron when both were made to vary similarly in temperature. This
suggested the possibility that the more positive metal might be subject to
the greater temperature-variation. According to this hypothesis, tin, which
_ occupies in the electromotive series a position intermediate to zinc and iron,
should give a correspondingly intermediate line for its temperature-variation.
It was impossible, however, with the means I had at my disposal, to arrive at
anything like a quantitative result for tin. Not having at the time another tin
surface, I was compelled to make use of either zinc or iron as the other con-
denser plate ; and, as both of these gave large deflections with tin, the readings
were wild and unsatisfactory. No experiment gave even self-consistent results;
and no two of them had much in common—except the undoubted characteristic
which indicated a similar “negative growth” with rise of temperature of the
tin surface.
As already noticed, the permanency of this negative-growth with temperature
increase after the surface is cooled—a characteristic which was established by
direct experiment in every case—proves conclusively that whatever change in
the electromotive force of contact of any two of the metals, iron, zinc, copper,
and tin, may be due directly to change of temperature ; such a possible change
is quite inappreciable by ordinary contact methods, and is altogether masked
by changes due to other and secondary causes. In seeking for such causes, we
must consider the probable alteration with temperature in the density of the
gaseous film condensed over the metal surface, which alteration, however, is not
282 DR CARGILL G. KNOTT ON
permanent on restoration to the original temperature, provided the surface
has remained the same chemically. Any permanent alteration in the density
of the condensed gases presupposes, then, a chemical change on the surface ;
and if there be no such permanent alteration, or if it be insufficient to account
for the observed phenomena, the last resource still seems to be chemical change,
to which accordingly we look as the only efficient cause, whether directly or
indirectly, of the changes observed in the mutual electrical relations of metals.
This hypothesis is also supported by the known phenomena of time-variation of
metal surfaces in both their chemical and electrical relations. The electrically
negative character of unpolished iron, copper, zinc, tin, aluminium, &c., to
polished iron, copper, zinc, tin, aluminium, &c., is generally attributed to surface
oxidation ; probably, then, the electrically negative character of polished and
heated iron, copper, zinc, and tin, to polished but unheated iron, copper, zinc,
and tin, is to be referred to a similar cause. If so, then the above experiments
lead to the result that for these metals at least, there is for every temperature
a definite surface condition which no amount of polishing can alter—a surface
condition produced most probably by a film of oxide or other similar compound
over the metallic surface by the action of atmospheric air ; and that, further, the
surface change due to change of temperature is a direct function of that tem-
perature-change. This surface state forms within the first few seconds after
polishing, perhaps instantaneously, and thereafter no appreciable change ensues
till several minutes have elapsed, when the inevitable time-variation of the
surface, as depicted in the curves of fig. 1, begins to show itself. Hence it
would appear that at ordinary temperatures a chemically pure surface of these -
four metals in air is an impossibility; and that the same holds true for other
metals, even for the so-called non-oxidisable, is a not improbable surmise. In
this connection it should be remarked that to the eye there was no appreciable
alteration of surface, no dimming of the bright metallic polish, even after the
lapse of several minutes.
The experiments which form the subject of this thesis were made in the
Physical Laboratory of Edinburgh, during the summer session of 1878, and the
winter session 1878-79. The apparatus was, for the most part, lent me by
Professor Tart, whom I here thank for the kindly interest he has evinced in
my work, and the ever ready advice with which he has aided me.
Added, May 1881.—As it was just possible in the above experiments that
the variations of potential observed might be affected by changes in the capacity
of the condenser, further experiments were made in which any such alteration
in capacity might be effectively eliminated. The two opposed surfaces of the
condenser, brought to within a millimetre distance of each other, were put into
metallic contact by means of external wires. In this way, after the method o
RESEARCHES IN CONTACT ELECTRICITY. 283
Kou rauscu, any change in the difference of potential could be measured in
terms of a Daniell cell. The results obtained fully corroborated the former
conclusions, as a glance at the following table will show. The first column,
headed 6 V, gives the variation of potential for a rise of temperature of 1° C.
expressed in terms of a Daniell cell; and the second column, headed p,
indicates the range of probable error in the estimate which was deduced as the
mean of several distinct experiments.
éV p
Zine, , : . —'0028 +0003
Iron, , ‘ ; . —'002 +0004
Copper, . : ; . —'001 +0002
Tin; ‘ ; . —'001 +0002
It may be noticed that of these zinc gave the most regular results. In
deducing these numbers it was assumed that the variation varied directly with
the temperature throughout the range of 60° C. Thus, polished zinc at 20° C.
gives with polished zinc at 80° C. a difference of potential equal to ‘168 of a
Daniell cell—the hotter surface being, of course, the negative surface.
Many definite results were also obtained for the time-variation for aluminium,
zinc, iron, and copper. The representative curves were in all cases similar to
those shown in fig. 1. This being understood, the following numbers indicate
the difference of potential between the polished metal surface and the same
surface after twenty-four hours’ standing.
Aluminium, . ; ; . 38
Zine, ‘ ; : Z ' ee : ;
Iron, ; 4 (in terms of 1 Daniell cell.)
Copper, . ; ; : ; 086
It was found, however, that different days’ experiments gave somewhat varying
results—the atmospheric conditions as to temperature, humidity, &c., having
probably some effect. Indications were also obtained in the course of experi-
ment that this time-variation depended upon the more arbitrary conditions
under which the varying surface was allowed to vary; whether, for example,
it was freely exposed to the air, or was left close to the opposed surface;
whether it was the negative or positive element in the condenser, and such like.
Where so many possible factors enter, however, it is extremely difficult to
draw any sure conclusions.
VOL. XXX. PART I. DEX
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XI—On Phosphorus-Betaines. By Professor Letts. (Plate X VIIL.)
(Read January 3, 1881.)
In a paper by Professor Crum Brown and the author on Dimethyl-Thetine
and its Derivatives,* attention was drawn to the analogies which frequently
exist between elements which have different atomicities, and which are usually
considered as belonging to different families. The most striking examples of
such elements are boron and carbon, gold and platinum, and phosphorus and
sulphur.
Since the publication of that paper, the author has pursued the subject, and
his experiments, which have been made with the object of comparing the
properties of analogous compounds of nitrogen, phosphorus, and sulphur, have
confirmed the view that the two latter elements are very closely related, and
that in many cases at least, phosphorus is more nearly allied to sulphur than
it is to nitrogen.
In the course of these experiments many facts and considerations relative
to the three elements have occurred to the author, which he believes have not
hitherto been presented in a clear and concise form. No doubt, some of them
have been noticed by other chemists, but he believes that such has not been
the case with all, and he is therefore induced to give a slight sketch of the
analogies and differences which the three elements exhibit, before proceeding to
describe his experiments.
A Comparison of the Properties of Nitrogen, Phosphorus, and Sulphur.
If we compare the three elements in the free state, we cannot but be struck
with the very close analogies existing between phosphorus and sulphur, and
the great dissimilarity of nitrogen to either.
Phosphorus and sulphur are solid bodies ; both exist in allotropic modifi-
cations which are produced by the action of heat on a particular form of each
element. Nitrogen is gaseous, and so far as is known does not exist in
more than one condition.
Again, both sulphur and phosphorus have what is usually termed “abnor-
mal” vapour densities; that is to say, in the gaseous state their molecules
contain more than two atoms. At a sufficiently high temperature, however,
the molecules of sulphur are dissociated into simpler ones containing two atoms,
* These Transactions, vol. xxviii.
VOL. XXX. PART I. 25
286 PROFESSOR LETTS ON PHOSPHORUS-BETAINES.
and this fact, considering the similarity of the two elements, renders it probable
that at a sufficiently high temperature the molecules of phosphorus would
behave in a similar manner.*
Regarding other physical properties of the three elements, such as specific
gravity, atomic volume, &c., it is not necessary to say much, as nitrogen, on
account of its gaseous nature, does not admit of a ready comparison with the
other two. It may be mentioned, however, that both the atomic weight
and specific gravity of phosphorus and sulphur are very close to each other,
and consequently their atomic volumes are nearly identical.+
Turning now to the chemical properties of the three elements (in the free
state), we again find a close similarity between phosphorus and sulphur,
Whereas nitrogen possesses scarcely a point of resemblance to either; for
whilst the former are characterised by their energetic attraction for other
elements, nitrogen is strikingly ert, and displays scarcely any tendency to
enter into combination.
The great affinity of phosphorus for oxygen needs no comment; that of
sulphur for the same element is considerably less, but is still well marked ;
whilst nitrogen possesses so slight an attraction for oxygen, that its oxides are
powerful oxidising agents. We have then in phosphorus, sulphur, and nitrogen
a group of elements which show a regular gradation in affinity for oxygen ;
and, as we might expect, the affinity of these elements for hydrogen is in
exactly the reverse order, ammonia being the most stable of their hydrides,
and phosphuretted hydrogen the least, whilst sulphuretted hydrogen stands
midway between them. We might perhaps expect from these facts that, as
ammonia is the most alkaline of all the hydrides, sulphuretted hydrogen would
be more alkaline than phosphuretted hydrogen; but this is not the case, for the
latter has a neutral reaction, and combines directly with hydriodic and hydro-
bromic acids, whereas sulphuretted hydrogen has a slight, but still a distinct
acid reaction, and does not, so far as we know, combine with any hydracid.
The difference observed in the affinity of phosphorus, sulphur, and nitrogen,
for oxygen and hydrogen, exercises, as we might expect, an important influence
on the properties of their compounds. Thus most compounds of phosphorus,
with electro-positive elements or compound radicals, oxidise spontaneously, as
in the case of phosphuretted hydrogen, many metallic phosphides, and the
* The author has communicated with Professor Vicror Mryer on this subject, who stated that he
had already made experiments in this direction, and that they indicated a diminution in the vapour
density of phosphorus at a high temperature. Professor Mnyrr having thus established his priority to
any experiments on the vapour density of phosphorus at high temperatures, the author has left the
matter in his hands.
+ According to Ramsay (Journ. Chem. Soc., 1879), the sp. gr. of sulphur at its boiling-point is
1:4799, and its atomic volume (in the sense in which Korr employs the term) 21:6. The same author,
in conjunction with Masson (Journ. Chem. Soc., 1880), gives the sp. gr. of phosphorus at its boiling-
points as 14850, and its atomic volume as 20°91.
PROFESSOR LETTS ON PHOSPHORUS-BETAINES. 287
phosphines ; and even partly oxidised compounds of phosphorus often greedily
absorb oxygen, and are, as a consequence, powerful reducing agents.
Similar compounds of sulphur do not as a rule oxidise spontaneously, or if
they do so the oxidation occurs slowly, as with solutions of sulphuretted hydro-
gen and metallic sulphides. But oxidising agents easily attack them and
convert them into oxidised products. Thus sulphuretted hydrogen, by simple
contact with sulphuric acid, is oxidised to water and sulphur. Organic sul-
phides (R’,S) are converted by treatment with nitric acid into sulphanes (R’,SO),
and sulphones (R’,SO,) ; mercaptans (R’HS) into sulphonic acids (R/HSO.).
Corresponding compounds of nitrogen show much less tendency to oxidise,
and only in a very few cases are they capable of directly fixing oxygen ; thus
in the case of the compound ammonias although oxidised products are known
(R’NO, R’NO,, &c.) they are not produced by direct oxidation.
These considerations help us to understand the action of reducing agents
on oxidised compounds of the three elements, and also explain why completely
different methods must be employed for obtaining their organic compounds.
A nitro-body is an oxidised compound of nitrogen; in it the oxygen is only
weakly held, consequently a reducing agent easily removes it, and usually
causes the addition of hydrogen.* Consequently an amine is readily obtained
by the reduction of a nitro-body. Oxidised compounds of sulphur are also
easily reduced. Thus nascent hydrogen de-oxidises sulphuric,.sulphurous, and
hyposulphurous acids, and converts them into sulphuretted hydrogen, and is
also capable of converting (certain at least of the) sulphanes and sulphones
into sulphides. But it is more difficult to reduce an oxidised sulphur com-
pound than an oxidised nitrogen compound. For instance, nitrate of potash
is easily reduced to nitrite, and eventually to oxide of potassium by heat alone ;
whereas sulphate of potassium suffers no change when heated unless a reducing
agent such as carbon is present ; in which case, however, the oxygen is removed.
But if we attempt to remove oxygen from an oxidised compound of phos-
phorus by ordinary reducing agents, we experience as a rule much greater
difficulty. It is stated that both phosphorous and hypophosphorous acids may
be reduced by nascent hydrogen,t but phosphoric acid is not affected by that
reagent, nor is the oxide of a tertiary phosphine. A powerful reducing agent
acting at a high temperature must generally be employed for the reduction
of an oxidised compound of phosphorus.
We can therefore readily understand why phosphines cannot be prepared
by the reduction of oxidised organic compounds of phosphorus, whilst amines
are produced by such a process with the greatest ease, and even sulphides are
formed from sulphines, sulphones, &c., without much difficulty.
* Not however in all cases, as we see in the preparation of azo-bodies.
+ This statement requires confirmation.
288 PROFESSOR LETTS ON PHOSPHORUS-BETAINES.
Respecting compounds of oxygen and of hydrogen with the three ele-
ments, it may not be superfluous to point out some of the more important and
interesting points of resemblance and difference which exist between them.
As regards their compounds with hydrogen, nitrogen forms a single
hydride ; sulphur, two; phosphorus, three. In all three cases the hydride
containing the maximum of hydrogen is gaseous, and possesses a powerful and
characteristic odour and energetic properties. All three of these gaseous
hydrides are decomposed by the spark, and phosphuretted and sulphuretted
hydrogen are decomposed by heat. Ammonia, however, is more stable.
As we might expect from the readiness with which both sulphur and phos-
phorus are oxidised, their compounds with hydrogen are very inflammable,
whilst ammonia can only be burnt under special conditions.
The strongest point of analogy between ammonia and phosphuretted
hydrogen is, that both are alkaline substances, in which respect they are unique
amongst the hydrides of elements. But the alkaline properties of phosphuretted
hydrogen are very weak, as it combines under ordinary atmospheric pressure
with only two acids, viz., hydriodic and hydrobromic acids, and its compounds
with these are so unstable that they dissociate at ordinary temperatures, and
cannot exist in solution.
As before pointed out, phosphuretted hydrogen, in respect of its alkaline
properties, is intermediate between the strong base ammonia and the faint acid
sulphuretted hydrogen. In other respects, phosphuretted hydrogen is more
allied to sulphuretted hydrogen than it is to ammonia. This is especially »
noticeable in its action on solutions of the heavy metals, where it acts either
as a reducing agent (gold, &c.) or precipitates a metallic phosphide (cadmium
and copper), or precipitates a mixture of the metal and metallic phosphide
(mercury).
Both sulphur and phosphorus form only two well-marked compounds with
oxygen ; whilst nitrogen, in spite of its slight affinity for that element, forms no
less than five oxides.
Phosphorus, as we might expect from its powerful affinity for oxygen,
combines directly with the maximum quantity of that element ; whilst sulphur,
when burnt, only forms its lower oxide ; and free nitrogen is not capable of direct
oxidation, except under special conditions.
The highest oxides of the three elements resemble each other in being
volatile solids, and in having a strong affinity for water. Nitric anhydride is
the least stable, and frequently decomposes spontaneously. Sulphuric anhy-
dride is decomposed at a high teniperature, whilst phosphoric anhydride dis-
plays a much higher degree of stability.
If we consider the oxy-acids of the three elements, we see that an undoubted
analogy exists between sulphuric and phosphoric acids. Both are very powerful
oaks oe
PROFESSOR LETTS ON PHOSPHORUS-BETAINES. 289
acids. Their salts are stable at a high temperature, and in a great many cases
their solubility is similar.
Nitric acid cannot be said to resemble either sulphuric or phosphoric acid,
nor can its salts be compared with sulphates or phosphates.
There is a distinct analogy between hypophosphorous and hydrosulphurous
acids, and between phosphorous and sulphurous acids. The first two are
extremely powerful reducing agents, and to the best of the author’s belief they
are the only substances which precipitate cuprous hydride from a solution of
a copper salt. Sulphurous and phosphorous acids are also reducing agents,
but by no means such powerful ones.
It is rather curious that in this series of acids, so far as their formule are
concerned, the only difference between corresponding terms is that all the
members of the sulphur series contain two atoms of hydrogen, whilst those
of the phosphorus series contain three.
H,SO, H,PO,
H,S0, H,PO,
H,SO, H,PO,
There is one point in which sulphur does not resemble either phosphorus or
nitrogen, viz., in the large number of oxy-acids which it forms. No oxy-acids
of phosphorus or nitrogen have been obtained corresponding with hyposul-
phurous acid or with the polythionic acids.
Phosphorus and sulphur also agree in their strong affinity for the halogens,
especially for chlorine, whilst nitrogen has almost no attraction for them. The
chlorides of sulphur and of phosphorus resemble each other in certain of their
properties. ‘Thus the higher chlorides of both readily dissociate into chlorine
and the lower chlorides, and this is especially the case with the chloride of
sulphur, SCl, which dissociates even at ordinary temperature into SCl,, or
SCI, and free chlorine. Again, these higher chlorides act upon the hydrates
of organic radicals, giving their oxychlorides, chloride of the organic radical, and
hydrochloric acid.
The two following equations will illustrate this—
C,H,—-COOH + SCl, = HCl + SOCl, + C,H,—COCl
C,H,—COOH + PCl, = HCl + POCI; + C,H,—COCl
The lower chloride of sulphur is decomposed by water, with formation of
hydrochloric and sulphurous acids (and free sulphur) ; and the lower chloride of
phosphorus is decomposed in a similar manner, with formation of hydrochloric
and phosphorous acids.
There is a very striking difference between the three elements in their affinity
for carbon—a difference that explains several facts which at first sight appear
anomalous. It is difficult to say whether nitrogen or sulphur has the strongest
290 PROFESSOR LETTS ON PHOSPHORUS-BETAINES.
affinity for carbon ; for although, undoubtedly, bisulphide of carbon is obtained
with greater ease than cyanogen—the compound ammonias (bodies in which
carbon is directly united to nitrogen)—are so numerous, stable, and so easily
obtained, that we must accord to nitrogen a very high degree of affinity for
carbon. Phosphorus, on the other hand, has but a slight attraction for carbon.
The two elements do not combine directly (so far as we know) to form a com-
pound analogous to cyanogen, and even the compounds which phosphorus forms
with hydrocarbon radicals (phosphines) are only obtained with difficulty.
This striking difference between the three elements explains, in the
author’s opinion (in some measure at least), the curious fact, that whereas both
nitric and sulphuric acid readily act on a large number of aromatic bodies in
such a manner that the nitrogen or sulphur becomes directly united to the
carbon which they contain, phosphoric acid or anhydride is without action on
them. Considering the analogies which certainly exist, and are always insisted
upon, between nitrogen and phosphorus, and also those which exist (but
are not so commonly insisted upon) between sulphur and phosphorus—we
should certainly be strongly inclined to predict, if we did not know to the
contrary, that ‘ phospho” bodies ought to be easily produced by the action of
phosphoric acid or anhydride on aromatic hydrocarbons. It is almost unneces-
sary to say that these bodies are known. We are acquainted with phosphinic
and phosphonic acids (R’PO(OH), and R’,PO(OH)), and with phosphine
oxides (R;PO), substances which are strictly analogous to sulphonic acids
(RSO,(OH)) and sulphones (R,SO,), and which are produced by a similar pro-
cess, viz., by the oxidation of phosphines, but their preparation from phosphoric
acid or phosphoric anhydride cannot be accomplished.
Organic Compounds of the three Elements.—Nitrogen is remarkable for
the ease with which it combines with carbon partly saturated with other
elements, and consequently the number of organic compounds containing
- nitrogen is very large. The number of these is increased by the fact that
nitrogen easily combines not only with hydrocarbon radicals, but also with
radicals containing carbon, hydrogen, and oxygen. Thus the amides are among
the most numerous of the organic compounds of nitrogen.
Compounds of sulphur and hydrocarbons are readily obtained, and the mer-
captans (compounds which may be considered as analogous to primary or
secondary amines) are also numerous. But compounds of sulphur with
oxidised organic radicals are scarce. However, we know of thi-acetic acid
((CH,—CO)SH) and sulphide of acetyle ((CH,—CO).S), which may be con-
sidered as analogous to primary (or secondary) and tertiary amides respectively.
Primary, secondary, and tertiary phosphines are known, and are analogous
in composition and in many of their properties to amines, but the author is not
PROFESSOR LETTS ON PHOSPHORUS-BETAINES. 29
aware that any phosphorus compound analogous to an amide has been obtained.
Phosphorus indeed displays but little tendency to combine with oxidised hydro-
carbon radicals. | }
If we compare the phosphines with mercaptans and hydrocarbon sulphides,
on the one hand, and with the amines, on the other, we find (as might indeed be
expected) very much the same difference between them as we notice between
phosphuretted hydrogen, sulphuretted hydrogen, aud ammonia.
Thus compounds of primary phosphines with the hydracids are decomposed
by water, just as phosphonium iodide is decomposed by water, and the phos-
phines oxidise with the greatest ease, and even spontaneously. The products of
their oxidation are analogous to those which the mercaptans and hydrocarbon
sulphides yield. Thus—
RSH gives R’SO,(OH)
Beas a aes.
REE, , RPO(OH),
R,PH ,, R,PO(OH),
nee POS
as the final products of oxidation.
The most characteristic property of a mercaptan is the readiness with
which it exchanges its hydrogen for metals. The author is not aware that
any attempts have been made to obtain analogous metallic derivatives of
primary and secondary phosphines, but it is highly probable that such bodies
may exist and could be easily obtained.
The organic compounds of the three elements which best admit of com-
parison are the tertiary amines and phosphines and the sulphides of hydro-
carbon radicals. These bodies have been well studied, and all of their most
important properties are known. Let us compare the properties of (CH;),N
with those of (CH;),P and (CH;),S. They are all volatile liquids of peculiar
and characteristic odour, and all possess alkaline properties. These are most
strongly marked in trimethyl-amine, least so in sulphide of methyl.
Perhaps the most characteristic property of a tertiary amine is the readiness
with which it combines with the iodide of a hydrocarbon radical to form the
iodide of a compound ammonium, the hydrate of which is a very powerful base.
A tertiary phosphine is perfectly similar in this respect, as it combines with
great readiness with an iodide of a hydrocarbon radical, and from the product of
union, salts of the compound phosphonium are easily obtained, analogous in a
great many respects to those of the compound ammonium. A sulphide of
a hydrocarbon radical also combines readily with the iodide of a hydro-
carbon radical. Thus on simply mixing sulphide and iodide of methyl, a
reaction at once occurs, and so much heat is developed by their combination
292 PROFESSOR LETTS ON PHOSPHORUS-BETAINES.
that it is necessary to cool the vessel containing the mixture in order to prevent
loss. The resulting sulphine iodide is very similar to the iodide of a compound
ammonium or phosphonium. Its hydrate is a powerful base which absorbs
carbonic anhydride from the air, and precipitates the hydrates of metals from
solutions of their salts.
But there is one important particular in which a tertiary amine is utterly
unlike a tertiary phosphine, or the sulphide of a hydrocarbon radical. 09451. CO, = 025775 € = 50:0 = C
Obtained. Calculated for
os Cl cl
Z a (CoHs)sPCH,COOH),. Neither by the action of heat
on any compound of the phosphorised betaine, nor by other reactions which
might be expected to give rise to this body, could it be obtained. The author,
VOL. XXX. PART I. 3 C
318 PROFESSOR LETTS ON PHOSPHORUS-BETAINES.
however, proposes to make other experiments with the view to obtaining it,
although he thinks it very possible it is not capable of existence.
Amongst the experiments made in this direction, may be mentioned one in
which alcohol was heated for more than a week in a sealed tube with the
hydrochlorate of triethyl-phosphorus-betaine at a temperature varying from
90°-100° C. Now the hydrobromate of dimethyl-thetine when heated with
alcohol gives thio-diglycollic ether. Thus-—-
CH,
2 (CHSC
T
The phosphorised betaine compound was however simply decomposed, even
at the temperature mentioned, into carbonic anhydride and chloride of triethyl-
methyl-phosphonium.
—COOH
+ 2C,H,O = S(CH,COOC,H,), + (CH,),8+2CH,Br+2H,0.
Action of Caustic Potash on Compounds of Triethyl-Phosphorus-Betaine.
The author was led to these experiments by an observation he had made,
that the product of action of bromacetic acid on triethyl-phosphine is readily
acted on by caustic potash, with formation of oxide of triethyl-phosphine.
The author was aware that bromacetic acid and triethyl-phosphine do not,
except under special conditions, givé a betaine derivative ; the product formed
by their union being of a different nature.
It occurred to him that caustic potash might, however, react with a
compound of the phosphorised betaine so as to give oxide of triethyl-phosphine,
and he deemed it of importance to decide this point by experiment.
Action of Potash on the Hydrochlorate.—A preliminary experiment showed
that an oily layer at once separated when strong potash solution was mixed with
the hydrochlorate.
13 gms. of hydrochlorate (once recrystallised) were dissolved in about 25 ce.
of water, and solid potash added by degrees. The solution grew very hot, and
developed a faint odour of triethyl-phosphine, which the author believes to
have been due to impurities present in the hydrochlorate. When 18 grms. of
potash had been added, the solution separated into two layers, the lower of
which consisted of an aqueous solution of the salts formed by the reaction.
The upper layer was of a yellow colour. It was separated in a tap funnel, and
fractionally distilled. The thermometer rose rapidly, and remained stationary
within a degree or two of 240° C., during which a colourless distillate passed
over, which solidified to a crystalline mass on cooling.
The boiling-point, zinc iodide compound, and other properties of this body,
at once characterised it as oxide of triethyl-phosphine.
It should have been mentioned, that before all the potash had been added
PROFESSOR LETTS ON PHOSPHORUS-BETAINES. 319
to the hydrochorate, an attempt was made to extract any substances which
might have been formed and which were soluble in ether (to which some
alcohol had been added). The oily layer from which the oxide of phosphine
was obtained was highly charged with ether, alcohol, and a solid salt, which
remained in the retort after all the oxide of phosphine had volatilised. This
was dissolved in water, then just accidulated with nitric acid, nitrate of silver
added, and the boiling solution filtered from the precipitated chloride of
silver. The filtered solution was just neutralised with carbonate of ammonia
and then allowed to cool, when a considerable quantity of crystals separated
having the appearance of acetate of silver, and which a determination of silver
showed were really that body.
0:2444 gave 01565 Ag =64:0 per cent. Ag.
Calculated for C,H,0,Ag=646
Thus caustic potash acts on the hydrochlorate to give oxide of triethyl
phosphine, together with chloride and acetate of potassium. The reaction is
expressed by the equation,
CH,—COOH
(CoH).PC + 2KHO = (C,H,),PO + KCl + CH,—COOK + H,0.
Action of Caustic Potash on the Hydrate.—A quantity of the base which had
been dried 7 vacuo was shaken with a strong solution of potash. It dissolved
after a short time, the solution grew warm, and an oily liquid rose to the
surface. This was separated, and consisted of a strong aqueous solution of
oxide of triethyl-phosphine.*
The remaining solution from which the oily layer had been separated was
neutralised with nitric acid, the mixture heated, and nitrate of silver added.
On cooling, the characteristic crystals of acetate of silver separated. Their
composition was verified by a determination of the silver which they contained.+{
0:3157 gave 0:2017 Ag = 63°9 per cent. Ag.
Calculated for CH,—COOAg= 646 “
Potash behaves then with the hydrate in exactly the same manner as with
the hydrochlorate, the reaction occurring as follows :—
CH,—COOH
(C,H) =PC +KHO = (C,H,),=PO + CH,—COOK + H,0.
OH
Action of Potash on the Ethyi-Chlorate.—The author has mentioned (p. 309)
that, whilst investigating the action of oxide of silver on the ethyl-chlorate, he
* Oxide of triethyl-phosphine appears to be completely insoluble in strong caustic potash solution,
+ The crystals became discoloured by phosphuretted hydrogen accidentally present in the air of the
room in which they were dried. The deficiency in silver is probably due to this.
320 PROFESSOR LETTS ON PHOSPHORUS-BETAINES,
noticed on mixing the two substances a very powerful smell of acetic ether,
which led him to suspect that part at least of the ethyl-chlorate had decom-
posed according to the equation,
CH,—COOC,H,
(CH =P + AgOH = AgCl + (C,H,),PO + CH,—COdAg.
The action of potash on the ethyl-chlorate has confirmed him in this
suspicion. On shaking some of the ethyl-chlorate with strong caustic potash
solution an oily layer separated, and at once a very powerful odour of acetate
of ethyl was developed.
It was not considered necessary to proceed further with the experiment, as
the odour of acetic ether is unmistakable, and the production of the oily layer,
experience had shown, always indicated the phosphine oxide. There cannot
be the slightest doubt that caustic potash acts on the ethyl-chlorate, converting
it entirely into triethyl-phosphine oxide, chloride of potassium, and acetic ether.
CH, —COOC,H,
(CH EPC + KOH = KCl + (C,H,),=P=0 + CH,—COOC,H,.
Nor can any surprise be felt at this reaction, considering the powerful
affinity of triethyl-phosphine for oxygen. It is indeed remarkable that such a
body as the hydrate of the phosphorus betaine is capable of existence at all,
and still more so that it does not split up into acetic acid and the phosphine
oxide when heated—
OHCs — (0,H,),PO + CH,—COOEH.
The author also tried the action of oxidising and reducing agents on the
hydrochlorate of triethyl-phosphorus-betaine, but without very interesting
results. Nitric acid acted readily on the hydrochlorate when the two were
warmed together, abundance of red fumes escaping. When all action was over
the nitric acid was distilled off, and a colourless liquid residue remained, which
suddenly effervesced at 220° C., red fumes escaping. The heating was stopped
and the residue was dissolved in water, and heated with chloride of platinum,
when an abundant light orange-coloured precipitate resulted. Analysis
showed this to consist of chloroplatinate of triethyl-methyl-phosphonium. Part
then of the hydrochlorate had escaped oxidation, and had simply lost carbonic
acid.
In the nitric acid which had distilled off a small quantity of oxide of
triethyl-phosphine was detected. The author could find no other definite
products of oxidation, except a minute quantity of an acid substance which
gave a white precipitate with sulphate of copper.
bo
=
PROFESSOR LETTS ON PHOSPHORUS-BETAINES. 3:
Action of Bromacetic Acid on Triethyl-Phosphine.
A preliminary experiment showed that a very violent action occurs when
the two bodies are mixed, so violent indeed that the greater part of the
mixture was blown out of the vessel in which it was made.
If, however, the two are mixed in the apparatus employed for preparing the
hydrochlorate of triethyl-phosphorus-betaine (see p. 301) and with similar pre-
cautions, the reaction is completely under control.
The bromacetic acid is at first dissolved by the phosphine, and the mixture
then grows very hot. If the phosphine is added slowly, and the mixture well
agitated from time to time, a colourless syrupy liquid results, which does not
solidify on standing. If, on the other hand, the phosphine is added rapidly,
and the temperature has not been kept down, the product is dark brown in
colour, and very often solidifies almost completely on standing. The colour-
less syrupy product also solidifies on cooling if it be heated for a short
time at 100° C., but it grows brown during the operation. The solidified
product is extremely deliquescent, liquefying almost immediately when ex-
posed to the air. It is very soluble in alcohol, but is insoluble in ether.
The addition of the latter to its alcoholic soluticn causes the precipitation
of an oily liquid which refuses to crystallise. It is also soluble in chloro-
form, and ether often precipitates it from its solution in that liquid in the
form of small rhombic crystals. It is, however, extremely difficult to recrys-
tallise it in this way, and the brown colouring matter adheres to the crystals
most obstinately.
The properties of the product either before or after recrystallisation are not
those of a salt of the phosphorised betaine. Thus it yields no crystalline
compound with chloride of platinum, nor could a crystalline chloroplatinate be
obtained after its bromine had been replaced by chlorine (by treating its solu-
tion with oxide of silver, filtering and adding hydrochloric acid).
It was found that its solution gave with carbonate or acetate of lead
crystalline compounds, and much time was spent in endeavouring to fix their
composition.
On adding carbonate of lead to the aqueous solution of the product,
effervescence occurs, and if the solution is hot, a crystalline precipitate is soon
formed. Also on mixing acetate of lead with a solution of the product, sparingly
soluble crystalline compounds are produced. If the solutions are cold a white
flocculent precipitate falls, which in tolerably dilute solution dissolves spontane-
ously. On scratching the sides of the vessel in which the two solutions have
been mixed, or on warming the mixture, a colourless salt is precipitated in
needles or plates. If the solutions are boiling two salts are often formed—one
322 PROFESSOR LETTS ON PHOSPHORUS-BETAINES.
crystallising in warty masses, the other in plates and needles. On dissolving
either of these in boiling water an insoluble residue is left, which appears to be
bromide of lead. (It melts to a yellow liquid, and does not char when heated).
The filtered solution deposits needles or plates on cooling, and very little of the
warty crystals ; and on again recrystallising, the salt is obtained almost free
from the latter.
The composition of the lead salt varies, and although a large number of
specimens were examined no two of them yielded the same numbers. The
crystalline form was often entirely different, and was altered by recrystallisation
of the salt. Moreover, a distinct smell of triethyl-phosphine was always noticed
when carbonate of lead was employed in its preparation.
The author could arrive at no definite conclusion as to the composition of
these sparingly soluble lead compounds. He thinks it advisable, however, to
give the numbers obtained—
I. LE WY, IV. V. VI.
Lead, . ; : 49:4 49:7 44°6 44:5 43°7 68:2
Bromine, : , 37:2 36'6 40:0 40:0 a 26°7
VIL. VIII. IX. Ke XI.
end : ; Of ee bcd 52°4 39°6
Bromine, f ‘ 25:2) 452 42:0 42°5 43:0
J. and IT. obtained with acetate of lead, and produced from a hot solution.
TLL; EV.,.end Vv, os % - BICOL | a
VI. and VII. obtained as I. and II.
VIIL, IX., X., and XI, obtained with carbonate of lead.
CH,—CO
B= CTO. = CHL). PC
Spal 2 ( 24*5/3 ‘sal
Lead. Bromine.
Calculated for 8 + PbBr, ; : 38'1 29°4
4 B+ 2PbBr, . : 45°5 ODD
i B+5PbBr, . ; 48°7 37°6
x B+4PbBr, . : 50-4 38'9
The preceding results having failed to establish the composition of the pro-
duct, other reactions were sought for which would decide this point. In con-
sidering how to attack this problem the question presented itself, is it not
possible that the action of triethyl-phosphine on bromacetic acid gives rise to
an isomer of hydrobromate of triethyl-phosphorus-betaine? Such a pheno-
menon would not be extraordinary, as chloracetic, bromacetic, and iodacetic
acid do not always act in the same manner.
PROFESSOR LETTS ON PHOSPHORUS-BETAINES. 323
It is quite conceivable that three bodies can exist having the composition of
hydrobromate of triethyl-phosphorus-betaine.
The constitution of these three may be represented by the formule—
if, 1G
2 gb Br
(CH) = PC (CH HPC
CH,—COOH, OOC—CH,,
Hydrobromate of triethyl- Aceto-bromide of
phosphorus-betaine. triethyl-phosphine.
1.
H
(CH)),PSC
OOC—CH.,Br ,
Bromacetate of triethyl-
phosphine.
No. II. would probably give no platinum salt, whereas No. IIL, if it gave
any, would give the chloroplatinate of triethyl-phosphine. No. III. would pro-
bably give no bromide of silver on treating its solution with nitrate of silver.
It occurred to the author that the action of caustic potash would decide
between II. and III. For if it reacted with them at all, the reaction would
probably be as follows :—
Br
(IL) (CH,)=PC + 2KHO = (C,H,,=P=0 +CH,—COOK+KBr+H,0.
00C—CH,
H
(II1.) (CyH,) =P + KHO = (C,H,),=P+CH,Br— COOK +H,0.
0OC—CH,Br
With II. potash would react to give oxide of triethyl-phosphine, acetate of
potassium, bromide of potassium, and water ; whilst III. would give with the
same reagent triethyl-phosphine and bromacetate of potassium (or glycollate
and bromide of potassium).
It was resolved, therefore, to submit the product of action of bromacetic
acid on triethyl-phosphine to treatment with caustic potash.
Action of Caustic Potash.—18 grms. of triethyl-phosphine were dropped
slowly into 20 grms. of bromacetic acid in the apparatus already mentioned.
The product was heated to 100° for about twenty minutes ; it became brown,
and a few bubbles of gas were evolved ; on standing it solidified. It was then
dissolved in chloroform, and a large excess of dry ether added—sufficient to
precipitate the product in the crystalline state. The mixture of chloroform
and ether was poured off from this, and it was then well washed with dry
ether, and the last traces of ether removed by gentle heating.
324 PROFESSOR LETTS ON PHOSPHORUS-BETAINES.
It was then dissolved in water and the solution warmed. 6 grms. of solid
caustic potash were added (dissolved in a little water), and the two solutions
mixed. No separation of triethyl-phosphine occurred. Another 6 grms. of
potash were then added ; triethyl-phosphine then separated, but so far as could
be judged it amounted to only 2 or 3 grms.
The aqueous solution was drawn off from it, and it was found that the
addition of strong caustic potash solution to this caused the separation of an oily
liquid which rose to the surface and collected in a layer.
The mixture was repeatedly extracted with ether (which dissolved the oily
layer), and the ethereal extract separated by a tap funnel, and fractionally
distilled.
As soon as the ether, water, and triethyl-phosphine had passed over, the
thermometer rose to 259°, and remained stationary at that temperature, whilst
a colourless liquid passed over, which solidified on cooling.
The boiling-point of this liquid, as well as its properties, left no doubt as
to its identity with triethyl-phosphine oxide.
The potash solution from which it had been extracted with ether, precipi-
tated, during the extraction, a colourless crystalline salt. To obtain more of
this, a considerable quantity of alcohol mixed with a little ether was added.
The insoluble salt was then collected on a filter, and washed repeatedly with
alcohol. It weighed 9 grms., and consisted entirely of bromide of potassium.
These experiments indicate that bromacetic acid unites with triethyl-
phosphine to give both the isomers, which, for the sake of convenience, we may
eall If. and III. For although neither acetate nor bromacetate of potassium
were specially sought for in the product of action (owing to the difficulty of
separating them from the large excess of caustic potash present), the pro-
duction of both triethyl-phosphine and the phosphine oxide may be considered
as almost conclusive evidence of the production of both isomers, and from the
quantities of these it would appear that II. is formed in far larger quantity
than III.
But shortly after these experiments were made, it was found that hydro-
chlorate of triethyl-phosphorus betaine also reacts with potash to give the
phosphine oxide, and both chloride and acetate of potassium, the reaction
occurring according to the equation,
Ol
(CoH) PK +2KHO = (C,H,),PO+KCl+CH,COOK+H,0.
CH,—COOH
(see p. 319.
The question therefore arose—is no hydrobromate of triethyl-phosphorus-
betaine formed when bromacetic acid acts on triethyl-phosphine ?
The hydrobromate was, therefore, prepared from the hydrochlorate (see
PROFESSOR LETTS ON PHOSPHORUS-BETAINES. 325
p. 304) and it was found (1) that it readily yielded a sparingly soluble platinum
salt ; and (2) that it yielded carbonic acid on heating (see p. 316).
Now it has been already mentioned that no sparingly soluble platinum salt
could be obtained from the product of action of bromacetic acid or triethyl-
phosphine, and it had also been found that this product yields only a very
small quantity of carbonic acid on heating (see p. 328), both of which results
are against the supposition that any of the true hydrobromate is formed.
Fresh experiments were, however, necessary to decide this point. 3:5
erms. of carefully dried and purified bromacetic acid were dissolved in about
20 cc. of perfectly pure and dry ether. 3 grms. of triethyl-phosphine were
dissolved in about the same quantity of ether, and the two solutions were
simply mixed, without any special precautions. ‘The flask in which the mixture
was made was then corked and placed in cold water: oily drops precipitated.
The flask was vigorously shaken from time to time, and was then left to
itself in the cold water. The contents began to crystallise in a short time,
and soon solidified to a solid mass. After a few hours this was broken up
and thoroughly extracted with dry ether. It was then placed in vacuo for
some hours.
Some of the snow-white product thus obtained was titrated with standard
nitrate of silver solution, and was found to contain the amount of bromine
required for the formula C,;H,,0,PBr.
(1) 03316 required 13:2 cc. AgNO,=0:1056 Br=31'8 per cent. Br.
(2) 04707 * eso 3 Se O1480) ed |e. Br.
Obtained.
r 1. Calculated for C,H,,0,PBr.
Bromine, . 318 . di4. ; : ole:
A portion of the product was treated with oxide of silver, and hydrochloric
acid was added to the filtered solution. On the addition of chloride of
platinum to this, a sparingly soluble orange-coloured salt separated exactly
like the chloroplatinate of triethyl-phosphorus betaine.
Moreover, on heating some of the product, carbonic acid was given off in
abundance, no charring occurred, and the residue solidified. On treating the
latter with oxide of silver, hydrochloric acid, and chloride of platinum in
succession, the characteristic chloroplatinate of triethyl-methyl-phosphonium
separated.
These results then are quite different from those previously obtained, and
indicate that some at least of the body produced by the action of bromacetic
acid on triethyl-phosphine is the true hydrobromate of triethyl-phosphorus
betaine. There was, however, no doubt whatever in the author’s mind, from
VOL. XXX. PART I. 3D
326 PROFESSOR LETTS ON PHOSPHORUS-BETAINES.
the numerous and carefully conducted experiments he had made on the action
of the two bodies, that under certain conditions none of the true hydrobromate
is obtained.
In the experiment just described both the bromacetic acid and the triethyl-
phosphine were diluted with a large quantity of ether, and the temperature
was not allowed to rise; whereas in previous experiments no ether was
employed as a rule, and the two bodies were allowed to react on each other
in the pure state. Much heat was developed, and as before stated the product
of action was frequently heated to 100° C. to cause it to solidify.
Now it has been shown that the hydrobromate (and other salts) of triethyl-
phosphorus betaine are decomposed when heated in such a manner that
carbonic acid escapes, and a salt of triethyl-methyl-phosphonium remains.
Xx x
(CH) ,PK = (CH) PC +CO,.
CH,COOH CH,
Whereas the product of action of bromacetic acid on triethyl-phosphine
yields on heating only a small quantity of carbonic acid, but a large quantity of
a solid volatile body (see p. 328). It is obvious then that the action of heat is a
ready method for estimating the amount of hydrobromate of triethyl-phos-
phorus-betaine present in any specimen of the product of action of bromacetic
acid on triethyl-phosphine.
2°9 germs. of the product just described, and which had been proved to con-
tain hydrobromate of triethyl-phosphorus-betaine, were heated in an apparatus
so arranged that any permanently gaseous products could be caught.
It began to effervesce at 200° C. At 215° C. the effervescence was very
brisk, and at 230° it suddenly solidified to a pure white product. 192 ce. of
gas were evolved.
The solid residue was heated over the naked flame, it fused, boiled, and a
considerable quantity of a pure white substance passed over at 303° C., which
solidified in the condenser. Were then is conclusive evidence that the product
did not consist entirely of the hydrobromate of triethyl-phosphorus-betaine ; had
it done so no volatile body would have been formed, and 373 cc. of carbonic
acid would have been produced. In round numbers, only half that quantity of
gas was evolved, so that at least one-half of the substance consisted of a
different body from the betaine compound.
Another experiment was made as follows :—12 grms. of triethyl-phosphine
were added rapidly to 14 grms. of bromacetic acid. The mixture was allowed
to grow very hot, and was cooled only when the phosphine boiled. As soon
as all action was over, the viscous dark-brown product was divided roughly
into two parts, one of which was heated in a distilling flask provided with the
arrangement already described for catching liquid and gaseous products. The
PROFESSOR LETTS ON PHOSPHORUS-BETAINES. 327
heating was performed with a BunseEn’s burner, the distilling flask being placed
on wire gauze. A volatile liquid first passed over, together with about 50 cc.
of permanent gas. The temperature of the distillate then rose rapidly to
303° C., and the latter solidified on cooling. No more gas was evolved.
The other half of the product was dissolved in water, and boiled with slaked
lime* until the solution was alkaline. Only a trace of triethyl-phosphine was
evolved. ‘The solution was then filtered, mixed with excess of dilute sulphuric
acid, and the precipitated sulphate of calcium separated from the solution by
squeezing the mixture on a cloth filter. The dark-brown solution thus obtained
was distilled until its volume was reduced by about three-fourths. The colour-
less distillate was saturated with oxide of silver, and the mixture boiled and
filtered.
On cooling abundance of crystalline matter separated, having the appear-
ance of acetate of silver. It was dried in the desiccator, and a determination
of silver made.
0:3202 gave 02057 Ag=64'3 per cent. Ag.
Obtained. Calculated for C,H,0,Ag.
Silver, , : F s 64:3 ; : : : 646
Now, in this experiment the triethyl-phosphine and bromacetic acid were
mixed in the pure state, and the temperature was allowed to rise considerably.
10 germs. or thereabouts of the product yielded when heated, only 50 cc. of
gas (presumably carbonic acid) ; whereas, had the product consisted entirely of
the betaine hydrobromate, 850 cc. of carbonic acid should have been evolved.
Therefore only about 5 per cent. of the product consisted of the betaine hydro-
bromate. Of what did the remaining 95 per cent. consist? The action of the
slaked lime may, the author thinks, be considered as proving it to be the
aceto-bromide of triethyl-phosphine—
Br
(C,H,) =P
2 ake O OUCH...
The lime acting in the same manner as caustic potash, and giving bromide and
acetate of calcium together with oxide of triethyl-phosphine.
Br
ACH =P car, + UCM OW:
5 3
= 2(C,H,),=P = O + CaBr, + (CH,—COO),Ca + H,0.
As before pointed out, any bromacetate of triethyl-phosphine would have been
detected by the evolution of triethyl-phosphine on the addition of the alkali;
whereas in this particular experiment mere traces of that body were given off.
* Employed instead of caustic potash, on account of its insolubility.
32
OO
PROFESSOR LETTS ON PHOSPHORUS-BETAINES.
There is another very powerful argument in support of this view of the
nature of the product.
There is no doubt whatever that when it is heated bromide of acetyl is
evolved (see below). Now, that is exactly what might be expected to occur
with the aceto-bromide. Thus—
‘Br
(CH)PC — (0,H,),PO + CH,—COBr.
0:0C—CH,
Action of Heat on the product of action of Bromacetic Acid on
Triethyl-Phosphine.
In some of his earlier experiments on the product of action of bromacetic
acid on triethyl-phosphine, the author had observed that when it is heated a
crystalline body volatilises.
This fact seemed to be one of importance, and he therefore determined to
obtain this crystalline body in quantity, and to examine its properties.
6 grms. of triethyl-phosphine were mixed in the usual way with 7 grms. of
bromacetic acid, without diluting the latter with ether. When the action was
at an end the product was at once submitted to the action of heat. It fused at
a low temperature ; a few cubic centimetres of gas were evolved, and later a
small quantity of a pungent fuming liquid distilled. This fuming liquid on re-
distillation passed over before 100° C. It had the odour of bromide of acetyle,
and its properties agreed with those of that body. On mixing it with water
much heat was evolved, and on distilling the mixture (previously diluted with
a considerable quantity of water) acetic acid passed over, and was identified
by its silver salt. The residue contained hydrobromic acid. Moreover, on
mixing some of the fuming liquid with fused acetate of potash, the odour of
acetic anhydride was at once apparent. There can be no question therefore
that it consisted mainly of bromide of acetyle.
After the fuming liquid had passed over the thermometer rose rapidly,
and a crystalline solid began to appear in the tube used as condenser. The
distillation was stopped when nothing but a black carbonaceous mass remained
in the distilling flask. The crystalline solid amounted to about 7 grms. in
weight. It was melted out of the condensing tube, transferred to a distilling
flask, and heated. It fused, and at first a little hydrobromic acid was evolved.
The thermometer then rose to 303° C., and remained stationary,* whilst a
colourless liquid passed over, solidifying to a white crystalline mass on cooling.
At the end of the distillation the thermometer stood at 305° C., and about 5
erms. of the crystalline product were obtained.
* The condensing tube was changed when the temperature became constant.
5
PROFESSOR LETTS ON PHOSPHORUS-BETAINES. 329
It was melted out into a test tube, and three weighed tubes filled with it.
These were then sealed up, and used for determinations of carbon, hydrogen,
and bromine.
Bromine—
0'6233 gave 0-4682 AgBr=019818 Br=31°7 per cent,
Carbon and Hydrogen. (By combustion of the substance with oxide of copper and
chromate of lead, a stream of oxygen being passed through the combustion tube at the end of
the analysis)*—
(1) 045361 gave 03184 H,O = 0:03577 H = 18 percent. H.
04536 , 0607 CO, = 0:065545 H = 365 . Cc:
(2) 0:3329 gave 0:2436 HO, = 0:02706 H
03829) | «5... 04515 ,.CO;,,= 0:12313 , C
ll
ll
8:1 per cent. H.
37°0 %5 Cox
In another experiment, conducted in the same manner with 12 grms. of the
phosphine and 14 germs. of bromacetic acid, the same phenomena were observed:
17 grms. of crude crystalline product were obtained. This was distilled twice.
It began to boil at 302°, the temperature was constant at 303°, and the distilla-
tion was ended at 306°.
The portion boiling from 302°-304° was at once melted intoa test tube, and
three small tubes were filled for analysis and sealed off.
Bromine—
0-7504 grms, gave 0°553 AgBr=0°234074 Br=31:2 per cent.
0:4203 t ss 01320 = ,, =31'4
Carbon and Hydrogen—
0:349 gave 0:2578 H,O =0:02864 H=8:2 per cent.
0349 > 04810". =O1s117 C= 376 5,
Another specimen similarly prepared boiled between 303°-308° C. The
results of its analysis were as follows .—
PE)
Bromine—V olumetrically.
(1) 0:296 gave 0:09120 Br=30°9 per cent. Bromine.
(2) 0800 ,, 024880 ,, =31:°0
Carbon and Hydrogen—t
04951 gave 06584 CO,=0:179564 C=36:3 per cent. Carbon ,
04951 , 03623 ,, =0:040255 H=8-1 2 Hydrogen.
2?
In these analyses the carbon and bromine agree with the percentages
required for a product of addition, of one molecule of bromacetic acid and one
of triethyl-phosphine.
* This combustion cannot be relied upon, as the substance volatilised with unexpected rapidity, and
probably some carbonic acid was lost.
+ Volumetrically by VotpHarpt’s method.
+ This combustion may have given a slight deficiency in carbon, as the substance volatilised very
rapidly when it was first melted out of the tube.
330 PROFESSOR LETTS ON PHOSPHORUS-BETAINES.
I. II. 19 E IV. Calculated for C,H,,PO,Br
Carbon, 36:5 37°0 376 36:3 374
Hydrogen, . 78 Si 8:2 81 7:0
———
Bromine, . 31-7 31:2 31:4 309 31:0 31:1
but the percentage of hydrogen is too high.
As the bromine was readily precipitated by nitrate of silver, it was con-
sidered that the body could scarcely be the bromacetate of triethyl-phosphine
H ,
((C,H,)y P< 600—CH,Br) and as the hydrobromate of triethyl-phosphorus-
betaine (CHP Et, coon) had been shown to give abundance of
carbonic acid, and to yield a different substance when heated, the new body
could not be identical with it.
There remains the isomer of the two preceding bodies (GH).PK GO C_cH
3
the aceto-bromide of triethyl-phosphine. It is quite conceivable that it would
be volatile without decomposition, and it is probable, if not certain, that its
bromine would be precipitated by nitrate of silver. The evidence appeared to
be in favour of the identity of this substance with the volatile product in
question, although the high percentage of hydrogen which the latter contained
was against this view of its composition.
The product was very deliquescent, and soluble in alcohol and chloroform,
but not in ether. It yielded no sparingly soluble compound with chloride of
platinum neither when alcoholic solutions of the two were mixed nor when it
was converted into chloride (by action of oxide of silver and hydrochloric acid).
Attempts were made to determine its vapour density by Vicror MEYER’s
method (using vapour of mercury as the source of heat), but without success,
as it charred.
It was considered probable that, by acting on it with oxide of silver, its
nature could be determined. For if its constitution were expressed by the
formula (C:H;);P Bante CH, oxide of silver should give either a correspond-
ing hydrate, or oxide of triethyl-phosphine and acetate of silver.
Br
(HPC “- +2AgOH = (C,H;),PO+ AgBr+CH;COOAg+H,0.
3
Several experiments were tried on the action of oxide of silver on the
product. The first of these showed that oxide of triethyl-phosphine is formed.
The oxide was collected in the pure state; its boiling-poiut determined, as well
as other of its characteristic properties. The bromide of silver produced at the
same time was identified, but no acetate or other soluble salt of silver could be
PROFESSOR LETTS ON PHOSPHORUS-BETAINES. 331
detected. One very carefully conducted experiment may be described to show
how this was proved. 10 grms. of the product boiling between 304°-306°, were
dissolved in water and mixed with excess of oxide of silver. Bromide of silver
was precipitated, but no gas was evolved. The mixture of bromide and oxide
of silver was then thoroughly squeezed from the solution in a cloth filter,
suspended in water, and a current of sulphuretted hydrogen passed for some time
until the mixture was thoroughly saturated. The aqueous solution was. then
filtered off from the sulphide of silver, and was heated in a distilling flask. No
acetic acid passed over. When hydrobromic acid of constant boiling-point
began to distil, the residue was heated in a water bath and evaporated to dry-
ness. A few flakes of crystalline matter (less than 0°5 grm.) remained.
Neither acetate of silver then, nor any other salt of silver could have been
precipitated with the bromide except in minute quantity. The aqueous solu-
tion squeezed from the bromide of silver was heated in a distilling flask con-
nected with an apparatus for collecting any gas that might be evolved, but none
came off. Water at first distilled, and later 5-7 grms. of oxide of triethyl-
phosphine boiling at 240°, and solidifying in the condenser. There remained
in the distilling flask only a drop or two of a substance which was too small in
quantity to be investigated. This experiment shows then, that when the
product is acted on with oxide of silver, only bromide of silver and oxide of
triethyl-phosphine are produced.
The results of these experiments are decidedly antagonistic to the view that
the volatile body consists of aceto-bromide of triethyl-phosphine, and in fact
may be considered as proving that it is not that substance. They indicate, on
the other hand, that it consists of a compound of hydrobromic acid with oxide
of triethyl-phosphine.
Crafts and Sitva* have investigated the action of hydrobromic acid
on oxide of triethyl-phosphine. By heating the latter with a 64 per cent
solution of the former to 110° C. they obtained a product which boiled at
205°-210° C. under a pressure of 2 inches of mercury. This was redistilled
under a pressure of 14 inch of mercury, and boiled at 198°-203° C.
The author subjoins the results of the analyses of these two products,
together with the mean of the numbers obtained by himself with the volatile
product boiling at 303° C., and the numbers calculated for a compound of four
molecules of oxide of triethyl-phosphine with three molecules of hydrobromic
acid—
Crafts’ and Silva’s product boiling at— The author’s Calculated for
05 “2007 0 9822203". product. -4[P(C,H,),0],3HBr.
Carbon, \/)\) “85:79 36:18 36°85 36:9
Hydrogen,. . 8:03 8:23 8-05 ey
Bromine, . . 32:17 31:16 31:22 30°8
* Journal of the Chemical Society, 1871, p. 637.
332 PROFESSOR LETTS ON PHOSPHORUS-BETAINES.
Crarts and Sitva also passed hydrobromic acid gas into the dry phosphine
oxide, and distilled the product. It began to boil at 260°, and about half passed
over at 270-°300° C. A residue was left in the retort at 310°, which began to
decompose.
The author considered it advisable to repeat this experiment.
Action of Hydrobromic Acid on Oxide of Triethyl-Phosphine.
7-8 germs. of the oxide were fused and a current of hydrobromic acid passed
through it. The gas was absorbed eagerly, much heat was disengaged, and the
product was coloured brown. As soon as the hydrobromic acid ceased to be
absorbed, the product was submitted to distillation. Below 300° a little liquid
passed over, the thermometer then rose slowly, whilst a colourless liquid passed
over, which solidified on cooling. It had much the same appearance as the
volatile product obtained by heating bromacetic acid and triethyl-phosphine,
but it did not solidify quite so readily as that substance. The thermometer
was tolerably constant from 320°-325° C., but a good deal of residue remained
above this temperature. In another experiment the oxide of the phosphine
was not saturated with hydrobromic acid, but was treated with rather more
than 30 per cent. of its weight of the gas, which as before was eagerly absorbed.
On distilling the product thus obtained only a few drops of liquid passed below
303°. But from this temperature to 308° almost every drop of the product
passed over, and solidified on cooling to a white solid.
A determination of the bromine which it contained was made with the
following results :—
03968 required 15:8 cc. decinormal AgNO,=31'9 per cent. Br
0:4761 sup jloOas 7 5 Peels
2
Although these numbers are somewhat higher than those obtained with the
product of the action of heat on bromacetic acid and triethyl-phosphine, the
difference is but slight, and very probably it would have been even less had the
substance been re-distilled.
The author considers that there can be no doubt as to the nature of the
volatile body obtained by heating the triethyl-phosphine and bromacetic acid ; it
is simply a compound of phosphine oxide with hydrobromic acid, or a mixture
of the two substances, similar to hydrobromic acid, or hydrochloric acid solu-
tions of constant boiling point.
Crarts and Sitva take the latter view of the nature of the substance
obtained by them by the action of hydrobromic acid on the phosphine oxide.
In the memoir already quoted they say, ‘“‘ Hydrobromic, like hydrochloric acid,
combines with the oxide of triethyl-phosphine in the same way that these acids
combine with water, and it is only under exceptional circumstances that a com-
ae ie ae iy
PROFESSOR LETTS ON PHOSPHORUS-BETAINES. 333
pound with a simple chemical formula is formed.” The author, however, is by
no means convinced of the correctness of this statement, for the numbers
obtained by them agree very well (as he has shown) with a simple chemical
formula, and although the latter does not consist of one molcule of the oxide and
one molecule of the acid, it must be remembered that phosphine oxides combine
with other bodies frequently in somewhat indefinite molecular proportions, in
the same manner that silicic acid combines with bases. Further experiments
are, however, necessary to decide the question.
The action of heat on the product of union of triethyl-phosphine and
bromacetic acid cannot be expressed by any simple equation.
It is, however, probable, from the fact that some bromide of acetyl is
evolved, that the first action of heat is as follows :—
Br
(CoH) =PC = (C,H,),PO+CH,—COBr.
~ CH,
The phosphine oxide then removes hydrobromic acid from the bromide of
acetyl, and the residue CH,—CO becomes carbonised.
Action of Bromide of Acetyl on Oxide of Triethyl-Phosphine.
Whilst the experiments which have just been described were in progress,
and the author had come to the conclusion that, under certain conditions,
bromacetic acid and triethyl-phosphine unite to form the aceto-bromide of
triethyl-phosphine, Dr Crum Brown suggested that it would be worth while
to try the action of bromide of acetyl on the oxide of triethyl-phosphine, as
by that means the same body ought to be formed.
(0,H,),=P=0+CH,—COBr = (0, HPC
OOC -—CH,.
The experiment was accordingly tried.
The two substances react with energy, and if they are undiluted much
heat is evolved, the mixture grows brown, and on cooling solidifies to a
buttery mass, having exactly the same appearance, and, so far as could be ascer-
tained, the same properties as the product of action of bromacetic acid on triethyl-
phosphine.
On heating, this product behaved exactly like the latter ; hydrobromic acid
and a small quantity of bromide of acetyl passed over first ; the thermometer *
then rose to 308° C., and remained stationary at that temperature, whilst a
colourless liquid distilled, which solidified on cooling, and had the appearance
* The thermometer employed was different from that used in previous experiments, and the author
cannot vouch for its accuracy.
VOL. XXX. PART L 3 E
334 PROFESSOR LETTS ON PHOSPHORUS-BETAINES.
of the product obtained by the action of heat on bromacetic acid and triethyl-
phosphine, but was rather softer and more buttery.
Determination of the bromine it contained gave the following numbers :—
(1) 07472 required 29'8cc decinormal AgNO, = 31:9 per cent. Bromine.
(GORGE ee ee LPEIEE ;
(3) 0°5665 ss, 230, ” » = 32°5 ”
These numbers are somewhat higher than those obtained with the product
of action of heat on bromacetic acid and triethyl-phosphine, but agree with those
which Crarts and Sitva found in the product of action of hydrobromic acid on
the phosphine oxide, before it had been re-distilled.
Although the author feels convinced that all three products have a similar
composition, he is unable at present to account for the slight differences
observed in the amount of bromine which they contain.
The experiment on the action of bromide of acetyl on oxide of triethyl-phos-
phine may be considered as confirming the view that the author has already
advanced concerning the nature of the product formed by the action of brom-
acetic acid on triethyl-phosphine.
The experiments just described show that the action of bromacetic action on
triethyl-phosphine varies with the conditions in a very interesting and remark-
able manner.
The author thinks that he has proved that, at low temperatures, the two
substances react so as to produce about equal quantities of hydrobromate of
triethyl-phosphorus betaine and aceto-bromide of triethyl-phosphine, or a mix-
ture of the latter with bromacetate of triethyl-phosphine.
At intermediate temperatures very little of the hydrobromate is formed, and
the product consists of the bromacetate and aceto-bromide ; whilst at higher
temperatures the aceto-bromide is almost the sole product.
Considering the very powerful affinity of phosphorus for bromine, the trans-
formation of
H
(C#H)s=PC
OOC—CH,Br
into
Br
(CoH) =P
OOC—OCH,,
is readily intelligible, and there can be little doubt that bromacetate of triethyl-
phosphine is a very unstable body.
PROFESSOR LETTS ON PHOSPHORUS-BETAINES. 30D
Now, in addition to having a strong affinity for bromine, phosphorus has if
anything a greater attraction for oxygen, whilst its affinity for carbon is slight,
so that it is almost surprising that
: Br
(CH,)s= PC
CH, — COOH
should be capable of existence at all. And it is certainly a remarkable feature
in the history of these substances that this body should lose oxygen when
heated (in the form of carbonic acid). It might rather be expected that it
would, when heated, be converted into the aceto-bromide. But all attempts
made in this direction have been unsuccessful.
In conclusion, I have to express my thanks to my assistant, Mr N. Cotte,
for the assistance he has rendered me during these experiments.
Vol XXX Plate XVIL
J. Bartholomew, Edm
(oar)
XII.—On Dust, Fogs, and Clouds. By Joun AITKEN.
(Read, Part I., December 20, 1880; Part II., February 7, 1881.)
Parr 1.
Water is perhaps the most abundant and most universally distributed form
of matter on the earth. It has to perform more varied functions and more
important duties than any other kind of matter with which we are acquainted.
From its close connection with all forms of life, it has been the subject of
deepest interest in all ages. It is constantly changing from one of its states to
another. At one time it is solid, now liquid, and then gaseous. These
changes take place in regular succession, with every return of day and night,
and every successive season ; and these changes are constantly repeating them-
selves with every returning cycle. Of these changes, the one which perhaps
has the greatest interest for us, and which has for long ages been the subject
of special observation, is the change of water from its vaporous state, to its
condensation into clouds, and descent as rain. Ever since man first “ observed
the winds” and “regarded the clouds,” and discovered that “fair weather
cometh out of the north,” this has been the subject of intensest human interest,
and at present forms one of the most important parts of the science of
meteorology, a science in which perhaps more observations have been made
and recorded than in all the other sciences together.
In the present paper I intend confining my remarks to this change
of water from its gaseous or vaporous to its liquid state, with particular
reference to that change when it takes place in the cloudy condensation
of our atmosphere. Let us look briefly at the process as it goes on in
nature. As the heat of the sun increases, and the temperature of the earth
rises, more and more water becomes evaporated from its surface, and passes
from its liquid form to its invisible gaseous condition; and so long as the
temperature continues to increase, more and more vapour is added to the
air. This increased amount of vapour in hot air compared to cold air is
generally explained by saying that hot air dissolves more water than cold air.
This, however, is not the case. Air has no solvent action whatever on water
vapour. Water vapour rises into air to the same amount that it would do into
a vacuum at the same temperature, only it rises into air more slowly than into
a vacuum, and the amount of vapour which can remain in the air is independent
VOL, XXX. PART I. 3 F
308 JOHN AITKEN ON
of the amount of air present, that is, independent of the pressure of the air,
and depends only on the temperature.
After air has become what is called “ saturated ” with vapour, that is, when
the vapour tension is that due to the temperature, a momentary condition of
stability is attained. Suppose the temperature to fall, a change must now take
place. All the water cannot remain as invisible vapour ; some of it must con-
dense out into its visible form. It is this condensed water held in mechanical
suspension in the air to which we give the names of fog, cloud, mist, and rain,
phenomena having some resemblance to each other, yet possessing marked
differences. The particles composing a fog, for instance, are so fine they
scarcely fall through the air, a cloud is a little coarser in the grain, while a
mist is coarser still in texture, and rain is any of these while falling, whether it
be a wetting mist or a drenching rain. And the question now comes, Why
this difference? Why should the water vapour condense out of the air in one
case in particles so minute they seem to have no weight, and remain
suspended in the air, while in another case they are large grained and fall
rapidly 2
As the key to the answer to this question is given by a very simple experi-
ment, it will be well for us here to have a clear conception of the conditions of
that experiment. Here are two large glass receivers, both connected to this
boiler by means of pipes. If we now allow steam to pass into this receiver,
which we shall call A, you will see the steam whenever it begins to enter.
There it comes, rising in a dense cloud, and soon you see the receiver gets filled
with the condensed vapour, forming a beautiful white foggy cloud, so dense
that you cannot see through it. Let us now pass some steam into the other
receiver, which we shall call B. Observe—nay, you may strain your eyes as
much as you please, you cannot see when the steam begins to enter, and now
it has been rushing in for some time, and yet you cannot see it. There is not
the slightest appearance of cloudiness in the receiver, yet it is as full of water
vapour as the receiver A, which still remains densely packed with fog.
Now, why this difference in the two cases? Simply this. The receiver A,
which is so full of fog, was at the beginning of the experiment full of ordinary
air—the air of this room—while the other receiver B was also full of the air
of this room, but before entering the receiver it was passed through a filter of
cotton-wool, and all dust removed from it. The great difference, then, between
the appearance of these two receivers is due to the dust in the air. Dusty air
—that is, ordinary air, gives a dense white cloud of condensed vapour. Dust-
less air gives no fogging whatever.
But why should there be this difference in the two cases? Why should
dust have this peculiar action? or rather, Why does not the water vapour
condense into its visible form in air free from dust? The air is “ super-
DUST, FOGS, AND CLOUDS. 339
saturated” in both cases, but in the one case it condenses out and forms a
cloudiness, while in the other it remains in its invisible vaporous form. It
will be necessary to diverge here a little from our immediate subject, to say a
few words on the conditions under which water changes from one of its forms
to another.
We have what are called the “ freezing-point ” and the “ boiling-point” of
water. These are, of course, the same as the melting-point and the condensing-
points of water. Water at 0° C. will freeze if cooled, or melt if heated. It
will pass into vapour if heated above 100° C., and will pass from vapour to
liquid if cooled below 100° C., that is, at standard pressure. But something
more than mere temperature is required to bring about these changes. Before
the change can take place, a “free surface” must be present, at which the change
can take place. I may here say that what I mean by a ‘free surface” is a
surface at which the water is free to change its condition. For instance, the
surface of a piece of ice in water is a “free surface” at which the ice may
change to water, or the water change to ice. Again, a surface of water
bounded by its own vapour is a “free surface,” at which the water may
vaporize, or vapour condense. What are called the “freezing” and. “ boiling
points” of water are the temperatures at which these changes take place at
such “free surfaces.” When there is no “ free surface” in the water, we have
at present no knowledge whatever as to the temperature at which these
changes will take place.
It is well known that water may be cooled in the absence of “free surfaces ”
far below the “ freezing-point” without becoming solid. Some years ago* I
showed reason for believing that ice in the absence of ‘‘ free surfaces ” could be
heated to a temperature above the “ freezing-point” without melting. Pro-
fessor Carnelly has quite lately shown this to be possible, and has succeeded in
raising the temperature of ice to 180° C.t Further, I have shown in the paper
above referred to, that if water be deprived of all “free surfaces,” it may be
heated in metal vessels while under atmospheric pressure to a temperature far
above the “ boiling-point,” when it passes into vapour with explosive violence.
From this we see that it requires a lower temperature to cause a molecule
of water to adhere to another molecule of water to form ice, than for a molecule
of water to adhere to a molecule of ice. Also that it requires a much higher
temperature to cause a molecule of water surrounded on every side by other
water molecules to pass into vapour, than for a water molecule bounded on one
side by a gas or vapour molecule to pass into a state of vapour ; and that a
necessary condition for water changing its state is the presence of a “free
surface” or “ surfaces,” at which the change can take place, if these changes are
* “Transactions Royal Scottish Society of Arts,” 1874-75.
+ “Nature,” vol, xxii. p. 435.
340 JOHN AITKEN ON
to take place at the “freezing” and “ boiling points.” At present we do not
know at what temperatures these changes take place when no “ free surfaces ”
are present. Indeed, we are not certain that it is possible for these changes to
take place at all, save in the presence of a “ free surface.”
Returning now to the condensation of the water vapour, we see from the
experiments given that precisely the same conditions are necessary for the
condensation of a vapour as for its formation. Molecules of vapour do not
combine with each other, and form a particle of fog or mist ; but a “ free surface ”
must be present for them to condense upon. The vapour accordingly condenses
on the dust suspended in the air, because the dust particles form “ free surfaces ”
at which the condensation can take place at a higher temperature than where
they are not present. Where there is abundance of dust there is abundance
of ‘free surfaces,” and the visible condensed vapour forms a dense cloud ; but
where there are no dust particles present there are no “ free surfaces,” and no
vapour is condensed into its visible form, but remains in a supersaturated
vaporous condition till the circulation brings it in contact with the “free
surfaces” of the sides of the receiver, where it is condensed.
We see, then, that each fog particle in the experiment was built on a dust
particle. This indicates an enormous number of dust particles in the air. We
must not, however, suppose that the particles of that dense fog we saw in the
receiver A represented all the dust particles in the air experimented on. The
experiment indicated an extremely foul state of the air indeed, but it does not
tell the whole truth. Those fog particles only represent a small part of the
dust particles present. That this is really the case is easily shown in the
following way :—Let as much steam be blown in as will form a dense fog.
Now allow this fog to settle, but do not allow any dusty air to enter. After
the fog has settled blow in more steam. Again you will find a dense fog con-
densed on the dust which escaped the first condensation. Allow this again to
settle, and repeat the process a number of times, when you will find, after many
repetitions, that there is still fog forming. But it will also be noticed that after
each condensation the fog becomes less and less dense, till at last it ceases to
appear as fog; but on closely looking into the receiver the condensed vapour
will be seen falling as fine rain. When the steam was blown in the first time
the fog was very fine textured; each particle was so small it floated easily
in the air. After each condensation the fog became less dense; it at the same
time became more coarse-grained and heavier, and was seen falling slowly.
Near the end, no fog was visible, and nothing but a fine rain to be seen
falling. If the air was still further purified, even the rain seemed to cease.
This experiment may be made in another way. A large globular glass
flask is provided, having a tight-fitting indiarubber stopper, through which
pass two pipes. One of these pipes is connected to an air-pump, and the
DUST, FOGS, AND CLOUDS. 341
other terminates in a stop-cock. To the other opening of the stop-cock is
securely fixed a tube tightly packed with cotton-wool. Some water is placed
in the flask to moisten the air. If now the stop-cock is closed, and one or two
strokes are made with the pump, so as to cool the air by expansion, it will be
noticed that a fog immediately appears in the flask. This fog is fine textured,
close grained, and will scarcely settle. Now pump out a good deal of the air
from the flask, and allow air, filtered through the cotton-wool, to enter in its
place. After the temperature equilibrium is established, again make one
or two strokes with the pump. The fog again appears, but is now open-
textured and coarse-grained. Repeat the process, admittmg more and more
filtered air each time, and it will now be observed that the dense light fog
which at first appeared gradually gives place to one coarser and coarser in
texture, till at last no fog appears ; but on looking closely a fine rain, as in the
previous experiment, will be seen showering down inside the flask. If the
process is continued still further the rain ceases, there being no more “ free
surfaces ” to form nuclei for rain drops.
These two ways of experimenting, as might be expected, give exactly the
same result, the conditions being so similar. In one the condensation is pro-
duced by the cold air mixing with the hot steam ; in the other the “ saturated ”
air is cooled by expansion in the flask. These experiments show clearly that
when there is dust in the air the vapour condenses out in a visible form, but
when no dust is present it remains in a supersaturated vaporous state. That
the air, when no dust is present, is really supersaturated, is evident from the
fact that when the dust particles become few, the fog particles are not only
few, but are much heavier than when they were numerous, and also by their
increasing in size as they fall through the air. Each falling particle becomes
a “free surface,” at which the supersaturated vapour can condense and increase
the size of the drop. Another way of showing the supersaturated condition
of the air is to allow unfiltered air to enter in place of filtered air. The
unfiltered air will at once show itself by the vapour condensing on its dust.
It will be seen rising from the jet into the pure air, falling over and spreading
itself over the bottom like a fountain of some viscous cloudy fluid.
It was in the autumn of 1875, when studying the action of “free surfaces ”
in water when changing from one state to another, that I first observed the
conditions necessary for cloudy condensation. I knew that water could be
cooled below the freezing-point without freezing. I was almost certain ice
could be heated above the freezing-point without melting. I had shown that
water could be heated above the boiling-poimt, and that the nature of the
vessel in which it was boiled had no influence on the boiling-point, and all
that was necessary for cooling the water below the freezing-point and for
superheating the ice, and the water, was an absence of “free surfaces” at which
342 JOHN AITKEN ON
they might change their state. Arrived at this point, the presumption was
very strong that water vapour could be cooled below the boiling-point for the
pressure without condensing. It was on looking for some experimental illus-
tration of the cooling of vapour in air below the temperature corresponding to
the pressure that I thought that the dust in the air formed “free surfaces” on
which the vapour condensed and prevented it getting supersaturated. Arrange-
ments were at once made for passing the air experimented on through a cotton-
wool filter, and it was then that I first found that air which was free from dust
gave no cloudy condensation when mixed with steam, and that the super-
saturated air remained perfectly clear.
Shortly after this, the investigation had to be abandoned, and all that
remained of it was a sketch of the apparatus in my notebook, together with a
description of the experiments made with it, till about the middle of November
last, when the investigation was continued. The apparatus with which the
experiments were made before the Society is the same as when used in the first
experiments.
The conclusions which may be drawn from these experiments are—lIst,
that when water vapour condenses in the atmosphere, it always does so on
some solid nucleus; 2d, that the dust particles in the air form the nuclei
on which it condenses; 3d, if there was no dust in the air there would be no
fogs, no clouds, no mists, and probably no rain. As we do not at present know
anything about the temperature of condensation of vapour where there are no
free surfaces, we cannot tel] whether the vapour in a perfectly pure atmosphere
would ever condense to form rain; but if it did, the rain would fall from a
nearly cloudless sky.
I have said that if there was no dust there would be no fogs, clouds, nor
mists; but that is not all the change which would be wrought on the face of
nature by the absence of dust. When the air got into the condition in which
rain falls—that is, burdened with supersaturated vapour—it would convert
everything on the surface of the earth into a condenser, on which it would
deposit itself. Every blade of grass and every branch of tree would drip with
moisture deposited by the passing air; our dresses would become wet and
dripping, and umbrellas useless; but our miseries would not end here. The
insides of our houses would become wet; the walls and every object in the
room would run with moisture.
We have in this fine dust a most beautiful illustration of how the little
things in this world work great effects in virtue of their numbers. The im-
portance of the office, and the magnitude of the effects wrought by these less
than microscopic dust particles, strike one with as great wonder, as the great
depths and vast areas of rock which, the palzontologist tells us, is composed
of the remains of microscopic animals.
¥
DUST, FOGS, AND CLOUDS. 343
Let us now look more closely into the action of dust in producing cloudi-
ness. It is very evident that the results are not always alike. In one case
the condensed vapour takes the form of a fog, so fine that it easily floats in the
air and never seems to settle. In another case the cloudiness is coarser
grained and settles down slowly, and in another case it is a very coarse-grained
mist which falls quickly (of course I am not here speaking of the coarse
grainedness produced by a number of small particles combining to form one).
From the experiments described, it would appear that, when the dust is
present in great quantities, the condensed vapour forms a fog, because as there
are a great number of dust nuclei each nucleus only gets a very little vapour,
and is not made much larger or heavier, so it continues to float in the air. As
the number of dust nuclei diminish, the amount of vapour condensed on each
particle increases, their size and weight therefore also increase. So that as
the density of the cloudiness decreases the size of the particles increases, and
their tendency to settle down also increases. Fogs will, therefore, only be
produced when there is abundance of dust nuclei and plenty of vapour.
There is probably also something due to the composition of the dust particles ;
some kinds of dust seem to form better nuclei than others.
We now come to the question of what forms this dust. What is its
composition? Whence its source? I have been unable to get any trustworthy
information as to the chemical composition of the dust. The only analysis
I have seen is of dust collected in rooms. Now it is evident that as this
dust has settled down, it will be, so to speak, winnowed dust, and will there-
fore contain too small a proportion of the finer particles.
As to where this dust comes from, it is evident it will have many sources.
Everything in nature which tends to break up matter into minute parts will
contribute its share. In all probability the spray from the ocean, after it is
dried and nothing but a fine salt-dust left, is perhaps one of the most important
sources of cloud-producing dust. It is well known that this form of dust is
ever present in our atmosphere, and is constantly settling on every object, as
evidenced by the yellow sodium flame seen when bodies are heated. There is
also meteoric dust, and volcanic dust and condensed gases. At present,
however, I wish to confine our attention to the action of heat as a producer
of atmospheric dust, and more especially in relation to its fog-producing
power.
Most of us on entering a darkened room, into which the sun is shining
through a small opening in the shutters, have observed the very peculiar effect
of the sun’s rays when seen under these conditions, the path of the beam
of light being distinctly visible, shining like a luminous bar amidst the sur-
rounding darkness. On closely looking at it, it is seen that this peculiar effect
is produced by the dust motes floating in the air of the room reflecting the
344 JOHN AITKEN ON
light, and becoming visible as they pass through the path of the beam. We
are struck by the marvellous amount of dust thus revealed ever floating in our
atmosphere, and which under ordinary conditions of light are not observed. It
is known that when air containing this dust is highly heated or passed through
a flame, all these motes are destroyed, and the path of the sun’s rays becomes
invisible.
Returning uow to the question of fogs, one might naturally conclude from
what we have said that air which had passed over or through a flame or
through a fire, where the combustion was perfect, ought to be nearly dustless,
and, therefore, ought not to be a good medium for fogs. Before, however,
coming to any conclusion on this point, it was deemed necessary to make more
direct experiments, and we shall presently see that, however natural our con-
clusion is, it is very far wrong. Heating the air may cause the dust motes to
become invisible; but so far as my experiments go, they prove that the
heating of the air by the flame does not remove the dust, but rather acts in
the opposite way, and increases the number of the particles. The heat would
seem to destroy the light-reflecting power of the dust, by breaking up the
larger motes into smaller ones, and by carbonising or in some way changing
their colour, and thus make them less light-reflecting.
Powerful as the sun’s rays are as a dust revealer, I feel confident we have
in the fog-producing power of the air a test far simpler, more powerful and
delicate, than the most brilliant beam at our disposal. When steam escapes
into the air it condenses on the dust particles, and thus by simply magnifying
their size, makes their number evident to the eye. Every fog particle in the air
was represented by a dust particle before the steam was added, but these were
invisible to the eye till increased in size by the vapour. This would seem to
indicate a condition of the atmosphere too impure to be true, yet I think we
are justified in our conclusion, as it has been shown that when there is no dust
there is no fogging. In the future, therefore, we will be compelled to look upon
our “ breath” as seen on a cold morning, as evidence of the dusty state of the
air. And every puff of steam as it escapes into the atmosphere will remind
us still more powerfully of the same disagreeable fact. If it was not for
dust we would never see our “breath,” nor would wreathes of steam be
seen floating in the air, nor would our railway stations and tunnels be
thick with its cloudiness. The only consolation we have is, this fine dust is
not easily wetted. The air we breathe is not deprived of all its dust in its
passage through the lungs. The air which we exhale is still active as a fog-
producer. If, for instance, we inhale the air by the nostrils, and pass it by the
mouth to the experimental receiver, we find it still full of dust and fog-
producing. We might have expected, that after passing over so much wetted
surface, the dust would have been all taken out of the air. This difficulty
i
DUST, FOGS, AND CLOUDS. 345
of wetting the dust in the air may be illustrated by passing air through ‘“‘ washing
bottles,” after which it will still be found to be full of dust. Further, during
wet weather, after rain has fallen for a long time, all the dust is not washed
out of the air. It is still active as a fog-producer, though in a less degree than
during dry weather.
I believe that at present some attempts are being made to collect and
estimate the dust in the air. These observations deal with the weight and
composition of the dust. I would here suggest that other observations be
made by this fog-producing power of the air, to get not the weight or compo-
sition of the dust, but the relative multitude of the dust-specks in it at different
times. There seems a possibility of there being some relation between dust
and certain questions of climate, rainfall, &c.
The composition of the dust will also be of great importance in determining
its power as a cloud-producer, as it is evident some kinds of dust will have a
greater attraction for water vapour than others. Fine sodic chloride dust, for
instance, we would expect would condense vapour, before it was cooled to the
saturated point, on account of the great attraction that salt has for water. The
instrument for these observations might be made to depend, either on the density
of the fog produced by steam, or on its density when produced by reduction of
pressure, as in the air-pump experiment.
Before making any experiment on the fog-producing powers of flames and
combustion, it was necessary to test the effect of heat on the apparatus to be
used, so as to be certain the effect was entirely due to the flame and nothing
due to the heating of the apparatus used in collecting the hot gases. I accord-
ingly experimented in the followimg manner :—The cotton-wool filter was
detached from the experimental receiver, and there was placed between it and
the receiver a short length of glass tube, so arranged that the air after passing
through the filter should pass through the tube on its way to the receiver. The
tube was so arranged that it could easily be taken out to be cleaned, and opened
for introducing into it any substance the effect of which we might wish to test.
The receiver was connected to an aspirator, by means of which filtered air was
drawn into the apparatus.
The glass tube was first carefully washed with soap and water, and then
with sulphuric acid, the acid being carefully washed off before the tube was
put in its place. Air was now drawn through the apparatus, the air being
tested from time to time by the admission of steam into the receiver. At
first the steam gave rise to cloudiness, but as the dust gradually got cleared
out the clouding become less and less, till at last it disappeared, indicating
a dustless state of the air in the receiver. After this condition was attained
the glass tube, through which the filtered air was passing, was heated,
to get the effect, if any, due to heating glass, and also to make sure that the
VOL. XXX. PART I. 3G
346 JOHN AITKEN ON
effect produced by any substance placed in the tube was due to that substance
alone. The result of heating the clean and empty tube was most remarkable,
and very unexpected. A slight heating was sufficient to give rise to a very
dense fog, on admission of steam to the receiver. We might have imagined
that the careful washing the tube received was sufficient to make the glass
clean. Yet we see it was still so foul that heat drove off sufficient matter in a
fine state of division as to give rise to a dense fog. The glass tube was now
highly heated, to see if heat would cleanse it. After cooling it was again
heated to the same amount as at first. It was now found to be quite inactive.
No fogging whatever appeared in the receiver. If, however, the tube was again
highly heated fogging appeared. In testing different substances placed in the
tube, it was therefore necessary to use only a low degree of heat, so that none
of the effect might be due to the tube. After each experiment the tube was
highly heated, to thoroughly cleanse it, before introducing the substance to be
tested. When this was done, and a lower degree of heat employed, I could
perfectly trust to the tube being inactive.
The next experiment was made with a small piece of brass wire placed in
the testing tube. While it was cold there was of course no fogging, but when
slightly heated, a dense clouding resulted. A piece of iron wire, and other
substances, all gave a similar result. The wires were now highly heated in a
Bunsen flame before being put in the testing tube. On heating they were
now found to be quite inactive, not the slightest fogging appeared. The high
temperature had acted on them as it acted on the glass, and destroyed their
dust-producing powers.
A piece of brass wire was now carefully filed bright, so as to remove all
uncleanness from it, it was then placed in the experimental tube, care being
taken that it was not touched with the hands. When heated it only gave
rise to the faintest cloudiness. These experiments prove that the cloudiness
was produced by some matter driven off by the heat from the outside of the
metal. The slight cloudiness produced by the filed wire being due to the
slight contamination got when being filed.
_ The amount of matter which is driven off these wires by heat is extremely
small, and its result as a fog-producer so great, that this apparatus places in
our hands a means of detecting in gases quantities of matter so small as
almost to rival in delicacy the spectroscope. The following experiment will
give an idea of the marvellous smallness of the amount of matter which may be
detected in this way. If we take a small piece of fine iron wire, 73> of a grain
in weight, and place it in the experimental tube, and apply heat, it will give
rise to a very decided cloudiness. Now take the wire out, and if you so much
as touch it with your fingers, on again returning it to the tube and heating,
the fact of your having touched the +3, of a grain of iron wire will be declared
DUST, FOGS, AND CLOUDS. 347
by the fog which forms in the receiver. The effect seemed so great for so
small a cause, that I repeated the experiment a great number of times, some-
times putting in the wire and getting the fog, and sometimes going through all
the motions and changes necessary for, but not putting it in, and getting no
fog, that I am compelled to come to the conclusion, that the fogging is really
caused by the contamination due to the touch.
- A great number of different substances were tested in this apparatus, and,
as might have been expected, all were active fog-producers. Amongst other
substances tried were different salts. One point noticed was that their
activity did not depend on their power of evaporating or subliming. Camphor,
though subliming and evaporating quickly, scarcely ever gave any fog, only a
heavy coarse-grained fog which settled at once, while ammonic carbonate,
sodic carbonate, and sodic chloride were very active, indeed the latter salt is
one of the most active substances I have tried. If we place a crystal of sodic
chloride 745 grain in weight in the tube, and apply heat, it will continue to
give off nuclei sufficient to form a dense fog for a long time, without apparently
losing in size.
We see from these experiments that when testing the fog-producing power
of a flame, it will not do to collect the products of combustion and draw them
into our experimental receiver, as the heat would raise a dust from the surface
of the collecting tube sufficient to cause a dense fog; another method of
experiment was therefore devised. It was, however, necessary before pro-
ceeding further, to test the effect of the gas to be burned, to see if it was
active as a fog-producer. Gas from the gas pipes was accordingly passed into
the experimental receiver, and tested with steam, and found to be perfectly
inactive. No cloudiness appeared. Any effect then produced by the burning
gas could not be due to dust carried in by the gas.
The apparatus was now arranged in the following manner to test the fog-pro-
ducing powers of the products of combustion from a gas flame :—Two receivers
were arranged alongside each other, and connected by means of a pipe.
Gas was led into the first receiver by a pipe terminating a short distance
inside the receiver in a glass tube, the end of which was drawn to a fine jet
at which the gas was burned. The receiver used for this purpose was so large
that the flame could not heat the glass sufficiently to make it active as a fog-
producer. After the gas was lighted, a current of filtered air was drawn through
the receiver to supply oxygen for the flame. The products of combustion were
drawn into the second receiver through the connecting pipe. In this second
receiver the products of combustion were tested from time to time with steam.
At first, of course, the air which came would be unfiltered dusty air ;
but as nothing but filtered air entered, this dusty air ought gradually to give
place to pure air. It was found, however, that after filtered air had been
348 JOHN AITKEN ON
drawn through for a long time, there was not the slightest sign of the air
becoming purer. To make sure the fogging was due to the flame, the gas was
turned off, and combustion stopped, while the circulation was kept up. In a
very short time after this was done, the air showed a marked decrease in
cloudiness, and after a time became pure.
This method of testing the effect of combustion does not seem, at first
sight, the best. The intention was to have, first, circulated the air till perfectly
pure, and steam gave no cloudiness, and then to light the gas and see the
effect. The difficulty of working in this way was that I could not light the
gas without introducing a disturbing element. It was intended to have lit the
gas by means of an incandescent platinum wire, but on testing the effect of
the hot wire alone, it was found to make the air active, and powerfully fog-
producing. By highly heating the wire, it was possible to make it less active
at lower temperatures, but the temperature produced by igniting the gas would
again make it active.
I have great hesitation in coming to any conclusion from this experiment.
At first sight it would look as if the small flame is very far from being a dust
destroyer, and is on the contrary a very active producer of it. It will be
remembered that the flame was fed with filtered air, and the result of the
combustion of filtered air and dustless gas is an intensely fog-producing atmo-
sphere, and that the fogging is due to dust cannot, I think, be doubted, as the
products of combustion, when filtered, give no cloudiness when steam is added.
Yet the question may be asked, Was the dust produced by the combustion ?
It seems almost possible it might be the result of soda driven off by the heat
from the glass jet.
On the 8th and 12th of January this experiment was repeated. The glass
jet at which the gas was burned being removed, and a platinum one put in its
place. Platinum was selected because it was thought in the highest degree
improbable that any nuclei could be driven off the platinum by the heat of
the gas flame. After the jet was fixed in its place it was highly heated to
thoroughly cleanse and make it inactive at the lower temperature produced by
the flame. The gas was lit, and the receiver then put in its place, and the
supply of filtered air drawn through the apparatus. The result was the same
as before. Increase of fogging on the gas being lighted, and the fogging con-
tinued so long as the gas was kept burning, and only stopped when the flame
was put out.
There seemed a possibility that the fogging might be due to some residual
motes still remaining in the receiver getting into the flame and being broken up
by the heat into a great number of parts. The experiment was accordingly
varied to meet this. A fine platinum wire, which could be heated by a battery,
was arranged so that the gas might be lit by it without opening the receiver,
:
DUST, FOGS, AND CLOUDS. 349
the platinum wire being previously highly heated to cleanse it as much as
possible. The receivers being closed, and the gas not lit, air was drawn
through the apparatus till the air in the receivers was purified ; and no cloudy
condensation took place on admitting steam. Contact with the battery was now
made, and the gas lit. At once a densely fogging atmosphere was produced.
No doubt part of this fogging was due to nuclei driven off the heated
platinum wire, but as the wire was previously cleansed, and only heated for a
short time, and quickly removed from the flame, there would be but little due
to this cause, and what dust it did give off would be so fine that the heat of
the flame would not be likely to break it up any further, and it would be
gradually removed by the circulation, and its place filled with filtered air. It
was, however, found that though the supply of air was kept up, and the flame
kept burning for some time, the fogging showed no signs of decreasing. On
shutting off the gas, the fogging at once began to diminish, and soon cleared
away, showing that the fogging was due to the products of combustion.
These experiments seem to indicate that the combustion of dustless gas
and dustless air do of themselves give rise to condensation nuclei, and do not
act by simply breaking up larger dust motes into smaller ones. These nuclei
produced by the combustion of gas must be extremely small, as a very small
flame so loads a considerable current of dustless air as to cause it to become
full of a very fine and closely packed form of fog when mixed with steam.
The question may here be put, Is it really dust which is driven off by the
heat from the surface of glass, from the brass and iron wires, and from the
other substances? It is extremely difficult to get a direct answer to this
question, but I think that, reasoning from the known conditions necessary for
the condensation of vapour, it is extremely probable that it really is an ex-
tremely fine form of solid matter which is produced under these circumstances.
Further, they have all been put to the test of the cotton-wool filter, and all of
them have been filtered out and the air made non-cloud-producing. If it was
some gas or vapour which was produced by the heat, we see no reason why the
cotton-wool should have kept them so completely back.
Another set of experiments was now made to test the fog-producing power
of air and gases from different sources. The air to be tested was introduced
into the experimental receiver, and steam blown in and mixed with it. Its fog-
producing power was tested by the density of the cloudiness produced, and also
by the time the fogging took to settle. It was always found that the air of the
laboratory when gas was burning gave a denser fog than the air outside, some-
times two or three times as dense. The products of combustion from a BuNSsEN
flame and from a smoky flame were compared. They were found to be about
equally bad, and both much worse than the air in which they were burned.
These products were collected by holding the open end of the receiver over the
350 JOHN AITKEN ON
flame, taking care not to heat the glass. Products of combustion from a clear
part and from a smoky part of a fire were tested, and found to be about equally
foggy, and both much worse than the air of the room.
From these experiments it would appear that combustion under all condi-
tions is bad as a fog-producer ; bad, whether the combustion be perfect, as in a
Bunsen flame and a clear fire, or imperfect as in a smoky flame and smoky fire.
It is therefore hopeless to expect that by adopting fires having a perfect com-
bustion, such as the gas ones now so much advocated, we would thereby
diminish the fogs which at present, under certain conditions, envelop our
towns, and give rise to so much that is both disagreeable and detrimental. All
fires, however perfect the combustion, are fog-producers when accompanied by
certain conditions of moisture and temperature. From this it will be observed
that it is not the visible dust motes seen in the air that form the nuclei of fog
and cloud particles, as these may be all destroyed by combustion, and yet the air
remain fog-producing. No doubt these motes also play their part in the condensa-
tion, but their number is too small to be of importance. The fog and cloud nuclei
are a much finer form of dust, are quite invisible, and though ever present in
enormous quantities in our atmosphere, their effects are almost unobserved.
A number of experiments have been made by burning and highly heating
different substances to test their fog-producing powers, and I have found that
highly heated sodic chloride, as, for instance, when burned in an alcohol flame,
or salt water spray heated in a BunsEN flame, gives rise to an extremely dense
fog when tested with steam. But perhaps the most active of all substances I
have yet tried is burning sulphur. The fog produced when steam has been
blown into air in which a very little sulphur has been burned is so dense that if
ever fog was “cut” it might or should be. So dense is it that it is impossible
to see through a depth of more than 5 centimetres of it. The sulphides when
burned also give similar results.
These experiments evidently introduce a new element into the investigation.
We have here not only to do with the attraction of the different molecules of
the same kind, but the gaseous molecules in this case have also chemical
affinities for each other. It is very difficult to understand this marvellous
fog-producing power of burned sulphur. Sulphur in burning gives rise to
sulphurous acid. Now from experiment I have made with sulphurous acid
prepared from sulphite of soda and sulphuric acid, and also from copper and
sulphuric acid, the sulphurous acid being carefully dried with sulphuric acid, I
do not find it active as a fog-producer. It gives riseto no fumes, it does not
increase the fogging of dusty supersaturated air, and produces no fog in filtered
supersaturated air.
Sulphuric acid vapour, it is well known, gives rise to dense fumes by com-
bining with the moisture of the air, and I find, under certain conditions, it also
DUST, FOGS, AND CLOUDS. 351
gives rise to a dense fog with steam, but I also find that these fumes and fog
owe their formation to dust. This is illustrated by the followimg experiment.
In a retort was placed a quantity of sulphuric acid. The stopper of the
retort was removed, and in its place was put a tube connecting the retort with
a cotton-wool filter. The neck of the retort was connected to a wash-bottle by
means of a glass tube. An aspirator drew the air out of the wash-bottle, and
thus kept up a current of air from the filter through the retort to the wash-
bottle, the air bringing the sulphuric acid vapour along with it. At first, when
unfiltered air passed, dense fumes filled the retort and wash-bottle, but when
the filter was introduced the cloudiness gradually disappeared. The absence
of dust entirely prevented any foggy condensation, even though there were
chemical affinities. After the experiment had been continued for some time,
slight fumes began to appear, even when filtered air was passing, but this only
happened when the acid became very concentrated, and much acid evaporated,
and the fumes with filtered air were very slight, while unfiltered air gave very
dense fumes.
It is not necessary to suppose the want of dust prevented the chemical
affinities from acting, it only prevented the new compound from condensing
in cloud form. When the acid was weak its vapour would combine with the
moisture in the air, but would remain as vapour when there was no dust for it
to condense upon. But when the acid became highly concentrated, the mole-
cular strain would be greatly increased on account of the vapour tension being
greatly in excess of that due to the temperature, and it would then seem to be
able to condense without the presence of a “free surface.” There is, of course,
the possibility that the filtering of the air was not perfect. I may remark here
that the fumes of highly concentrated sulphuric acid are found to be an excellent
fog-producer. If we dip a glass rod in the acid, and heat it highly, and allow
a little of the fumes to pass into the experimental receiver, steam will now give
a very dense fog indeed.
The effect of dust in producing the cloudy form of condensation of other
vapours than water was tried. With all the vapours experimented on, which
included alcohol, benzol, and paraffin oil, it was found that pure air gave no
clouding whatever, while unfiltered air gave more or less cloudiness with all
of them.
The cause of the blue colour of the sky has long afforded interesting
matter for speculation. The theory which seems most satisfactorily to explain
its blue colour depends upon the property which very small particles of matter
have of scattering only the rays of the blue end of the spectrum, and the
question is, What are these very small particles composed of? It has been
suggested that they are very small particles of condensed water vapour. Now,
we have shown the high improbability of water vapour ever condensing out
352 JOHN AITKEN ON
in a visible form in pure air, and that if it did condense in those circum-
stances, the particles would be large. From the all-pervading presence of the
infinitesimal atmospheric dust, the idea naturally suggests itself, that the blue
sky may be caused by the light reflected by this dust. What seems to support this
theory is that, as we ascend to high elevations, the sky becomes deeper blue,
this being caused by fewer and only the finer of the dust particles being able
to keep floating in the thin air at these elevations. Further, after rain the
sky is darker blue, this deepening of the colour being caused by much of the
dust being washed out by the falling rain.
I wish now to apply the result of these experiments to the great fog
question, which Dr ALFRED CARPENTER opened at the last Social Science
meeting, and to which at present so much attention is being directed. The
increased frequency and density of our town fogs are now becoming so great as
to call for immediate action. But before doing anything, a much clearer
knowledge of the conditions which produce a fog is necessary, or much time
will be lost and expense uselessly incurred. I wish, therefore, to call attention
to the teaching of the experiments described, so far as they bear on this
important question. What I have to say on this point must, however, be
received with reservation. The conditions of a laboratory experiment are so
different and on so small a scale, that it is not safe to carry their teaching to
the utmost limit, and apply them to the processes which go on in nature.
We may, however, look to these experiments for facts from which to reason,
and for processes which will enable us to understand the grander workings of
nature.
We have seen that fogs and clouds are produced by the condensation of
vapour on the dust particles floating in the air. The condensation is
produced by cold, the result of radiation or expansion of the air, either by
reduction of barometric pressure or by the elevation of the air into higher regions.
A fog, therefore, before it appears, is every particle of it represented by a
particle of very fine invisible dust ; the thick visible fog was previously repre-
sented by an invisible dust cloud. Now, it is very evident that if there is
an enormous number of these dust particles in the air, so that they are very
close to each other, then each particle will only get a very small amount of
vapour condensed upon it. It will therefore become but little heavier, and
will float easily in the air. To this light and dense form of condensation we
give the name of fog. If there are fewer dust particles, then each particle
gets more vapour, and each particle is heavier and settles sooner, It must
not be supposed, from this, that rain only falls when these dust particles are
few, and the vapour particles very large, because there seems to be always
enough dust in the air to make the cloud particles small enough to keep
suspended. Their union and fall as rain is determined by certain conditions
DUST, FOGS, AND CLOUDS. 353
on which the present inquiry throws no light. But of clouds there are vast
degrees of texture, the fog being the finest grained, most dense and pie
almost never settling down.
From this view it will be seen that the vapour condenses on the solid matter
floating in the air, whether that matter be fine dust or condensed smoke.
This view I am aware is different from the one generally received, namely,
that cloud particles are hollow vesicles, hollow to enable them to float, and
that smoke, &c., attaches itself to the outside of these vesicles.
Since, then, fogs are produced by an over-abundance of fine atmospheric
dust in a moist atmosphere, and as we have but little control over the moisture
in the air, our attention must be directed principally to the diminution of the
atmospheric dust, if we wish to reduce the density of fogs. We have seen
that all forms of combustion, however perfect, are great producers of this less
than microscopic dust. The brilliant flame, the transparent flame, and the
smoky flame are all alike fog-producers. Perhaps there may be some form of
combustion which is not a dust-producer, or some form of combustion which may
give a coarse-grained dust. If there is, it ought to be more generally known.
As a correction of the present form of combustion, perhaps something could
be done to arrest the dust before it escapes into the atmosphere. But any
plan which at present suggests itself is too troublesome and expensive ever to
be put into general use. To prevent mistakes I may here remark, that when
speaking of the dust produced by combustion, I do not mean the dust usually
spoken of in connection with fires, as it is comparatively heavy, and soon
settles to the ground, nor do I refer to smoke or soot. The dust I refer to is
the invisible dust, so fine that it scarcely settles out of the air. If we put air
into the experimental receiver and leave it for days without any communica-
tion with the outer air, we will still find it fog-producing, though in a very
marked degree less than at first.
All our present forms of combustion not only increase the number and
density of our town fogs, but add to them evils unknown in the fogs which
veil our hills and overhang our rivers. In the country the fogs are white and
pure, while in towns they are loaded with smoke and other products of
imperfect combustion, making the air unwholesome to breathe and filthy to live
in. But why should these two miseries always come together? Either the fog
or the smoke is bad enough alone ; why should the smoke which usually rises
and is carried away by the winds fall to the ground when we have fogs? I
think that the conditions which account for the fog also account for the smoke
falling. When we have fogs, the atmosphere is nearly saturated with vapour,
and the smoke particles, being good radiators, are soon cooled, and form
nuclei on which the vapour condenses. The smoke particles thus become
loaded with moisture, which prevents them rising, and by sinking into our
VOL. XXX. PART I. 3H
~354 JOHN AITKEN ON
streets add their murky thickness to the foggy air. This seems to explain the
well-known sign of falling smoke being an indication of coming rain. That the
colour or blackness of what is called a pea-soup fog is due to smoke, is, I
think, evident from the fact that a town fog enters our houses and carries its
murky thickness into our rooms, and will not be induced to make itself
invisible however warmly we treat it. It will on no account dissolve into
thin air, however warm our rooms, for the simple reason that heat only
dissolves the moisture and leaves the smoke, which constitutes a room fog,
to settle slowly, and soil and destroy the furniture. If the fog was pure, that
is to say, was a true fog and nothing but a fog, such as one sees in the
country, it would dissolve when heated, as every well-conditioned country
fog does—at least I never remember meeting a fog in a country house.
But while admitting the bad effects of a fog aggravated by smoke, yet we
must not forget the probable good effects of the smoke. It has been else-
where pointed out that the suspended smoke or soot may exercise the well-
known disinfectant properties possessed by the different forms of carbon.
Before utterly condemning smoke it will be necessary fully to consider its
value as a deodoriser. And further, we must remind those who are crying
for more perfect combustion in our furnaces and grates, that combustion,
however perfect, will not remove or diminish fogs. It will, however, make
them cleaner, take away their pea-soupy character, but will not make them
less frequent, less sulphurous, less persistent, or less dense.
We have shown that sulphur in its different forms when burned is most
active as a fog-producer. Now, almost all our coals contain sulphur, which is
burned along with the coal, and it is certainly worth considering whether some
restriction ought not to be put on the amount of sulphur in the coal used in
towns. The quantity of burned sulphur that escapes from our chimneys is
very great. Suppose we put the amount of coal annually consumed in the
London district at a little over 7,400,000 tons. Now, the average amount of
sulphur in English coal is more than 1:2 per cent. Suppose that it is 1 per
cent., so as to be within the mark, that would give 74,000 tons of sulphur
burned every year in London fires, or at the rate of about 200 tons in an
average day, and the amount will be greater in a winter day—a quantity some-
what alarming, and quite sufficient to account for the density of our fogs. Its
presence and effects during our fogs is very evident in the discoloured metal
on our street door and in our houses.
But, like smoky fires, burnt sulphur is not an unmitigated evil. During
fogs the air is still and stagnant ; there is no current to clear away the foul
smells and deadly germs that float in the air, and which might possibly be more
deadly than they are if it were not for the powerful antiseptic properties of the
sulphurous acid formed by the burning sulphur. Before condemning the
DUST, FOGS, AND CLOUDS. 355
smoke and fog-producing sulphur, it would be well for us thoroughly to in-
vestigate their saving properties and weigh their advantages, lest we substitute
a great and hidden danger for an evident but less evil.
While we look upon fires and all forms of combustion as fog-producers, yet
we must remember there is ever present plenty of dust in the air to form clouds
and even fogs; fires simply increase the amount of the dust. Now it is
evident that as the rain is constantly washing the dust out of the air, fresh
supplies must therefore be constantly added.
We have every reason for supposing that there are immense quantities of
very fine salt-dust ever floating in the air. This is evidenced by the ever-
present sodium lime that at one time so troubled spectroscopists. One source
of the supply of this salt-dust is evidently the ocean, and it affords us another
example of how very closely the phenomena of nature are interlinked. The
ocean, which under a tropical sun quietly yields up its waters to be carried
away by the passing air, almost looks as if he repented the gift, when tossed
and angry under tempestuous winds, as he sends forth his spray, which dried
and disguised as fine dust becomes his messenger to cause the waters to cease
from their vaporous wanderings, descend in fertilising showers, and again
return to their liquid home.
Parr LI.
Since making my first communication to this Society on Dust, Fogs, and
Clouds, many of the experiments have been repeated under different conditions
and with improved arrangements of apparatus. I shall first give a short de-
scription of the changes made in this direction, which seem to fill up some points
wanting in the first paper, and shall then describe some experiments made in a
department of the subject which I have only touched upon.
We have seen that when steam is blown into dustless air there is no cloudy
condensation, and that the vapour remained supersaturated till it came in
contact with the sides of the receiver, on which it deposited itself. My next
experiments were to determine to what extent dustless air can be super-
saturated without the vapour condensing into drops—to determine whether
vapour molecules can combine with one another to form a liquid, or whether
they must have a nucleus to condense upon even when the vapour is very
highly supersaturated. It is evidently very difficult to get a definite answer to
this question, and I shall only describe the direction in which I sought to get
an answer, the experiments not being sufficiently conclusive to settle the point.
The first thing to be done was evidently to get quit of all “free surfaces ”
of all nuclei of condensation, and the experiments have resolved themselves
very much into questions of filtration, as I have not yet arranged any experi-
356 JOHN AITKEN ON
ment in which I have been certain there might not have been some nuclei
present. The first step in this direction was to test the action of the filter
through which the air passed. All the cotton-wool was removed from the
filter and a fresh quantity put im. At first only a thin layer was used, and
its effect tested, noting the degree of cloudy condensation produced. More
cotton-wool was then put over the first layer, and the improvement noted.
Fresh quantities were added till no improvemeut was observed. Then double
the total quantity was put in, and the filter was now considered to be doing all
that cotton-wool could do to purify the air of the receiver from dust.
The result was—when a small quantity of steam was blown into the
receiver there was no cloudy condensation whatever ; the receiver remained
perfectly clear. But when the steam valve was opened wider and more steam
allowed to enter, although no effect was noticed at first, yet after a time the
vapour became so supersaturated that it condensed and fell as fine rain. Ifa
still greater amount of steam was blown in, then it was seen condensing on
entering the receiver, and the falling rainy condensation was seen tossed about
by the rush of the entering steam.
Attention was now directed to the steam. It seemed possible that nuclei
might be given off from the hot sides of the boiler, and from the hot parts from
which the steam was rising. To prevent any nuclei which might be formed in
this way from entering the receiver, the end of the steam pipe inside the
receiver was covered with a cotton-wool filter, The result was, however, as
before, with little steam, no condensation, with much steam, rainy condensa-
tion. On account of the tendency of the cotton-wool to get wetted by the
steam, the action of the filter did not seem satisfactory, some parts getting wet
and stopping the passage of the steam, and throwing all the duty on the weak
parts. The experiment was accordingly arranged in the following way :—The
steam was generated in a glass flask. This flask, filled with water, was placed
in a vessel full of water, kept boiling during the experiment. In order to make
the water in the glass flask boil, or rather evaporate, under these conditions, a
stream of filtered air was blown through it, and the mixture of air and vapour
blown into the receiver. Again the result was as before—rainy condensation
when highly supersaturated. By this last arrangement it seems impossible any
nuclei could be given off from the vessel in which the water was boiled, and
the fine drops given off by the bubbling of the air and the vapour in the flask
are probably all caught on the sides of the pipes, because if they did enter they
would form nuclei in very slightly supersaturated, as well as in highly super-
saturated vapour. We may therefore conclude from these experiments that
the nuclei of the rainy condensation in highly supersaturated vapour are either
some fine form of dust which the cotton-wool cannot keep back, or are pro-
duced by the vapour molecules combining together without a nucleus.
DUST, FOGS, AND CLOUDS. 357
Tf all nuclei are absent, water may be cooled below the “freezing-point” or
heated above the “ boiling-point ” without any change taking place ; but there
seems to be a limit to the amount it may be cooled or heated under these con-
ditions without the water freezing or boiling. However carefully we may make
the experiments after the water has been cooled to a certain amount, it always
freezes without the presence of a free surface, and it also boils without the
presence of a free surface when heated much above its “boiling-point.” In
these cases there always, however, appears to be some want of continuity or
uniformity produced by the presence of some substance which exercises an in-
fluence on the water, and determines a weak point at which the change begins,
and when once begun progress is of course rapid. In water we can easily under-
stand how the sides of the vessel and the surfaces of foreign matter, &c., will
form weak points, from which “free surfaces” are developed, extending into
the mass of the liquid ; but it is much more difficult to understand how weak
points can be formed in gases, and even when started they have no power of
propagating themselves. These considerations would seem to suggest that the
rainy condensation in filtered air may be produced by some form of nuclei
which passes the cotton-wool filter, and which are perhaps very small, and do
not become active as nuclei till a considerable degree of supersaturation is
attained.
There are, however, certain considerations which show that if the degree of
supersaturation is sufficiently great, then condensation will probably take place
without nuclei. Professor JaAmMEs THomson* has shown that the isothermal
curves obtained by Dr Anprews from his experiments on carbonic acid at
temperatures below the critical temperature of that substance may not be
really so discontinuous as they appear, and that there may be a condition of
that substance which would be represented by a continuation of the vapour
part of the curve beyond the “boiling” or “condensing line.” To test this
point Professor THomson suggested an experiment in which saturated steam,
surrounded by a heated vessel, was to be expanded till it was cooled below
its condensing point for its pressure, and the effect on the volume and pressure
noted. This experiment, I believe, has never been made. We, however, see
from the experiments described, that the theoretical extension of the curve
discovered by Professor THomson has a real existence. This curve of Professor
THomson’s shows that the degree of supersaturation possible has a perfectly
definite limit, beyond which supersaturation is impossible. Further, if we
examine these curves of Dr ANDREWS, which we may extend to water, they
show us that it is only for temperatures below the critical temperature of the
substance that supersaturation is possible. At temperatures above the critical
* “ Proceedings of the Royal Society,” No. 130, 1871.
358 JOHN AITKEN ON
temperature there is no boiling and condensation, the change being perfectly
continuous from the one state to the other, if under those conditions we can
say there are two states.
All the previously described experiments have been made at temperatures
at which the condensed water was in a liquid state. It was now desirable that
they should be made at lower temperatures, to see if the same conditions are
necessary when the vapour condenses at temperatures below the “ freezing-
point,” and passes from the gaseous to the solid state. The experiments were
made with the air-pump arrangement of apparatus, the condensation being
effected by the cooling produced by expansion in the receiver. In the first
experiments the receiver was placed in a freezing mixture. They were,
however, repeated under more favourable conditions during the severe cold of
January last. The apparatus was removed to the open air and experiments
made with it. The temperature at the time was 8° Fahr. The results were
the same as at higher temperatures—cloudy condensation with unfiltered air,
and no condensation when filtered air was used. ‘The amount of cloudiness
produced was not so great as at higher temperatures. This is due to the
smaller amount of vapour in the air at the lower temperature.
I did not succeed in observing any of the optical phenomena produced by
small crystals of ice in our atmosphere. This was probably due to the
conditions under which the crystals in the experiment were produced. As the
crystals were rapidly formed, there would not be time for the vapour molecules
to arrange themselves in the simpler forms of crystallisation, but by being
forcibly compelled to solidify, would form complicated shapes, which do not
give rise to any peculiar optical phenomena.
In the first part of this paper I have referred to the detection of small
quantities of matter driven off by heat from pieces of iron, brass, and other
kinds of matter. By the arrangement of apparatus then described, it was
shown to be possible to detect the dust drawn off so small a piece of iron wire
as the 745 of a grain. In later experiments in this direction, the apparatus
has been entirely changed. In place of using the supersaturation produced by
mixing steam and cold air, the air-pump arrangement of apparatus has been
employed, and is found to work much more satisfactorily than the other. The
impurities drawn off so small a piece of iron wire as the zo55 of a grain can
with ease be detected with it.
The arrangement of the apparatus for this purpose is as follows :—A glass
flask provided with a tight-fitting stopper, through which pass two tubes,
which rise to a short distance into the interior of the flask. One tube is
connected to an air-pump, the other terminates in a stop-cock, to which is
attached a cotton-wool filter. A piece of glass tube is introduced about the
middle of the length of this pipe. Some water being placed in the flask, the
DUST, FOGS, AND CLOUDS. 359
apparatus is complete. The glass tube must now be thoroughly cleansed.
This is done by highly heating it in a BuNsEN flame, while air is being drawn
through it. The end of the glass tube next the filter is now opened, and three or
four small pieces of iron wire introduced into it. The pieces of wire are placed
some distance from each other, and near one end of the tube. The tube is
now closed, and the Bunsen flame placed under the other end of the tube, and
far enough away from the pieces of iron so as not to heat them. The air in
the apparatus is now thoroughly cleansed by pumping out the air and admitting
filtered air, till no cloudiness appears. During this process the height of the
flame has been reduced, so as the temperature may not be high enough to drive
anything off the glass tube. When the air is quite pure, and all rainy
condensation ceased, the flame is reduced to about one-half, so as to leave a
good margin of safety. After this is done, one of the small pieces of iron wire
is drawn from the cold part of the tube by means of a magnet, and dropped
- in the hot part, and two or three strokes of the pump are made, to cause a
current of air to pass through the tube and bring whatever impurities are
driven off the iron into the flask. The stop-cock at the filter is now closed,
and a slight vacuum made. The amount of nuclei given off by the wire is
indicated by the amount of cloudy condensation which now takes place.
To make further certain that the impurities came from the wire, the piece of
iron is now removed by means of the magnet, when the filtered air is now found
to come into the flask without any nuclei, the air remaining cloudless on
expansion. To make still further certain of the result, another of the pieces of
wire is drawn into the hot part of the tube, when the cloudiness again appears,
and again disappears after its removal, or after it has been highly heated.
The pieces of iron wire experimented on weighed from zo55 tO gogq Of a
grain. With pieces so small as this, so abundant and evident is the cloudiness
produced, that I feel certain that if I could have manipulated, say the z5,o55
of a grain, the effect would have been perfectly definite and decided.
Thousands of particles driven off the zo55 of a grain, and the wire not
perceptibly lighter afterwards, indicates almost molecular dimensions. It
seems probable that some of the nuclei in these experiments are driven off as
gases or vapours. These gases and vapours will afterwards condense when
cooled in the receiver. It is not necessary that these gases should have nuclei
on which to condense, as they will be highly supersaturated when cooled to the
temperature of the receiver, and we know that it is only when supersaturation
is slight that nuclei are necessary. These gases will, according to their com-
position, condense either to solid or liquid nuclei, on which the water vapour
will condense.
In the first part of this paper attention has beenjcalled to the importance of
the composition of the atmospheric dust. It was pointed out that some kinds
360 JOHN AITKEN ON
of dust will have a greater attraction for water vapour than others, and that
chloride of sodium dust would probably condense vapour and cause fogging in
an atmosphere which was not saturated.
There are evidently two ways in which dust may exert an attraction for
water vapour, and determine its condensation while still unsaturated. The
first is the attraction which the surface of some kinds of matter has for vapour,
a power which they have of condensing a film of water on their surface. This
power they possess at all degrees of saturation, but the amount they condense
depends on the degree of saturation. Glass might be taken as an example of
a substance whose surface has a strong affinity for water, a fact which dis-
agreeably demonstrates itself in the conducting power of glass insulators of
electrical apparatus in damp weather. The dust nuclei are so small that the
condensing power of fine pores is not likely to have any influence. The other
form of attraction which may exist between the dust and water vapour, is the
chemical affinity which exists between the two. ‘This will evidently depend on
the composition of the dust or nuclei. Asan example of this form of attraction,
it will be sufficient here to mention the well-known affinity which chloride of
sodium and other salts have for water, causing them to become wet when the
air is moist.
We shall presently see that besides these two ways in which nuclei may
condense vapour in unsaturated air, there is another way in which the conden-
sation may be produced in unsaturated as well as in saturated air without
nuclei. This happens when there are gases or vapours present which have
an affinity for each other, and the resulting compound is in a highly super-
saturated condition. These new compounds under these conditions condense
and form nuclei, which may be solid or liquid, and may or may not have
affinity for water.
Now it is evident that if there are any kinds of matter in the form of dust
in the air which have an affinity for water vapour, they will determine
condensation in unsaturated air. Some experiments were made to see to
what extent cloudy condensation could be produced under these conditions.
My first experiments were made by burning sulphur, and vapourising chloride
of sodium. A small quantity of sulphur was lighted, and an open-mouthed
receiver held over it for a few seconds, and then placed on the table. At first
scarcely anything was visible, but after a time a decided haze made its
appearance, and the density of this haze or fog was always in proportion to
the moisture present in the air. The damper the air the thicker the fogging,
and if the air was nearly saturated, the result was very remarkable. If the
inside of the receiver was wetted so as to moisten the air, the sulphur products
were a little more evident, and on placing the receiver on the table, a thin haze
could be seen. After a time, however, this haze grew denser and denser, and
DUST, FOGS, AND CLOUDS. 361
after fifteen or twenty minutes the receiver was full of a dense white fog,
which remained for a long time.
Similar results were got by vapourising chloride of sodium. The salt was
in some cases vapourised by a Bunsen flame. It was also vapourised by
placing it on a piece of hot iron, and the receiver held over it to collect the
vapour, which condensed and formed nuclei, which determined the condensa-
tion of the water in unsaturated air. In some experiments the salt was
vaporised in a heated platinum tube and drawn along with air through a coil
of pipe to cool it, before admitting it into the receiver. In these experiments
the density of the fogging was in proportion to the vapour present, and if the
experiment was made in a wetted receiver, the fog took some time to attain its
maximum density.
The condensing power of sulphur products and salt can be illustrated in
another way. The air with either of these substances in suspension, is drawn
through a coil of pipe to cool it. If now this stream of air is made to strike
any wetted surface, the wetted surface looks as if it had suddenly become
heated—a stream of condensed vapour flows away from it. This vapour is,
of course, invisible if ordinary air is used, and without the powerfully con-
densing nuclei.
Experiments on a larger scale were also made with these two substances.
A little sulphur was burned in a cellar, the air of which was damp, but not
saturated. The temperature was about 43° Fahr., and the wet and dry bulb
thermometers showed a difference of from 3° to 1° during the experiments.
After the sulphur was burned a fogginess was evident, but, on returning half an
hour afterwards, the fogging was found to have increased very greatly in density,
the air was very thick, and not the slightest smell of sulphurous acid perceptible.
This fog hung about the cellar for many hours. The experiment was repeated
with chloride of sodium, the salt being sprinkled over an alcohol flame. The
result was similar to the sulphur products, a fogging which gradually increased
in density, and very slowly cleared away.
Experiments have also been made by burning sulphur in the open air.
When the air is dry the fumes can only be traced a short distance, but as the
amount of moisture increases the cloudiness becomes more and more evident,
and in certain conditions of the atmosphere the cloudiness can be distinctly
seen flowing away in the passing air, leaving the sulphur in a pale thin stream
of vapour, which gradually increases in size and density, and rolls away in a
horizontal cloudy column, ten or fifteen feet in diameter, clearly marked out
from the surrounding air.
There may be a certain amount of doubt as to the action of the heated salt
in these experiments. When heated in the BunsEN flame it is probable decom-
position of some of the salt takes place, and part of the result may be due to
VOL, XXX. PART I. 31
362 ; JOHN AITKEN ON
the hydrochloric acid set free. In order to prevent this decomposition as much
as possible, I have made some experiments at as low temperatures as possible,
and the results are the same as when higher temperatures are used, allowance
being made for the smaller amount of salt volatilised.
The action of the products of combustion of sulphur would appear to be
something like the following :—When the sulphur combines with the oxygen of
the air, sulphurous acid is formed. I have shown in the first part of this paper
that sulphurous acid has but little condensing power ; we must therefore look
to the change which takes place in the sulphurous acid for the explanation of
the wonderful condensing power of the sulphur products. The sulphurous acid
becomes further oxidised in the air, and sulphuric acid is produced, and it is
the great affinity which this sulphuric acid has for water which enables it to
rob the air of its moisture and condense it in visible form. It does not seem
to take long for the sulphurous to change to sulphuric acid in the air. A
short time after the sulphur was burned in the cellar all smell of sulphurous
acid was gone, and I am informed by Dr Wallace that he has found that all
traces of sulphurous acid cease at a short distance from calcining ironstone
bings in which much sulphur is being burned. The gradual thickening of the
sulphur fog will probably be in part due to this gradual change of sulphurous to
sulphuric acid. The gradual thickening of these fogs is also in part due to
the slow evaporation of the water from the sides of the receiver, and subsequent
condensation on the absorbing nuclei.
I find that the fumes from highly concentrated sulphuric acid have a fog-
producing power similar to the products of combustion of sulphur. If we
highly heat a glass rod wetted with sulphuric acid, or heat the acid in a
platinum cup, and admit a little of the fumes into the receiver, they are found
to have a very strong fog-producing power.
The above represents something like what the action of sulphuric acid is in
moist air, in which there are no other vapours or gases with which this acid tends
to combine. Before considering these more complicated effects I shall describe
some experiments made to test the action of acid vapours on moist filtered air.
The apparatus consisted of the air-pump arrangement, with test receiver or
flask, one pipe as before being connected with the air-pump, and the other with
the filter. Between the receiver and the filter was placed a test tube, in which
was placed the acid to be experimented upon. The filtered air was caused to
bubble through the acid on its way to the moist air in the receiver, the acid
being generally kept at the temperature of the room.
When nitric acid is put in the test tube and filtered air passed through it, it
is found that its vapour always gives rise to fumes when mixed with the moist
air in the receiver. These fumes—as cloudy condensation in unsaturated air
may be called—may therefore be produced without nuclei when nitric acid is
DUST, FOGS, AND CLOUDS. 363
used. When the air in the receiver is expanded and cooled, this cloudy con-
densation becomes thicker.
When commercial hydrochloric acid is put in the test tube, its vapour does
not give rise to fumes on mixing with the moist air in the receiver, and on ex-
panding and cooling the air, no fumes appear, only the rainy form of conden-
sation is produced. A quantity of very strong hydrochloric acid was prepared
by keeping the solution in which the acid was condensed in a freezing mixture.
This acid fumed abundantly in the air, but gave no fumes in filtered air, and
only rainy condensation when the pressure was reduced.
These two acids act very differently, the first condensing freely at many
centres, and without nuclei, and giving a foggy condensation in pure and unsatu-
rated air, while the hydrochloric acid only condenses with difficulty, and at few
centres, and only gives the rainy form of condensation when supersaturated.
The next experiments were made with commercial sulphuric acid, and also
with some of the acid concentrated by boiling in a glassvessel. The, air which
had passed through this acid gave no fumes, but on making the slightest ex-
pansion a fog appeared. This fog is quite characteristic of sulphuric acid, and
is quite different from any artificial fog I have seen. The particles are
extremely small, and the display of colour remarkably brilliant, and when
properly lighted rivalling in distinctness the colours of the soap bubble. This
beautiful fog is only got when the acid is strong, and I think is best produced
when the entering airis dry. This point, however, requires confirmation, though
the result might be expected, as the surface of the acid will then be less
weakened by moisture abstracted from the air. After the acid has absorbed
much vapour, or if water has been added to it, the fogging decreases and gives
place to the rainy form of condensation when expansion is made. This rainy
condensation also disappears when the acid is very weak. If we heat the strong
acid to a temperature of about 60° or 70° C., the vapour condenses and forms
fumes in pure air without nuclei, and without being expanded.
These experiments show that water vapour may be condensed without
nuclei being present. The affinities which the vapours of the acids have for the
water, causing the formation of new compounds, and these compounds being
highly supersaturated, condense easily without nuclei, and in certain circum-
stances this condensation may be determined in even unsaturated air. These
water-acid nuclei once formed, continue to act as centres of condensation. In
these cases the manufactured nuclei are liquid, but solid nuclei may be formed
in a similar manner. This may be shown by the following experiment. Place
hydrochloric acid in the receiver or flask, and pump out all the air and replace
it with filtered air. If, after this is done, and the acid shows no sign of cloudi-
ness, and nothing but rainy condensation on expansion, we take the stopper
out of a bottle of ammonia and hold it near the filter, so that the escaping
364 JOHN AITKEN ON
gaseous ammonia may pass along with the air through the filter, the ammonia
on arriving in the flask will combine with the hydrochloric acid and form a
dense cloud of sal-ammoniac. When the ammonia and the hydrochloric acid
combine in the filtered air, the tension of the sal-ammoniac vapour so formed
is enormously greater than that due to the temperature, and it easily condenses
without nuclei. This experiment suggests that part of the rainy condensation
given by hydrochloric acid may be due to the ammonia in the air combining
with the acid and forming sal-ammoniac nuclei on which the vapour condenses.
These experiments show how nuclei may be formed from gases in the air,
and these nuclei may have so great an affinity for water vapour as to cause
it to condense on them from an unsaturated atmosphere.
Returning again to the action of the products of combustion of sulphur in
air, we have seen that these products alone can determine the condensation of
water vapour from unsaturated air. There are, however, many substances in
the air with which this acid will tend to combine. It would be impossible
to go over all the substances in the air which have affinities for this acid,
and consider the effects of these new compounds, in moist air. I have, how-
ever, selected one, which from the magnitude of its effects deserves special
notice. That substance is ammonia, another of the products of combustion of
our coal fires. If we take an open-mouthed receiver wetted on the inside,
and hold it over a little burning sulphur for a few seconds, as in the previous
experiment, we will get a thin haze, which we know tends to thicken. But if
on placing the receiver on its tray, we put a drop of ammonia on a piece of
glass and introduce it into the receiver, the result is very striking. Dense
fumes will be seen to rise from the ammonia, and in a few minutes the receiver
will be full of a fog so thick it will be impossible to see an object in the middle
of the receiver. In this case there are evidently formed solid nuclei, composed
of sulphite and sulphate of ammonium, in a very fine state of subdivision.
The intense cloudiness is only in part due to this solid, the greater part is due
to the condensation of water vapour. If the experiment is made in dry air the
fogeing is not nearly so intense as in moist air. By burning a larger amount
of sulphur in the moist air of the receiver, we can easily make a fog so very
intense that it is impossible to see through an inch of it. This fog is found to
be very suitable for experiments on vortex rings, as it is easily prepared, and
the “ dead ” rings dissolve, and do not thicken the air of the room to the same
extent as the usual sal-ammoniac rings.
Experiments were also made in the cellar with this fog-producer. The
wet and dry bulb thermometers at the time showed a difference of fully one
degree. Yet by burning a few grains of sulphur, and dropping on a piece of
paper a little ammonia, the cellar became filled with a most intense fog, —
many times more intense than would be produced by the sulphur alone.
DUST, FOGS, AND CLOUDS. 365
Using the same apparatus as was used for determining the fuming power
of the different acids in filtered air, it is found that when experimenting on
sulphuric acid and vapour of ammonia, that sulphate fumes are formed in the
receiver if the acid is slightly heated, thus showing that this sulphate dust can
form without nuclei. It, however, seems in the highest degree probable that
when dust is present the dust particles will form the centres on which the
sulphate will condense.
Almost all salts when heated in a Bunsen flame produce nuclei which
determine condensation in unsaturated air. The condensing power of the
different products, however, differ greatly. The bicarbonate of soda gives but
little effect, while chloride of calcium and bromide of potassium are much
more powerful. But by far the most powerful artificial fog-producing substance
when used in this way is the chloride of magnesium. If we put a small
quantity of this salt on a piece of wire-cloth, and heat it with the BuNSEN flame,
and collect the products in a wetted receiver, the fog will be seen rapidly
forming and showering down the sides of the receiver. As rapidly as the
water is evaporated from the sides of the receiver it is condensed by the active
nuclei in the gases. After the receiver has been placed on the table for a few
minutes it will be found full of a fog so dense it is only possible to see through
a depth of five centimeters of it. When a little of this chloride was heated in
an alcohol flame in the cellar the result was a fog many times more dense than
that produced by sulphur alone. The fog-producing power of the heated
chloride of magnesium would appear to be due to the salt beig decomposed
by the heat, and free hydrochloric acid being driven off in a highly concentrated
state. The amount of hydrochloric acid is, however, small considering the
density of the resulting fog. The density of this fog is very much greater than
the fog produced by hydrochloric acid prepared from chloride of sodium and
sulphuric acid.
In all these cases the reactions are excessively difficult to trace. Other
experiments in which the action is much simpler were made by burning a little
sodium in the receiver. The combustion of this substance gives rise to its
oxides in a fine state of division. This fine soda-dust when mixed with dry
air gives but little cloudiness, but when mixed with damp air a dense fogging
results. Potassium when burned gives a similar effect, but the fog is not so
intense.
We may conclude from these experiments—1. That as regards cloudy con-
densation of vapour in our atmosphere there is dust and dust. Some kinds of
dust have such an affinity for water that they determine the condensation of
vapour in unsaturated air, while other kinds of dust only form nuclei when the
air is supersaturated, that is, they only form free surfaces on which the vapour
may condense and prevent supersaturation. In many of the experiments it
366 JOHN AITKEN ON
was noticed that when the air was nearly purified, when all the dust which had
an affinity for vapour had received its burden of water and settled down, that
there remained to near the end of the experiment some particles which seemed
to require a certain degree of supersaturation before they became active. In
highly supersaturated air all kinds of dust will form nuclei and determine
condensation, but in unsaturated air only those kinds of dust which have an
affinity for water will be active. We have precisely corresponding phenonema
to this in freezing, melting, and boiling. We have water in a solid state at a
temperature above the “ melting-point,” when it is combined with some other
substance, as in the water of crystallisation of salts. Water may be liquid at a
temperature below the “ freezing-point ” when mixed with some salts. Water
boils at a temperature above its “ boiling-point ” when it holds some salts in
solution, and boils below its “ boiling-point ” when mixed with some substance
having a lower “ boiling-point ” than water.
2. This affinity which some kinds of dust have for vapour explains why it
is that our breath and escaping steam dissolve even in foggy air. The large
cloudy particles in our breath and in condensed steam tend to evaporate in the
same air in which condensation is taking place, because the dust particles on
which the breath has condensed have had their affinities more than satisfied, they
therefore tend to part with their surplus by evaporisation in the same air as those
particles which have not had their affinities satisfied tend to condense it.
3. Dry fogs are produced by the affinity which the dust particles have
for water vapour, in virtue of which they are enabled to condense vapour in
unsaturated air. From the experiments with chloride of sodium, from the
known affinity of that salt for water, and from the fact that great quantities of
salt-dust are ever present in the air, it is evident that if it is not the cause of
dry fogs in the country it must play some part in those phenomena. There will
doubtless be other kinds of nuclei having affinities for water which will cause dry
fogs. The nature and composition of these other nuclei will probably be best
arrived at by collecting the fog particles by washing or otherwise, and analysing
them.
4. That as the products of combustion of the sulphur in our coals, espe-
cially when mixed with the other products of combustion, such as ammonia,
have the power of determining the condensation of water vapour in unsaturated
air, and give rise to a very fine-textured dry fog, they are probably one of
the chief causes of our town fogs, as they have a greater condensing power than
the products of combustion of pure coal.
Though there may seem to be but little doubt that products of combus-
tion when mixed with the sulphur compounds are most active producers
of town fogs, yet we must not rest satisfied that they explain everything.
There may be other causes at work, and conditions yet requiring explanation,
DUST, FOGS, AND CLOUDS. 367
but as these involve intricate chemical reactions, it will be advisable that the
matter be now handed over to the consideration of the chemist.
These chemical nuclei, as they might be called, though found in far greatest
abundance in the air of our towns, will no doubt be also found in the air of
the country. We know that sulphuric acid and ammonia are constantly being
produced by decomposing animal and vegetable matter, and we know that
these substances, along with nitric acid and other gases and vapours, are
always present in the air.
Again, we have the gases given off from volcanoes, and the amount from
this source must be considerable. There are about two hundred active vol-
canoes constantly discharging their gases into our atmosphere, and it has been
roughly calculated that volcanoes evolve ten times more carbonic acid than is
given off by the combustion of all kinds of carbonised material. With this
carbonic acid there is given off great quantities of sulphurous and other gases
which will condense and form nuclei.
Vegetation, both when alive and when dead, gives off vast quantities of
small organic particles, and microscopic life, which almost seem to populate
the air we breath, and will of course add much to the dust in our atmosphere.
Professor TyNpALL has shown that light decomposes certain gases and
vapours, and that this decomposition is greatly aided by the presence of
other gases or vapours. It seems therefore probable that the sun’s rays will
decompose some of the gases and vapours in the air, and if these decomposed
substances have a lower vapour tension than the substance from which they
are formed, they condense into very fine particles. These particles may be
solid or liquid, and will form nuclei for the condensation of water vapour.
We know that there are ever present in our atmosphere great quantities of
chloride of sodium and other kinds of dust which have affinities for water.
These dust particles by their affinities for water vapour cause condensation
to take place in unsaturated air, and if present in great quantities give rise
to dry fogs. “Let us look briefly at the effect of this affinity between the dust
and the vapour. If there was no affinity between the two, then condensation
would only begin when supersaturation began, and those dust particles which
permitted the vapour to condense on them easiest would get most vapour, and
would tend to grow largest. This would evidently tend to inequality in the
size of the cloud particles which would determine the fall of some of them
through the others. But if there is an affinity between the dust and the vapour,
then each particle of dust tends to take the same amount of vapour, and if one
particle gets more than its proportion, the others tend to rob it of its surplus.
This evidently tends to equality in the size of the cloud particles, and tends
also to prevent any of them falling through the others, and thus prevents it
beginning to rain, that is, if rain drops are formed by the collision and union of
368 JOHN AITKEN ON DUST, FOGS, AND CLOUDS.
the quickly falling particles with those falling more slowly. It would thus
seem that while on one side if we have no dust we would have no clouds and
probably no rain, as we don’t know whether the air would ever become suffi-
ciently supersaturated to condense without nuclei. On the other hand, an
over-abundance of dust having affinities for water vapour also prevents the
vapour falling as rain, as the vapour under these conditions condenses into
minute particles which all tend to be of equal size, and none of them are able
to fall quickly enough amongst the others to cause collisions. The result is the
condensed vapour cloud instead of falling in minute parts as rain, tends to fall
as a whole. The air becomes so loaded with the water held in mechanical
suspension that it is dragged downwards by its weight. If we make artificial
fogs with sulphur fumes and ammonia, or by heating chloride of magnesium,
the fog is so heavy it can be poured from one vessel to another.
After the affinities of the dust particles are satisfied, this tendency to -
stability no longer exists. After this stage the growth of the particles becomes
unequal, and, as has been shown by Professor CLERK MAXWELL,* the larger
drops or particles in a cloud tend to rob the smaller ones, or rather, from what
we now know, will tend to prevent them growing after the affinities of the
nuclei are satisfied.
It would appear, then, that condensation will always begin in our atmosphere
before the air is saturated. There is, however, still much to be done in this
department of our subject to determine whether the amount of cloudy conden-
sation is always the same for the same degree of saturation, or if it varies; and
if it varies, to find the composition and source of the nuclei which cause the
variations.
I feel that these two papers only start this inquiry. Much, very much, still
remains to be done. Like a traveller who has landed in an unknown country,
I am conscious my faltering steps have extended but little beyond the starting-
point. All around extends the unknown, and the distance is closed in by many
an Alpine peak, whose slopes will require more vigorous steps than mine to
surmount. It is with reluctance I am compelled for the present to abandon
the investigation. It is, however, to be hoped it will be taken up by those
better fitted for the work, and that soon the roughness of the way will be
levelled, the difficulties bridged, the country mapped, and its resources
developed.
* «Theory of Heat,” Professor CLERK MaxwE.L, p. 270,
}
q
_
( 369 )
XIII..— The Effect of Permanent Elongation on the Specific Resistance of Metallic
Wires. By Tuomas Gray, B.Sc., Demonstrator in Physics and In-
structor in Telegraphy, Imperial College of Engineering, Tokio, Japan.
(Plate XVIIIa.)
(Received 23d October 1880.)
The object of this investigation was to obtain information as to the change
of specific resistance produced in wires of various metals by different amounts
of elongation. ._The present paper refers to experiments on copper, iron, and
German silver wires.
Besides the effect of permanent elongation, I have added the results of a
number of observations on the effect of elastic elongation. These results were
obtained in the course of the other experiments, and, the two taken together,
may serve to throw some light on the cause of the change of resistance.
In order to render the effect of elastic elongation intelligible, it is necessary
to form an estimate of the change of section due to the stretching. This can
be readily done if we know the ratio of linear contraction, at right angles to
the direction of pull, to the extension in the direction of pull. If we suppose
this wire isotropic this can be obtained from the Youne’s and rigidity moduluses
(THomson and Tarr’s “ Natural Philosophy,” § 684). I give a determination of
these constants for several of the wires experimented on, both before and after
a measured amount of elongation, from which an approximate estimate of the
above ratio is derived.
In reckoning the change of specific resistance, the resistance of 1 metre,
weighing 1 gramme, has been taken as the specific resistance of the material.
IT have thus left out of account the effect due to any change of density which
may have resulted from the stretching of the wires. This change of density
was in the later experiments carefully noted, and is recorded in the tables of
results. It will be found, on examination, that the change of density was in
every case small, that it sometimes increased and sometimes diminished, but
that, in either case, there was little difference in the change of resistance. So
far as these experiments go then, no effect, due to change of density simply,
was discovered.
The fact that the density remained almost constant all through the experi-
ments, gives a very easy method of observing the effect of elastic elongation.
Generally the density of a wire is diminished by elastic elongation, and there-
fore, if change of form is sufficient to account for the change of resistance, the
effect of elastic elongation should be somewhat /ess than that of permanent
VOL. XXX. PART I. 3K
370 THOMAS GRAY ON THE EFFECT OF PERMANENT ELONGATION
elongation. I find, however, that if the change of resistance due to stretching
be measured when the stretching weight remains on the wire, the effect is
considerably greater than if it be measured, for the same elongation, with the
weight off. This shows that the resistance of the wire is increased by pulling
it, altogether independently of the change of form due to the pull. This same
result has been obtained by THomson (“ Electro-Dynamic Qualities of Metals,”
Phil. Trans., 1856) and by Tomuinson (Proc. Roy. Soc., 1877, vol. xxvi.).
The ratio of lateral to longitudinal change of dimensions was used by
THoMSoN, and afterwards by ToMLINSon, in the deductions from their experi-
ments. 21 3°58 2°26
=p ; ; - 21 5°05 3°32
(gheApril) 1. +: 5) ‘Obs 671 3-65
15th April, . : : 10:00 0:00 0:00 noe No. 2.
hee : : : 21:00 1:23 0°82 ere Sac
» 22°5 2°01 1:13
» 23°5 3°06 1:56
» 24:5 3°49 1:66
” 26 4:07 2:18
5 27 5:07 2°66
» 28 6°33 3°41
: : c 29° 7:20 3°56
16th April, . 3 ; 35°5 8:58 4:84
Fs ‘ é : 37° 9:03 4°80
. c c ‘ 37° 9:90 5:14
376 THOMAS GRAY ON THE EFFECTS OF PERMANENT ELONGATION
TABLE I.—continued.,
WINS ROn Percentage as ef : Number of
Date. ape oun Elongation. Ma Density. Experiment.
esistance.
| 17th April, 10:00 0:00 0:00 No. 3
. 15-00 0:37 0-22
s 175 0°69 0°32
. 20 1:34 0°66
5 21 1:80 0°84
i 22 2-00 1:02
i 24 2°43 1:36
: 24 3°33 1:94
‘ 25 3-65 9°34
Be 26 4°38 2:96
Fs 26 5:47 3°24
19th April, 27 5-90 3-36
‘ 28 6-08 3-46
3) 29 7°48 4:20
3 30 8°88 5:24
bs 31 9°63 5°79
20th April, 31 10:02 6:38
. 31 10°21 654
27th April, 32°5 10°36 6:58
‘ 32°5 ip i yg 6°60
1st May, 17:50 0:00 0:00 No. 4
5 17°50 0:95 0:54
ahs) 1s, 0°82
3d May, 20 1:98 1:24
3 21 2:25 1:40
2 21 2°50 1:51
re 22 3°11 C77
E 23 3°78 2°32
i 24:5 4:48 2:70
iy 27°0 6:04 3°82
ce 29:0 8:34 4:98
‘ 30:0 9:85 572
a 51:0 10°64 6°16
i 315 11-46 6-40
ks 31°5 12:11 6°94
32 12°66 7:06
: 32:25 13-71 774
4th May, 32°4 14:62 8:26
. 32°7 14:90 8°40
2 33 15°85 8°80
? 33°4 16:91 9:40
22d June, 5:00 0:00 0:00 8:945 No. 5.
‘ 15:50 0:95 0°68 ste =a
‘ 20:50 3-40 2-46
: 25 6:32 4:44.
M Bs 6-21" 4:33 (2)
* Probably slightly stretched by removing the weight.
ON THE SPECIFIC RESISTANCE OF METALLIC WIRES. SWAT
TABLE I.—continued.
Weight on | p ‘ Cea | ee
ercentage nerease 0 4
Date. the yen Elongation. Specific oy Huperinent
TE v8 Resistance.
22d Tune, 25: 6-35 4-50 No. 5.
Bs 27° 8°33 5:44 Bes
* 28: 10°76 7°32
BS : 30° 14:39 9°74
by oF 14:24 9°34
‘ | 85: 14:38 9°70
23d June, d 25° 14:38 9°69 ay
3 30° 15°92 10°73 8°884
TABLE II.—Specimen of English Copper.
3 Percentage
Weight on Percentage | Increase of : Number of
Date. ie ison Elongation. poe Bessie _ Experiment.
17th June, 19-00 0-00 0:00 8°895 No. 1.
2 93: 1:23 1:04 ss ee
5 103: 2°64 1:94
A 112: 4:79 2°96
- 122: 6:01 4:26
‘ 127° 7-82 5-42
a 19: 7°70 4-40
.s 102: 7°82 bd2
: 137° 9°53 6:48
e 141° 11:06 7:42
18th June, i144 11:06 Wao
Me ISI 12:60 7:90
yi 27° 15°27 822 54
‘ 130° 15°44 9:38 8-873
TABLE III.—Specimen of English Iron.
. Percentage
Weight on 5
© Percentage | Increase of . Number of
Date. me oe BlleHeation, Specific Densiny- Eeeaament
Resistance.
12th May 16:00 0:00 0:00 No. 1.
=A 20:00 0:39 0:26 sole
s D2) 1:10 0°78
i 24:50 1:95 1:46
. 26°75 3°32 2°36
# 26°75 3°66 2°62
ry 27°75 4-24 3°04
‘ 29°95 ole 5:18
VOL, XXX, PART I,
380 THOMAS GRAY ON THE EFFECTS OF PERMANENT ELONGATION
TABLE VI.—Specimen of German Silver. .
: Percentage
Weight on Percentage | Increase Sf A
Date, the — Blongation. Specific Density. » Daan
: Resistance.
21st May, . : : 10:00 0:00 O00 Te Gre No. 1:
i ; ; : 32° 0:21 0:06 wat
» . ci 5 ol 0:54 0°30
24th May, . . .| 42 1°76 1:00
3 ; ; ; 45: 2°39 1:30
5 46: 3°01 1:76
+ 50° 3°87 2:08
> 50: 4:45 2°36
oy 52° 5:42 272
) 54:5 581 2°98
25th May, 545 6°72 3-24
” 56° 715 3:46
Bs 58 i (to's) 3°68
» 60°5 9:18 4:12
By 61°5 10-38 4:48
» 64:25 12:19 5:04
» 64'5 12°62 5:12
26th May, 31 sie No, 2
” 41°5 1:44 0°84
” 43°5 2°20 0°62
» 47 2°71 0:96
Pp 49'5 3°50 2°76
” 53 4-01 2°78
” 53 4:72 3°06
» 54 5-41 3 42
” 555 5°70 4:40
» 56:5 6:27 4:54
” 57 5 6°50 4 64.
» 585 Tal 4:94.
” 59 5 7:99 5 10
» 60 8:44 5:22
» 61 9:00 532
, 62 9:47 5°40
” 66 10°56 5 78
JEL: 0:00 0:00 8801 No. 3.
11th June, 32° 0:21 0:174 we nae
” ahh 1:25 0 74
3 40 1:47 1:44
- 43 B06 1:96
x 49 6:11 3°43
r 50 700 3°84
ON THE SPECIFIC RESISTANCE OF METALLIC WIRES. 381
TABLE VI1.—continued.
4 Percentage
Weight on Percentage | Increase ‘of : Number of
Date, ve ie Til isation, Specific Bou Experiment.
A Resistance.
11th June, . : ; aps 9-44 4:72 ae No. 3.
% , : 14: 9:20 4:54 fie was
S) ; ; 55: 9:44 4:72
” : ‘ OG 10:28 5:12
3 61° 11°87 556
53 14: i lg ca! 5:34
tp A ; 56° 11:99 5°63
12th June, ‘ : Da) 11:99 5°63
» - A“ 61° 13°34 al
7 63° 14:79 5:93
es 64: 16°02 6 46
3 14:00 15°73 6:21
5 58: 16: 6:43
Fr 65° 16:96 6°64
= 14: 16°59 6:43
5 ; ‘ ; 61: 16°93 6°67 er
93 : : : 67° VT 6°83 8786
VOL, XXX, PART I, 3M
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XV .—On some new Species of Fossil Scorpions from the Carboniferous Rocks of
Scotland and the English Borders, with a Review of the Genera Eoscorpius
and Mazonia of Messrs Meek and Worthen. By B.N. Preacu, A.R.S.M.,
F.R.S.E., of the Geological Survey of Scotland. (Plates XXII. and
XXIII.)
(Received 24th June 1881).
In the progress of the Geological Survey of the South of Scotland, specimens
referable to the genus Hoscorpius have been gradually accumulating. In 1876
J. BennizE, Fossil Collector to the Survey, obtained an example from the Coal-
measures of Fife. Since then fragments have been disinterred by him and by
A. Macconocuig, also Fossil Collector to the Survey, from the Calciferous Sand-
stone series in the counties of Edinburgh, Berwick, Roxburgh, Dumfries, and
Northumberland and Cumberland. It was not till the spring of last year (1880)
that they began to be found in such a state as to necessitate a description of
the fossils. In the summer of that year A. Macconocuiz obtained an almost
entire example from the neighbourhood of Langholm, in Dumfriesshire. This
year (1881) J. Bennie has secured several good though fragmentary specimens
from the neighbourhood of Edinburgh, while A. Macconocuiz has sent in several
from the counties of Berwick and Northumberland. In my capacity of Acting
Paleontologist, I have had an opportunity of studying these remains, and by the
permission of A. C. Ramsay, LL.D., F.R.S., Director General of the Geological
Survey of Great Britain, and Professor A. Grixiz, LL.D., F.R.S., Director of
the Geological Survey of Scotland, I have been allowed to describe them.
Previous LITERATURE RELATING to CARBONIFEROUS SCORPIONS.
In 1835 Count Sternsere published a description of a fossil scorpion from the Coal formation of
Chomle, near Radnitz, Bohemia,
In 1836 Corpa described and named the above specimen under the appellation of Cyclopthalmus
senior, from the smaller eyes being .srranged in a circlet round the two central larger ones.
(Corpa in “ Bohmischen Verhandlungen,” 1836, and Wisemann’s “ Archiv,” 1836, vol. ii.
p. 360). Figured in the Transactions of the Bohemian Museum.
In the same year Dr Buckuanp reproduced the figures in his “ Bridgewater Treatise,” pls. 46’ and
46”, fig. 13, the description being given in vol. i. p. 407.
In 1839 Corpa added a new genus to the Pseudo-scorpions under the name of Miciolabis, the
specimens being obtained from the same locality as the Cyclopthalmus.
In 1868 Messrs Mrrx and WortHEN described the remains of a fossil scorpion (Hoscorpius) from
VOL, XXX. PART I. 3 Q
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CONTENTS.
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Chapters on the Mineralogy of Scotland. Chapter Seventh.— Ores of Manganese,
Iron, iireraseaty, crm Titanium, By Professor Heppir, . 7 . 427
7 On the Nature of the Curves idee Stenson give the Imaginary Roots iF an
oa _ Algebraic Equation. By Tuomas ae ascii MA. FE.RBS.E. (Plate
z { alae iat . o. . 4 . . . . : 467
" BA, Rev Coles, 0 Oxford. (Plates XXV. to XXVIL es aid ‘ S. 481
“Further Researches among the Crustacea and Arachnida of the Carboniferous
ef ~ Rocks of the Scottish Border. By B, N. Pxacu, A.R.S.M., F.R.S.E,, of the
Wh jira cy Survey of Scotland. (Plates XXVIII. and XXIX.), . o OFL
R eport on Fosuil Plants, collected by the Geological Survey of Scotland in Esk-
oY dale and Liddesdale. ‘By Robert ae ‘(Plates XXX. to XXXIL),. 531
Mirage ‘By Eaaterar Tax. (Plate XXXIIL Dy? ‘ vam «+ 551
ie 1 y W. Percy Suapmy, £8, 80S (ur ee erg
‘ bw
fecuiine on Vegetable and bas Cells; their Structure, Division, and
* History. By J. M. Maorartane, B.Sc. Communicated by Professor
_ Dickson. (Plate XXXV.), : ; ‘ ' i i=)
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XVIII.—Chapters on the Mineralogy of Scotland. Chapter Seventh.—Ores of
Manganese, Iron, Chromium, and Titanium. By Professor HEDDLE.
(Read 20th February 1882.)
I have thrown together, in this chapter, the ores of several members of a
family of the elements, which may be called the family of the magnetics;* and I
have also, from its frequent chemical association with iron, placed titanium
along with them.
_ No attempt was made by me to analyse the ordinarily-employed iron ores,
but only such as, from their apparent purity, or from the excellence of the
specimens, appeared to be of mineralogical interest.
Specimens of doubtful, or of an unrecognised appearance were, however, also
examined ; and the so doing led to the discovery or recognition, for the first
time as British, of the two minerals, Turgite and Martite.
ORES OF MANGANESE.
I have verified the occurrence of manganite on Laverock-braes Farm, Grand-
holm, Aberdeenshire ; and of pyrolusite at Arndilly, near Rothes; but I have
not yet analysed the specimens which I there collected. The first manganese
ore which I have analysed is pst/omelane, from the Orkneys.
GEORGE Low, writing in 1774, says :—“ The ores of iron in Hoy are of two
kinds, and found in great plenty in two different places. That dug near the
kirk is hematites..... Another kind may be had in vast quantities from
Hoy Head, where it runs in many regular veins in the very brink of the sea
rocks. This is blacker than the former in appearance: it is much more solid
and weightier, looks as if it had been once in fusion, and had settled in a number
of bubbles, which I dare say had not been the case: its first formation is from
an indefinite number of small particles or drops adhering very firmly together,
and growing still more solid as they imbibe more of the iron, till at length it
becomes a flint-like mass of the colour above described. Some years ago a
company of adventurers from London dug several tons of this last, which they
imagined was an ore of cobalt, but without foundation. They sent several
specimens to London, but how it turned out I could never learn. The work,
however, was given up. When Mr. Banxs was in Orkney on his way from
Iceland he took a step to this mine, and smelted a piece of the ore, and assured
me of its being iron.”
A little west of the highest point of Holy Head there is a turret-like pro-
* Though the members of this family are not all magnetic, yet it includes all the metals which are so.
VOL. XXX. PART Il. 3X
428 PROFESSOR HEDDLE ON
jection called Braebrough. About three hundred yards further south, a locality
called Lead Geo is reached. As the ruins of a turf hut are to be seen here,
and as the writer found a buried deposit of about four-hundred weight of the
ore, near to where there were evident signs of working, there can be no question
that this is the locality alluded to by Low; and, as no galena is now at least to
be seen here, the following extract of a letter of Mr. Low may probably explain
the name of Lead Geo. “Has not your friend* perhaps something mistaken
the words of the historian with respect to the black and white lead (Plumbum
album et nigrum) Buch. History? I have never heard of black lead or ‘ wad’
to be found here, but common lead in many places.”
The common confusion between wad and graphite, taken along with the
manner in which the hands are soiled in working among the ores which occur
at this spot, doubtless led to the adoption of the incorrect name.
The ore described by Low is, however, not one of iron, but is, for the most
part, psilomelane ; his “ flint-like mass” is a very dense wad. There is, it is
true, a small quantity of limonite, but not enough to explain the extraordinary
statement as to iron having been smelted upon the spot apparently,—for so the
language used would imply.t Low’s description of the ore is most accurate, and,
as it will be seen, most suggestive and shrewd.
The veins are situated about 200 feet below the summit of the cliff, here
called 1130 feet in height.
There are three or four veins still to be with difficulty seen; for the work-
ing has, from the precarious footing and the danger of the position, been of a
rough and destructive description.
The appearance of the pszlomelane varies in each of the veins; it occurs in
finer masses here than at probably any other known locality.
In its commonest and least interesting appearance, it presents itself in
mammillated masses, with an obscure fibrous structure, and a dull lustre. Of
this variety, the specimens, merely as such, are the finest. Such masses sheathe
the sides of the vein, enveloping any loose or projecting processes which may
occur in its vacuous centre. Though the surfaces of these mammillations are
dull, and so soft as to soil the hands, they may, wheu dry, be polished by friction ;
but when wet, the mineral may by brushing be diffused through water to a
large extent.
There is therefore in these specimens a certain approach to wad.
Another appearance, though a rare one, is in large flat sheets, which possess
a mirror-like lustre, and have little trace of fibrous structure.
In another vein it is of an exceedingly peculiar appearance, resembling a
* Pennant. Mr, ANnpeERSON, in his introduction to Low’s work, very clearly shows the vampire
character of Pennanvt’s friendship for Low.
+ Could Sir Josrru Banks have “smelted” iron—anywhere ?
THE MINERALOGY OF SCOTLAND. 429
quantity of wires, of the thickness of needles, laid longitudinally together. The
wires can be separated from one another with perfect ease. They pass trans-
versely from side to side of the vein, which is about eight inches in width.
Another vein is of the nature of a dense wad: it is about two inches in
width, is devoid of structure, if it be not of a granular description, and it breaks
with a well-marked conchoidal fracture. This, therefore, is probably Low’s
“ flint-like mass.”
There is one marked fact which is to be observed of all these veins; it is
that at their sides, the yellow, loose-grained sandstone-rock is stained by the
manganese, in a manner which forcibly conveys the impression that the ore did
not exude from the rock into the vein-rent, but was poured into the rent, and
then soaked to a small extent into the porous stone. The limit of the stain is a
sharp line of demarcation ; it does not shade off with a fainter tinge to the
smallest extent.
Low, in his remarks upon this ore, says that it “looks as if it had been
once in fusion, and had settled in a number of bubbles.” Though its usual
occurrence, in fibrous mammillations after the manner of the hematites, by no
means indicates such a mode of deposition, yet I have already had to allude to
indications of its having been intruded into the veins from without ; and there
are certain modes of its occurrence now to be described, which go a very long
way indeed to show that some portion of it at least had been in a state of
liquidity from heat.
These modes of occurrence group themselves into four varieties.
1. Drops which seem to have been sprinkled over a surface.
2. Drops which seem to have fallen into narrow spaces, and to have moulded
themselves to the bounding walls of those spaces.
3. Pendulous masses which seem to have run down the surface of the sus-
taining substance.
4. Drops which exhibit shrinkage markings, and which, having fallen one
upon another, have taken an impression or cast of the shrinkage markings
of the underlying drop; and which drops are free from all attachments.
In the case of the first three varieties, the so-called drops invariably lie
upon the surface of the glossy limonite: in the case of the last they do not do
so, but upon either the mammillated psilomelane, or upon other drops.
In the first two cases the drops are perfectly spherical, except where in
contact with their support, or where by juxtaposition they impinge upon each
other. They vary in size from the smallest sparrow-hail, to bullets which would
be about four to the pound.
_ Their internal structure is obscurely fibrous. The pendulous masses have
also an obscurely fibrous structure ; but the drops which come under head No.
4 do not show any structure,—being like flint when broken.
430 PROFESSOR HEDDLE ON
Certain specimens show slabs of the rock vg nace coated with a thin layer
of the glossy limonite.
The rock has a very vitrified appearance ; and the absence of the iron com-
pound from part of its surface, considered along with the reniform margin of:
of the portions of limonite which sheathe it, is of difficult explanation under
any supposition of its having been deposited from water.
Over the smooth and glossy surface of this limonite, and occasionally also
over the sandstone itself, there are sprinkled vermiform aggregates of minute
spheres of coalescent psilomelane.
The limonite layer is here about the sixteenth of an inch in thickness.
In other specimens it is about the fourth of an inch, and the surface, though
glossy, is stalactitically fibrous and rough; globules larger than swan-shot are
singly or confluently sprinkled over this.
In still others, the glossy limonite (which sheaths botryoidal psilomelane)
has a thickness not much exceeding that of a coat of varnish; and upon this,
large rounded masses lie; and narrow, tortuous, and more recently formed
drops overlie both the limonite and these drops of psilomelane.
Of these specimens it may be argued that they are not cases of droppings
at all, but merely of local segregations of matter which had not deposited itself
in a uniform layer over the surface of the limonite; and that it had not done
so on account of the smoothness of the latter not only affording but few points
or centres for radiant growth, but on account of its oil-like surface acting
repellantly to the exercise of ordinary adhesion ; and that once that crystalline
shoots emanated from the few rough centres which did exist, the succeeding
growths were localised at these,—as is so frequently seen in zeolites of a radi-
ating character.
While giving all due weight to this argument, it has to be replied that the
manner in which the limonite ordinarily coats the psilomelane, negatives the
idea that there had been any repulsion between the two minerals ; and that the
above argument in no way meets the fact of some of the drops reposing upon
the comparatively rough sandstone.
Certain rare specimens show an apparent flow of molten matter over the
limonite.
Others seem occasionally to point to a large drop or drops of a plastic sub-
stance which has taken a cast of the narrow crevice into which they had fallen.
None such were found adherent to the wpper part of any drusic cavity.
The drops have often fitted themselves in between the two coats of the
psilomelane which had sheathed the surfaces of the rock-rents.
The specimens which fall to be considered under the fourth head, however,
seem to be inexplicable upon any view save that of a succession of molten
masses alighting upon one another, after the lapse of definite periods of time,
EE
THE MINERALOGY OF SCOTLAND. 431
—each period having been of such a duration as sufficed for the solidification
of each preceding drop.
In these, a number, sometimes a large number, of Joose drops are superim-
posed upon one another, without even so much adhesion as to allow the speci-
men to be removed from the rock without their falling apart.
There is here no limonite,—drop lies upon drop in immediate contact.
The surface of each drop is highly polished ; but it is marked throughout
with a number of projecting ridges, which bear the most perfect resemblance
to a solidified crust that has been rent and roughened by the contraction of a
shrinking and still liquid centre.
Each drop has taken the most perfect cast of that which it has fallen upon
(or at least of what it lies upon), both as regards the converging curvitures
thereof, and the above-mentioned linear rugosities; and each drop is on ?zts
upper surface lined and roughened in a perfectly similar way.
If it be a large drop, it envelops several of those which are smaller and
inferior, filling up every interstice between them; and the rugosities upon the
upper surface of a large drop are ever larger and more boldly marked than
those upon a small one; as might be expected from the contraction of a more
ample mass.
While such a structure as this is in every way accordant with igneous
liquidity, it appears to be altogether inexplicable upon the theory of watery
solution, or of deposition of particles which had been in suspension in a liquid;
and the observant Mr. Low was fully justified in saying that it “looks as if it
had been once in fusion, and had settled in a number of bubbles.”
I may here state that I possess from another locality a specimen of perfectly
amorphous psilomelane, which fills up all the interstices between a number of
“stalactites” of hematite—and these stalactites have a markedly scorified
appearance.
But the question of the liquefiability of the mineral may be, to some extent,
determined by actual experiment.
In ascertaining the amount of the water in the two manganesian minerals
which occur here, it was found that after the application of the heat—nearly a
white heat—obtainable from a three-jet Griffin blast furnace, the crushed powder
of the psilomelane had agglutinated throughout; while the portion thereof which
was in contact with the sides and bottom of the crucible, had fused so far as
to be firmly adherent thereto, and to have become glistening in lustre.
The fine powder of the wad, again (which differed from that of the psilome-.
lane in its comportment under heat, in this, that it became brown at a red heat,
while the colour of the psilomelane was unchanged), was not only fused to the
crucible in its lower portions, under the influence of the white heat, but had
collected into distinct drops, which were more or less rounded.
432 PROFESSOR HEDDLE ON
It has to be kept in view that, under the concentrated energy obtainable in
close cavities, and with the larger amount of alkalies which the wnaltered
mineral would contain, the amount and ease of the liquefaction must have been
more complete.
Psilomelane.
The massive sub-fibrous variety was that analysed.
8. G. 4° 607
Manganous Oxide, F 66°995 = 71°868 MnO,Mn,0,.
Cobalt Oxide, : : ; F 1°478
Magnesia, . : : : ; °098
Baryta, i : f d ‘ 14°876
Potash, : : A , : 5
Soda, . : : } : : *003
Oxygen, . ’ ; ' : 6°712 6°658,
Water, : i ; ; : 6 205i: 6 °003
101° 484
Hygroscopic Water, é f 1-+201 per cent.
Heated barely red, lost . : 6°051 of water.
» bright red, : 2 1: 066 of oxygen.
» toa white heat, . : 5 ‘646 more.
Cavities in this psilomelane are rarely covered with a velvet coating of
mangansammat-ere.
The wad which occurred as a vein of about two inches in thickness, of a
blue-black colour, and brown streak, was analysed. When steeped in water a
considerable quantity of a saline efflorescence exudes from it ; as the specimen
had been washed, some of the alkalies must have been thus lost.
8. G. 4:4,
This yielded—
Manganous Oxide, F P ’ 64°87 = 69:58 MnO,Mn,0,.
Cobalt Oxide, . ; ; ; 1:°995
Magnesia, . 3 § : ‘ -199
Baryta, : 4 : ; : 14:97
Potash, a : ; f b ‘247
Soda, . : ; ; ’ ; * 259
Alumina, . ; F F : 1:097
Silica, : , : ; *898
Oxygen, ‘ , ; : : 5 S211
Water, aH : ; P 5 +688
| 100454
THE MINERALOGY OF SCOTLAND. 433
Hygroscopic Water, f . 694
Heated barely red, lost, . , 5°688 of water,
» bright red, , . 2°383 of oxygen.
» white heat, A ; 3°138 more.
These two analyses show that the “ London adventurers” were not alto-
gether wrong in conceiving the mineral to be an ore of cobalt.
From the old Workings of the Heegh-pirn Mine at Wanlockhead.
This psilomelane was found by Mr. DupGEon and myself, among plates of
grouped crystals of quartz, in a number of curved scales about the size of the
nail, and three or four times its thickness. These curved scales stood upon
their edges, as if they had coated some substance which had been afterwards
dissolved away. They were of a brownish-black colour, and were soft-and dull
on their outer surface. They were not much harder within.
They were separated from quartz with much difficulty ; so that the insoluble
matter is doubtless quartz.
The speeimens had on their surface a little plumbo-calcite, vanadinite, and
a trace of chrysocolla.
The quantity of the mineral which could be gathered was too small for
ascertaining the specific gravity.
Manganous Oxide, . : =) (OF ot MinOsiin,O,.
Oxygen, . : ‘ : ‘ : 9° 088
Protoxide of Copper, ; ‘ ‘ "54
Protoxide of Cobalt, : P ; “37
Baryta, . ; : ; : ; 3°66
Lime» . : ’ : . 228
Magnesia, ; ; : : "012
Potash, . : : i : : 4°088
Soda, . _ : , 5 ‘ * 262
Water, . : : : 5 ; 4-02
Insoluble, p 2 : : : Dalat
100-688
I have lately, through the kindness of Dr. Witson of Wanlockhead, got
much larger and finer specimens of psilomelane from the Leadhill mines. These
are in botryoidal forms, though of a small size. Their fractured surface is blue-
black and lustrous ; being thus less like wad than the above.
A singular combination, apparently of wad and calcite, occurs at the Lead-
hills. It is in masses of the size of an egg. The structure is like that of an
onion ; the successive layers are about an eighth of an inch in thickness, and
have the usual calcite cleavages. The inner layers are largely impregnated with
434 PROFESSOR HEDDLE ON
wad, and have almost a black colour. This diminishes in quantity as the layers
pass from the centre of the lump, the colour passing to brown. The impregna-
tion suddenly ceases, when the concentric structure at once disappears. These
layers, when placed in a weak acid, yield very varying amounts of insoluble
matter,—apparently wad.
Here the manganesian mineral seems to have imparted to the calcite its
own tendency to concentric deposition.
Wad.
This was found fillmg small cavities and rifts in white quartz boulders
which lay in the bed of the “ Dirty Burn,” to the south of Dunoon, Argyllshire.
These quartz boulders were quite fresh in appearance, and seemed to have
been swept down from a corry in the Bishop’s Hill. They contained in other
cavities, chlorite, and pyrite in fine crystals. The ‘“‘ wad” was in a loose, inco-
herent, powdery state, and of a blue-black colour. It yielded 23:7 per cent. of
water in the bath. .
Dissolved in moderately strong acid, it yielded—
Manganous Oxide. A ; ; 38° 575
Ferric Oxide, : ‘ : ; : 11-828
Alumina, . ; ; : ‘ 5 6°317
Lime, . ; : 5 ; : 2° 784
Magnesia, . ; ; : ; ; 1:008
Potash, 1:497
Soda, . : ; ; : , 1°415
Water and Oxygen, . : : 13-184
76 *608
And insoluble,—which, upon fusion with Fresenius’s flux, yielded
Silica, . ; c : P F 2 16°532
Alumina, . ; : 5 +376
Lime, . : : ; ; ; *903
Magnesia, . : : ’ : *403
23-214
99-822
Insoluble Silica «812 per cent.
This seems to be a very impure wad.
Craigtonite.
Stains, dendrites, and thin filmy coatings on rocks, are very frequently pro-
nounced to be “manganese,” or manganesian, if these have a brown, or even a
THE MINERALOGY OF SCOTLAND. 435
blue colour. I have ascertained that this they sometimes are, to the extent at
least of containing manganese. The substance I now notice is one such.
It occurs as a thin coating on red granite, in the upper quarry of Craigton,
Hill of Fare, Aberdeen. Colour blue-black, here and there with the lustre of
graphite; cuts with knife. Being only a thin coating, it was dissolved off the
granite with very weak hydrochloric acid, which seemed hardly to affect the
lepidomelane present in the granite ; which seemed to be otherwise altogether
unaffected. It contained, in addition to the lepidomelane, only red orthoclase
and quartz.
Analysis of the solution gave—
Alumina, . ’ ; : p : 32°203
Ferric Oxide, d : ; ; : 38°305
Manganous Oxide, c é 7°458
Magnesia, . . ; : 5 16°61
Potash, ; : ; ; , 3 4°'745
Soda, . : ‘ ’ : : ; ‘678
Silica, . ; : ‘ ; . f trace.
Chlorine was evolved during the solution, so that the manganese must have
been partly at least in the state of Mn,O,.
This is the only specimen of such dendritic coatings which I have got in
quantity sufficient for analysis, But the result lends some countenance to our
considering such coatings, especially when they occur in Old Red Sandstone, as
being, like this, a very impure wad. I have attached the name, merely to
draw attention to this substance.
NATIVE TRON.
A chromiferous magnetite, afterwards to be noticed as occurring in the bed
of the Dale Burn in Unst, was found to be so difficult of decomposition that
comminution under water, with repeated decantation, was had recourse to.
Towards the conclusion of the process, the pestle was found to jump over a
number of particles which no force could reduce to powder, though several
were found to be flattened out by the pressure into thin scales. These were
thoroughly washed, and found to be strongly magnetic. When placed in an
acidified solution of a copper-salt, they became instantly coated with the red
metal. They readily dissolved in acid without residue, and gave the tests for
iron. In the pounding of the magnetite it had never been touched by an iron
or steel tool; and, from the time when they were collected to that in which
they were examined as above by him, they were never out of the writer's
possession. ‘These grains, therefore, are nutive tron.
VOL. XXX. PART IL, 3 Y¥
436 PROFESSOR HEDDLE ON
The occurrence of grains of this substance in a metamorphic rock is new,
frequent as is its occurrence in rocks of an igneous nature ; and the occurrence
of metallic iron in a rock primarily of a sedimentary nature is difficult to
explain. Until, however, a laminable, magnetic substance, which precipitates
a salt of copper, which dissolves in acid without carbonaceous residue, and
which gives the iron reactions, can be shown to be other than iron, this must
stand for such. The grains had been protected from atmospheric action by
a coating of magnetite, a substance lately proposed and patented for this very
purpose.
It is perhaps necessary that I should here state that the pounding of this
chromiferous magnetite under water was executed by the writer himself; and
that he, upon the observation of the somewhat flattened metallic scales, called
his assistants to witness the deposition of the copper upon the iron, from an
acidified cuprous solution. Since the analysis of this Unst specimen, he has
found metallic iron at a second locality, sheathed also in magnetite. In both
cases the quantity was so minute as to preclude any examination for nickel ;
carbon was, however, in both cases absent; and the view entertained by the
writer is that this is a meteoric dust of iron, which had settled to the bottom
of the sea, in which its presently containing rock was being sedimented. Such
a view receives much countenance from the discovery of such metallic dust
at the bottom of certain oceans explored during the “ Challenger” expedition.
Lately I have had occasion to examine for His Grace the Duke of Sutherland
a quartz vein or reef, which occurs at Suisgill. The quartz was seen to con-
tain ilmenite and magnetite ; but, after crushing, it yielded so considerable a
quantity of magnetic iron, which rusted with extreme rapidity, precipitated
copper, and was bruised by a pestle, that I communicated with Messrs. Joun-
son & Maruey (who had crushed the quartz), as to the possibility of its
having been abraded from the stamps. The following reply was received :—
“Tn answer to your letter we beg to state that the sample of mineral sent
by you was crushed in a cast-iron roller-mill. We do not, however, think that
any particles of iron became mixed with the ore during the process of crush-
ing.—Yours, &c., Jounson, Maruey, & Co.”
I accordingly examined the iron, so far as to quantitatively determine the
silica and the carbon. Of the first, there was 12°1 per cent. ; of the last, ‘79.
This being a proportion of carbon very much smaller than any cast-iron con-
tains, it at least becomes a question if some native iron be not present in the
rock,—sheathed, like that of Unst, in magnetite.
THE MINERALOGY OF SCOTLAND. 437
PEON ORES.
Specular Iron.
Found in the “China-Clay Quarry” near Pitfechie, Monymusk ; this quarry
is on the west side of the hill of Monymusk, in Aberdeenshire. It occurs
almost solely filling cavities between quartz crystals. Is in bundles of foliated
crystals of considerable size ; jet black in colour ; streak brownish ; high lustre ;
powder orange-red.
Much of the quartz in the vicinity has a pavonine tarnish ; probably from a
thin coating of this mineral.
8. G. 4°583.,
On 1°303 grammes—
Ferric Oxide, ‘ s , : 81° 704
Ferrous Oxide, . 7°74
Alumina, , : : : ! 4°861
Manganous Oxide, : : 076
Lime, . : : : : : °601
Water, 2 ; : 1°178 to 1°868
Silica, . ; i ; 3° 837
SOS SIF)
This used to be regarded as an ore of manganese. Huge rough crystals
of orthoclase occur in this quarry.
Specular iron—hematite—occurs in crystals of the
form drawn, in gneiss, opposite to the Drongs, Hills-
wick, Shetland.
Martite.
This was given me by Professor ARcHER, as having been gathered on the
sea-shore, on the north-west side of Bute. The parcel consisted of rolled octa-
hedral crystals ; a considerable portion of several of these was of a red colour
and a loose structure; the largest quantity, however, was in hard blue-black
lustrous crystals. A very few of these crystals were feebly magnetic, the
largest quantity being entirely destitute of magnetism. The powder was red ;
but in other respects the mineral seemed to be unchanged magnetite, the
hardness and gravity being normal. The black, lustrous, apparently unaltered
crystals, were those chosen for analysis.
438 PROFESSOR HEDDLE ON
1 gramme yielded—
Ferric Oxide, , ‘ 97-049
Ferrous Oxide, 1:105 -1:°089, . ; 1:096
Manganous Oxide, . é 3 : ‘2
Lime, . P , : : i : "952
Silica, . : : ; ‘ ; . Ar
100 : 067
This is the first notice of this mineral as a British species.
Ilmenite.
I had hoped that my observations on the occurrence, and my analyses of
ilmenite and of iserine, would at least have gone a long way in determining the
question of the specific tdentity, or the opposite, of these substances. All that
I can however say is, that I have been able to satisfy myself that the first named
mineral may occur in granite, syenite, gneiss, and in primitive limestones; while
it never, in Scotland at least, is to be found in volcanic rocks; and that the latter
occurs in these alone, and is therefore entitled to BREITHAUPT’s name—trap-
pisches eisenerz. Also, that the former appears in flat lamellar plates, and
rarely in crystals ; these are unquestionably rhombohedral; while the few minute
forms which are with the microscope to be seen among the myriad “black
sand” grains of the latter, if they be not octahedral or cubo-octahedral, are
portions of much more acute rhombohedrons than are to be seen among the
faces of the ordinary crystals of ilmenite.
That all the “black sands,” however, which are to be found in Scotland,
—very commonly coating the bottoms of runlets of water on the roads of a
metamorphic district after rainn—are to be set down as iserine, I very much
doubt. Many of these may consist of comminuted ilmenite ; many are doubt-
less magnetite.
Ilmenite was first recognised as a British mineral by the writer, who found
it in 1848, in flat crystals (form of fig. 8) imbedded in white quartz blocks,
which lay upon the beach at the head of Loch Long. A year or two after-
wards these blocks were traced by him to a belt, which occurs at a height of
700 feet, on the east side of Crois. Since then he has found it in so many
localities in Scotland that he sets it down as being not only one of the most
widely distributed, but one of the most common minerals in Scotland. It is how-
ever, though not confined thereto, very much more abundant in one special
variety of gneiss than in all the other rocks of the country.
This rock is a chloritic gneiss. A great belt of this rock, in. some spots
tending to chlorite-slate, first appears in the east of the country, in the neigh-
THE MINERALOGY OF SCOTLAND. 439
bourhood of Fortingall, passes south-westward, and reaches the ocean verge
about Loch Killisport, and the island of Gigha.
It is in the less schistose—the most felspathic and highly convoluted por-
tions of this rock—that the mineral occurs; where the quartz segregates in veins,
with a more or less crystalline separation of the felspar, and a nodose segrega-
tion of chlorite in matted flaky crystals.
Where the quartz becomes stained with yellow, and, above all, where it is
hyaline and of a purplish-brown colour, the ilmenite may be expected, with
rutile, as a not infrequent associate.
The following are some of the localities in which the writer has found |
ilmenite in this belt of rock, tracing it from east to west.
In quartz, upon the east slope of the summit of a hill, 3240 feet high, which
lies about a mile immediately to the south of Carn Marig, in Perthshire.
In quartz with chlorite, near Loch-na-Chat, at the east foot of Meall
Garabh, Ben Lawers.
With chlorite, at the foot of Craig-an-Lochan, of Meall-nan-Tarmachan.
On the summit of Craig Cailliach, with rutile in quartz.
In brown hyaline quartz, with chlorite, on the north side of the Mid Hill,
—and near Corrycharmaig, on the north slopes of Craig Mohr.
On the north-east side of Stob Luib.
About 300 feet from the summit of Ben More, on the north side, with
chlorite in quartz.
On the south-east side of the summit of Am Binnean, in hyaline quartz.
In the southern rocky corries on the south side of the summit of Stob
Garabh, with chlorite in quartz.
Near the summit of Cruach Arden.
On Meall Damph, in quartz.
On the south slope of the summit of Ben-a- Chasteal of Glen Falloch, with
chlorite.
Ben-a-Chabhair, south side, with chlorite and quartz.
In quartz with chlorite, in a quarry on the north side of the road from
Loch Lomond to Arrochar.
On the north-west slopes of Ben Ime, in quartz, in large foliated crystals,
with chlorite. Their form is that of the figure. I have
found plates of the mineral on this hill, three inches by
two, and a quarter of an inch in thickness. poe
On Crois.
On the south side of the square pillar of the Cobbler, with rutile and chlorite.
On Ben Lochan, in quartz.
In the great rents on the summit of Ben Bheula, with rutile and chlorite.
440 PROFESSOR HEDDLE ON
In quartz with schorl, on the north side of Glen Finnart.
On the eastern slopes of Clach Beinn, above Loch Eck, in quartz.
In fact, wherever the quartz belts of the gneiss become associated with
chlorite, along the whole of this range of mountains, ilmenite and rutile are to
be expected.
The rock which carries ilmenite with a frequency next to chloritic gneiss, is
ordinary gneiss ; though it will be seen that it is almost invariably the case
that it is where that rock becomes chloritic that the ilmenite occurs.
Some of the localities where the writer has found ilmenite in this rock are
the following :—
In Shetland, at the Kebber-Geo, Point of Fethaland ; in plates, imbedded
in “ potstone.”
At Hillswick Ness, at Vanleep, opposite the Drongs; in curved lamellar
plates in quartz, with chlorite and margarodite, in the vicinity of kyanite.
At the south end of the Wart of Skewsburgh, a little to the north of the
“iron mine ;” in quartz with kyanite. It is here almost in the clayslate, and is
crystallised in forms, like those of Washingtonite (fig. 8).
In Sutherland, in quartz veins, along with chlorite, rutile, and muscovite, at
the Clach-an-Eoin, between the mouth of the Borgie and the Naver.
In small loose boulders which had formed part of felspathic veins; with
chlorite and quartz, near the north foot of Ben Hiel.
Inverness-shire.— With kyanite and chlorite, in the corry on the north side
of Meall Buidh, east of Loch Tulla. With chlorite on the
slopes east of the lake on Ben Creachan. Near Loch
Treig, on the north slopes of Stob Coire Meadhoinich, with
chlorite and hyaline quartz ; and on the south slope of the
cone of the hill, a distinct crystal (fig. 2) imbedded in lepi-
domelane gneiss. With chlorite in hyaline quartz on Stob
Coire-na-Gaiphre. With chlorite in quartz, on the north-west slopes of Mullach-
na-Coirean, Glen Nevis.
Aberdeenshire.—At Dobston Quarry, two miles west of Inverury, in thin
plates ; with lepidomelane, oligoclase, chlorite, apatite, and agalmatolite (%) in
pseudomorphs after apatite (?).
Perthshire.—In Glen Shee, about one mile above the Bridge of Cally, on the
west side of the Blackwater; in thin plates, with chlorite and epidote, in quartz
veins.
Ben Dorean, near the top; on the south-west side, in white and green
quartz, with chlorite and muscovite.
Bangshire.—In foliated talc, with chrysotile in a serpentine quarry, two
miles west of Rothiemay.
Fig. 2.
THE MINERALOGY OF SCOTLAND. 441
In quartz, with pyrite and chlorite, on the north slopes of Alsait Hill, near
Tomantoul.
Argylishire.—At about the summit level of the Devil’s Staircase; in a eneiss
which shows no trace of chlorite, but only a brown mica, apparently lepido-
melane. The ilmenite was in thin curved plates.
Loch Creran, on the south slopes of Fraochaidh, in chlorite and quartz.
Forfarshire.—With finely crystallised chlorite, in quartz veins, about three
miles from the foot of Glen Effock, Tarfside.
In pegmatitic veins, on the north-west side of Garlat Hill, in the same dis-
trict. The veins carry graphic combinations of quartz and white orthoclase,
with crystallised kyanite (in twins), and muscovite. Also with kyanite, on the
south-west side of the same hill.
Ilmenite also occurs in “primitive limestone ;”—at least in that limestone
which is a member of the same formation as that of the rocks above stated to
be its matrix.
I have so found it, associated with sphene, crystallised repidolite, and
pyrrhotite in Edentian Quarry, on the south side of Tullich Hill, Blair
Athole.
With sphene in limestone, with repidolite veins, in a quarry on south side
of the Garry, opposite Blair Athole.
In granite, and in syenite it rarely occurs.
In the coarse-grained veins of the granite of Anguston, in Aberdeenshire, it
occurs along with orthoclase and oligoclase, sphene, Haughtonite, and
Allanite.
In a large syenitic boulder, which lay upon the hill of Ben Bhreck, near
Tongue, it was associated with a great assemblage of minerals, among which
were amazon-stone, Babingtonite, sphene, Allanite, and orangite.
In quartzose veins of the granite quarry at Cassencarie, Dumfriesshire,
with chlorite and epidote.
It is worthy of note that I have never found this mineral in Hebridian
gneiss.
From among this large range of localities I have analysed the mineral from
the following :—
1. Found in plicated crystals, imbedded in quartz, with chlorite and talc,
at Vanleep, Hillswick, Shetland. Magnetite in crystals also occurs here. The
crystals of ilmenite are from one to two inches in length and breadth, by
one-eighth in thickness. They are much plicated, following the curvatures of
the quartz.
442 PROFESSOR HEDDLE ON
8. G, 4916.
Titanic Acid, : ; ‘ ’ 4 20°6
Silica, ; , P : ; : 1:4
Alumina, . : , ’ : ' 1° 443
Ferric Oxide, : : 5 : ‘ 63 +549
Ferrous Oxide, . : : : . 11°26
Manganous Oxide, . - : : °018
Lime, . : : : : ) ; 1°792
100 : 062
2. Taken from the great amazonstone boulder, from the west side of Ben
Bhreck, Tongue. Occurred very rarely in blue-black plates, between crystals
of the felspar. It was in very small quantity. It was very much more readily
powdered and elutriated than was usual for this mineral. The powder was
reddish or brownish-black,—not blue-black, as is usual.
‘464 grammes yielded—
Titanic Acid, } : : aa 50 * 646
Ferric Oxide, : ; : : 9° 873
Ferrous Oxide, . Z : : : 17° 784
Manganous Oxide, . : : . 5°172
Lime, . 2 ; : : ‘ i Salat
Magnesia, . 5 : ; : : 11 +637
Silica, : ; : i : ‘ Pere
99° 373
This is very much the most highly titaniferous ilmenite which I have
analysed.
3. From the “crocus” veins of the grey granite of Anguston, Aberdeen-
shire. Occurs in thin brown-black plates, up to an inch in length; these lay
between the quartz crystals, and seemed to have been of late deposition. The
sphene, and Allanite which accompanied it in small quantity, were deeper-
seated in the vein, and were quite closely imbedded.
S. G. 4:908.
Titanic Acid, ; : : : : Zorion
Ferric Oxide, ; ; > : : 43 - 064
Ferrous Oxide, . F ‘ : ’ 29-011
Manganous Oxide, ; ; , 2° 341
Lime, , ; , : : ; 1-006
Silica, 2° 066
LOL -.158
When analysed by the “bisulphate process” only 22°88 per cent. of titanic
acid was got; the above analysis was executed by employing Fresenius’s flux.
THE MINERALOGY OF SCOTLAND, 443
4, MACKNIGHT, writing in 1810 of an elevated point of Ben More, says,
“At this station veins appear filled with quartz, and containing also mica,
chlorite, and a valuable variety of iron-glance, crystallised in thin tables”
(Mem. Wernerian Society, vol. i.).
That which I analysed occurs in large foliated crystals about 300 feet below
the summit of Ben More, Perthshire, on a small flat, near a knoll on the north-
east side. It was associated with chlorite, and rarely tourmaline. The colour
is blue-black ; it has a high lustre.
This is without doubt Macknicut’s mineral.
On 1 gramme—
Titanic Acid, 18°4
Ferric Oxide, 55° 305
Ferrous Oxide, 23 * 863
Lime, 1°344
Silica, 2
100: 412
5. From the hill Crois, north-west of Arrochar, Loch Long, Argyllshire ;
also from quartz boulders on the shore at head of Loch Long.
On the hill it occurs in rudely-formed crystals, imbedded in the quartz
veins of chlorite slate, especially in a quartz cliff about half way up the hill.
The colour is black, with but a slight tinge of blue. Powder brown. S.G. 4°86,
On 1 gramme—
Titanic Acid, . , : : 40:4
Ferric Oxide, ; ‘ . : 41° 886
Ferrous Oxide, . ; , 4 ‘ 15-402
‘Manganous Oxide, .. : ; : 2
Line, : ; : 1 456
Silica, .. : wy ee oat |
100 : 044
The ilmenites, iserines, and chromites proved so difficult of decomposition,
that the most extreme perfection of comminution was found to be requisite
before any of the processes of decomposition availed in resolving with certainty
the whole quantity operated on. This, as afterwards to be noticed, was not,
even with that precaution, in all cases accomplished. The following method of
pulverisation was adopted. If it was found necessary—but not otherwise—
the chips, cut up by pliers to fragments of the size of small shot, in order to
separate quartz and other impurities, were crushed, but no more, in a diamond
mortar. They were then transferred to an agate mortar, which held about
three ounces of water. About five grains of the crushed mineral were placed in
the mortar under half an ounce of water, and were rubbed under the water with
the pestle till the powder was impalpable. About two ounces of water were
VOL. XXX. PART II. 3 Z
444 . PROFESSOR HEDDLE ON
then added and rubbed up. The grinding end of the pestle was then washed
clean by a jet of water into the mortar, which in the so doing was now nearly
filled. It was allowed to stand undisturbed for three minutes, when about two
ounces of the muddy liquid was drawn off steadily by a pipette, and allowed
to fall into a large precipitating glass, containing about thirty ounces of dis-
tilled water. This was left undisturbed for ten minutes, when its contents, all
but about two ounces at the bottom, were poured into a second larger preci-
pitating glass. This was again left undisturbed for a quarter of an hour, when
all, but about three ounces, was poured into a capacious glass jar.
The coarser portions at the bottom of all the glasses employed were in turn
returned to the mortar, and the process was continued and repeated, wntil every
- portion of the quantity originally placed in the mortar was floated off, and uni-
formly mixed in the one large settling jar. This was found to be absolutely
necessary in some cases, (¢.g., in the magnetic sands from Granton), as some
portions— either where there might be an admixture of ordinary magnetite, or
some softening through incipient alteration into martite—were found to be
much more readily comminuted than others. Such softer portions were found
to contain less titanium, and more ferric oxide.
The settling was generally complete in three days.
Notwithstanding this extreme amount of subdivision, several of the sub-
stances examined partially resisted decomposition by the ordinary methods of
fusion with Fresenius’s flux,—potassium bisulphate,—and calcium and ammonium
fluorides,—used singly, or even successively.
It was, where possible, found better to operate upon an entirely new
quantity,—comminuting and floating off still more finely,—than to recomminute
the unresolved portion (mixed up with some flux to prevent loss). It was
observed that the quantity which had jist escaped decomposition was more
difficult to resolve even when recomminuted, than it was when fused up along
with a quantity which was undergoing decomposition.
This is an illustration of “ communication of energy,” similar to silver im-
parting, in an alloy with platinum, the power of combination with nitric acid to
the more noble metal.
In several cases of fusion with potassium bisulphate, the separation of the
titanic acid was found to be either slow or incomplete, some of it coming down
at later periods of the analysis. In such cases the following process, somewhat
modified from one recommended in a foreign journal, was adopted.
After fusion with Fresenius’s flux and solution in acidulated water, with
separation of the silicic acid and some titanic acid, ammonium chloride in
strong solution was added, and then ammonia in slight excess.
The precipitate of ferric oxide, alumina, and titanic acid, thus thrown down,
was filtered off, washed, ignited, and weighed. It was then mixed with potas-
THE MINERALOGY OF SCOTLAND. 445
sium bisulphate, and therewith fused. When cold the flux was dissolved in
tartaric acid, made slightly alkaline with ammonia, and the iron separated by
ammonium sulphide.
The alumina and titanic acid, with the filtrate, were evaporated to dryness,
ignited, burned white, and then mixed with concentrated sulphuric acid, in
order to convert the sulphate of potash into bisulphate.
After evaporation to dryness this was again fused; the enamel of the
bisulphate of potash fusion was again dissolved, and it was then treated with
an excess of caustic soda. This holds in solution the alumina completely, and
leaves behind the insoluble titanate of soda.
This titanate of soda was filtered off, ignited, and once more fused with
potassium bisulphate ; from the solution of this, when diluted and boiled, all
the titanic acid settles, although somewhat slowly.
The alumina was separated from its solution in caustic soda by neutralisa-
tion with acid, and reprecipitation by ammonia. The other parts of the process
were those usually adopted. Though, from the number of fusions, very time-
consuming, and though entailing somewhat more loss, this process was found
to yield a slightly larger proportion of titanic acid than do any of the older
processes, except the very tardy one with sulphuric acid ; and the perfect purity
of the titanic acid seemed to be by it more assured. Unless there is abundance
of material to operate on, a bisulphate fusion is however to be preferred, as the
evaporation to dryness of the mass, after the addition of the sulphuric acid, was
sometimes extremely troublesome.
Tserine.
It is singular that, although former writers on Scottish minerals do not
notice ilmenite, they should in several instances have noted the occurrence of
iserine,—sometimes under that name, sometimes as “magnetic iron sand,”
and “black sand.”
As before stated, however, they have sometimes confounded magnetite
with true iserine; and they have also termed crystalline magnetite “ titanic
iron.”
The records which we have of the occurrence of iserine in Scotland are the
following :—-
“ On the bank of the Deveron, below the bridge of Macduff.”
“On the shore of Canna.” .
“Titanic iron with hornblende on Carrick Common, in Roxburgh.”
446 PROFESSOR HEDDLE ON
The fullest account we have, however, is one by THomson (Philosophical
Magazine, vol. xxxv.) of two varieties which he analysed from different parts
of the bed of the Don. The first, he terms “ iron sand,”’—the second, “ iserine.”
“1. Iron sand.—Iron black, magnetic, octahedric, brittle, easily powdered’;
powder greyish-black; S.G. 4765; not acted on by acids; lustre feebly
elimmering.
Protoxide of Iron, . 85°3
Red Oxide of Titanium, . : ; 9°5
Arsenic, . : ‘ 5 : d ; :
Silica, 1
Alumina, 5 ; f 5 ( :
Loss, ; r : ' : ; : 2°7
“2. Tserine.—Iron black to brown, angular grains, larger than iron sand,
lustre semi-metallic, fracture conchoidal, brittle, easily powdered,—powder
iron black ; 8. G. 4:490; scarcely attracted by the magnet.
Titanic Protoxide, . ‘ ‘ : ‘ 41:1
Protoxide of Iron, . 3 ; ; A 39°4
Protoxide of Uranium, : : 3°4
Silica, . ; ; : : : ; 16°8
Alumina, or?
103°9
“ Abstracting impurities—
Titanium Protoxide, ; ‘ ; ; 48°8
Tron Protoxide, : : : 3 : 48-2
Uranium, : F : ; ' P 4°
This statement of the presence of arsenic and wranium in such a compound
induced me to examine “black sands” to a greater extent than I would
otherwise have done. For the great difficulty of separating them at all
satisfactorily from commingled siliceous sands, and the doubt which always
remains as to the presence or absence of ordinary magnetite, made the |
investigation more or less of a drudgery. I did not qualitatively examine
many of these black sands,—(though several quantitatively analysed were so
examined),—but I was quite unable to detect either uranium or arsenic in any ;
though in several I found traces, larger or smaller, of chromium.
I hardly think that any one is in a position to pronounce unhesitatingly
upon the nature of the “iron sands” so frequent upon the shores, and in the
THE MINERALOGY OF SCOTLAND. 447
stream beds of Scotland. Even after having analysed these sands from several
localities, I would not speak with much confidence, unless the sand could be
traced to its rock source. If they lie near to, or on a lower level than an igneous
rock, they probably are titanic ; if the rock, on the other hand, be granitic, or
any of the schistose rocks other than chlorite state, they most probably consist
merely of powdered magnetite. A rock of chlorite schist would yield ilmenite,
rather in fragments, than in powder.
While it would be well-nigh endless to enumerate the localities in which I
have observed “ black sands” of a doubtful nature, I may note my having found
iserine, in fragmentary-looking masses which have taken a cast of the faces of
the contiguous minerals, in two classes of rocks.
First, in a diorite which passes into or assumes the features of syenite; and
secondly, in the denser varieties of the Tertiary doleritic and basaltic traps.
In the first named rock, it occurs in very small amount, in the diorite which
is seen both to the east and to the west of Portsoy.
It is in quite visible particles or patches, in the easterly belt of that rock
at Retannach, associated with labradorite, augite, paulite, and pyrrhotite. It
is seen in fully larger pieces in the giant-crystalled diorite of Glen Bucket.
Its associates here are hornblende, Biotite, sphene, and labradorite. With
much the same associates, it is seen south-east of Tullyjuke, at the head of the
Deskery, and on the north slopes of Morven ;—-the rock here tending more to
syenite, before it shades off into the granite of Cuilbleen. In granite itself,
iserine seems to give place to magnetite ; the titanium finding a lodgment in
the sphenes, which begin to show themselves where diorites shade off into
syenites ;—which are characteristic of syenites ;—and which also affect the in-
termediate gradations of syenites into granites.
The iserine of traps is generally in minute grains. Here, as at localities
near St. Andrews (Kinkell) and Elie, its associates are saponite, sanidine,
olivine, and pyrope.
The largest imbedded particles which I have seen were from the acidic trap
rock—termed “ syenite”—of Ben Grigg, in Mull. These were shapeless, and
in parts rusty brown; they were not half the size of a bean.
Near Tilquilly, and at Badnagauch on the Deskery, in Aberdeenshire, similar-
sized pieces are imbedded in diorite, along with dark green hornblende, labra
dorite, Biotite, Allanite, and sphene.
The difficulty connected with the recognition of iserine may be shown by
stating, that what I myself collected at the mouth of a stream at Sangoe Bay,
Durness, Sutherland, as an iron sand, proved after examination to be totally
non-magnetic, and was probably pulverised black hornblende; and that another
“black sand” sent me by Mr, ALEXANDER CRUICKSHANK of Aberdeen, as iserine
from the parish of New Deer, proved after analysis to be pounded schor/, with
448 PROFESSOR HEDDLE ON
merely a trace of magnetite. In this last case even inspection with the micro-
scope did not suffice to disclose its nature.
Granting that most “black sands” are mixtures of true iserine with mag-
netite, the magnet does not suffice for their separation, for I have found that
the more titaniferous portion is occasionally the more powerfully magnetic of
the two; though this may be the result of a partial change of the magnetite
into martite. With the exception of those from Elie and from St. Andrews,
I regard all the samples analysed by me, as being probably mixtures.
1. Is found in very minute magnetic black grains in the sand of the shore,
a little to the north of the Manse of Hoy, Orkney. A considerable quantity
of black sand may be gathered, very little of which is magnetic. There is no
appearance of the mineral in the flaggy rock of the neighbourhood, and as
igneous rocks lie about a mile to the west, these probably were its matrix.
The magnetic portion yielded—
Titanic Acid, 5 . : : : 18°4
Alumina, . ; ; ; ‘ ; °6
Ferric Oxide, ; . : . : 54:979
Ferrous Oxide, . : F 5 ; 14°422
Lime, . , ; é ‘ : 5°6
Magnesia, . : ; . : ‘ "2
Silica, . ; : : : : : bal
100°301
It appeared as very minute black grains, which differed considerably from
ordinary granular iserine. When examined with the microscope they were
found to consist almost entirely of oval grains with rounded outline. They
shine like little bits of graphite ; have few fractures, which are highly lustrous.
There was very rarely a doubtful outline of a worn octahedron. The non-
magnetic, or very feebly magnetic portion of this black sand, was, under the
microscope, quite similar to the magnetic portion. That portion may have
passed into martite.
2. Was found in very considerable quantity on the surface of a quicksand,
on the west shore of the lake at Sandwood, on the west coast of Sutherland.
The Torridon sandstone forms the south shore of this lake, and the
Hebridian gneiss, the greater part of its northern shore. The black sand
probably came from the last named rock.
THE MINERALOGY OF SCOTLAND. 449
It yielded —
Titanic Acid, : : : ; ‘ 10°6
Alumina, . : : : : ; °072
Ferric Oxide, : ‘ ; ; : 80° 876
Ferrous Oxide, . ‘ = : , 5:961
Manganous Oxide, . : : : "4
Lime, . P : ‘ ‘ : 5 °952
Silica, P : ‘ : ; : ILS
100-361
3. Occurs in imbedded fragmentary or sharp-angled masses, of the size of
peas, in a basaltic dyke which cuts tufa, half a mile east of the Summer House
on Elie Ness.
Colour velvet black, fracture conchoidal, very hard ; associated with olivine,
saponite, and pyrope.
On 1 gramme—
Titanic Acid, F i : 3 : DAL
Ferric Oxide, ‘ : : 5 ; 42673
Ferrous Oxide, . ; ; ; ; 21°894
Manganous Oxide, . 3 : 5 "%
Lime, . : : F : i ‘ 4°48
Magnesia, . . ; ; : : 1-6
Silica, . . p : : : 5 fee
100° 147
4. Was found, along with Professor GEIKIE, in small, brilliant, crystalline,
highly magnetic grains, on the surface of the sand, below the sandstone cliffs
near Ardross Castle, St. Monance, Fifeshire.
On 1 gramme—
Titanic Acid, . . ; : ; : 16.
Ferric Oxide, : : ; : : 43 +743
Ferrous Oxide, . P : F ; 28:01
Manganous Oxide, : : ‘ , “dl
Lime, . : ; : : : ; 4-4
Silica, . : ; : : , ; Tis
99 +253
Under the microscope, showed as a mass of fine grains of a blue-black
colour. Many of these seemed to be regular octahedrons.
5. Is found at the mouth of a:small stream in small quantity, on the surface
450 PROFESSOR HEDDLE ON
of the sand; the stream enters the sea at the south end of the east sands
of St. Andrews. It runs past a trap “agglomerate.” The iserine is in highly
brilliant but minute bluish-black grains, which are strongly magnetic.
1 gramme yielded—
iigdiedcid: » .« ow . ShinQope
29
Ferric Oxide, : ; : ’ ; 22° 867
Ferrous Oxide, . é ; : é 30°98
Manganous Oxide, dh
Lime, . 5*936
Magnesia, : ; ; : al)
Silica, . : F : ‘ 4 t Seal!
100° 363
Under the microscope this showed as a fine-grained sand, the cleavages of
which were not flat. Only one crystal was seen ; it had one face truncated, and
it seemed to be a rhombohedron.
6. Found in 1848, on the shore at Granton, Edinburghshire. It was about
the spot where the west breakwater now leaves the shore. It occurred mixed,
but not largely, with quartz sand. Was well washed therefrom, and then
ultimately separated by the magnet. Two substances were present,—one
granular and hackly, not strongly magnetic ; the other, amounting to about
one twentieth of the bulk, was strongly magnetic, of brilliant lustre, and
apparently in octahedra, or fragments thereof.
The portion analysed was almost totally the jormer of these, there being of
the latter an insufficiency for analysis.
The first analysis was by fusion with potassium bisulphate ; the second by
long continued treatment with sulphuric acid.
i. 2.
Titanic Acid, . ; ‘ . 14°4 GIL
Alumina, , : : te Babe 11°465
Ferric Oxide, . 5 : Sh arse QrAl 39° 285
Manganous Oxide, . : : 6 6
Lime, : ; ; mn OO 7:°896
Magnesia, : : ; ee alt diigeto)
Silica, ; ‘ : » gon 24°
101:°516 100 - 946
7. Found about the year 1850, in large quantities on the sea-shore at
Granton, Mid-Lothian, about a fourth of a mile westward of the breakwater.
It lay, as is usual with these black sands, on the surface, and could be collected
by merely scraping with the hands. It was afterwards separated from sea-sand
THE MINERALOGY OF SCOTLAND. 451
by the magnet. Much the larger proportion of this was decidedly, though none
of it very strongly, magnetic; perhaps a fiftieth was very feebly or almost non-
magnetic. An attempt was made to separate it totally from quartz sand,
by stirring up in water and rapid decantation of the latter, but the separa-
tion was not quite perfect. The most highly magnetic portion of this sand
yielded
On 1 gramme—
Titanic Acid, ; : : : j 19:4
Ferric Oxide, : : . : : 37° 972
Ferrous Oxide, . : : F : 24.°325
Manganous Oxide, °8
Lime, . 3 Z : : ; . 6°5
Silica, . : s : ; , 2 10°8
99 :'797
Examined with the microscope, this portion had a black colour inclining to
blue. It showed many apparently regular octohedra; some of these had
apparently all their six angles truncated by the faces of the cube. Two dis-
torted cubes, like square prisms, were seen also. The truncation of six angles
by square faces would prove this species to be cubic; and the crystals not to be,
as held by some, acute rhombohedra with merely the summit and basal angles
truncated.
8. The non-magnetic portion of the black sand, of which there was a com-
paratively small portion mixed with the more highly magnetic, yielded
On 1 gramme—
Titanic Acid, : : : ; 15
Ferric Oxide, : : : : ; 40°729
Ferrous Oxide, . , ‘ : : 18: 244
Manganous Oxide, . : Ae:
Lime, . : : ‘ F ie
Silica, . : : ; ; ; : Cota |
100°0738
The colour of this portion was rusty brown.
Examined with the microscope, it showed a hackly structure, no crystals
and no cleavages. There was a good deal of non-separable adherent silica.
These two black sands, therefore, though found within a short distance of
each other, and gathered within two years of each other, differed considerably,
both physically and chemically.
9. From the sea-shore, a little east of the mouth of the Almond, Mid-
VOL, XXX. PART Il. 4A
452 PROFESSOR HEDDLE ON
Lothian. It is jet black, strongly magnetic, and appears free from sand or
impurity.
It yielded, on 1 gramme—
Titanic Acid, ; 4 4 : ‘ 1"
Ferric Oxide, é ; : L x 39° 607
Ferrous Oxide, . ; : ' ; 26° 742
Manganous Oxide, : . : 5 "6
Lime, . ; ; 5 : ' 5 6°%
Silica, . ‘ ; ; ‘ : 8:4
100 +049
Being a composition very similar to that of the bu/é of the Granton mineral.
Under the microscope this appeared as a powder of small grains, which were
fragmentary, with cleavages which were not flat, but somewhat hackly. Only
one crystal was seen; this had a truncation, the face of which was an isosceles
triangle. Along with this, there is mixed a very small quantity of non-magnetic
grains, which were much larger than the magnetic. All of these were rounded.
They sometimes much resembled water-worn cassiterite ;—sometimes they were
like worn bits of somewhat rusty iron.
A highly-magnetic blue-black iron sand, of which the individual grains are
for the most part perfect octahedra, occurs on the south shore of Macrahanish
Bay, Cantyre, at a spot called the Geldrens. Though there is much igneous
rock in the neighbourhood, yet this may have come from the gneiss, and be
only magnetite.
MAGNETITE.
This mineral has been several times noted as occurring in Scotland, though
I am not aware that any analysis of Scottish specimens have been anywhere
published.
In glancing over the quoted localities, I find that such as are associated
with rocks of chlorite slate, or of serpentine may be set down as correct; but
several mistakes have been committed regarding granitic localities.
In the Transactions of the Geological Society, vol. ii. 1814, MaccuLLocu
writes— I should scarcely have introduced any remarks on Rona, were it not
for the purpose of mentioning that wolfram, hitherto unnoticed in this spot,
is found in the granite veins that traverse the gneiss of which this island is
principally formed.”
That Hast Rona is here referred to, and not North Rona, as quoted by
GreEG and LeETTSoM, is shown by a reference to Blue Bay.
THE MINERALOGY OF SCOTLAND. 453
In Dr. Maccutiocy’s Western Islands, of date 1819, no mention is made
of wolfram in Rona; his geological remarks on which conclude with “I have
only to add, that tetrahedral grouped crystals of oxidulous iron are not un-
frequent in the granite veins.” GREG and Lerttsom give a figure of hemitrope
octahedrons from the spot.
It was hardly excusable for a man like Dr. MaccuLtocu, whose compass
was constantly picking out the errors of MAckENzIr’s chart, to mistake
magnetite for wolfram. ;
In the Traveller's Guide through Scotland,—written in 1806, by JouNn
Watson, father of the late Dr. Watson Wemyss of Denbrae, Fifeshire, and
which Guide contains a fuller and more accurate account of Scottish minerals
than any work I am acquainted with,—we read—“ It is said that Mr. Raspe
found a specimen of wolfram in Tiree.’ Raspe seems to have had a faculty of
finding everything—everywhere. No one has found wolfram since his time in
Tiree, so that Ais wolfram was probably also magnetite.
A common error seems to be to set down such magnetite as occurs in
granite veins with a faint biuish tarnish, as being “titanic iron.” We find
even JAMESON doing this, in speaking of that which occurs in the granite veins
of Harris. This my analysis below shows to be a magnetite which contains
no trace of titanium.
The largest mass of magnetite I have seen in Scotland was a loose-lying
lump which lay upon Drum-na-Raabm, in the Coolins. It consisted of inter-
locked crystals about the size of peas, and might have weighed forty or more
pounds.
The largest solid lumps were got in blasting graphic-granite at Rispond, in
Sutherland. These were cleavable masses, nearly the size of a fist.
I make no attempt to record the localities in which I have found magnetite
in Scotland; it is of interest, however, to note its occurrence in definite
crystals.
1. Among the cliffs, a little to the west of the houses at Aith, on the south
shore of Feltar, in Shetland, it occurs in yellow precious serpentine, in minute
cubes.
2. It occurs imbedded in massive aphrosiderite at
Pundygeo, near Fethaland, Sutherland, in hemitrope
octahedra, over half an inch in size (fig. 3).
3. In dodecahedra, with faces striated towards
octahedral facettes ; in serpentine, at Vanleep, opposite
the Drongs, at Hillswick, Shetland.
454 PROFESSOR HEDDLE ON
4. In tetrahedral crystals with octahedral modifi-
cations; in graphic granite, at Rispond, in Sutherland.
(fig. 4).
5. In the combination of the octahedron with dodeca-
hedron ; in coarse oligoclase-granite, in the cliffs near
Caligaig (fig. 5).
6. In twin éetra-octahedrons, in a syenite boulder
near Tongue (fig. 6). With amazon stone, ilmenite, &c.
Octahedral crystals also occur here.
7. In flattened octahedra, in the great granite veins
of Roneval, in Harris.
The form is as figured—o. Figure 70 is the
simplest form of ilmenite ; these are drawn in natural
position (figs. 7 and 8).
The similarity of these, when the ilmenite crystal
is placed in vertical position, quite excuses JAMESON
setting this magnetite down as being ilmenite. But o
on 7=122°30’, and 7 on 7’=86°10' (fig. 8);
while 0 on 0o’=109°28’, and o’ on o”=
109°28’, (fig. 7).
8. In granite, with dolomite and pale-
green fibrous hornblende, in the Sally-
villy Quarry, near Alford, Aberdeenshire, in twin tetra-octahedra, somewhat
like fig. 6.
9. In chlorite slate, at several spots on the shores of Loch Fyne, in minute
octahedra.
1. Is found imbedded in minutely foliated chlorite at Pundygeo, Fethaland,
Shetland. It occurs in simple and also in hemistrope crystals, up to one inch:
in size.
Its colour is jet black, its lustre brilliant ; the powder is blue-black. It is
very difficult to reduce it to powder, even under water.
THE MINERALOGY OF SCOTLAND. 455
The crystals are somewhat penetrated by the chlorite, and so yield some
_ foreign matter. .
On 1° gramme—
Ferric Oxide, .. ; ; P ‘ 65-617
Ferrous Oxide, . ; : 32166
Manganous Oxide, ; : 5
Silica, 2 : ; : : : ach
Alumina, ; ; 393
Lime, . F : ; $ : , ey
Maenesia, . ; : ; d : * 684
100° 184
2. This was taken from the ‘“ Great Boulder” at Tongue. It is in im-
bedded nodules, and rarely in octahedral crystals. The nodules are the size of
peas and beans, of a jet or blue-black colour, and a high lustre. The powder
is reddish-brown, and strongly magnetic.
1* gramme gave—
Ferric Oxide, 5 83 ' 482
Ferrous Oxide, . ; ; ; 12°632 12°7—12:°564
Manganous Oxide, pe?
Silica, . 2
Alumina, "233
Lime, . * 896
Magnesia, a)
100° 148
This magnetite contained minute specks of malleable metallic tron, in the
centres of some of the crystals or nodules.
3. Occurs in imbedded cleavable lumps, from the size of walnuts to that of
the fist ; in the graphic granite of Rispond. The colour is blue-black, and the
powder brownish. S. G. 5°15.
It yielded on 1° gramme—
HesOr, ‘ , : : ; 63° 186
FeO, . : 4 ; : : : 29 * 586
MnO, . : : ee “4
CaO, ; ; : A 1: 624
MgO, . ; ; ; 1-1
Silica, 379
99 - 796
Magnetite is here rarely seen in flattened octahedral crystals.
456 PROFESSOR HEDDLE ON
4. Occurs in imbedded patches, and rarely in dodecahedral crystals, in the
granitic belts of the gneiss, on the cliffy shore opposite to the island of Koil-
skeer, in the north of Sutherland. The colour is somewhat of a brownish-
black, the lustre rather dull.
It yielded—
Ferric Oxide, : : ; : ; 89 * 632
Ferrous Oxide (Fe. 3:208 —3°389), av. 4°241
Manganous Oxide, . : - : 3
Lime, : : : : : ; 2° 688
Magnesia, . : : : . : a)
Silica, : ; , 3 : ; 1:9
Titanic Acid, : : : F : 45)
100 +161
There is here a marked passage into martite; but the specimen analysed
was taken from a stone in a wall, and may have suffered from long exposure.
5. Was taken from the great granite veins in the east foot of Roneval,
Harris. It is found, along with Haughtonite, in imbedded plates, which are
rough flattened octahedrons.
These are sometimes an inch or more in size.
Their colour is blue-black; the colour of the powder is the same. S. G. 5°154.
It yielded on 1+ gramme—
Ferric Oxide, ' : : ; : 68: 095
Ferrous Oxide, . : ; : ; 29: 014
Manganous Oxide, : ™5
Alumina, . : : : ; : -615
Lime, . A ‘ : 3 , : 168
Magnesia, . : ; :; : : 6
Silica, ; , ; 5 : : is
100 «002
There was possibly a slight admixture of Haughtonite, but none was visible.
Chromiferous Magnetites.
I have stated above that I found several of the “ magnetic iron sands” to
contain traces of chromium.
Where these sands may have been extracted from a serpentinic rock, or
from diorite, this may fairly enough be assigned to a small admixture of
chromite. Dr. WoLuasTon states that the metallic specks which occur in the
THE MINERALOGY OF SCOTLAND. 457
serpentine of Portsoy are chromite; and very probably there is an admixture of
that substance with magnetite.
The substances, the analyses of which follow, cannot however be regarded
as mere mixtures,
1, A black iron sand was found somewhat sparingly by Mr. DupGEon and
myself among the ordinary siliceous sands of the Dale Burn, in Unst, Shetland.
The locality was at the point where the burn turns abruptly to the northward.
This sand was of a blue-black colour, decidedly but not strongly magnetic ;
under the microscope it seemed much split or cleaved; of a hackly fracture,
and it showed no crystalline forms.
It was, so far as the small quantity obtained arated, separated from
siliceous and non-magnetic sand by repeated stirring up in water and decanta-
tion, and ultimately by the magnet.
When magnified it appeared to be, with the exception of a small admixture
of siliceous grains, uniform.
On an analysis it afforded—
1 2.
Ferric Oxide, ; : 57° 285 62 - 464
Chromium Sesquioxide, 9°4 10+ 25
Ferrous Oxide, . ; 24:944 27:°199
Manganous Oxide, , "4 '436
Lime, ; hae ey Pos
Silica, . ‘ ‘ : fae
100 - 349 100 * 349
2. Gives the proportion, after abstracting the silica and lime, as these are
undoubtedly present from mere mechanical admixture.
The question is, can this be an admiature of magnetite with chromite ?
No one point connected with it favours such a view. Its geographical and
geological position does not ;—it is found about two miles from the nearest
chromite, with more than one hill ridge between ; its altitude is greater than
that of the chromite, and the stream which sweeps it towards the sea, flows
from a hill of mica schist.
It was physically purified by the magnet, which readily abstracted it from
the siliceous admixture. Chromite is, at most, and that only rarely, feebly
magnetic.
Its powder had a uniform blue-black colour; the crushed powder of
chromite is brown.
Lastly, an admixture of chromite with magnetite would not yield the per-
centages above given. The results of the analysis point rather to a replacement
458 PROFESSOR HEDDLE ON
of ferric oxide by chromic oxide, though it is not altogether accordant with
that.
3. A “black magnetic sand” was noted as occurring on the shores of the
Loch of Trista, by Dr. Fiemine (£d. Phil. Jour., vol. iv. p. 114). He says
that it “occurs along with iron sand, imbedded in small grains, in the primitive
limestone in the neighbourhood. Small crystals of sphene occur along with
the iron sand imbedded in the limestone.”
It is found both on the north and south shores of the lake ina granitic sand;
in this it occurs to the amount of about one hundredth part of the whole.
The Rey. Davin WEBSTER writes the author that it probably was derived
from a valley to the north-west, called the Dullans, from whence a stream runs
into the lake. The high state of the lake prevented the author from obtaining
more than a trifling quantity of the sand; and he is indebted to Mr. WEBSTER
for the supply which he examined and analysed.
Mr. WesstTeER holds the view that the sand is derived from masses of bog
iron ore which sprinkle the surface in profusion, at the Dullans ; these masses,
however, when examined by the writer, yielded none of the sand; and even
eranting that they had done so, it could only have been caught up from the
surface during the formation of a substance now recognised universally as an
outcome of organic change.
Mr. WEBSTER also sent the writer a very similar sand from the sea-shore on
the east side of Trista Voe.
The sand from the Loch of Trista presents an appearance under the micro-
scope which is different from that of any magnetic or “ black iron sand” which
I have examined. Among the grains there occur a few well-defined, and very
slightly abraded octahedral crystals, evidently of the regular system ; they are,
as is the rest of the sand, jet black and lustrous. The great bulk of the sand
is composed of rounded grains, which have at first sight a vitrified appearance ;
but this is due to their surfaces being pitted with a multitude of minute conchoidal
fractures, doubtless from repeated collision in the surf of the lake ; their frac-
ture therefore is conchoidal, and the lustre is extremely high. Many of the
grains still retain adherent transparent quartz, whence I assign their matrix to
the gneissic rock.
Excepting the octahedral crystals, the appearance of the grains is uniform;
there is no admixture ; the proportional quantity of crystals is very small.
The sand had been originally separated from the granitic granules by the
magnet, and the process was repeated several times to free it from quartz ; it
did not appear, however, that there was, as is frequently the case with mag-
netic sands, a more- and a less-strongly magnetic portion.
Mr. Wesster, from observations on - spot, came to the same conclusion.
THE MINERALOGY OF SCOTLAND. 459
Notwithstanding the adherent quartz, I have no reason to doubt the con-
clusions of so excellent an observer as FLEMING, and therefore regard the
occurrence of this ore in limestone as most interesting.
Ilmenite I know to occur in some of the primitive limestones of Aberdeen,
along with sphene.
The powder of this sand was black, with a slight tinge of brown.
Its analysis yielded—
Ferric Acid, 5 : : : : 56 * 692
Sesquioxide of Chromium, . : ; 07253
Ferrous Oxide, .-.. : ; ; 15 -548
Manganous Oxide, . . : ; "6
Lime, . : : - : : : 1-288
Magnesia, . : ; , - “ 3°9
Silica, F . ; ’ : : 5:1
100 ° 658
There was no titanic acid. ;
The above, however, does not represent the total amount of the ferrous
oxide.
‘It was found that the ordinarily elutriated mineral could not be decomposed
by potassium fluoride and chlorhydric:acid, for the determination of what
amount of the iron was in the /ferrous state. It was therefore attacked by
calcium fluoride and chlorhydric acid, after having been again elutriated twice,—
thrice,—and lastly, that portion only which was held in suspension in water for
three days was used.
Quantities separately operated on as above gave respectively 15°026,
15°38, 15°548 per cent. of ferrous oxide. In every case, however, a quantity
of brown powder remained undecomposed ; the amount, even in the last case,
was found to be as much as 37 82 per cent. of the whole quantity taken.
As elutriation, and our processes for decomposing minerals for the estima-
tion of the ferrous oxide, can go no further, I must for the present rest, with the
admission that the above probably does not correctly represent the composition
of the mineral, so far as the state of the oxidation of the iron is concerned.
From the nearly constant quantity decomposed by the hydrofluoric and
hydrochloric acids, it would appear as if two substances were mixed in this
sand; but the microscopic appearances in no particular countenance such a view.
Dr. FLEMING, however, it should be stated, regarded it as “iserine, mixed with
iron sand” (? magnetite).
Although the above analysis, and that of the Unst sand now introduces
for the first time a magnetic chromium-ore as British, such a compound has
been before noticed.
VOL. XXX. PART Il. 4B
460 PROFESSOR HEDDLE ON
GARRETT, in his examination of the American ores, found a magnetic and
a non-magnetic “ chrome sand.”
In his formulation of these he makes the
Non-magnetic, . : : Fe Cr, 89 : 42., Fe Fe, 6 * 26,
The Magnetic, ; : ; Fe Cr, Gi" 07a), Be Fe, 38 * 64,
The imperfect determination of the state of oxidation of the iron prevents
the Shetland sands being tabulated in the same manner as yet. They are
evidently much poorer in chromium.
All these analyses show that although the richest chrome ores are non-
magnetic, valuable magnetic varieties, which may be said to shade off into
chromiferous magnetites, exist ; and large deposits of magnetic iron sands should
be examined, in the hope that they may prove to be more or less rich in
chromium. Should that metal be found to be a constituent of the sand, it
would be of greater advantage to the manufacturer or extractor, that the same
should prove to be @ mixture; as ordinary chromite, however intractible, is
markedly less so than this substance (which is apparently a compound) has
proved to be. .
CHROMITE.
- 1. From the large quarry at Hagdale, Unst, Shetland. The sample taken
was a very crystalline mass, almost in isolated octahedra; the crystals were
separated from one another by flakes of foliated pennite. After careful pick-
ing, small grains of translucent quartz were still visible, though none could be
seen in the uncrushed mineral.
It was associated rarely with emerald nickel, and contained imbedded specks
of a bronzy mineral which resembled Pentlandite. Other associates are tale,
aragonite, and Kammererite.
On 1:001 grammes—
Silica, d 7 ; 5 ; 4. Fol
From Alumina, : : ‘ °04
Sibi
Protoxide of Iron, : : : : 17° Sls 19° 465
Protoxide of Manganese, . . . *499
Sesquioxide of Chromium, . ; : 44°555
Lime, . . ; ; ; : ; 1° 286
Alumina, . : : ‘ ; ; 23,741
Silica, ; . : . , ; 11-088
98 * 688
THE MINERALOGY OF SCOTLAND. 461
The absence of magnesia from this sample is peculiar ; as I found that some
well-defined octahedral crystals from a -vein near Buness House contained
nearly half as much magnesia as chromium ;—showing chromite to be a true
spinel.
2. The substance now noticed was found by me in a single specimen near
the summit, on the north-west front of the precipitous hill of Haiskeval, in
Rum. Before analysis I conceived it to be martite. It occurred as a vein of
about one quarter of an inch in thickness, imbedded in a granular brown belt
of rock, in augitic trap; this belt was apparently chiefly altered olivine. The
mineral was granular in structure, jet black in colour, highly lustrous, very hard,
not magnetic, and had a S. G.=4'163. It was evidently a uniform substance.
It was first fused with Fresenius’s flux; but, as a small quantity of a fawn-
coloured powder remained undissolved, a second quantity was fused with
potassium bisulphate and nitre. No titanic acid being found, the insoluble
powder of the first fusion was fused with the last-named salts, and found to
contain chromium.
It was found that the mineral could not be decomposed by any of the pro-
cesses usually employed for the ferrous oxide determination; so that the iron
is merely conjectured to be in the ferrous state. The whole available quantity
was employed in the analysis.
The insoluble precipitate of the first analysis was insoluble in hydrochloric
acid. It was not weighed, but was re-fused, and the ferric oxide and chromium
sesquioxide separated, and added to the results of the soluble portion of that
analysis. The quantity of this insoluble precipitate was too minute to give any
countenance to the view that the total amount of chromium can be assigned to
an admixture of chromite with magnetite.
As a large excess was obtained in the first analysis by Fresenius’s flux,
the mineral was analysed a second time by fusion with potassium bisulphate,
but with a very similar result.
The first analysis was by means of Fresenius flux, operating on ‘43 grains ;
the second by potassium bisulphate, on ‘93 grammes—
Chromium Sesquioxide, . : : 26 + 304 26° 343
Alumina, : : , F 17° 957 18-279
Ferrous Oxide, 5 : ; 5 384: 239 34°112
Manganous Oxide, . : : : 869 752
Lime, . : ; ‘ ; : 6°573 6 + 382
Magnesia, ; ‘ : ‘ 13 * 913 14 - 086
Silica, . j 4 : ; : 6° 543 6° 236
106-398 106:191
Even if the chromium be tabulated as protoxide, there still would be an
excess of over 2 per cent.
462 PROFESSOR HEDDLE ON
This unsatisfactory result, or sum total, leaves it much to be desired that
the mineral should be re-examined ; the more especially as the occurrence of
ghromite in augitic trap is altogether new.
TURGITE.
Found in isolated imbedded cubic crystals, in oar -slate, in the island of
Kerrera; and also to the east of Oban, These crystals have invariably a hollow
in their centre ; they are red-brown, and stain the skin of the same colour.
They yielded— .
S. G, 3°534,
Ferric Oxide; ..- °. F ' , 86 * 585
Lime, : : ae ; ; *818
Water, : ‘ 3 : z ‘ 5° 559
Silica, ome ts : : : ; 7° 692
100° 654
As unaltered pyrite occurs in the same rock in the vicinity of these crystals,
they undoubtedly have resulted from the alteration of that mineral ; and this
may be regarded as a pseudo-pyrite.
GOTHITE.
1. Occurs in fibrous reniform masses, the fibres being about an inch and a
half in length, in veins in the cliffs of the gorge of the Burn of the Sail, in the
Bring, Hoy, Orkney. |
Its colour is chocolate-brown, sometimes banded with oe belts ; its
fibres are very minute ; it is quite similar in appearance, and colour of powder,
to limonite, but is somewhat harder. 8S. G. 4°13.. .
‘Ferrie Oxide," § ~.. ° 25 #) gas
Ferrous Oxide, . ; ‘ poh be ° 054
‘Manganous Oxide, : ' “ae
“Maming,"\\S.. ; ; : ‘ 1° 295
Lime, . : ; , : : : 1° 324
Water, A katie ’ f ; 10 * 863
Silica, ars ; : : oe
100 +031
The greater part of the silica was insoluble in acid.
THE MINERALOGY OF SCOTLAND. 463
Minute highly lustrous crystals of this mineral also spangle in the druses of
a massive granular hematite, which is found at the same spot.
2. In the Traveller’s Guide through Scotland we read :—“ Beautiful speci-
mens of radiated hematites are found in the quarry near Holyrood House.
These are intermixed with steatites, green fibrous iron ore, and calcareous spar,
forming a very uncommon mass.
“ Veins of calcareous spar beautifully stripped (szc), also lac-lune, zeolite,
and amethystine quartz crystals, are met with in many places.”
These specimens from the Salisbury Crags occurred in fine plumose radiated
crystals, of a high lustre, and deep brown colour,
Specific gravity 4° 146. +. 2. 2 +2py 0
+f jn(n— \(m=2)(n—B)ae*+ 2 a... eee ee ea
Or, re-arranging the terms according to their dimensions,
dia Un py, Wot LN 2 yy He
af at ry es heli ty
get US a EO DE nae a )
+psja = ray ne aT q “yt. j
A= hn =3
_ ea aaa ty Sos i OS
The directions of the infinite branches, 7 in number, are given by the terms
of highest dimensions ; and equating these to zero, we have
a w-n—1 n.n—1.n—2.n—3 ,-4.4
i gee cee
ay? + — rim Gor Pt 4 ag A EO.
472 THOMAS BOND SPRAGUE ON THE CURVES WHOSE INTERSECTIONS
Now since
m.M—1 noo 2.n—1.n—2.
(a+ iy)*=a" + nia 'y ——5 2" scaling ih i
m.N—1 no 9
(a—ty)*=2" — nia "y——5— 2" y+ .
we see that the above equation is equivalent to (a + iy)" + (a —ty)"=0
If we put x=7 cos 6 and y=7 sin 6, this becomes
r{(cos 0+7 sin 0)”+(cos @—7 sin #)"}=0,
or 27" cos nO=0. Hence for the infinite branches we have cos n6=0, or
pa 3 5 2n—-1
17) Fe taps Spel Prey UPA A IS sate ego li}
a7 30 On 2n—1
and O=F, 5 on? On 5 Gib S Se T.
This shows that there are » real asymptotes, the directions of which are
arranged at equal intervals through the first two quadrants. Also since the
equation
oe Wn alley Soon ails n—1. M—2.N—3 4.4 =,
Ca ag Des gy >a is
is satisfied by x=y cot5_,y cot 5 27, &e., the first member of it must be iden-
om 2n
tical with the prods
(2 y cot 3 )(x—y y cot 3 creda _(@ x—y cot” 1
Having thus determined the direction of the asymptotes, we have next to find
where they cut the a-axis. Take the asymptote for which 0=(27—1)z :2n;
then, observing that the equation to P may be put in the form
(0+ iy) + (ei) tr (wy +(e)"
+pj{(atiyy? +(e) *}+ .... =0,
and that «—y cot 2” = Tis a factor of the first term, we have
“a—y cot ats T
—1 2n bee
“—-y Cob at eee pay Lena S(a + ty)" + (a —ty)""}
GIVE THE IMAGINARY ROOTS OF AN ALGEBRAIC EQUATION. 473
a—y cot — en
+ pe (c+1y)” +(“e@—w)” (x+ty)"? + (a —iy)"t
EAT det ‘iyi: —Oetike a b4ches. eter tspanon)
é : on —
If in the term multiplied by p, we substitute y cot Es a for x, and neglect
the following terms, which vanish when « and y are infinite, we shall obtain
the equation to the asymptote. On making this substitution, the fraction,
2r—1
“—y cot 5
Tv
0
Gtyy tea? takes the form 7:
Differentiating both numerator and denominator with respect to x, the value of
the fraction is the same as that of
1
n(e+iy)""*+n(a—ty)"*
and the term multiplied by p, therefore becomes # sand the equation to the
asymptote is
x“x—y cot n+ f=0.
The intercept of the asymptote on the «z-axis is therefore —p,:n, or is the
same for all the asymptotes, which therefore all intersect the x-axis in the
same point. This result might have been at once obtained by observing that,
if we increase the roots of the original equation f(z)=0 by the same quantity
pr: n, or transfer the origin of co-ordinates for that distance to the left, the
term p,x"' disappears from the equation.
We have next to determine the asymptotes of Q. Expanding the equation
(Q), we get
na" * + (n—1)pya"? + (1 — 2) psa” P+ FDad
arare (nm —1)(n—2)a"~* + (x —1)(n—2)(n—3) pa" 4+ 2...
+0Nn (n—1)(n—2)(n—B)(n— Ha. bo . . . =,
n.nm—1.n—2.n—3.n—4 n-
y+ ‘ a” a
or ae i Na
5!
+ ps} (n— Tar? B12 Santee Spite
3!
APe Mase ra. ake ph oO,
474 THOMAS BOND SPRAGUE ON THE CURVES WHOSE INTERSECTIONS
or (x + 2)" —(e— ty)" +p, (w+ ty)" —(2@— wy)
+p, (a+ wy ?—(x—iyy "+ .... =0.
The directions of the asymptotes are given by (x +7%y)"—(x—iy)"=0, and put-
ting «=r cos 0, y=r sin 0, this leads to 7” sin n0=0,
whence nMO=0, a7, 27, ... n(M—l er,
eer) as 20 3a n—1
and ss Rate
VW vi) Td W
The first of these values corresponds to the x-axis, which is not an asymptote,
but is part of the locus of the equation sin (vz,) f(x)=0; and the other values
show us that the »—1 asymptotes of Q are all real, and that their directions
bisect the angles between the directions of the asymptotes of P. It may be
proved, as in the case of P, that all the asymptotes pass through the same
point on the x-axis at a distance —p,:n from the origin, so that the m asymp-
totes of P and the »—1 asymptotes of @ all meet in a point, and midway
between each adjacent two of the former lies one of the latter.
We will next examine whether the infinite branches lie above or below the
asymptotes. For this purpose we resume the equation (A), (see p. 473), and
expand w in a series proceeding by negative powers of y. It will, however,
simplify the process very much if we transfer the origin to the point of inter-
section of the asymptotes, or, what comes to the same a put p,=0, which
may be done without any loss of generality. Putting ee ii 9, 7=a, equation
(A) becomes
a=y cot a—_~_4 Pane poi(atiyy?+(e—-wy r+...
(e+ iy)" +(@—iy)"
Our first approximation to the value of a is x=y cot a, and we shall get a
second approximation by putting this value of 2 in the term involving p,.
Making this substitution, we get
ps
= arp {(cos a+7 sin a)"~’+ (cos a—7 sin a)"~*}
(a+ ty)" +(a—w)"”
| Sat
= = 3, C08 (n—2)a.
Also we have seen that, when we make the same substitution,
w—y ch _ becomes = : einaeit
(2+iy)"+(e—w)" ” = nab iyy + n(a—iyyr 2ny"—! cos (n—1)a
GIVE THE IMAGINARY ROOTS OF AN ALGEBRAIC EQUATION. 475
Hence we have approximately
Po Sin @ cos (n—2)a
ny cos (n—1)a
xZ=y cot a—
Now since the roots of f(x) =0 are all real and p,=0, we know from the theory
F : ks or — ;
of equations that p, is negative. And since a= ts and is therefore -+ ++ 9,73 and when the
GIVE THE IMAGINARY ROOTS OF AN ALGEBRAIC EQUATION. 477
point R moves off to an infinite distance, all the angles RAX, RBX ....
become equal, and their sum will be 7 : 2 for the first asymptote, 37:2 for the
second, 57:2 for the third, and so on, being equal to the sums of the angles
when R approaches A, B,C... . respectively. We have thus proved that.a
branch proceeds from A to the first asymptote, another from B to the second
asymptote, and so on; but it may be still more conclusively demonstrated as
follows.
We have seen that the x-axis cuts the curve (P) in ” real points, and that
a line parallel to it at an infinite distance also cuts the curve in 7 real points,
being coincident with the points in which it cuts the asymptotes; and I will
now prove that any line parallel to the x-axis cuts the curve in 2 points. Sup-
pose y to have the fixed value &, and x to receive all values from + to —o ;
; k . . 7
then as « decreases from + to a, tan~’ —— continually increases from 0 to = ;
and as x continues to decrease to —o#, the angle similarly increases from
a:2 to 7. 3 = eet th: 5 a, we get for each, one
decreases from +0 to—o, tan
value of x; or in other words, whatever value & we assign to y, there are n
real values of x which satisfy the equation (P). It is easily seen that if, instead
: k : : :
of supposing tan, to increase from 0 to 7, we suppose it to increase from
a to 27, or from 27 to 3a, &c., and if we make the like suppositions with
regard to the other angles, we shall always get the same values of x if we
take in each case the proper value of oc.
Similarly for the curve Q, the equations (B) and (C) (see p. 436) show that
sin (vez) f(@)=0, leads to sin (a+ B+ ....+A)=0,0ra+B+.... =m7,
where m is an integer ; or c=7, 27, 37. . . . (w—1)a7. Now we know that Q
cuts the «-axis in (n—1) points, one of which lies between A and B, another
between B and C, and so on; and reasoning as above we see that when R
moves up to the first of these points, o becomes equal to 7; for the second, 27;
and so on. Also the asymptotes are inclined to the z-axis at angles = F ;
3 — é ! ;
pape Si et a; and when R moves to infinity along the first asymptote, each
nN N ;
of the angles a, 8, y . . . . becomes equal to 7:n, and their sum is 7; for the
478 THOMAS BOND SPRAGUE ON THE CURVES WHOSE INTERSECTIONS
second asymptote, the sum is 27; and so on. Lastly, if we suppose y to have
the fixed value 4, and assign to o the values, 7, 27, 37... ., we get (n—1)
values of x ; and since the values of o lie singly between two adjacent values of
o for the curve P, we see that the »—1 points in which the straight line y=A,
cuts the curve Q, lie singly between the » points in which it cuts P. Thus the
proposition enunciated at the outset is completely established.
When the roots of f(«)=0 are not all real, the equations (P) and (Q) still
admit of a simple geometrical interpretation. Suppose there is a pair of
imaginary roots f+ig, f—7g; then the corresponding factors in f(x + 7) become
Bath —ig +1y)(x—f+ ig +iy)=R,R,(cos w +7 sin p)(cos vy +7 sin v)
=R,R,{cos (u+v)+7 sin (u+v)}
if Ri=(«@—f)+(y—g), Ri=(x@—fy+(y +g)’, tan pait tan polit,
It is easy to see from this that cos (us;) J (a) =0 leads to
a ot Be a esl -1Yt9 aye
tan "pg t ban aoe : . +tan oe . pray Da Sy tm.
In fig. 19, let R. be the point. (2, y), OA=a, OB=5,.... OF=f,
RS=RT=g; then the equation expresses that the sum of the angles RAX,,
BB Xtras st Siw LER Se is is equal to = , or on, or 3m, &c.; or the
curve P is the locus of a point for which this is the case. Similarly the curve
Q is the locus of a point for which the sum of the angles is z, 27, 37,....
Whether the roots of f(~)=0 are real or imaginary, the asymptotes of P and
n—1 asymptotes of Q, are all real; but when some or all of the roots are
imaginary, our demonstration that the infinite branches lie below the asymp-
totes, no longer applies ; for p, may then be either positive or negative.
In conclusion, it may be useful to give a few examples of the actual forms —
of the curves. .
. First, we will take a case where all the roots are real
at — 25a? + 60a—36 =(«—1)(x—2)(x2—3)(a +6) =0.
Then the equations to the two curves are
oy —6a'y? +a*+25(y’—a’)+60x—36=0 . . . . (P)
2y°x — 2a? + 25%—30=0 pele ei ers Te (2)
and the curves assume the shape shown in fig. 20, where the thin branches
belong to P and'the thick belong to Q. Consistently with what has gone before,
P and Q do not intersect, but a branch of Q lies between each adjacent two.
branches of P; and, the equation being of the fourth degree, P has four asymp-
GIVE THE IMAGINARY ROOTS OF AN ALGEBRAIC EQUATION. 479
totes and Q has three, which all pass through the origin, and are arranged at
equal angles around it as already explained.
Next take an equation with all its roots imaginary, say 1+/—1,
—1+,/—2, so that f(«)=(e°—2v+2)(v’+2xv+3) and the equation is
+a? —20+6=0.
Then the equations to the two curves are
y—6ey +a*—-y +a°—224+6=0 . . . . (P)
2y°x —20? —x+1=0 9 shai, hie inGQ)
and the curves intersect in four points, as shown in fig. 21,
When the four roots are all imaginary, the curves may be arranged?in a
widely different way from that here shown, Thus, if the roots are 1+4,/—1,
—1+8,/—1, so that
a+ 78x? — 96x02 +1105=0
the equations to the two curves may be put in the form
y? =a? + 89+ /8x'+ 1562+ 9674416 . . . . (P)
24
y =e +39—— vase $a2 (Q)
and the curves will lie as shown in fig. 22. They still intersect in four points,
but the branches of the P curve now touch the asymptotes (1, 4), (2, 3), instead
of (1, 2), (3, 4), as in fig. 21. It follows that there will be a transition position,
in which the branches will touch the asymptotes (1, 3), (2, 4), and will cross, so
that the curve P will have two double points.
Lastly, take an equation with two real and two imaginary roots, say
1+,/—1,2,—4, so that «*—1027+20%2—16=0. Then the equations to the
two curves become
yf =38e? —5 + J/8a*—2027—20a+41.. . . (P)
5
a)
y =x? —5+— Sts» (OY,
In this case the curves intersect in two points, as shown in fig. 23. Here the
real part of the imaginary roots lies between the two real roots; let us there-
fore take another instance in which this is not the case. Thus let the roots be
2+,/—1, —1, —3, so that «*—8v’+8x%+15=0. Then the equations to the
two curves are
y= 30? —4& /8a'—160"—8e+1 . . (P)
ypod—44— Fee Mees)
VOL. XXX. PART II. 45
480 THOMAS BOND SPRAGUE ON CERTAIN CURVES.
and the curves intersect in two points, as shown in fig. 24. Comparing this
with fig. 23, we see that, whereas the infinite branches of P then touched the
asymptotes (1, —4), (2, 3), (4, —1), (—2, —83), they now touch the asymptotes
(1,, 2). (3. — ola e 1) (—3, —4). It follows that there must be a transi-
tion position in which the branches touch the asymptotes (1, 3), (2, —1),
(4, —1), (2, —3), so that P has two double points.
If we now examine the relations of the P and Q curves in figs. 20-24, we
see that they satisfy the conditions laid down at the outset, bearing in mind
that the x-axis must in each case be considered, for this purpose, a part of the
Q curve.
Since the foregoing was written I have met with some remarks of the late
Professor DE MorGan on the curves P and Q, contained in a paper of his read
before the Cambridge Philosophical Society on 7th December 1857. He
remarks that these curves “are such that two branches, one of each curve,
“ cannot inclose a space.” ‘This is a particular case of the properties investi-
gated in the early part of this paper. He also remarks that the curves “ always
“ intersect orthogonally,” but he gives no proof of this. It may be proved
as follows.
Let h, k, be the co-ordinates of a point of intersection of P and Q, and 8, 6’,
the angles which the tangents to P and Q at the point, respectively make with
the z-axis. If ¢(xy)=0 is the equation to a curve, then for any point (a, y),
oY ~$+o. Applying this formula to (P) and (Q) (p. 430) we have
PW -SPW) + EL
tan 0= : st gaps
- ae
hf"(h)—s Sh) + ates
en LO aET OF ETO
a aaeae =
aa h )— yt h) —
Hence pithy “2 yny ae f(hy—
tan @ tan = Bia : Ws =
LIF Phy .
and S@Z7"@)+ Sy)
tan 6 tan +1= eae in
sf (h)— =i Ul 1) + om
and the numerator of this fraction = 0, since h, /, satisfy the equation (Q).
Hence tan # tan #’= —1, or the tangents are at right angles to each other.
VOLXKK. Plate XXIV,
,
iS
2 Sn
(9 48d)
XX.—On the Anatomy and Histology of Pleurocheta Moseleyi. By F. E.
BEDDARD, B.A, New College, Oxford. (Plates XXV. to X XVII.)
(Read 17th April 1882.)
Two specimens of the worm which forms the subject of this memoir were
brought to Professor MosELEy, in 1872, by a coolie trained for the purposes of
collecting by Dr. Tawairss, F.R.S., the distinguished curator of the Peradeniya
Gardens at Kandy ; each was found at the bottom of a deep burrow, in com-
pany with a single ege-case, in the neighbourhood of that town. Professor
MosELEY entrusted me with them for study and description, and I have to thank
him for much valuable assistance during the course of my work, which was
carried on in the Oxford Natural History Museum.
This earthworm in external characters presents some resemblance .to
Pericheta leucocycla of ScHMARDA,* and my friend Mr. W. Hatcuett JAcKson
informs me that its colour when it first arrived from Ceylon agreed perfectly
with ScHMARDA’s description of P. leuwcocycla, the white line on each segment
being very noticeable. But its organisation differs to so marked an extent
from all the other Perichetous worms which have been hitherto studied, that
I am unable to regard it as really belonging to this group; and, moreover,
ScHMARDA’S description, except in the matter of the colour, does not in the
least apply to the species I have studied. His species has no clitellum,
and consists of 88 segments, each segment being provided with a continuous
ring of setz; in my species there is a distinct clitellum present, and the
number of segments is 260, each provided with about 140 sete not arranged
in a continuous ring, but failmg on the dorsal and on the ventral median line.
Furthermore, the shape of the sete differs in the two species ; in SCHMARDA’S
worm the more swollen part is in the centre, while in the species which forms
the subject of this memoir the more swollen part is in the upper third of the
seta (cf. figure given by ScHMARDA with Plate XXVI. fig. 13).
The description given by TEmprLeTont of Megascolexr coeruleus agrees rather
more closely with the worm I am about to describe, but differs in many
important particulars ; in Megascolex the circle of setz is not continuous, there
being left a dorsa) area on which no setz are developed. ‘This description of
* Soumarpa, Neue wirbellose Thiere.
+ Proceedings of the Zoological Society, 1844, pp. 89, 90.
VOL. XXX. PART Ii. 4F
482 MR. F. E. BEDDARD ON THE
TEMPLETON’ is entirely misunderstood by ScHMARDA,* who makes him respon-
sible for the statement that only a dorsal row of setz is present, and LEON
VAILLANT, in a workt which will be alluded to at greater length presently,
falls apparently into the same error. In my annelid there is in addition a
ventral area on which no setz are developed, and this is rather more marked
than the dorsal area, from the fact that it is perfectly regular and sym-
metrical, while in the former the setz leave off at different distances from the
median line in different segments, which causes it to appear rather less con-
spicuous than the ventral area; but at any rate an observer who noted the
one could hardly fail to note the other. Moreover, in Megascolex, the genera-
tive organs are described as occupying the 16th, 17th, and 18th segments.
SCHMARDA appears to consider that this description refers to the clitellum,
which he accordingly states, on the authority of TEMPLETON, to be developed in
those segments; in the annelid to be described here, the clitellum occupies
about seven segments commencing after the 12th, and the testes are developed
in the 12th: hence I have no hesitation in regarding this annelid as quite
distinct from Megascolex coeruleus.
Whether ScuMarpa and myself are describing the same animal or not is
rather difficult to say; I am on the whole inclined to suspect that we are,
from the similarity of the colour ; the absence of the clitellum and the number
of the segments may be accounted for on the hypothesis that the specimen
described by SCHMARDA was a young one. But whether this is so or not, a
careful study has convinced me that this annelid cannot be classed with the
genus Pericheta, since their affinities, which will be pointed out later on, are not
of so close a character as to warrant the inclusion of the two types in the same
genus ; accordingly, I have placed it in a genus by itself, and propose for it the
name Pleurocheta Moseley. The generic name serves to express the most
important external character, viz., position of sete in two lateral groups ; the
species I call after Professor MosELEy, since it is through his liberality that I
have had the opportunity of studying it. :
I will give briefly the most important facts in the anatomy of this animal
before discussing in detail its various structures.
Pleurocheta Moseleyi is about 28 inches in length, and is made up of some
260 segments, of which from seven to nine are occupied by the clitellum, and
twelve are pre-clitellian. The sets are developed in all the rings of the
body, but are more numerous in the post-clitellian region, being there about
140 to each segment. Sete are present in the ventral part of the clitellum. The
alimentary canal consists of the ordinary divisions, pharynx, cesophagus,
* Loe. cit.
+ “ Note sur Anatomie de deux espéces du genre Pericheta et essai de classification des Anne-
lides Lumbriciens,” Annales des Sciences Naturelles, 5th series, vol. x.
, eS . ——
_—
ANATOMY AND HISTOLOGY OF PLEUROCHATA MOSELEYI. 483
gizzard, small and large intestines ; the large intestine is characterised by an
extraordinary development of specialised glands. Certain of the anterior
mesenteries are thickened and muscular; dorsal pores are very distinct, com-
mencing after the clitellum, and extending to within eight or nine segments of the
end of the body. No segmental organs were detected. Vascular system con-
sists of a dorsal trunk, a ventral supra-nervian trunk, two small supra-intestinal
trunks and two lateral ; the dorsal and ventral vessels are united by six pairs of
arches, which increase in size from before backwards, the last two pairs being
the thickest. The other vessels are not directly united, but indirectly by means
of capillaries. The generative system consists of one pair of testes, which have
the form of racemose glands, and are situated in the 12th segment; of two
receptacula seminis opening respectively between the 7th and 8th, and 8th and
9th segments ; of four fimbriated organs, with ciliated openings into body cavity,
and duct opening to exterior through body wall of segment behind; these
organs, concerning the nature of which it is difficult to speak with certainty, are
situated in 11th and 10th segments on anterior wall of mesentery. A pair of
rosette-shaped glands are found on mesentery separating 11th from 10th segment,
the nature of which again is doubtful. In the 17th, 18th, and 19th segments
are three pairs of openings, the middlepair of which are continuous with the
ducts of two large solid white glands ; with the other two pairs of openings, no
ducts were seen to be continuous. The clitellum extends from 13th segment
to about 20th inclusive, and is readily distinguished from rest of body by its
yellow glandular appearance ; another pair of openings, to which Professor
MosELeEy drew my attention, are situated in the 13th segment.
These are the main facts in the anatomy of Plewrocheta. I will now proceed
to consider them in detail, and in so doing shall adopt the order in which
M. Perrier, in his numerous and valuable memoirs on the anatomy of
Oligocheta published in the Archives de Zoologie Expérimentale and other
journals, describes the various organs and systems, for the purposes of an
easier comparison.
Tegumentary System.
Under this head will be described the five layers which separate the body
cavity of the animal from the external medium, commencing from the outside.
(1) Cuticle—There is nothing particular to be said concerning its structure ;
it appears to resemble in every detail the same structure in other worms, exhi-
biting fine striz running in two directions nearly at right angles to each other,
and minute pores situated frequently at the intersection of two strie.
(2) Hypodernis.—The cellular layer which underlies the cuticle is generally
described by this name ; concerning its structure in Plewrocheta I am not able
484 MR. F. E. BEDDARD ON THE
to say very much. The specimen from which my sections were taken, though
admirable for displaying many points in the histology of the animal, had not
its hypodermic layer well preserved, the constituent cells were not distinguish-
able, the whole was visible simply as a granular mass; this may be owing
perhaps to the fact that the tissues were hardened with alcohol, which PERRIER
states to be a very poor reagent for displaying the structure of the hypodermic
cells. But one very important fact in the constitution of the hypodermic layer
I was able to make out—the presence of capillaries. In a short paper on the
epidermis of the leech, Professor LaNnKEsTER,* describes and figures capillaries
in the same situation lying between the epidermic cells, and at the same time
states the only other annelid in which they had been hitherto found to be the
earthworm, and there not generally throughout the body wall, but only in the
clitellum. In Pleurochwta they are very evident, running up through the two
muscular layers and ending in the hypodermis ; their exact relation to the con-
stituent cells I was unable to make out, for the reasons already stated, nor
could I satisfy myself as to their exact mode of ending, though I should pre-
sume, from analogous cases, that they terminate in loops. In many of my
sections, especially those stained in aniline blue, the capillaries of the integu-
ment were most beautifully conspicuous ; the coagulated blood having taken
up the staining fluid rather more than the surrounding muscles, connective
tissue, &c. It is very possible that the distribution of capillaries to the outer
epidermic layer of worms and other animals is much more common than is
generally supposed, and they may have been in many cases overlooked, owing
to their insignificant size ; it seems natural that many of these animals without
a specialised respiratory apparatus, should breathe by means of their skin; and
this would be greatly facilitated where the epidermis and cuticle are at all
thick, by a capillary network in the epidermis itself. I intend to direct my atten-
tion to this point on some future occasion.
(3) Muscular Coats.—The two muscular layers of the body wall are, as in
other worms, an outer transverse and an inner longitudinal layer. The
individual muscles are of various sizes, and appear to resemble in histological
structure the muscles of other annelids. My observations agree with those of
CLAPAREDE and Perrier.t The arrangement of the muscles is, however, very
peculiar, and requires a minute description, as it appears to differ considerably
from anything that has been yet observed, with the exception of Pontodrilus
described by PERRIER in the memoir just alluded to. A transverse section
through the body wall in a direction at right angles to the outer circular layer
is shown in Plate XX VI. fig. 5. It will be observed, that immediately beneath
* Quarterly Journal of Microscopical Science, vol. xx.
+ Archives de Zoologie Experimentale, vol. ix., 1881.
ANATOMY AND HISTOLOGY OF PLEUROCH ATA MOSELEYI. 485
the hypoderm, which is represented diagrammatically, is a network of fibrous
tissue, within the meshes of which lie the muscular fibres cut transversely,
either singly or in groups of two or more. The strands of connective tissue
separating the muscles appear to be elastic tissue; they are stouter in the
lower part of the transverse coat than in the upper; towards the surface they
become finer, but here and there stouter bands form largish compartments, which
are again divided up by the finer bands between which lie the muscles. A
more deeply stained continuous membrane separates the muscular from the
hypodermic layer; beneath the fibrous bands of the circular coat are perfectly
continuous with those of the longitudinal coat.
The longitudinal is essentially similar to the circular coat, but the fibrous
bands are far slighter ; in fact, unless the section is rather stretched, it is very
easy to miss them altogether, but quite impossible in the case of the outer
circular coat. The advantages of this elastic network to the animal must be
enormous, giving its skin so great a flexibility, and that not at the expense of
its muscles. It is rather difficult to compare the thickness of the two coats, as
the presence of the elastic tissue renders them so easy of compression or of
extension, that in the case of a given section one cannot say with certainty
whether it really represents the skin of the animal in its normal condition or
not. On the whole, it would appear that the two coats are about equal in
thickness, except in the anterior part of the body where the longitudinal coat is
considerably thicker (see Plate X XVI. fig. 15, which is taken from a young
specimen, but would do perfectly well for the adult in this respect), and has
a much more strongly developed fibrous meshwork (Plate X XVI. fig. 13).
PERRIER* figures and describes a somewhat similar arrangement in Pontodrilus
marionis, but apparently confined to the inner longitudinal coat ; the meshes
also enclose a far greater number of fibres.
In his researches into the common earthworm, CLAPAREDE? figures and
describes strands of fibrous tissue separating the bundles of muscular fibres in
the inner longitudinal coat, giving to the muscles the bipinnate arrangement so
characteristic of the earthworm. This is very evident on examining sections
of the integument of the earthworm; but, as PERRIER remarks, it is not
at all generally found among the Oligochwta. Comparing, however, sections
of the integument of Lumbricus with that of Pleurocheta, and finally with
the figures given by Perrier of the same structure in Urochwta,{ it would
seem that the arrangement in Luwmbricus is only an extreme modification
of what is found in Pleurocheta, and that there exist in this latter arrange-
* Perrier, Joc cit., pl. xvi. fig. 27.
+ “ Histologische Untersuchungen ueber den Regenwiirm,” Zeitschrift fiir Wissensch. Zoologie, 1869.
t Perrier, Archives de Zoologie Experimentale, vol. iii., 1874.
486 MR. F. E. BEDDARD ON THE
ments of the muscular fibres showing various intermediate stages between
the bipinnate muscular bands of Lwmbricus and the fibres of Urocheta, which
are present in a continuous mass without any dividing septa of connective
tissue. In Lwmbricus the longitudinal muscular layer may be regarded as
being composed of a series of compartments formed of trabecule of fibrous
tissue, in the interior of which lie the actual muscular fibres. On Plate XX VI.
fig. 10 is a diagram of this; the fibres are developed close to the septa
themselves, and thus give rise to the bipinnate arrangement so well dis-
played in the drawings of CLApAREDE. In Pleurochwta a distribution of
the muscular fibres exactly like this does not exist, but in the anterior
segments the longitudinal coat is divided in a precisely similar manner into
compartments, only that there are more muscular fibres in each compartment,
and they are not all developed close to the septa. In a young specimen not
more that 14 inches in length, which I had the opportunity of examining,
and which will be described in the last part of this memoir, a section through
the anterior end of the body (Plate XX VI. fig. 15) showed the muscular fibres
arranged in vertical lines, which were more thickly congregated in the neigh-
bourhood of the septa, and possessing therefore an “orientation deter-
minée,” differing only in degree from that of ZLumbricus. In the adult
Pleurocheta sections through the body wall in the anterior region show a
somewhat similar arrangement; the longitudinal coat, which is here rather
more than double the thickness of the circular coat, is divided into com-
partments, bounded by very thick bands of fibrous tissue, the interior of each
compartment being again subdivided by other trabecule ; between each
pair of compartments (Plate XX VI. fig. 13) there is frequently a space for the
insertion of the lower end of a seta, in which only delicate fibres of connective
tissue are visible : in this case, however, the muscle fibres have no fixed and
definite arrangement, and they are not specially developed at the margin of the
compartment. In the hinder part of the body the longitudinal muscular layer is
not divided up, but here and there (Plate X XVI. fig. 4, a) a stronger trabecula
serves to point out the boundary of regions which correspond to the anterior
compartments ; here too, as already stated, the development of fibrous tissue is
much slighter than in the anterior part of the body ; a comparison of figs. 4
and 13 will make this clear. Finally, in the figures of Urochwta, given by
Perrigr, the longitudinal muscular layer (as well as the circular) is entirely
without this fibrous network.
PERRIER, in his account of the anatomy of Pontodrilus, in which animal
the longitudinal muscles are arranged in a manner similar to that which has
already been described as occurring in the posterior region of the body wall of
Pleurocheta, comparing the account given by CLAPAREDE for Lumbricus with
his own description of Pontodrilus, says (page 186), “ La difference essentielle
ANATOMY AND HISTOLOGY OF PLEUROCH ATA MOSELEYI. 487
qui existe entre cette disposition et celle qui est propre aux Lombrics c’est que
dans chaque groupe de faisceaux, ces derniers n’ont pas une orientation
determinée et l’on ne retrouve plus par conséquent cet arrangement si regulier
qui frappe tout de suite chez ces derniers animaux.” I have attempted to show,
in the preceding description of the muscular layers of Plewrochwta, that there
are a series of transitions between the muscles of Lwmbricus and those of other
forms; this series is not very complete, but it serves to indicate that there is
nothing really peculiar in the muscles of the former.
Sete are found in great numbers in Pleurochwta, and their characteristic
distribution has been already treated of. They are in shape like the ordinary
forms of setze among the Oligocheeta, that of an elongated S ; in Pontodrilus we
have apparently the only exception to this rule; in that genus the sete are
straight and rod-like. The length of the sete of Pleurocheta vary from
035 mm. to (066 mm.; they are therefore rather small in comparison with those
of other Oligocheta ; in Pontodrilus, for example, the length is about ‘16 mm.,
and the largest sete of Lwmbricus that I have measured myself are from ‘1 mm.
to 12 mm. Plate XXVI. fig. 18 shows one of the sete in position. The
section is taken from the anterior part of the body; the seta, which is of the
ordinary amber yellow tint, lies in a diverticulum of the outer chitinous
layer of the integument, and extends downwards through the circular muscu-
lar layer and someway into the longitudinal (@ marks the boundary of
the two coats); towards the middle of the seta there is a slight swelling,
which appears to contain spaces filled with air; this swollen part is developed
about the end of the upper third of the seta; in other worms its position
is rather different ; it appears to be fairly central in the Pericheta described
‘by Leon Varriant.* In Urochwiat it is rather nearer the upper end, and also
in Lumbricus.
The free extremity is curved rather sharply, the opposite end being rounded
off, and very faintly bifurcate. The texture is uniform, except for the presence
of faint wavy transverse markings and longitudinal striations. The arrangement
of the setze and the muscles which move them present no important differences
from other Oligocheta. The seta is enclosed in a “ cul-de-sac” formed by a
fold of the cuticular membrane. Each is provided with its special muscles,
which are inserted into the cuticular covering of the seta at one end, and at
the other some of them appear to be inserted close to the hypoderm, and
others to form part of a continuous layer of muscles connecting the several
setze of one segment, while others again seem to join the outer or transverse
muscular layer of the body wall. These special muscles of the seta appear
to be arranged in about six bundles, radiating outwards from the cuticular
* VAILLANT, loc. cit.
+ Porrrisr, loc. cit.
488 MR. F. E. BEDDARD ON THE
covering of the seta; in Plate XX VI. fig. 16, which represents an oblique section
through the body wall in the neighbourhood of a seta, three of these bundles
are seen in longitudinal section reaching from the cuticle, which surrounds
the seta itself, to the base of the hypoderm layer; the others are cut trans-
versely, and lie behind the seta.
Clitellum.—The histological structure of this differentiated part of the
integument will be best considered in this place in relation to the rest of the
integument, while the description of the number of segments of which it is
composed, and the positions of the apertures of the generative organs, will be
deferred until the generative system is treated of.
The clitellum has been carefully studied by CLaparEDE,* and more recently
by Moussisovics,t in the common earthworm ; and since this is the only type in
which, up till the present, the clitellum has been accurately described and
figured, it will be as well to give briefly the results of these two observers, for
the sake of comparing it with the clitellum of Pleurocheta, which is i some
respects different.
According to Mougstsovics, the clitellum of the earthworm differs from the
rest of the integument (1) by the modification of the hypoderm cells, and (2) by
the additional presence between the hypoderm and circular muscular coat of a
glandular layer well supplied with blood-vessels. The hypoderm cells differ
from those over the rest of the body by being much more granular; the
glandular layer consists of several rows of flasked-shaped cells finely granular,
and frequently possessing a. nucleus, imbedded in a network of connective
tissue. These two layers differ chemically, as is shown by coloration with
picro-carmine and logwood (see figs. 9, 11 of his memoir). The capillaries
extend half way up the outer hypoderm layer.
CLAPAREDE'’S account differs somewhat; he figures a hypoderm layer distinct
from the subjacent glandular layer, which latter he subdivides into “obere ”
and “untere Saiilenregion;” beneath this again a special vascular layer.
Accordingly the “ hypoderm layer” of Mousisovics equals the hypoderm plus
the “obere Saiilenregion” of CLaparEDE. Both observers agree that the
glands are unicellular. MoJsisovics figures the capillaries extending half way
up the hypoderm cells, leaving off just where, on CLAPAREDE’S interpretation,
the hypoderm cells begin (compare figs. 9, 11 of Moustsovics, with plate xlvi.
fig. 1 of CLAPAREDE’S memoir), and this makes one almost suspect that the
earlier idea of CLAPAREDE may be after all the right one.
In Pleurocheta the glandular layer of the clitellum appears to be distinct
from the hypoderm layer which covers it; there is a band of fibrous tissue
dividing the glandular layer from the hypodermic ; this band is readily seen
* CLAPAREDE, loc. cit.
+ Mosstsovics, “ Kleine beitriige zur Kenntniss der Anneliden,” Sitz. Acad. Wissensch., 1877.
ANATOMY AND HISTOLOGY OF PLEUROCHATA MOSELEYI. 489
in sections stained with picro-carmine, as it shows a rose tint, while the gland-
ular tissue is stained of an orange-yellow ; so far there is a similarity with the
clitellum of Zumbricus, as understood by CLAPAREDE ; but in Plewrochwta, the
capillaries, which are in this part of the integument larger, and far more
numerous than over the rest of the body, are continued into the hypodermic
layer, instead of stopping short at the septum, as they do in the earthworm.
Unfortunately, none of the cells of the hypodermic layer were in a fit condition
for examination ; as in the case of the rest of the integument, nothing was left
to indicate the form of the cells, and their relations to the capillaries. The
glandular layer is divided up into columns by trabecule of connective tissue,
running down to join a stouter fibrous septum, which separates off the gland-
ular layer from the circular muscular coat. This septum (Plate X XVI. fig. 7)
is perforated here and there for the transmission of blood-vessels. Between the
trabecule lie the glandular cells, which do not seem to have any definite
arrangement ; they are of various sizes, occasionally provided with a nucleus at
their lower end, and flask-shaped, the “neck” of the “flask” being produced
upwards as the duct of the unicellular gland. The appearances displayed in
fig. 17 do not mean that the glands are multicellular, they would seem rather
to be the effect of reagents on a single cell. But though, as in Lumbricus, the
glands of the clitellum are unicellular, there are here and there indications of the
combination of the gland cells into veritable glands. Plate X XVI. fig. 3 shows
this; here in a definite region the gland cells are massed together, forming a
more or less oval-shaped body, while on either side the cells continue isolated
from each other; but there is no common duct. Each cell is, as in the rest of
the clitellum, as far as can be made out, provided with its own duct; this,
however, is the first step in the formation of a specialised compound gland.
These glands can be recognised on the clitellum with the naked eye as
yellowish spots and patches. Plate X XVI. fig. 6 is a general view of a section
through the clitellum; at a are the remains of the hypoderm cells, and
the more or less distinct fibrous band separating the hypoderm from the
subjacent glandular layer ; in this latter lie the cells 6 of various sizes, arranged
in columns by the trabecule of connective tissue c. Beneath these are
the two muscular layers. As in the rest of the body, the muscular fibres
in the two coats are divided up into groups, by branching and anasto-
mosing trabecule. The muscular fibres of the circular coat are occasionally
found trespassing on the outer side of the septum, which separates the
glandular from the muscular coat (see fig. 11). Seta are found on the
clitellum, but their form is in nowise different from the sete found over
the rest of the body.
(4) Peritoneal Membrane.—This structure, which lines the peritoneal cavity,
VOL. XXX. PART Il. 46
490 MR. F. E. BEDDARD ON THE
forming therefore the innermost layer of the body wall, differs in no respect
from the same structure in Lumbricus,
Body Cavity.
There is not very much to be said under this head. The body cavity com-
municates with the exterior by a series of dorsal pores, one to each segment, com-
mencing after the clitellum, and continuing to within eight segments of the end
of the body; these dorsal pores are very general in the Oligochwta, and are found
in Pericheta, Lumbricus, and other genera, but not in Pontodrilus and Urocheta.*
Another fact of importance is the enormous thickening of some of the anterior
mesenteries, which is not peculiar to Plewrocheta, but is found elsewhere. The
last of these thick mesenteries separates the clitellum from the fore part of the
body, and therefore marks the posterior boundary of the 12th segment, There
appear to be six of these specially thickened mesenteries ; they extend forward
to the posterior end of the gizzard, the first one marking the boundary between
the 6th and 7th segments ; these mesenteries are united by ligamentous cords
one to another, and as the “ hearts ” lie in this region of the body, their function
may be to aid in their contraction, or perhaps they are merely protective.
Similar thickened mesenteries are described by PERRIER as existing in Anteus
and Urocheta ;+ and as Pleurocheta ought possibly to be regarded as one of the
Intraclitellian Oligocheta, this fact may be of some significance. A transverse
section through one of these thickened mesenteries shows that they are com-
posed of two layers of muscular fibres.
In the posterior region of the body the mesenteries are thin and mem-
branous: in the most anterior segments the mesenteries are hardly at all
separated, but are metamorphosed into a mass of muscles connecting the
pharynx with the body wall (see Plate XXV. fig. 1).
As has been already mentioned, there are no segmental organs in Pleuro-
cheta; it is, however, not a unique example; in a Pericheta from Java, Dr.
Horst{ asserts the absence of segmental organs, and generally throughout the
genus Pericheta there is an absence or a very small development of these
organs.
Alimentary Tract.
The alimentary canal of Plewrocheta resembles that of most other Oligo-
heta in its main divisions. The mouth leads into a pharynx, the walls of
* Perrier, loc. cit., p. 192.
+ Perrier, Arch. de Zool. Exp., vol. iii.
* Horst, “ Ueber eine neue Pericheta von Java,” Nederlandisch, Archiv. fiir Zoologie, iv. p. 163.
ANATOMY AND HISTOLOGY OF PLEUROCH ATA MOSELEYI. 491
which are thick and muscular ; the pharynx is bound to the body wall by a
quantity of muscles running in every direction, in the interstices of which lie
the pharyngeal glands ; these glands are compound and tubular, and appear to
ramify everywhere among the muscles of the pharynx. Their presence is noted
by PerRiIER* in Pontodrilus, but according to CLAPAREDE,t they are absent
from the earthworm. After the pharynx comes the cesophagus, which is folded
several times upon itself, so as to occupy only one or two segments; the
-eesophagus is entirely unprovided with glands, and in this respect Plewrocheta
differs from most other worms. In Pericheta Houlleti, t for example, there are a
great many variously specialised cesophageal glands ; and in many other types,
such as Urocheta, there are the so-called glands of Morren, opening into the
cesophagus, which in the common earthworm have been termed the “ calciferous
glands.Ӥ The gizzard, which forms the next division of the alimentary canal, is
somewhat pear-shaped, the broad end lying towards the fore part of the body.
The posterior portion of the gizzard has enormously thickened muscular walls,
the anterior portion (see Plate X XVII. fig. 8) is thinner and more glandular ;
its walls are thrown into longitudinal corrugations. The walls of the gizzard
secret a chitinous layer which forms a perfectly continuous structure attached
to the walls of the gizzard only at its two extremities ; it presents the appear-
ance of a cone of stiff white paper with various prominences and folds; its
shape will be understood from a glance at fig. 8, where it is drawn in position in
the interior of the gizzard. This cuticular lining exhibits in thin sections a
certain structure: the whole membrane is perforated by a series of minute
canals, and the inner half appears distinctly granular, while the outer half, with
the exception of the canals, is homogeneous. The histological structure of the
walls of the gizzard is not remarkable. There is an inner layer of tall columnar
cells, which are about ‘0125 mm. in length and ‘0005 in breadth, and an outer
layer of muscular fibres arranged in a direction transverse to the long axis of
the gizzard, forming in fact a circular coat; near to the epithelium lining the
gizzard there are also a set of muscular fibres running at right angles to circular
muscles, radiating outwards from the epithelium ; these fibres are, however,
interspersed among the circular fibres, and do not form a distinct layer.
Leading out of the gizzard, we have the intestine, which is primarily divisible
into two portions,—an anterior “small intestine,” which extends from the 8th
to the 16th segments, and a posterior “ large intestine,” which occupies the rest
of the body, and is itself divisible into several regions. The small intestine is
* PrRRIER, loc. cit.
+ Cuaparnpe, loc. cit.
+ Perrier, “Mémoires pour servir a lhistoire des Lombriciens terrestres,” MVouvelles Archives du
Muséum, 1872.
§ Vide Darwin on Harthworms, London, 1881.
492 MR. F. E. BEDDARD ON THE
considerably the narrower of the two; its diameter is about 4 of that of the
large intestine (see Plate X XV. figs. 1, 7), and its walls, at any rate in the first
portion, where it is attached to the thick mesenteries already described, are
stouter. In the 16th segment commences the large intestine quite suddenly,
there being no transition between it and the small intestine. The large
intestine extends from the 16th segment to the end of the body, with no
alteration in size. When the intestine was first opened, the contents, consisting
of earth, vegetable débris, &c., showed a marked dissimilarity in colour ; in the
anterior half the contents were ofa pale yellowish colour, in the posterior half, of
arich and dark greenish-brown tint ; this is no doubt owing to the fact that the
glandular development of the posterior half of the large intestine is far greater;
the intestine itself showed no signs of a typhlosole, and in this structural
peculiarity Plewrocheta resembles Pontodrilus, the only remnant of the
typhlosole being in these two forms the supra-intestinal vessel; in Pericheta
and Urocheta also the typhlosole is very much simplified. In the first six
segments occupied by the large intestine the glandular epithelium is chiefly
developed in a double series of shallow dorsal pouches in lines running across
them at right angles to the long axis of the intestine. The gland cells examined
were large, and appeared to be loaded with the products of their secretion in
in the form of yellow granules ; at the 22nd segment the dorsal pouches become
deeper ; they are still arranged in pairs, one pair to each segment on either side
of the median dorsal line ; these pouches extend as far as the 44th segment (see
Plate XXV. fig. 1) or thereabout, and are eminently glandular. In the first
fourteen sets of pouches (7.¢., from the 22nd to 36th segmeuts inclusive) there is
developed on the septum dividing each pouch from the one following it a folded
membrane, covered with large glandular cells altogether similar to those
described, which extends down the side of the septum. After these comes
another set of pouches forming a continuation of the series, but with the
glandular substance arranged differently ; each pouch contains eight or nine folds
of a dark brown colour, extending right across it from the posterior to the
anterior septum, presenting very much the appearance of a fish’s gill; there are
from six to eight pairs of these pouches. Beneath the dorsal blood-vessel is a
longitudinal fibrous band running along the course of the intestine, and above
the supra-nervian vessel, on the ventral surface of the intestine, is another fibrous
tract. The pouches are arranged on either side of the dorsal fibrous band,
and deepen gradually from the middle line outwards ; in the region of the six
posterior pouches there is an additional pair of fibrous bands developed on either
side of the ventral band (see Plate X XV. fig. 8). Nothing like this has been
to my knowledge described in any other Oligochetous worm. In the first part
of the large intestine (down to about the 76th segment), which includes the
region occupied by these pouches, the glandular development is very feeble, the
re —e——E
ANATOMY AND HISTOLOGY OF PLEUROCHAITA MOSELEYI. 493
intestine here being much paler in colour than in the posterior half; but cells
similar to those already described in the dorsal pouches are found scattered
about. Unfortunately, the intestine in this region was not in a very fit condition
for histological examination, but a curious arrangement of the muscular coats
could be made out. Instead of being separated into two layers, a longitudinal
and a circular, as is generally the case in the alimentary tract, there appeared
to be a simple network of muscular fibres running in every direction, most of
them, however, being arranged parallel with the long axis of the intestine, and
at right angles to it, but forming only one distinguishable layer ; the fibres are
of various diameters, anastomose with each other, and are frequently curled
into spirals, as if this part of the intestine was capable of extension, and served
rather as a store-house for the food, the most active part of the digestion taking
place in the posterior half of the intestine, where there is a more abundant
development of glandular epithelium and of specialised glands. The posterior
half of the large imtestine, commencing from about the 76th segment, and
extending to the anus, is very different in appearance to the anterior half, being
of a brownish colour, and showing under the microscope an abundant develop-
ment of epithelium and the ordinary muscular coats (Plate XX VI. fig. 12).
The walls are thrown into a series of transverse folds, one to each segment. In
last thirty segments of the body the intestine is quite smooth internally, with the
exception of three folds, but otherwise does not differ in appearance, and can
hardly be distinguished as a special rectal region.
Plate XX VI. fig. 12 is a section through the intestine in the region of the
“kidney-shaped glands,” to be described shortly. The outer layer is composed
of a quantity of large cells filled with granules, answering to the so-called
hepatic cells on the intestine of the earthworm, which have, it is perhaps hardly
necessary to remark, no relation to any intestinal secretion, but are merely
the cells lining the body cavity of the animal. Beneath these come the
muscular layers; the middle transverse coat being the most strongly de-
veloped, and divided up into compartments by septa of connective tissue ;
below the epithelium is a thin longitudinal layer, which may be muscular, or
composed of connective tissue only.
From the 86th to the 101st segment or thereabouts, are a series of glandular
bodies, in all fifteen pairs, which lie on the dorsal wall of the intestine, but are
quite distinct from it, being separated by a layer of the granular cells already
described as lining the perivisceral cavity in this region. Each of these glands
is faintly divided into lobules by furrows running at right angles to the long
axis of the gland, and is somewhat kidney-shaped in outline, opening into the
alimentary canal by a short but distinct duct, situated on its under surface.
In the region of these kidney-shaped glands the walls of the intestine are
very vascular ; the vessels are of a brownish tint, and exceedingly conspicuous ;
494 MR. F. E. BEDDARD ON THE
their arrangement is as follows :—The dorsal vessel gives off on either side in
each segment three vessels, of which one is very small, and supplies the
mesentery (the mesentery receives its chief blood supply from the supra-nervian
vessel). The other two vessels are large and very conspicuous; one runs over
the kidney-shaped gland, sending off branches which run along its furrows ;
after leaving the gland it is distributed to the walls of the intestine : the other,
which is somewhat larger, runs between the glands, being attached to the
intestinal wall by a series of short branches, which appear to end abruptly (in
blood spaces ?), and give this vessel a very characteristic appearance (see
Plate XXV. figs. 11, 12). Throughout a considerable extent of the intestine,
both anterior and posterior to the kidney-shaped glands, the blood-vessels were
turgid, and appeared to be rather larger than the same vessels in the other
parts of the intestine. Anterior to these glands, the vessels of one segment
are represented in Plate X XV. fig. 10, where it will be seen that the vessel a,
which is the homologue of the vessels which supply the glands, resembles the
interglandular trunk, in being attached to the surface of the intestine by a
series of short branches, ending, as far as could be made out, abruptly. These
vessels just described appear, like the same vessels in other parts of the
intestine, to end in a plexus (in two instances this was perfectly clear), and not
to be connected with any sub-intestinal vessel, nor with the supra-nervian
trunk. Whether a supra-intestinal trunk exists for the whole length of the
intestinal tube or not I cannot say ; it was traced as far back as the 20th
segment, being in this region single instead of double, but having a trace of the
other trunk running beside it. All the details of the intestinal circulation can
only be made out by a series of careful injections; the facts given here are
based upon a partial natural injection of the capillaries, which may of course be
misleading. The general features of the circulation in this part of the body
appear to be as follows :—The wall of the intestine itself is supplied with a rich
network of vessels derived from the branches of the dorsal trunk (two in
each segment). The supra-nervian trunk supplies the integument and the
mesenteries, the latter receiving also a small twig from the dorsal vessel,
which no doubt serves to put the dorsal and ventral systems into communi-
cation. .
The kidney-shaped glands in transverse section (Plate XX VI. fig. 19; Plate
XXVII. fig. 9) show an outer layer of granular cells, which belong, as already
mentioned, to the perivisceral cavity, and not to the coat of the glands; below
this is a fibrous layer, which sends off trabeculz into the substance of the gland,
larger ones dividing the gland into lobules or smaller ones lying simply between
two adjacent columns of cells. The gland itself presents the appearance of a
compound tubular gland, or perhaps rather of a folded membrane ; the duct
opens on to the transverse fold in the intestine. The cells which compose the
ANATOMY AND HISTOLOGY OF PLEUROCH ATA MOSELEYI. A495
glands are columnar, each provided with a nucleus, the outer border of the
cell is hyaline, and does not stain deeply with colouring reagents.
The existence of these highly specialised glands is no doubt the most
remarkable point in the anatomy of Pleurochwta, and their presence may
perhaps be correlated with the absence of segmental organs,
Circulatory System.
The fact that the specimens at my disposal were preserved in spirit, hindered
very accurate researches into the distribution of the smaller branches of the
vascular system; but in the case of the more important vessels, their large
size, and the frequent presence of coagulated blood, rendered their study fairly
easy. Consequently, the following description is, I hope, correct for the main
trunks of the vascular system, but some errors may have crept in with respect
to the smaller vessels.
The vascular system of Pleurocheta consists of six longitudinal trunks.
(1) The dorsal vessel, (2, 3) two supra-intestinal trunks, (4, 5) two lateral or
“intestino-tegumentary,” and finally, (6) one ventral supra-nervian vessel.
This system differs from that of any other Oligocheetous worm by the presence
of two supra-intestinal vessels, but with this exception conforms to the ordinary
type, being very similar in its general arrangement to Pericheta, Urochwia, and
Pontodrilus. 'The dorsal vessel lies on the dorsal side of the alimentary canal,
in actual contact with it in the anterior and posterior portions; it is only in
the region which lies between the 8th and 16th segment, that the dorsal vessel
lies well above the alimentary canal, as shown in Plate XX VI. figs. 1, 2, which
represent diagrammatic vertical sections through the body of the worm in this
region. The dorsal vessel takes its origin from a capillary network on the
anterior part of the pharynx, and has the remarkable peculiarity of not remain-
ing a single uniform tube in its course backwards, but bifurcates no less than
five times in the first eight segments, the bifurcations always coalescing again
directly ; this is shown on Plate X XV. fig. 2. The dorsal vessel gives off one or
two branches in the anterior segments, and in the 8th, 9th, 10th, 11th, 12th, and
13th gives off a branch on either side, which unites it directly to the ventral
trunk ; these arches increase in size from before backwards, and the four last,
which are the stoutest, are no doubt contractile, and function as “hearts.” The
moniliform character of these vessels described in other worms is very con-
spicuous here in the pairs occupying the 10th, 11th, 12th, and 13th segments ;
the two pairs anterior to these are much slighter, and before joining the ventral
vessel give off on either side a trunk (Plate XXV. fig, 4, 5), which in the case of
the posterior one, at least, gives off another branch perforating the mesentery
behind (Plate X XVI. fig. 2, ~). In the 7th segment, another pair of branches
496 MR. F. E. BEDDARD ON THE
are given off from the dorsal trunk, which after joining a branch supplying the
vascular plexus on the surface of the gizzard, and then giving off three other
small branches, which are distributed to the mesenteries, dividing 7th from
8th, and 8th from 9th segments, become united with the first arch—joining the
dorsal and ventral vessels—before its division. This arrangement of vessels, as
well as the vascular plexus on the gizzard, to be described shortly, is given in
Plate XXYV. fig. 5. The supra-intestinal vessels, two in number, I was unable
.to trace further forward than the 10th segment, or further backwards than the
20th; they would seem to be equivalent to the single “ sus-intestinal” vessel
described by Perrier in Pontodrilus, Perichwta, and Uvrocheta, which he
regards as the only representative of the typhlosole left in these worms.
In Urocheta and Pericheta, certain of the “ hearts,” or transverse contractile
trunks connecting the dorsal and ventral vessels, are in reality connected at
their upper end with the supra-intestinal, and not the dorsal trunk; these are
termed by PERRIER “ cceurs intestinaux ;” the anterior hearts connecting the
dorsal vessel proper with the supra-nervian trunk being distinguished by the
name of “cceurs lateraux.” In Pontodrilus,* there are the same two sets of
hearts, but the communications of the “ cceurs intestinaux ” are rather
different ; there are occupying segments 5 to 11 inclusive, a pair of lateral
hearts to each, and in the two following segments are two pairs of intestinal
hearts readily distinguishable from the others by their greater size. These
last mentioned are not only connected with the supra-intestinal trunk, as in
Urocheta and Pericheta, but also have a delicate branch connecting them with
the dorsal vessel. This same arrangement is described by PERRIER as existing
in Titanus Forguesti, a representative of an entirely distinct group, that of the
Intraclitellians. In the Ante-clitellian forms, of which the common earthworm
is an example, there is no such differentiation of the hearts; they all alike
connect the dorsal vessel with the supra-nervian. “ L’existence des cceurs
intestinaux,” says Perrier, “parait bien reellement limitée aux Lombricidés
intra et post-clitelliens,” but whether all worms belonging to these two groups
are thus provided is another question. In Pleurocheta, which, from the
arrangement of its generative apertures, and their relation to the clitellum,
ought perhaps to be classed with the Intraclitellians, but is most certainly not
Ante-clitellian, no trace of any intestinal hearts was to be found, though after
making myself acquainted with Prerrier’s memoirs, I naturally looked very
carefully ; still it is possible that the additional communication with the supra-
intestinal vessel may be present ; but at any rate the communication of all the
hearts with the dorsal vessel is perfectly obvious, so that, in this respect,
Pleurocheta differs materially from Pericheta.
At present our knowledge of the circulatory organs in the Oligochwtu is not
* Perrier, Arch. de Zool. Exp.,-vol. ix.
ANATOMY AND HISTOLOGY OF PLEUROCH ATA MOSELEYI. 497
very extended, D’UpExkem,* LANKESTER,t and CiapArnDE{ have made us
thoroughly acquainted with these organs in Lumbricus, PERRIERS has
increased our knowledge enormously with respect to the three genera, Ponto-
drilus, Urocheta, and Pericheta; to the last genus also VAILLANT || and
Horst * have added details of considerable importance ; but of the circulatory
organs in the many interesting genera described by PERRIER in the Mémoires
du Muséum, owing to their bad state of preservation, not much could be
asserted with confidence. It would be useless, therefore, with the comparatively
scanty materials that we have at hand, to attempt to generalise ; on the whole,
in the number and character of the main trunks of the vascular system,
Pleurocheta seems to stand midway between the Ante-clitellians, ¢9., the
common earthworm, on the one hand, and the Intra and Post-clitellians on the
other, with rather more affinities to the latter groups, but no more special
relationship to any particular genera among those which compose these two
somewhat heterogeneous groups can be made out.
The vascular system in the Oligochwta, as far as we know it, contrary to
what we might expect from the analogy of other groups of animals, does not
form a good basis for classification. The main trunks are constant through so
many and so widely different genera, and the number and position of the
hearts, which might at first sight seem likely to be useful in this direction,
vary in the most capricious manner from one species to another; for example,
in Pericheta cingulata, described by VAILLANT,** there are three pairs of
hearts, and in a Perichwta described by Horst,t{} there are in all six pairs of
hearts, and one unpaired half-arch. Among the various species of Pericheta
described by PeErriER, the same variations are observable—‘‘l’appareil circu-
latoire possede une grande variabilité qui ne semble guere autoriser l’employer
dans une caractéristique.”
To resume the account of the vascular system of Plewrochwta; in the 11th,
12th, and 13th segments the hearts, connected as in the other segments with
the dorsal vessel, give off two branches directly after issuing from it, the
posterior one is distributed to the mesentery behind, and the anterior one to
the walls of the alimentary canal; the mesenteric branch appears to be given
off in the other segments anterior to the 11th, but not the intestinal, at least it
was not visible in either of the specimens dissected. From the supra-intestinal
* D’Upekem, Nouv. Mém. de V Acad. Roy. Bruz., t. xxxv., 1865.
{ Lanxester, “On the Anatomy of the Earthworm,” Quarterly Journal of Microscopical Science,
1864-65.
{ Cuapargpg, loc. cit.
§ PrrRieR’s numerous memoirs already cited.
|| Varnuant, loc. cit. {| Horst, loe. cit.
** Variant, loc. cit. ++ Horsv, loc, cit.
{tt Perrier, Nouvelles Archives du Museum, p. 26.
VOR SX. PART II. 4H
498 MR. F. E. BEDDARD ON THE
trunks two or three branches are given off to the walls of the intestine.
These trunks with their branches are displayed in Plate XXYV. fig. 3. Behind
the 13th segment the dorsal vessel is ampullated, and appears to give off three
branches in each segment.
The supra-intestinal vessels run back for some considerable distance, but
they appear to unite into a single trunk, as has been already stated in the
account of the alimentary tract, where also the details of the intestinal circula-
tion are given.
The two lateral vessels at first run beneath the intestine, and are closely
adherent to it (Plate XX, VI. figs. 1, 2) ; ineach segment a branch is given off to
the mesentery. In Plate X XV. fig. 5 the distribution of the vessels in the anterior
part of the body is shown, including the 7th, 8th, and 9th segments ; the lateral
vessel (/) has here moved from the under surface of the intestine, and occupies
a lateral position ; it gives off one mesenteric branch in the 9th segment and
two in the 8th ; in the 7th and 8th segments a branch is given to the vascular
plexus on the surface of the gizzard, the ultimate ramifications of which are
connected by direct anastomosis with the branches given off from the first of
the transverse trunks uniting the dorsal and ventral vessels, and which haye
been already described. In the same figure the two anterior hearts (/) are
shown; each before joining the supra-nervian vessel (v) gives off a trunk
which supplies the body wall and mesentery. In fig. 6 the further course
forward, and the termination of the lateral and supra-nervian trunks, is shown;
they each give off corresponding branches to the mesenteries, which have the
relation to each other of artery and vein; the lateral trunks terminate among
the muscles of the pharynx, and the supra-nervian following closely the course
of the nerve cord ends on the upper surface of the anterior part of the pharynx
near to the cerebral ganglia.
The lateral vessels seem chiefly concerned with the blood supply of the
mesenteries. I was unable to trace them further back than the 18th segment,
which is no doubt owing to the fact that in this part of the body the mesenteries
are supplied with blood by the supra-nervian trunk.
The supra-nervian vessel runs continuously from one end of the body to the
other, lying just above the ventral nerve cord; in each segment it gives off a
branch on either side, which supplies the body wall and mesentery ; in the
region of the hearts, however, this branch is not given off, the mesenteries
being supplied from the dorsal and lateral vessels ; in the anterior part of the
body the ventral vessel runs between the spermathece, giving off two main
branches on each side, which have been already described as corresponding to
branches of the lateral vessels.
These are the chief facts in the circulatory system of Pleurochwta; a
general scheme of the whole circulation is shown in Plate XXV. fig. 4.
ANATOMY AND HISTOLOGY OF PLEUROCH ATA MOSELEYIT. 499
Nervous System.
The nervous system of Pleurocheta consists of a pair of cerebral ganglia
fused in the middle line, but still perfectly distinguishable, occupying the first
segment of the body, which are connected with a ventral chain by a pair of
commissures. From either end of the cerebral ganglia a bunch of nerve
filaments is given off, running towards the anterior end of the body. The
commissures uniting the cerebral ganglia with the ventral chain are swollen in
the middle, where they give off a number of nerves, one set from the anterior
surface and another from the posterior. This part of the nervous system is
represented slightly magnified on Plate SEXO fig. 1; the posterior part of the
commissure is seen in this figure to be separated here and there from the main
mass, and would appear to represent the rudiment of a visceral nervous system
so generally developed in the Oligochwta, and to resemble more closely the
visceral nervous system of Urochwta, which consists of a second cesophageal
collar, rather than that of the other types of Oligochwta. In fig. 2 we have the
anterior part of the ventral chain, together with the cerebral ganglia, and one
of the commissures uniting the former with the latter. From the first ventral
ganglion the nerves are given off anteriorly, but from all the rest the nerves are
given off in pairs at right angles to the axis of the cord; from each ganglion three
nerves take their origin on each side, of which two become united immediately
after leaving the ganglion ; there is in each segment another pair of nerves given
off between each of the ganglia. After the 12th segment the ganglia diminish
considerably in size. The first ventral ganglion is placed in the second segment
of the body, and following this there is one to each of the other segments. On
the upper surface of the cord is a hyaline band extending along its whole length;
this appearance may be produced by the “giant nerve fibres” lying on the
dorsal surface of the cord. These structures, which are very general throughout
the Annelida, have received various names ; they are the “giant nerve fibres”
of Leypie, the “ tubular fibres ” of CLAPAREDE, the “ neural canal” of M‘INTosH ;
they have been compared to the notochord of the vertebrate, and also to the
neural canal, but this latter hypothesis is not borne out by the description
of the development of the medulla in Lumbricus by KovaLevsky and by
KLEINENBERG. Quite recently SpenceL* has described a single tubular body
with coagulated fluid contents in the nerve cord of Echiwrus Pallasii. In all
annelids where these structures have been observed, they are seen to consist
of three longitudinal tubes filled with a coagulated fluid, and provided each
with a special fibrous sheath; this is the case, for instance, in Lumbricus and
in Pontodrilus. In Pleurochwta these tubes are four in number, three of which
are arranged on the ordinary plan, and the fourth, which is about equal in size
* SpencEL, Zeitschrift fiir Wissenschaftliche Zoologie, 1880.
500 MR. F. E. BEDDARD ON THE
to each of the two smaller lateral ones, lies beneath the central larger tube.
Each of these tubes (see Plate XX VII. figs. 3, 4, 5) is provided with a special
fibrous sheath, outside which is another thicker fibrous sheath; these outer
coats, however, are more or less continuous with each other, and with the
septa dividing up the interior of the medulla, and perhaps ought not to be
regarded as forming another special sheath to each of the tubular fibres.
This description is more in accord with that of CLAPAREDE* for the common
earthworm, than with the description of Pontodrilus by PErriER,t who denies
the presence of a special sheath to each of the tubular fibres. The nerve cord
of Pleurocheta is surrounded by a thick membrane, which has the appearance
of elastic tissue ; in this are imbedded muscular fibres, sometimes singly and
sometimes two or three together (fig. 3). The structure of the medulla itself
varies according to the region from which the section is taken; fig. 4 is a
section through one of the ganglia, and fig. 5 through the middle part of a
commissure between two ganglia. The difference is at once apparent. There
are no nerve cells in fig. 5. The nerve cells are developed on the under surface
of the ganglia, and are found to extend some way along the commissures.
Fig. 3 is a more highly magnified section through the middle of one of the
ganglia. All the details given in the following description of the minute struc-
ture of the nerve cord will be found represented in one or all of the figures
already mentioned.
Each ganglion is in reality composed of two fused ganglia, which is very
clear on examining a section; the nerve cells are arranged in two lateral groups,
and there are two circular areas separated off from the rest of the ganglion by
septa of connective tissue, which are the interganglionic commissures uniting
the different ganglia of the nerve cord with each other. In those parts which
lie between the ganglia, the whole cord is made up of these commissural
masses, there being no nerve cells present; these areas are occupied by a
reticulum of connective tissue, in the meshes of which lie the nerve fibres, and
a few small nerve cells differing altogether in size and appearance from the
large nerve cells found in the ganglia. The rest of the ganglion is divided up
by a finer meshwork of connective tissue, with stouter fibres here and there ;
the nerve cells, which are pear-shaped, lie with their apices pointing towards the
interior of the ganglion; the processes of these cells, which are for the most
part unipolar, were generally traced into connection with the fibres constitut-
ing the interganglionic connectives; each ganglion cell is provided with
a large nucleus and nucleolus and lies in a space in the otherwise continuous
meshwork. The fibres which make up the lateral branches given off in every
* CLAPAREDE, loc. cit.
t+ Perrier, Arch. de Zool. Exp., vol. ix.
ANATOMY AND HISTOLOGY OF PLEUROCH ATA MOSELEYIT. 501
segment from the nerve cord are almost entirely derived from the
central commissural masses, but some take their origin from other parts of the
ganglion.
Generative System.
The genital apparatus of Plewrochwia is manifested externally by the
clitellum, by the apertures of the spermathece, and by four other pairs of
apertures, of which three lie in a hollow sucker-like structure just at the
posterior end of the clitellum, and the remaining pair still within the clitellum,
but opening more anteriorly in the 13th segment.
The clitellum itself is a little difficult to map, but I have considered that
all those segments form part of it upon which any glandular development is
visible with the naked eye. Counting in this way, one specimen showed a
clitellum consisting of seven, possibly eight segments, but in the last segment
the glandular development was very slight, and the sete were as numerous as
in any of the posterior rings not belonging to the clitellum. In the other
specimen the clitellum was far more strongly developed, occupying apparently
nine segments, in the first and last of which a complete series of sete were
present. In the segments forming the clitellum, with the exceptions just
mentioned, the development of setze is very slight, and entirely confined to a
small tract on either side of the median ventral region, where, as in the rest
of the body, no sete are developed. Among the Oligochwta some forms are
provided with setz on the clitellum, and some are not; in the species of
Pericheta described by Horst the clitellum is marked by an absolute lack
of setee, but in Perichwta afinis described by Perrier, ‘ on distingue parfois
nettement le circle des soies caracteristique des Pericheeta.” The clitellum
commences after the 12th ring, and its segments can be counted either by the
mesenteries or by the lines of setz which, as just described, exist on the
clitellum of this animal; the last of the specially-thickened mesenteries forms
its anterior boundary. Of the intimate structure an account has already been
given, under the description of the body wall.
At the posterior end of the clitellum in the median ventral line is a hollowed
out area (Plate X XV. fig. 9), upon which no glandular development has taken
place ; it is divided into four cavities, by two ridges running at right angles to
each other ; the transverse ridge bears upon the end nearest to the clitellum,
on either side, an aperture which is continuous with the duct of a solid white
gland (Plate X XV. fig. 7), occupying the 18th segment. Each of the four cavities
or hollows formed by the two ridges bears another aperture; the anterior
pair open into the 17th segment, and the posterior into the 19th. These
apertures were not directly visible from the interior, being apparently covered
502 MR. F. E. BEDDARD ON THE
by a layer of the peritoneum. No ducts were visible in communication with
either of these pairs of orifices in either specimen.
The sucker-like structure is possibly used by the animal during copula-
tion.
The two openings in the 15th segment, which were only visible in one of
the two specimens at my disposal, had again no apparent duct connected with
them.
The clitellum of Plewrocheta is remarkable for being composed of an
unusually large number of segments; in Perichwta the number is almost
constantly three ; m Pontodrilus there are five, and in Urocheta hystrix as
many as seven segments in the clitellum ; but Iam unable to recall any form
except Pleurocheta in which there are more than this.
PERRIER,” in an important memoir which has been already several times
spoken of, divided the Oligochwta into three groups, according to the position
of the male generative orifices.
(1) The Antechtellians, e.g., Lumbricus.
(2) The Lntraclitellians, e.g., Urocheta.
(3) The Postchtellians, e.g., Pericheta.
On PERRIER’S system the genus Pleurocheta would be regarded as one
of the Intraclitellians, the generative openings lying within the clitellum; if,
however, the apertures in the 17th and 19th segments in reality are connected
with the testes, which unfortunately I have been unable to prove, then their
position is somewhat intermediate between the Intra- and Postclitellians ;
whether this be so or not, the number and distribution of the generative orifices
in Pleurocheta are so peculiar and so different to anything known in the
Oligocheta, that PERRIER’s system would be very artificial, if it proposed to
unite in one family two such very divergent types as Urochwta and Pleurocheta.
In many characters Pleurocheta resembles Perichwta, which is one of the Post-
clitellian group; for instance, in the absence of segmental organs, in the
presence of a pair of “ prostate” glands, and in the fact that the ovaries are
small and difficult to find (I have not satisfied myself as to their existence in
Pleurocheta) ; the last two characters distinguish the Postclitellians as a group.
On the other hand, the presence of two ceca on the alimentary canal, and the
double spermathecze, are invariably characteristic of Perichwta; these are
absent from Plewrocheta.
The characters in which Pleurocheta agrees with the Intraclitellians are,
firstly, the position of the generative openings (?); secondly, the possession of
only one pair of testes, which is a character found also in Urochwta and
Titanus, and remarked as of importance for classificatory purposes by PERRIER,
though it is not universal in the Intraclitellians. The thickening of the
* Perripr, Nouvelles Archives, &c.
)
ANATOMY AND HISTOLOGY OF PLEUROCH ATA MOSELEYI. 503
anterior mesenteries described above is also found in Urocheta, though,
whether a modification of this kind can be made use of for the determination
of systematic relations is perhaps more than doubtful. The structure of
the alimentary canal at once distinguishes Plewrocheta from any described
genus, as does also the distribution of the sete. There seem to be no special
relations with the Anteclitellians, except perhaps the absence of “ cceurs
intestinaux.”
This résumé of the structural relation of Plewrochwta with other forms,
leaving out for the present the consideration of the generative apertures, shows
that it occupies a position between the Intraclitellians and Postclitellians, with
perhaps rather closer affinities to the latter group, but that it cannot definitely
be classed with either, but ought rather to form a group apart. This conclusion
is stengthened when we come to study the generative apertures; they are so
peculiar that they cannot be considered as conforming to the Postclitellian or
Intraclitellian type, though they are more closely allied to the latter than to the
former. We must then either regard the existing classification of PERRIER as
unsatisfactory, since it is not elastic enough to comprehend this new genus, or a
new group must be formed and added to the three groups already created by
PERRIER ; on the whole, the latter seems to be the wisest course. The state of our
knowledge with respect to the Oligochwta, as has been remarked several times
in the course of this memoir, is by no means advanced, and therefore it is use-
less at present to alter a classification which is extremely convenient ; whether
it will prove to be of permanent value is another question, which cannot yet. be
answered. On the principle of nomenclature adopted by PeERrtER for the
classification of the Oligochwta Terricola, it does not seem easy to select a name
that will have any meaning ; perhaps Jn/raclitellian will do, though it must be
admitted that the name is not a very expressive one.
Returning to the description of the generative organs. Pleurocheeta pos-
sesses one pair of testes situated in the 12th segment (see Plate XXV. fig. 7;
Plate XXVII. fig. 10), and presenting the appearance of racemose glands,
which is an extremely unusual character in the Oligochwta, but is paralleled in
the case of Plutellus* and Digaster.
In the 11th and 10th segments are two pairs of complicated folded organs
(Plate X XVI. fig. 8), concerning the nature of which there is some uncertainty ;
they lie in either case on the posterior wall of their respective segments, and
they are each continuous with a fine duct which runs backwards perforating the
mesentery, and is lost in the body wall of the segment behind ; it seems likely
that these fimbriated organs are the expanded terminations of the vasa deferentia,
but in this case we should expect to find them uniting into two tubes running
down the body wall on either side of the nerve cord ; nothing of this sort was
* Perrine, “ Etude sur un genre nouveau de Lombriciens,’ Arch. Zool. Exper., vol. ii. 1873.
504 MR. F. E. BEDDARD ON THE
visible, and they appear to open separately on to the exterior; however, in
Acanthodrilus, a Postclitellian worm, there are four male apertures instead of two,
so that, after all, there would be nothing so very remarkable in finding the same
thing in Plewrocheta, though their being so far in advance of the testes would —
seem to throw some doubt on the hypothesis of their being vasa deferentia.
The histological structure of the fimbriated expansion is shown on Plate
XXVI. figs. 14, 18; the last figure shows the columnar epithelium from above,
the cells are seen to be of a polygonal contour ; in transverse section (fig. 14) this
layer of columnar cells with their cilia is seen, beneath is a layer of connective
tissue which is crowded with blood-vessels. This extreme abundance of blood-
vessels is very characteristic of these organs ; when viewed entire from above, the
epithelium is seen to cover a plexus so closely pressed together that there is
hardly any space between two adjacent vessels; this largely developed vas-
cular supply makes it doubtful whether these organs may not be after all the
only remains of the segmental organs left in the animal.
On the opposite side of the mesentery, and corresponding with the anterior
pair of fimbriated organs, are two small rosette-shaped glandular bodies (Plate
XXVI. fig. 9) ; it is possible that these are the ovaries, though a careful histo-
logical examination revealed none of the characters peculiar to those organs ;
the absence, however, of ova may be perhaps accounted for by the fact that the
animal was found in a burrow with its cocoon, which evidently had not long
been deposited, and, accordingly, one would hardly expect to find the ovary,
having for the time ceased from its function, to consist of anything more than
a mass of indifferent cells ; a second pair could not be found; on the view that
these are ovaries, we may consider the fibriated bodies as oviducts; but in
this case we have the anomaly of four oviducts to two ovaries, and the
absence, as In Anteus *), of vasa deferentia.
There are four spermathece opening in pairs between the 7th and 8th, and
the 8th and 9th segments. Their position is shown in Plate X XV. figs. 6,7 ; in
the former figure, that of the posterior right hand spermatheca is considerably
larger than the others ; this is drawn from one of the two specimens that I
dissected ; in the other, all the four spermathece were as nearly as possible of
the same size.
Each spermatheca (Plate X XV. fig. 13) consists of two divisions ; the part
opening externally is much smaller than the other, but has far thicker walls ;
the chief part of the spermatheca has thinner walls.
Cocoon and Embryos.
Each of the specimens of Plewrochweta was found, as already stated, at the
bottom of a deep burrow, together with a single egg-case; these two cocoons
ANATOMY AND HISTOLOGY OF PLEUROCHATA MOSELEYI. 505
- differ slightly in size, the larger measuring 3°9 c. in length and 1°85 c. in
breadth, and the smaller 3:1 c. in length and 1'9 cc. in breadth. The cocoons
_ are glassy in appearance and of a dull bottle-green colour, the smaller specimen
with three bands of a darker green at one end, the larger specimen of a uniform
colour. Each cocoon appeared to have two openings, one at each end; the
anterior opening was obvious, but of the existence of the other I was not
quite able to satisfy myself. The chitinous wall of the cocoon exhibits no
particular structure. Plate X XVII. fig. 12 represents one of the cocoons of
the natural size. The larger cocoon was opened, and contained two embryos
slightly folded upon each other, as shown in fig. 11, and surrounded by a
quantity of firm coagulated matter, which no doubt is the remains of the
food yolk. The embryos lie, as represented in the figure, with their anterior
extremities towards the orifice of the cocoon. The two embryos separated
from each other, and entirely freed from the food yolk, are shown in figs.
6, 7. One of these two was selected for study, but my time was unfor-
tunately limited, so that only a few points in its structure were made out.
The first thing to which my attention was directed, was naturally the distribu-
tion of the sete, but the embryos were so far advanced that the setz were.
present in their full number, and with the characteristic distribution found in
the adult (Plate XXVII. fig. 15). Fig. 13 of the same plate represents a vertical
section through the body wall in the dorsal region, where the longitudinal
muscular coat ¢’ undergoes a curious alteration ; instead of the fibres being
arranged in compartments separated by trabecule of fibrous tissue, as in other
parts of the body, there is a network of connective tissue, which has very much
the appearance of the reticulum of fat, and which at the two sides becomes
gradually continuous with the fibrous trabecule; about the middle of this
reticulum is a single line of muscular fibres, which appear to be of a somewhat
greater diameter than those in the other parts of the longitudinal coat. The
circular coat undergoes also an alteration in this region; the fibres are more
wavy, and less regular in their arrangement; this is displayed also in fig. 16,
which represents a strip of the skin torn off and examined entire ; moreover,
the changes undergone by the two muscular coats are shared by the epithelium
and by the cuticle, both of which are increased considerably in thickness.
- What the meaning of this is I cannot guess, neither had I any time to re-
examine the adult to see if there was the same alteration of structure on the
dorsal surface; since, however, this band was perfectly visible to the naked
eye, and as there was no such difference apparent in the adult it would seem
after all to be-peculiar to the young specimen.
VOL. XXX, PART II. = 4
506 MR. F. E. BEDDARD ON THE
Postscript—(added Nov. 21).
(1) Since writing the above account of the anatomy of Plewrocheta, I find
that a memoir has been overlooked which explains the anomalous structure of
the dorsal vessel. This memoir is by Dr. F. Vespovsky, and is abstracted in the
Journal of the Royal Microscopical Society for 1880. Dr. VEspovsxy, in study-
ing the development of Criodrilus, discovered that the dorsal vessel is formed
by the coalescence of two completely separate rudiments—the same mode of
development had been previously shown by Kova.Levsky to take place in
Lumbricus—these facts, VEsDOvsKY points out, are of extreme importance in
considering the relationship between the Annelida on the one hand, and the
Vertebrata and Crustacea on the other, since in the Vertebrata generally, and in
Apus among the Crustacea, the heart is formed in the same way by the
coalescence of two rudiments which at first are distinct. The Hermellida,
according to DE QUATREFAGES, possess two dorsal vessels in the posterior part
of the body which are joined into a single tube anteriorly, and in Pleurocheta
the same embryonic character is shown in the dorsal vessel, but in a much
more marked degree ; it is evidently formed of two incompletely fused tubes
(cf. Pl. OXY. ties).
(2) Ihave attempted to show that there is a fundamental similarity in the
structure of the muscles of the longitudinal coat throughout the Oligocheta, and
that Lumbricus is not to be regarded as differing essentially from other
Oligocheta in this respect. This conclusion is quite justified by the facts
brought forward by the Drs. Hertwie in their “ Coelomtheorie,” * which I had
not read at the time that I was preparing this paper. These authors show the
general similarity, both in structure and development, that exists between the
muscles of the Annelida, Chetognatha, Vertebrata, and other orders in which
there is a true enteroccele. In these groups the muscular tissue is developed from
the epithelial lining of the perivisceral cavity, and almost without exception
from the parietal layer; the elements—the fibrillee—are invariably bound together
to form higher unities ; such as, for example, the fibril bundles of many verte-
brates, and are also characterised by the regularity of their arrangement. In
the Mollusca and Platythelminthes, and other groups in which there is not a
true enteroccele, the muscles are developed from cells of the ‘‘mesenchym,”
which have the character of connective tissue cells ; they frequentlypossess
longitudinal striz, which are not, however, to be regarded*as expressing a
fibrillation, and are always arranged irregularly, crossing each other in various
directions, and contrasting very strongly with the regular arrangement of the
“ epithelial” muscles of the Annelida, Vertebrata, &c.
* Jen, Zeitsch. fiir Natirwiss., 1881.
ANATOMY AND HISTOLOGY OF PLEUROCHATA MOSELEYI. 507
On plate iii, of the “Ccelomtheorie” there are figures of the muscles in
a great variety of animals belonging to different groups, and a comparison of
fig. 13, with my drawing of the muscular compartments of the young Pleuro-
cheta (Plate X XVI. fig. 15), shows a very striking resemblance, and it seems
highly probable that the muscular compartments of Pleurocheta are homologous
with the “ Muskelkistchen” of Petromyzon. On page 6 of the ‘ Coelomtheorie,”
the authors sum up briefly the account of the anatomy and development of the
muscles given in a previous memoir on the Chetognatha:—“ As in the Actinize
from the epithelial cells of the diverticula of the Archenteron, so in the Cheetog-
natha from the parietal epithelial layer of the Coelome (=Somatopleure) are
secreted muscular fibrillee, which become united into a lamella. In the further
process of development of this lamella it becomes folded, and gives rise to
muscle plates (Muskelblitter.)” This statement surely is not reconcilable
with that made on page 63 of the same memoir :—“ Each muscle plate (in
Petromyzon) is formed by the neighbouring borders of two myoblasts .... .
the close resemblance to the muscle plates in the Chetognatha, many
Nematoda, and the Annelida, is so obvious, that it is sufficient merely to have
called attention to it.”* It is certainly quite true that the resemblance here
remarked upon is very close, but of course there can be no real similarity in detail
if the development in Sagitta is such as it is stated to be in the former of the two
passages cited; there is clearly no “folding” in the case of Petromyzon. Still
less can there be any comparison made between Lumbricus and Petromyzon, since,
according to the Drs. HErtwie, a second folding has taken place in Lumbricus,
so that a “ fibril” here is not the-equivalent of a fibril in Sagitta or Petromyzon ;
at the same time, the letter fis made use of to denote the fibrils in all the
three types, which is rather confusing, and might lead one at first to believe that
they were considered to be homologous structures. The development of the
muscles in Lumbricus is at present not known, so that any comparisons made
with other forms can only have a slight value; the evidence that we have,
however, appears to me to point to the conclusion that there is no need to
imagine a second folding in the longitudinal muscles of Lumbricus. Had there
been a second folding, we might have expected to find a septum of connective
tissue between the secondary lamella, continuous with that separating the
primary lamellz ; but this does not seem to be the case ; although CLAPAREDE
describes the central fibrous septum as sending branches between the fibrils,
the inter-fibrillar substance is of a very different appearance from that forming
the septum, according to the figures given on plate iii. of the “ Ccelomtheorie.”
It is a delicate granular substance with frequent nuclei, and is more like
the part left over in the original myoblast after the secretion of the muscle
fibrils. At any rate, the absence of capillaries and pigment granules, which are
* Jen. Zeitsch. fir Natiirwiss., 1880,
508
MR. F. E. BEDDARD ON THE
abundantly found in the septa, mark it out as something distinct. These facts
(in the absence of embryological data) are also quite in harmony with the view
that the muscle plate in Lwmbricus is like that of Petromyzon, “ formed
by the neighbouring borders of two myoblasts,” and that the septa form the
boundaries of muscular compartments which are comparable to those of
Pleurocheeta or to the “ Muskelkistchen” of Petromyzon.
EXPLANATION OF PLATES.
PLATE XXV.
d, Dorsal vessel. l, Lateral vessel.
s, Supra-intestinal. x, Prostate glands.
b, Supra-nervian. p, Dorsal pouches.
h, Heart. y, Spermathece.
1.—General view of Plewrocheta Moseleyi, half natural size. , kidney-shaped glands.
2,—Dorsal vessel; a is the same.as a@ in fig. 5.
3.—Vessels of segments 11th, 12th, and 13th; the letter ilies on the intestine ; m,
mesenteries ; the lateral vessels are left out to simplify the figure.
4.—General scheme of circulation.
5.—Vessels of segments 7th, 8th, and 9th.
6.—Anterior course of lateral and supra-nervian trunks.
7.-—General view of the anterior part of the body, rather more than half the natural size.
The main divisions of the alimentary canal are shown. ¢, testes; 0, oviducts (?).
8.—Portion of body with intestine laid open, to show the dorsal pouches; ¢ points
to the dorsal fibrous band, / to the ventral, and a to one of the lateral ones.
9,—Clitellum showing the four pairs of apertures ; three pairs close together at posterior
margin, barely within the clitellum.
. 10.—Vessels of one segment on one side—a little anterior to kidney-shaped glands.
‘ig. 11.—One of the kidney-shaped glands, showing its duct and. blood-vessels of same
Fig
segment.
. 12,—Three of the kidney-shaped glands, with adjacent blood-vessels. Twice natural size.
Fig. 13.—Spermatheca. About three times the natural size.
PLATE XXVI.
1.—Diagrammatic transverse section through anterior part of body, to show arrangement
of vascular trunks, which are lettered as in preceding plate. , nerve cord.
2.—Section through body in front of fig. 1, showing absence of supra-intestinal vessels.
3.—Transverse section through clitellum, showing one of the glands. ¢, transverse
muscular coat ; 7’, longitudinal. x 60.
4.—Section through body wall cut transversely to the longitudinal coat, showing .
capillaries ending in epithelium. x 120,
=
Fig.
Fig.
Fig.
ANATOMY AND HISTOLOGY OF PLEUROCHATA MOSELEYI. 509
5.—Section through body wall cut transversely to circular coat: septa of fibrous tissue
and muscular fibres between. x 120.
6.—Section through clitellum. a, remains of hypoderm; below this gland cells; ¢,
circular muscle coat; 7’, longitudinal muscle coat. x 60.
7.—Section through clitellum, more highly magnified. x 200.
8.—Fimbriated organ. x3.
9.—Mesentery, showing relative positions of a, rosette-shaped body ; 8, fimbriated organ ;
c, ventral blood-vessel.
. 10.—Diagram of longitudinal muscle coat of Lwmbricus, cut transversely.
g. 11.—Portion of clitellum, to show invasion of muscular fibres into glandular layer. x 540,
g. 12,.—Transverse section through intestine in region of kidney-shaped glands; d, cells of
peritoneal cavity.
. 13,—Section through body wall in anterior region, cut rather obliquely; a, marks
boundary between circular and longitudinal coats; 0, special muscular layer
uniting setze of one segment. x 200.
. 14.—Transverse section through fimbriated organ.
. 15.—Transverse section through anterior end of young Plewrocheta, to show the com-
partments in which the longitudinal muscles are arranged. x 200.
. 16,—Oblique section through body wall, showing special muscles serving for the protrusion
of the seta. x 120.
. 17.—Unicellular glands, from clitellum. x 540.
g. 18.—Polygonal epithelial cells, from surface of fimbriated organ.
g. 19.—Section through kidney-shaped gland. «a, septum between two lobules. x 20.
IP GATE Xexev Til.
1.—Commissure connecting cerebral ganglia with ventral nerve chain.
2,—Anterior part of nerve cord. ¢, cerebral ganglia; 0, commissure, enlarged in fig. 1.
3.—Section through a ganglion of ventral chain. x 200.
4,—Section through a ganglion of ventral chain. x 30.
5,—Section through middle part of commissure uniting two ganglia. x60,
. 6, 7. Embryos taken from cocoon, Natural size.
8.—Gizzard cut open in middle, showing the chitinous lining, a. Natural size.
9.—Section of a portion of one of the kidney-shaped glands. x 200.
. 10.—Stout mesenteries in anterior part of body. Natural size.
11.—Embryos from cocoon before being separated from each other. Natural size.
ig. 12.—Cocoon. Natural size.
g. 13.-—Transverse section through body wall of embryo on dorsal side. ¢, hypoderm; ¢,
transverse muscular coat; ¢’, longitudinal coat.
14.—Strip of the skin of young Plewrocheta, to show the setee and their special muscles.
15.—Diagrammatic vertical section through Plewrocheta, to show arrangement of setz.
16.—Strip of skin from dorsal part of embryo, from the same region as fig. 13.
VOL, XXX. PART II. 4k
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NEUROPTERIDER. 10. Lepidodendron, sp.
5. Neuropteris heterophylla, Brongn, 11. Lepidophyllum lanceolatum, L. & H.
In comparing the list of the species contained in this collection (except those
from Canonbie) with the fossil plants from the Calciferous Sandstone series
in the neighbourhood of Edinburgh, their similarity will be at once apparent.
This is remarkable when viewed in relation to the fish and crustacean
remains which have been already described from Eskdale and Liddesdale, by
R. H. Traquatr, Esq., M.D., F.R.S., and Beng. Peacu, Esq., F.R.S.E., which,
as far as at present known, are mostly peculiar to these districts.
This points to some local physical conditions, which, though favourable for
the growth of plants, widely distributed in other parts of Scotland, seem to have
favoured the existence of a fauna peculiar to itself.
DESCRIPTION OF GENERA AND SPECIES.
THALLOPHYTA.
ALG,
Chondrites, Goppert.
Fucoides, Brougn.
Chondrites plumosa, sp. nov., Kidsten.
Plate XXX. fig. 3, and Plate X XXII. fig. 2.
Description.Frond much branched, pinne about an inch long, densely
covered with short filamentous segments. Main and secondary axes threadlike.
Remarks.—None of the specimens of this plant are complete, so its original
length cannot be ascertained. It must have been a much-branched species,
and attained some inches in length.
The whole plant appears to have been very delicate, and the ultimate
divisions of the fronds are clothed with closely-set and very fine filamentous
segments about a quarter of an inch long, which give it a plumose
appearance.
It is all but impossible to place fossil A/gw in a true systematic classifica-
COLLECTED IN ESKDALE AND LIDDESDALE. 533
tion, owing to the imperfect manner in which their remains occur, and the
entire absence of fruit.
I have placed this and the following species in Chondrites, Stern., but it
appears to me that they might have been placed with equal propriety in
Fucoides, Brongn.
Position and Locality.—Frequent, but mostly in a fragmentary condition,
in the Cement-stone group of the Calciferous Sandstone series, Glencartholm,
Eskdale.
Chondrites simplex, sp. nov., Kidston.
Plate XXXI. fig. 14.
Description.—F¥rond filamentous, simple.
Remarks.—This Alga appears to have consisted of separate simple fila-
ments, from a thirtieth to the tenth of an inch broad, reminding one of the
recent genus Chorda, and probably growing in the same tufted manner.
The greater number of the component filaments appear in this specimen
to lie in a somewhat confused mass. It is probable that each of the parts was
separate when growing, but have assumed the tangled appearance subsequently.
In the larger filaments, neither apex nor base is shown, so an estimate can-
not be formed as to the length of the perfect fronds.
Only one specimen of this Alga has been obtained.
Position and Locality.—From the Cement-stone group of the Calciferous
Sandstones, Glencartholm, Eskdale.
Crossochorda, Schimper.
Crossopodia, MacCoy.
Crossochorda carbonaria, sp. nov., Kidston.
Plate XXX. fig. 4.
_ Character.—Frond pinnate, segments filamentous, springing laterally from
the central axis, from which they bend gently outwards and upwards.
Remarks.—This Alga was also probably of considerable length, though the
most perfect individual is only two inches long.
In their width the fronds vary considerably, some being fully half an inch,
others only the tenth of an inch broad.
The main axis appears as a furrow running down the centre of the frond,
from the sides of which the ultimate segments spring, and in their upward bend-
ing become somewhat adpressed, giving a plumose appearance to the plant.
The only other species with which this fossil is likely to be mistaken are
Crossochorda (Crossopodia) Scotica, MacCoy, and Cruziana semiplicata, Salter.*
* Mem. of Geo. Survey, vol. iii. p. 291.
534 ROBERT KIDSTON ON FOSSIL PLANTS
The former is easily distinguished from the present species by its small
size and much more delicate structure, and the latter, by the presence of a clear
border extending past the “ fringe.”
It has been suggested that the two genera, Crossochorda and Cruziana,
should be united, as the only generic distinction rests on the presence or
absence of the clear border extending past the ultimate segments.*
Several specimens of this plant have been found.
Position and Locality.—From the Cement-stone group of the Calciferous
Sandstone series, Liddel Water, near New Castleton, Liddesdale.
Bythotrephis, Hall.
Bythotrephis, sp.
Remarks.—Two specimens of a large Alga, which should probably be placed
in this genus, occur in Eskdale.
init
Both are imperfect, but the better example gives a fair idea of the plant.
It appears to have possessed a well-marked dichotomous growth.
The frond measures fully three-quarters of an inch in breadth, immediately
below the lowest dichotomy shown in the fossil.
Each dichotomy is accompanied by a slight constriction at the point where
it takes place.
The discovery of Alge in Scottish Carboniferous rocks being of rare occur-
rence, I have inserted a figure of this specimen, natural size, to draw the atten-
* Schimper and Zittel, Handb. der Paleontologie, Band ii. Lief i. p. 52.
COLLECTED IN ESKDALE AND LIDDESDALE. 535
tion of geologists to this plant, as more perfect specimens must be secured
before it can be satisfactorily determined.
Position and Locality—Glencartholm, Eskdale, in the Cement-stone group
of the Calciferous Sandstone series.
FILICACE..
SPHENOPTERIDE.
Sphenopteris, Brongn.
Sphenopteris linearis, Stern.
Sphenopteris linearis, Brongn., Hist. d. végét. foss., p. 175, tab. liv. fig. 1.
Lind. and Hut., Fossil Flora, pl. 230.
Sternberg, Flora d. Vorw., tab. 42, f. 4.
ehy ”
” ”
htemarks.—A tew specimens of this fern occur in the collection.
Position and Locality.—From the Cement-stone group of the Calciferous
Sandstone series at Docken Beck, near Langholm; Tinnis Burn, near New
Castleton, Liddesdale ; and Glencartholm, Eskdale.
Sphenopteris furcata, Brongn.
Sphenopteris furcata, Brongn., Hist. d. végét. foss., pl. xlix. figs. 4, 5.
Geinitz, Steinkohlf. in Sachs, tab. xxiv. figs. 8-13.
L. & H., Fossil Flora, pl. 181.
2 ?
” ”?
Remarks.—This fern occurs plentifully.
The specimens agree more fully with Bronentart’s figure of this plant than
with that of LinpLry and Hutton in their Fossi/ Flora, which appears to have
been a less lax form.
Position and Locality—From the Cement-stone group of the Calciferous
Sandstone Series, foot of Tarras Water, Eskdale.
Sphenopteris Geikiet, sp. nov., Kidston.
Plate XXX. fig. 5, and Plate XX XI. fig. 9.
Description.—Frond (?) bipinnate, narrow, linear, tapering suddenly to an
acuminate point; pinne alternate, rhomboidal, narrow; pinnules finely
divided into three or four narrow linear segments; nerves numerous.
Remarks.—This fern can be at once distinguished by its narrow lanceolate
form, and its much divided pinnze, composed of long narrow segments.
As far as I am aware, there is no other fossil fern with which this species
could be mistaken.
Of the five specimens of this plant which have been obtained, that figured
536 ROBERT KIDSTON ON FOSSIL PLANTS
was the most perfect, but on another the pinne were rather larger; all the
other examples were much less.
Though the pinnules of this fern in their tripartite segmentation show some
points of resemblance to Scutmper’s genus 77iphyllopteris, I have placed it in
Sphenopteris, to which it appears to be more closely related.
It gives me much pleasure to name this species after Dr. A. GEIKIE.
Position and Locality—From the Cement-stone group of the Calciferous
Sandstone series, Glencartholm, Eskdale.
Sphenopteris bifida, L. & H.
Sphenopteris bifida, L, & H., Fossil Flora, pl. liu.
as a Hibbert, “ Limest. of Burdiehouse,” Roy. Soc. Ed., vol. xiii.
, Ke Miller, Test. of the Rocks, p. 423, fig. 129.
Trichomanites bifidus, Geepp., Syst. Fil., tab. xv. fig. 11.
Todea Lipoldi, Stur., Culm-Flovra, tab. xi. fig. 8.*
Remarks.—This fern occurs very plentifully in Eskdale and Liddesdale.
Among these specimens is one showing its mode of growth very beautifully.
This specimen is nine and a half inches long, but the rachis does not appear
to be complete at its lower extremity.
Two inches above the apparent break the stem bifurcates.
On the main axis, below the bifurcation, are a few very small, and what may
be regarded as rudimentary pinne, which gradually increase in size from below
upwards, but the largest is only two-fifths of an inch long.
One of the main forks has been broken off about three inches above the
bifurcation, but the other is entire.
The portion of the broken fork is of the same size as the corresponding
part in the perfect one, so we may reasonably presume they were originally
equal. It would appear that this bifurcating of the main axis, a short distance
above its base was characteristic of the Sphenopteris linearis group (to which
group I feel inclined to refer the present species), as in several of the other
ferns of this class I have observed the same structure.t
The ultimate segments of the pinne consist of little more than a nerve with
a very narrow margin of delicate cellullar tissue.
In Linpiey and Hurron’s figure this narrow cellular margin has been
entirely destroyed;{ and in that of Stur its state of preservation has been
little better.§
* C. W. Peacu on “ Fossil Plants from the Calciferous Sandstone around Edinburgh,” Bot. Sce.
Ed., vol, xiii.
1
t Mr. C, W. Peacu has shown me young fronds of S. afinis in the circinate condition, exhibiting
very beautifully the two forks rolled up in a crozier-like manner,
{ os. Flora, vol. i. pl. liii.
§ Srur., Culm-Flora, tab. xi. fig. 8.
COLLECTED IN ESKDALE AND LIDDESDALE. 537
All these forms are shown among the numerous specimens comprised in this
collection.
Position and Localities—¥rom the Cement-stone group of the Calciferous
Sandstones at Kershope Burn and Tweeden Burn, Liddesdale; Plashetts
Burn, North Tyne, Northumberland ; and River Esk, Glencartholm, Eskdale.
Sphenopteris eacelsa, L. & H.
Sphenopteris excelsa, L. & H., Fossil Flora, pl. ecxii.
Plate XXX. fig. 2, and Plate XX XI. figs. 7 and 8.
Remarks.—This fern is extremely plentiful, and affords a very good example
of the latitude which must be allowed for deviation in minor details in the
various individuals of a given species.
The type figured by LinpLry and HurTon represents what may be regarded
as the middle form of the Eskdale specimens.
Departing from this, we have on the one hand a very lax form (Plate XX XI.
fig. 8), and on the other a more compact variety (Plate X XX. fig, 2).*
Had these two forms not been connected by a series of specimens, passing
from one to the other by almost insensible gradations, it would have been diffi-
cult to recognise them as belonging to the same species.
The fronds of this fern must have been large, judging from the size of the
pinnee, probably at least three feet in height. Hence it is extremely likely
that the small portions figured held different relative positions on the fronds
from which they came.
LinD.ey and Hutton say of the plant figured by them : “The specimens of
this beautiful fern are so imperfect, that we can neither ascertain what the
margin was of the leaflets, nor the nature of the veins... . . It appears, how-
ever, to belong to the genus Sphenopteris.”
In the specimens from Eskdale, the veins are well preserved, and show this
fern to be atrue Sphenopteris (Plate XX XI. fig. 7). The outline of the leaflets
also, in their figure, agrees with those specimens I have called the middle form.
Sphenopteris cuneolata+t of the same authors is perhaps only an ill-preserved
specimen of this species, exhibiting a bifurcation of the axis, similar to that
shown in Plate XXX. fig. 2. They also say in regard to this plant: “Nota
trace of veins could be found in the specimen from which the drawing was made.”
Position and Locality.—From the Cement-stone group of the Calciferous
Sandstone series, Glencartholm, Eskdale.
* This is not so well shown in the small portions figured as in the larger specimens,
+ Los. Flora, vol. ii. pl. 214.
538 ROBERT KIDSTON ON FOSSIL PLANTS
Sphenopteris Hibberti, L. & H. (var.)
Sphenopteris Hibberti, L. & H., Fossil Flora, pl. elxxvii.
Plate XXX. fig. 1.
Remarks.—Two specimens obtained in Eskdale I have placed under this
species.
They are more compact in their mode of growth, and the pinnules less seg-
mented, than in the type of this plant figured in the Fossil Flora of Great Britain,
pl. clxxvii. These differences, however, appear to be insufficient for the creation
of a new species.
Position and Locality.—From the Cement-stone group of the Calciferous
Sandstone series, Glencartholm, Eskdale.
Sphenopteris Honinghausi, Brongn.
Sphenopteris Honinghausi, Brongn., Hist. d. végét. fos., tab. liii.
: : Geinitz, Verst. d. Steink., tab. xxiii.
‘A * Andre, Vorwelt. Pflanz., tab. iv., v.
i 55 Schimper, Paléont. végét., tab. xxix.
Remarks.—The specimens of this species are more similar to LINDLEY and
Hurton’s drawing of this plant than to Bronentart’s original figure.
Position and Locality—¥rom the Cement-stone group of the Calciferous
Sandstone series, Glencartholm, Eskdale.
Sphenopteris decomposita, sp. nov., Kidston.
Plate XXXII. figs. 1, la, 4, and 5.
Description.—Frond tripmnate; primary pinnee, alternate, deltoid, their
margins touching or overlapping; secondary pinne narrow-deltoid, again
divided into pinnee of the third degree, which bear two or three pairs of cuneate
segments with slightly rounded angles, the lower pair notched or divided into
three pinnules ; veins numerous ; rachis thick.
Remarks.—This beautiful fern appears to be very distinct from any species
with which Iam acquainted. The portion drawn on Plate XX XII. fig. 1 is from
the central part of a frond; that at figs. 4 and 5 shows the lower extremity of
the rachis, which bears smaller and much less divided pinnee.
From this it appears that the perfect frond was broadest towards the centre,
tapering gradually to each extremity.
In the general appearance of the ultimate segments, this plant has a slight
resemblance to Sphenopteris dilatata, L. & H.,* but is distinguished from this
species by its much-divided pinne and the cuneate pinnules, which become
attenuated into a small stalk. |
* Sphenopteris trifoliolata artis, s.p.
COLLECTED IN ESKDALE AND LIDDESDALE. 539
Position and Locality —¥rom the Cement-stone group of the Calciferous
Sandstone series, Glencartholm, Eskdale.
Sphenopteris, sp.
Remarks.—Among the collection are a few Sphenopteroids, which, though
too imperfect for identification, are, I believe, distinct from any already
mentioned.
Position and Localities.—From the Cement-stone group of the Calciferous
Sandstone series, at Glencartholm ; Docken Beck and foot of Tarras Water,
Eskdale; and Liddle Water, Newcastleton, Liddesdale.
Staphylopteris, Presl. (Lesq. 1870).*
Sorocladus, Lesq., 1880.+
Staphylopteris Peachii, Balfour.
Staphylopteris Peachti, Balfour, Bot. Soc. Ed., vol. xii. p. 176.
5 » OC. W. Peach, Quar. Jour. Geo. Soc., vol. xxxiv. pl. viii. p. 133.
Plate XX XI. fig. 6.
Several specimens of this fossil have been obtained. It is extremely pro-
bable that the original specimens, on which the species was founded, belong to
Sphenopteris linearis, Brongu., as this fern, and it alone, most frequently occurs
on the same slab. Hence I include Staphylopteris Peachit among the Sphenop-
teroids. Through the kindness of Mr. C. W. Pracu, I have been enabled to
compare the Eskdale specimens with the original plants in his cabinet, and
though on an average they are slightly larger, place them in the same species,
as the types vary in size among themselves.
In deference to the opinion of certain geologists, who object to the genus
Staphylopteris being used for the reception of “ fructifications of ferns,” other
than Tertiary species, LEsquEREUX has proposed the name Sorocladus, in which
to include the Carboniferous forms. Under this name he places species whose
“sori have various forms,” and presumably belonging to distinct genera. As
both these names are at the best of a most provisional nature, the constitution
of a new genus, whose only character requires that the specimens be Carboni-
Jerous, appears to possess no advantage over the older name, hence I retain the
original name Stuphylopteris for these fossils.
Position and Locality.—From the Cement-stone group of the Calciferous
Sandstone series, Glencartholm, Eskdale.
* Geo. Sur. of Iilin., vol. iv. + Coal Flora of Pennsyl. and U. 8.
{+ I differ from Mr. C. W. Psacu in the identification of his Sph. affinis, and prefer calling the form
which occurs on the slabs with Staphylopteris Peachii, Sph. linearis. What I regard as Sph. affinis
differs from S, linearis in having much smaller pinnules. It is most likely that these two ferns should
form only one species, and, at the most, S. affinis be regarded as a variety of S, linearis.
VoL. XXX. PART IL. 4p
540 . ROBERT KIDSTON ON FOSSIL PLANTS
Eremopteris, Schimper.
Eremopteris erosa, Morris.
Sphenopteris erosa, Morris ; Murchison, Geo, of Russia, ii., pl. C. f. 3.
Position and Locality.—Plentiful in the Cement-stone group of the Calciferous
Sandstone series, Glencartholm, Eskdale. .
Evremopteris Macconochii, sp. nov., Kidston.
Plate XXXII. figs. 3 and 3a,
Description.—Frond bipinnate ; pinne alternate, lanceolate ; pinnules rhom-
boidal, distinct, margins laciniate or cut into narrow linear segments, dentate
at their apices, the pinne attached to the rachis by their attenuated decurrent
bases ; veins numerous.
Remarks.—Only one specimen of this fern has been met with. It is dis-
tinguished from Hremopteris elegans, Ett., by its regular rhomboidal and dis-
tinctly separate pinnules.
These characters and the regular mode of its growth, clearly define this
species from the other members of the genus.
I have pleasure in naming this fern after Mr. ArtHur Macconocuis, who
was the chief collector of the Eskdale and Liddesdale fossils.
Position and Locality.—From the Cement-stone group of the Calciferous
Sandstone series, Glencartholm, Eskdale.
Rhacophyllum Lactuca (Sternb.), Schimper.
Rhacophyllum Lactuca (ster), Schimper, Paléont. végét., tab. xlvi. f. 1; xlvii. f. 2.
Schizopteris Lactuca, Presl. in Sternb. FV. d. Vorw., it, p. 112.
. 5 Genitz, Ste/nkohl. v. Sachs, tab. xxvi. f. 1; tab. xviii, xix. (specimina speciosissima).
Pachyphyllum Lactuca, Lesq., Geo. of Pennsyl., vol. ii. pl. viii. f. 4, 5.
Hyinenopyllites Clarhii, Lesq., Paléont. of Illinois, ii. pl. xxxix.
Remarks.—Of this fossil, concerning whose true affinities so many opinions
are held, only one specimen has been obtained.
Position and Locality —F¥rom the Cement-stone group of the Calciferous
Sandstone series, Docken Beck, Eskdale.
PALAOPTERIDEA,
Adiantites, Brongn.
Adiantites Lindseeformis, Bunbury.
Racopteris Machaneki, Stur., Culm-Flora, tab. viii. fig. 4.
es paniculifera, Stur., Culm-Flora, tab. viii. fig. 3.
Remarks.—This plant is certainly identical with Racopteris Machaneki, Stur.,
COLLECTED IN ESKDALE AND LIDDESDALE. 541
and also I think with his R. paniculifera. Tis figure of the former species
appears to be the lower part of a frond, that of the latter an upper part, very
beautifully showing its mode of fructification.
Among the Eskdale plants are two which exhibit a similar bifurcation of
the main axis, as shown in his figure of A. paniculifera.
Sphenopteris alciphylla, Phill.,* appears to have been a specimen of this
plant, where the ground tissue of the pinnules has been destroyed and the veins
only preserved.
Position and Locality—A few specimens from the Cement-stone group of
the Calciferous Sandstone series, Glencartholm, and Foot of Tarras Water,
Eskdale.
NEUROPTERIDES.
Neuropteris, Brongn.
Neuropteris cordata, Brongn.
Neuropteris cordata, Brongn., Hist. de végét. foss., pl. lxiv. fig. 5.
femarks.—One pinnule of this large species has been obtained.
Position and Locality—From the Cement-stone group of the Calciferous
Sandstone series, Glencartholm, Eskdale.
Neuropteris (Cyclopteris) Trichomanoides ? Brongn.
Neuropteris (Cyclopteris) trichomanoides, Brongn., Hist. de végét. foss., pl. Ixi. fig. 4.
Remarks.—A small specimen about an inch broad, and rather less than an
inch long, may perhaps belong to this species.
Position and Locality.—From the Cement-stone group of the Calciferous
Sandstone series, Glencartholm, Eskdale.
STIPES FILICINA.
Caulopteris, L. & H.
Caulopteris minuta, sp. nov., Kidston.
Plate XX XI. figs. 1 and la.
Description.—Scars oval, somewhat less than the fifth of an inch long, and
rather more than the tenth of an inch broad at their greatest diameter. They
' stand about three-tenths of an inch apart, and are arranged in spiral series.
The impression of the vascular bundle forms a narrow oval band, running
* Tllustrations of Fossil Botany, G. A. Labour, pl. xxxvii., 1877.
542 ROBERT KIDSTON ON FOSSIL PLANTS
parallel to the contour of the scar, having a sharply inflected notch at its upper
extremity.
Remarks.—The specimen is five and a quarter inches long and one inch
broad, but appears to have been originally broader.
The upper part of the fossil is covered by a smooth carbonaceous film, which
probably represents the outer surface of the bark.
At first sight one would take this plant for a species of Stigmaria, but from
the form of the scars and the shape of the vascular bundle impression, it must
be placed in Cawlopteris, as that genus is at present defined. Only one specimen
has been obtained.
Position and Locality—¥rom the Cement-stone group of the Calciferous
Sandstone series, Kershope Burn, Liddesdale.
EQUISETACEA.
Volkmannia, Sternb.
Volkmannia, sp.
I have placed under this name a specimen containing several small cones
referable to the Calamites.
The cones are an inch and quarter to an inch and three-quarters in length,
and about the fifth of an inch in width.
They spring from a common stem, to which they are attached by stalks
about three-quarters of an inch long.
The little bracts bearing the sporangia arise from the axis of the cone at
right angles, but as to how many bracts may have formed a whorl, I am unable
to determine.
These cones resemble Volkmannia sessilis, Presl., and Calamodendron
commune Binney, in the verticillate manner in which they spring from the main
stem and in the arrangement of the bracts round the axis of the cone, but
differ from them in being longer and proportionately narrower.
These two genera are included by some authors in Paleostachya, Weiss, but
I have used the genus Volkmannia in preference, as it means little more now
than the cone of a Calamite,
This appears better than placing it in a restricted genus, from which it
would probably require to be removed, when more perfect examples have been
examined.
Position and Locality —F¥rom the Cement-stone group of the Calciferous
Sandstone series, Glencartholm, Eskdale,
COLLECTED IN ESKDALE AND LIDDESDALE, 543
LYCOPODIACE.
Lepidodendron, Sternberg.
Iipidodendron Sternbergii, Brongn.
Lepidodendron Sternbergii, Brongn., Prodr., p. 85,
i ~ Lind. & Hut., Foss. Flora, pls. iv. and exii,
_ 3 Schimper, Paléont. végét., pl. lviii.; lix. fig. 2; Ix. figs, 3, 4.
3 obovatum, Sternb.. Flor, d. Vorw., tab. xvi. figs. 3, 4, 5.
i; elegans, Brongn., Hist. d. végét. foss., ii. tab. xiv.
9 » Lind, & Hut., Foss. Flora, pl. cxviii.
. gracille, Brongn., Hist. de végét, foss., tab. xv.
9 » Lind. & Hut., Foss. Flora, pl. ix.
A acerosum et dilatatum, Lind, & Hut., Foss. Flora, pl. vii. figs. 1, 2.
Sagenaria dichotoma, Sternb., Geintz, Steinkoh. in Sach., tab. iii. figs. 2-12.
Position and Locality A few specimens from the Cement-stone group of
the Calciferous Sandstones, Glencartholm, Eskdale.
Lepidodendron, sp.
Remarks. —Several other specimens of Lepidodendra occur, but are not
sufficiently well preserved to admit of determination.
Locahties,—Hartsgarth Burn, Liddesdale; and River Esk, Glencartholm,
Eskdale.
_ Lepidostrobus, Brongn.
Lepidostrobus variabilis, L, & H.
Lepidostrobus variabilis, L, & H., Fossil Flora, pls. x., xi.
Carruthers, Coal Plants from Brazil, Geo, Mag., vol. vi., 1869, p. 151.
Remarks,—Of frequent occcurence.
Position and Localities—From the Cement-stone group of the Calciferous
Sandstone series, stream above Saughtree, Liddesdale ; and Glencartholm, Esk-
dale.
Lepidostrobus fimbriatus, sp. nov., Kidston.
Plate XX XI, figs, 2, 3, and 4,
Description.—Scales cordate acuminate, margins of upper portion distinctly
fimbriated or produced into regular spiny projections; mid-rib prominent,
bearing a sporangium towards its lower extremity,
Remarks.—Of this cone nothing but separate scales have been obtained
nearly all of which show the inner surface.
The sporangium occupies the centre of the basal expansion of the scale, its
position being indicated by a raised carbonaceous film. It usually shows on
544 ROBERT KIDSTON ON FOSSIL PLANTS
each side a small conical elevation, but what this may represent I am unable
to determine. From the constancy of their occurrence, I am inclined to regard
them as an integral part of the structure.
In some of the specimens, part of the tissue has been destroyed, causing
the bract to appear as if composed of a terminal and basal portion (fig. 4).
In fig. 2, the missing portion is slightly indicated, while fig. 3 shows a perfect
specimen.
Position and Localities—Frequent in the Cement-stone group of the
Calciferous Sandstone series, Lewis Burn, North Tyne, Northumberland ;
Tweeden Burn, Liddesdale ; and Glencartholm, Eskdale.
Lepidophyllum, Brongn.
Lepidophyllum lanceolatum, L. & H.
Lepidophytlum lanceolatum, L. & H., pl. vii. figs. 3, 4.~
Position and Localities.—Of frequent occurrence in the Cement-stone group
of the Calciferous Sandstone series, Tweeden Burn, Liddesdale ; ae River
Esk, Glencartholm, Eskdale.
Lycopodiaceous sporangia.
Position and Locality.—They occur very plentifully in an impure limestone,
in the Cement-stone group of the Calciferous Sandstone series, Tinnis Burn,
and Kershope Foot Limestone Quarries, Liddesdale.
Cordaites, Unger.
Pycnophyllum, Brongn.
Cordaites, sp.
Remarks.—Only a few fragmentary specimens of this genus have been
obtained.
Position and Locality—From the Cement-stone group of the Calciferous
Sandstone series, Tweeden Burn Foot, Liddesdale.
Stigmaria, Brongn.
Stigmaria jficoides, Brongn.
Stigmaria ficoides, Brongn., Classif. d. végét. foss., tab. i. fig. 7.
i ” Lind. & Hut., Yossil Flora, pls. xxxi,-xxxvi.
‘4, »- Geinitz, Fl. d. Kohlenf. Hain, Ebersd. u. Floh. Kohlenbassins, tab. xi. figs. 1, 2.
“3 Goepp., Foss. flor. d. perm. Form., tab. xxxiv.—Xxxvii.
* », Schimper, Paléont. végét., lxix. figs. 7-9.
Remarks.—Of frequent occurrence.
COLLECTED IN ESKDALE AND LIDDESDALE. | 545
Position and Localities.—From the Cement-stone group of the Calciferous
Sandstone series, Peel Burn, near Myredykes, Liddelhead, and Saughtree,
Liddesdale.
FRuvirts.
Cardiocarpus, Brongn.
(?) Cardiocarpus apiculatus, Gopp & Berger.
(?) Cardiocarpus apiculatus, Gépp. & Berger, De fruct., tab. ii. fig. 32.
(2) 4%) % Lesq., Coal Flora of Pennsyl., p. 571.
Plate XX XI. figs. 13 and 13a.
Remarks.—One small slab has been collected thickly covered with these
fruits. The individuals differ considerably in general outline, as shown in the
two figures. ~The present specimens are somewhat smaller than those figured
by Lesquereux.* Their border also appears to be narrower. It approaches,
however, so closely to his figures that I have little doubt as to the identity of
the species.
Position and Locahty.—From the Cement-stone group of the Calciferous
Sandstone series, Lewis Burn, North Tyne, Northumberland.
Cardiocarpus, sp.
Plate XXXII. fig. 6.
Remarks.—A single specimen of another species also occurs in Eskdale.
It is rather less than four-tenths of an inch long, and slightly over two-tenths
of an inch broad. The marginal border is narrow, and the central portion
marked with three ridges.
I have not succeeded in identifying this fossil, but being only represented
by a single individual, I am unwilling to raise it to the rank of a new species.
Position and Locality —¥rom the Cement-stone group of the Calciferous
Sandstone series, River Esk, Glencartholm, Eskdale.
Schutzia, Gein.t
Anthodiopsis, GOpp.t
Schutzia, sp.
Plate XX XI. figs. 10, 11, and 12.
Remarks.—Of these curious fossils several specimens have been collected.
They usually occur on the slabs in masses, but only in one instance have I been
able to detect any attachment of the fruit to a stem (fig. 12).
This species appears to be closely allied to Schutzia anomala, Gien.
s ‘Atlas, Coal Flora of Pennsyl., pl. Ixxxiii. figs. 6 and 6a.
+ Fos, Flora der Permischen Formation, Goppert, 1865.
546 ROBERT KIDSTON ON FOSSIL PLANTS
(Anthodiopsis Beinertiana, Gopp.), from the Permian of Bohemia and Silesia,
but the specimens from Liddesdale are not sufficiently well preserved for satis-
factory determination.
The three figures given in Plate B. show the more characteristic forms.
Schimper places this genus among the Coniferw@, but Géppert mentions that
these fruits occur along with Neggerathie as well as with Walchia piniformis,
Sternb. Their association, however, with these two plants he regards rather as
accidental, than as throwing any light on their affinities.
The plant originally described as Schutzia bracteata by LESQuEREUX, from
the Carboniferous formation of the United States, is a totally different fossil,
and has now been placed by its author in a new genus, Cordianthus, Lesq.*
Position and Locality.—From the Cement-stone group of the Calciferous
Sandstone series, Tweeden Burn, and Kershope Burn, Liddesdale.
Description of Plants from Canonbie.
FILICINE.
SPHENOPTERIDE.
Sphenopteris multifida, L. & H.
Sphenopteris multifida, L, & H., Fos. Flora, pl. exxiii.
Locality. Byre Burn, Canonbie, Dumfriesshire.
Only one specimen has been obtained.
Sphenopteris obtusiloba ¢ Brongn.
Sphenopteris oltusiloba, Brongn., Hist. d. végét. foss., tab. lili, fig. 2.
Ps +5 Schimper, Puléont. végét., tab. xxx. fig, 1.
Remarks.—One small specimen, though too imperfect for satisfactory
determination, probably belongs to this species.
Locality.—Byre Burn, Canonbie, Dumfriesshire.
Sphenopteris, sp.
Locality.—Byre Burn, Canonbie, Dumfriesshire.
Staphylopteris, sp.
Plate XX XI. fig. 5.
Remarks.—Ouly two small stems of this Staphylopteris have been obtained,
but unfortunately on neither of them are any traces of fruit. They are much ~
more robust than Staphylopteris Peachit.
Locality—Archerbeck, Canonbie, Dumfriesshire.
* Geo. of Iilin., vol. iv., Lesq.; and Coal Flora of Pennsyl., Lesq., 1880.
COLLECTED IN ESKDALE AND LIDDESDALE. 547
NEUROPTERIDEZ.
- Neuropteris heterophylla, Brongn.
Neuropteris heterophylla, Brongn., Hist. d. végét. foss., tab. 1xxi., lxxii. fig. 2.
Gleichenites neuropteroides, Goepp., Syst. Fil. foss., tab. ili., iv.
Locality —Of this plant there are only a few imperfect specimens from
Archerbeck Rowan Burn, and Byre Burn, Canonbie, Dumfriesshire.
ALETHOPTERIDE.
Alethopteris, Brongn.
Alethopteris lonchitica, Sternb.
Pecopteris lonchitica, Brongn., Hist. d. végét. foss., tab, xxxiv.
He heterophylla, L. & H., Fossil Flora, pl. xxxviii.
33 urophylla, Brongn., Hist. d. végét. Foss., tab. 1xxxvi.
% Mantelli, Brongn., a tab. Ixxxiii. figs. 3, 4
; Davreuxii, Brongn., - tab. Ixxxviil.
Alethopteris lonchitidis et vulgatior, Sternb., Flora d. Vorwelt., ii. p. xxi. tab. liii. fig. 2.
Remarks.—Only three specimens of this widely distributed species have
been collected.
Localities.—Byre Burn and Rowan Burn, Canonbie, Dumfriesshire.
PECOPTERIDE.
Pecopteris, Brongn.
Pecopteris nervosa, Brongn.
Pecopteris nervosa, Brongn., Hist. d. végét. foss., tab. xcv. figs. 1, 2.
35 Sauveurii, Brongn., 5 tab. xcv. fig. 5.
iy nervosa, L. & H., Foss. Fiora, tab. xciv.
Alethopteris nervosa, Goepp., Foss. Farrn., p. 312.
Locality.—One specimen from Byre Burn, Canonbie, Dumfriesshire.
Pecopteris, sp.
Locality.—Byre Burn, Canonbie, Dumfriesshire.
EQUISETACE.
Calamites, Suckow.
Calamites, sp.
Locality —One imperfect specimen from Archerbeck, Canonbie, Dumfries-
shire.
VOL. XXX. PART II, 4Q
548 ROBERT KIDSTON ON FOSSIL PLANTS
LYCOPODIACE.
Lepidodendron, sp,
Locality. Archerbeck, Canonbie, Dumfriesshire.
Lepidostrobus, Brongn.
Lepidostrobus variabilis, L. & H.
Lepidostrobus variabilis, Lind. & Hut., Fossil Flora, pls. x., x1.
Locality.—Rowan Burn, Canonbie, Dumfriesshire.
Lepidophyllum, Brongn.
Lepidophyllum lanceolatum, L. & H.
Lepidophyllum lanceolatum, L. & H., pl. vii. figs. 3, 4,
Locality.—Archerbeck, Canonbie, Dumfriesshire.
P.S.—9th Dec, 1882,—Since compiling the above list, a few more specimens
have been handed to me for examination. Among them were the two following,
which must now be added :—-
Plants from Eskdale and Liddesdale.
ALG.
Chondrites Targionii, Brongn.
Fucoides Targionti Brongn., Hist. d. Végét. Fos. p. 56, tab. iv. fig. 4.
Chondrides Targionii, Schimp., Traité de Paléon, Végét, vol. i. p. 170, tab. iii. fig. 7,
A few specimens of this plant have been collected.
Position and Locality—From the Cement-stone group of the Calciferous
Sandstone series, in limestone beds on the shore between the gardener’s cottage
and Borron Point, Arbigland, Kirkcudbrightshire.
EQUISETACE.
Pothocites, Paterson.
Pothocites Grantonii, Pater.
Pothocites Grantonii, Paterson, Trans. Bot. Soc. Ed., vol. i, pl. iii., 1841.
Pothocites calamitoides, Kidston, On the affinities of the genus Pothocites, Annals and Mag. of Nat.
ITist., Nov. 1882.
Of this specimen I have already given a short description. It is the only
perfect example that has yet been discovered, and shows that Pothocites,
COLLECTED IN ESKDALE AND LIDDESDALE, 349
Paterson, is not the inflorescence of a monocotyledon, but the fructification of
a calamitaceous plant. Since writing the short notice above mentioned, I have
compared this specimen with the original type, and find that it is not specifically
distinct from P. Grantonii (Paterson).
The specimen was collected by Mr T. Stock, by whom it has been kindly
submitted to me for examination.
Position and Locality.—From the Cement-stone group of the Calciferous
Sandstone series, Glencartholm, Eskdale.
EXPLANATION OF THE PLATES.
PLATE XXX.
Fig. 1. Sphenopteris Hibberti, var., L, & H.
Fig. 2. Sphenopteris excelsa, L, & H. A pinna showing a bifurcation of the axis.
Fig. 3. Chrondrites plumosa, Kidston,
Fig. 4. Crossochorda carbonaria, Kidston.
Fig. 5. Sphenopteris Geikiet, Kidston.
PLATE XXXI.
Fig. 1. Caulopteris minuta, Kidston.
Fig. la. r er Scar enlarged, showing vascular impression.
Fig. 2. Lepidostrobus fimbriatus, Kidston, Cone-scale showing sporangium.
Fig. 3. 5 » »
Fig. 4. 3 ‘5 3) 25
Fig. 5. Staphylopteris, sp.
Fig 6. Staphylopteris Peachii, Balfour. Small fruiting specimen, showing the sporangia.
Fig. 7. Sphenopteris excelsa, L. & H. Two pinnules from the upper portion of a pinna,
showing the venation. Enlarged.
Fig. 8. Sphenopteris excelsa, L. & H. Pinna of lax form.
Fig. 9. Sphenopteris Geikiei, Kidston. Pinnule enlarged.
Figs. 10, 11,12. Schutzia, sp. Three of the more characteristic specimens, in different states
of preservation. Natural size.
Figs. 13, 13a. Cardiocarpus apiculatus, Gopp. & Berger.
Fig. 14. Chondrite simplex, Kidston. |
PLATE XXXII.
Fig. 1. Sphenopteris decomposita, Kidston. Portion of a specimen showing pinne from the
central part of a frond.
550 - ROBERT KIDSTON ON FOSSIL PLANTS.
Fig. la. Sphenopteris decomposita, Kidston. Small portion pies to show the venation.
Fig. 2. Chondrites plumosa, Kidston.
Fig. 3. Eremopteris Macconochit, Kidston.
Fig. 3a. " . Enlarged pinnule, showing venation. —
Fig. 4. Sphenopteris decomposita, Kidston. Lower extremity of a frond, showing decrease in
the size of the pinne, and increase in the size of the pinnules.
Fig. 5. Sphenopteris decomposita, Kidston. Lower extremity of a frond, showing decrease in
the size of the pinnee, and increase in the size of the pinnules.
. 6. Cardiocarpus, sp.
Le 5]
=r
ge
Trans. Roy. Soc. Edin? Vol. XXX. Plate XXX.
-Widston, delt + M¢Parlane & Erskine, Lith? Edin®
1. Sphen. Hibberti, var. L. & H. 3. Chondrites plumosa, Kidst.
2. Sphen. excelsa, L. & H. 4. Crossochorda carbonaria, Kidst.
5. Sphen. Gethkiei, Ktdst.
Trans. Roy. Soc. Edin? Vol. XXX. Plate XXX1.
@eiidston, del? McFarlane & Erskine, Lith Edin
» 14a. Caulopieris minuta, Kidst. 6. Staphylopteris Peachii, Balfour. 10-12. Schutzia, sp.
4. Lepidostrobus fimbriatus, Kidst. 7, 8. Sphen. excelsa, L. & H, 13, 13a. Cardiocarpus apiculatus, Goipp. & Berger.
. Staphylopieris, sp. ; g. Sphen. Geikiel, Kidst. 14. Chondrites simplex, Kidst.
Trans. Roy. Soc. Edin? Vol. XXX. Plate XXXII.
R. Kidston, delt M‘Farlane & Erskine, Inth™s Edin®
I, 1a, 4,5. Sphen. decomposita, Kidst. 2. Chondrites plumosa, Kidst. 3, 3a. Evemopteris Macconochit, Kidst.
( 551 )
XXIIL.—On Mirage. By Professor Tair. (Plate XX XIII.)
(Read 5th December 1881.)
I was led to the following investigations while seeking an elementary, and
at the same time instructive, application of HAmILton’s General Method in
Optics.* They were completed in all but a few of their numerical details
before I met with the remarkable paper by WoLLAsTon,t in which the subject
of multiple atmospheric images seems first to have been treated by a sound
physical method. Wot.asTon’s experiment with a long bar of iron raised to
a high temperature suggests undoubtedly the true explanation of at least many
of the curious phenomena seen by VincE,{ Scorespy,§ and others. But he
seems to have thought that sufficient temperature-differences for the natural
production of the phenomena could not exist in the atmosphere; and thus the
latter part of his paper, in which he tries to explain them by the agency of
aqueous vapour, presents a singular contrast to the strength and correctness of
the earlier part. A good deal of what follows is implied, if not directly
stated, in WOLLASTON’S paper; but I think there is sufficient novelty in what
remains to justify my bringing it before the Society.
The subject is one which offers immense facilities for the construction of
elegant “Problems,” but I have confined myself to the simplest hypotheses
which (while enabling me to obtain exact results) promised to throw light
upon it :—feeling that anything else would be out of place in endeavouring to
explain a class of phenomena which have probably never occurred twice in
exactly the same way. I have, however, shown at least the general nature of
the alterations to which my results would be subject in consequence of modi-
fication of the assumptions.
1. Most of the images seen by ScorEsBY were inverted, and elevated above
the apparent position of the object seen directly, and each series of them (when
there were more series than one) can be explained at once by the existence of a
horizontal stratum of air in which the rate of diminution of refractive index in
ascending is greater than that in the air immediately below. [This is merely
the sort of arrangement which, as is perfectly well known, produces the mirage
of the desert ; but turned upside down.| But the chief phenomenon figured by
* Trans. R.I. A., 1833. + Phil. Trans., 1800.
t Phil. Trans., 1799. § Greenland, and Trans. Roy. Soc. Edin., ix. and xi.
VOL. XXX. PART II. 4k
552 PROFESSOR TAIT ON MIRAGE.
VincE, and also in a few cases by Scoresby, involves an inverted image with a
direct image above it. In some other cases observed by Scorgssy, the direct
or the inverted image alone was seen, the object itself being situated far below the
horizon. Some excerpts from Scoressy’s figures (which are themselves com-
posite) are given in fig. 1. A comparison of these observations with VINCE’s
diagram of the supposed courses of the rays seemed to me to show that a single
transition stratum may be capable of giving either a single image, direct or in-
verted according to circumstances, or an inverted image with a direct image
above it. As, in at least the greater number of the observations to which I
have referred, both the object and the spectator seem to have been below the
transition stratum which caused the phenomena, I do not think that Wot-
LASTON’s square bottle with two inter-diffusing liquids presents a fair analogy.
For, with that arrangement, the rays enter and emerge from the transition
stratum by its ends, and not by its lower side, as, from VINcE’s diagram, they
would appear to do in nature.
I propose to return to the consideration of this arrangement of WoLLASTON’s.
But meanwhile I will sketch (1) the mode in which I was led to see that, under
proper conditions, a simple continuous law of refractive index may lead to the
formation of three images, (2) how the consideration of the mode in which these
are produced-in a medium whose refractive index varies to four-fold or more of
the minimum value, led me by necessary steps to see how they can be produced
in the lower atmosphere whose refractive index can vary, even in extreme cases,
by only zo too OF SO.
2. To fix the ideas, we will begin with a particular case, which is a thoroughly
illustrative one so far as theory is concerned, and is also interesting as it
reproduces, with singular accuracy, the exaggerated diagram by which VINCE
endeavoured to explain his observations.
The ordinary characteristic of a maximum or minimum is that it differs from
neighbouring values of the function by a quantity depending on the square of
the increment of the independent variable. Assuming then, without any
inquiry as to the other physical circumstances, the existence of a medium
whose refractive index is represented by the equation
w=a+y? :
it is clear that y=0 is a plane of minimum refractive index.
HAmILton’s equation for this case is, 7 being the characteristic function,
ary GN ieee at “alle
since it is obvious that the path is in a plane perpendicular to y=0.
PROFESSOR TAIT ON MIRAGE. 5538
A complete integral is
Hence the equation of a ray is
dy :
C=2—-—a gia : st @):
[This result might, of course, have been at once obtained from the corpus-
cular theory. For its principles give
eee Y= Je +y— a J
Equation (2) has two distinct forms according as a is greater or less than
a, These are separated by the limiting form when a=a, viz :—
zr
y=Ce* ,
a logarithmic curve asymptotic to the axis of 2. When a is less than a, the ray
passes through the plane y=0, and we need not consider it further.
We may therefore assume
=a +1,
and it is obvious that y cannot be less than 7. With this expression for a, the
mere form of the equation (2) shows that the curve has a vertex at the point
y=n, and that it is symmetrical about the ordinate through that point.
We must remark, in passing, that this property of symmetry about an axis,
at the extremity of which is a vertex, is common to groups of rays in all media
in which the refractive index depends only on the distance from a particular
plane :—the groups which possess it being those which either do not reach that
plane, or pass through it more than once.
3. Let us now consider only rays which have vertices, and which pass
through a particular point z=0, y=. Thenif € be the x-cdordinate of the
vertex, equation (2) becomes
ta ldttf ae ete
Vy—7
This is the equation of the Locus of Vertices of all rays (having vertices) which
pass through the point 0, 6. We may write it in the form
2 —
£= Ja? +7? log SS . (3).
554 PROFESSOR TAIT ON MIRAGE.
To draw the corresponding curve we may construct, for different values of 0,
the set of curves
; b ee.
é =tee( 24/5 i ) Se ke ee
2bi ees
|
or
The ordinates of these curves are proportional to the reciprocals of those of
a common catenary.
Next construct, for the given value of a, the equilateral hyperbola whose
equation is
aie Jat+7?.
Then we have, at once, for any given value of n,
ee
For the purpose of carrying out this process we have tabulated as below, a few
rough numerical values :—and by the help of these the curve (4) has been
drawn, along with (8), in three forms ; forb=2a, b=4a,and b=6a. See fig.
2. In each case (4) is represented by a dotted curve, (3) by the corresponding
full curve.
soho Bgl JOPTC Ye Ok age a aya
> log (+ 73 1: id 73 atR (ratio).
0:0 oe) 1-0 0°5 05
0:05 3°69 0:99 0-51 0:51
0-1 2°99 0:99 0°51 051
0:2 2°29 0:98 0:54 0:55
0°3 1:87 0:95 0°58 0°61
0:4 157 0-92 0:64 0°70
05 1:32 0°87 071 0°82
0°6 1:10 0:8 0°78 0:97
07 0°89 0-71 0°86 1:20
0°8 0°69 ° 06 0:94 1:56
0-9 0:47 0:44 1:03 2°36
10 0:0 0:0 112 ~
4. Let us digress to consider what we learn, in any case, from the form of
the Locus of Vertices.
It is obvious that if, instead of the special law of refractive index assumed
in the preceding section, we had written quite generally
w=fy) »
(3) would have become
i eee: ae :
E=sonf, Fiaia ° : - (ey
PROFESSOR TAIT ON MIRAGE. 555
while (2) would have been (for rays passing through the point 0, d),
0=1—-a uf Vig)—@ . . ° : . (2’) .
The new form of (2’) shows that, for a given value of y, x increases with
increase of a; provided no vertex is reached. For the denominator of the
differential is less, and the integral is multiplied by a greater factor, than
before. Hence two contiguous rays from the same point cannot again
intersect till one, at least, has passed its vertex. When the vertex is included
within the limits of integration, (2’) may by the symmetry of the ray be
written
aA == a? ste Tes ee noha =etaf” Tes Sar
Now the middle term (as we have seen) is positive, and increases with a,
if y>b. Hence the second intersection of the rays which have the common
point 0, b, is at a point where y> 48, if and only if, € increases as a increases ;
é., if the line, drawn from the vertex of the ray nearer to the minimum
plane to that of the other, leans back towards the first common point of the
two rays. The converse is easily seen to hold, by taking the second point of
intersection as the starting-point and reversing the rays. Hence, if the
minimum stratum be horizontal, two neighbouring rays, issuing from a common
point below it, and originally directed above the horizon, intersect again before
they have got back to the level of their former intersection, if their vertices
be at a part of the curve of vertices where the tangent leans backwards over
the starting-point, and vice versd. This proposition is, in fact, obvious
from a mere inspection of the diagram fig. 3, in which the dotted curve is that
of vertices, the eye being at E.
To apply it to the case of phenomena such as those observed by VINCE and
ScoRESBY, suppose the strata of equal refractive index to be horizontal. Then
two rays slightly inclined to one another, leaving any point in a common
vertical plane, will in general intersect one another before they again reach the
level of the starting-point, if, and not unless, the vertex of the higher ray be
horizontally nearer to the starting-point than that of the lower ray; 2.¢., if the
part of the curve of vertices concerned leans towards the starting-point. Also,
as is well known, when two rays slightly inclined to one another, cross once
between the eye and the object, the image formed is an inverted one.
5. Hence the following graphical method for finding the numberand characters
556 PROFESSOR TAIT ON MIRAGE.
of the images of an object situated at the level of the eye. Trace the curve of
vertices for all rays leaving the eye in the vertical plane containing the object.
Draw also a vertical line midway between the eye and the object. The inter-
sections of this line with the curve of vertices are the vertices of all the paths
by which the object can be seen, when the eye is in the assigned position. Or,
what comes to the same thing, but (unlike the simpler construction) admits
of application to an object at any level, draw the curve of the vertices as
before, and then draw another for an eye placed at the object. Their intersec-
tions determine the vertices of the rays giving all possible images.
It is easy to see that, at the intersections with the vertical line midway
between eye and object, the curve of vertices, if continuous, must alternately
lean from, and towards, the eye, 7.¢., the images seen are alternately erect and
inverted; their number depends of course upon the form of the curve of
vertices ; which, in its turn, depends not only upon the law of refractive index
in terms of level, but also upon the position of the eye. [This alternation of
images does not necessarily hold when eye and object are at different levels. |
Thus, as has long been known, the vertices of all the coplanar paths in
which a projectile, fired with a given velocity, can move, with different
elevations of the piece, lie in an ellipse whose major axis (double the minor
axis) is horizontal. The lower half of this ellipse leans fromthe gun, the upper
half towards it, and these correspond to angles of elevation of the piece,
respectively less and greater than 45°. In the former case (when the
elevation is less than 45°), a slight increase of elevation increases the range on
a horizontal plane, so that the new path is wholly above the old one; which,
however, would intersect it wnder the horizon. In the latter case a slight
increase of elevation shortens the range, so that the two paths must intersect
before reaching the ground.
6. Recurring to the imagined medium in which
we=a2+y2,
we see by fig. 3 the paths of the rays by which the three images of AB are
seen by an eye placed at E. This figure, as already remarked, is (with the
exception of the introduction of the curve of vertices) almost identical with that
of Vince in the Phil. Trans. for 1799.
But it is easy to see that, although this shows the possibility of three
images in the relative positions observed by V1NcE, it is in no way capable of
explaining his observation. For the existence of three images, in such a
medium, requires (as I have found by an approximate method)* that 6 be at
* When 2 =0, we have 1 +S =a ke 1 tog (= + ns ye 371). Plotting the curves whose or-
dinates (in terms of 7) are ae by these v5 quantities, ie find that they touch when b = 3°68a.
PROFESSOR TAIT ON MIRAGE. 557.
least =3'68a. Hence the refractive index at the level of the eye (Wa’+2’)
must be at least 3°8 times that in the minimum stratum. And the distance at
which an object on the horizon requires to be situated, in order that there may
be three images of it, lies within exceedingly narrow limits, unless the
refractive index at the level of the eye very greatly exceed this lowest admissible
value.
7. The possibility of three images of an object at the level of the eye evidently
depends on the existence of three values of y, for the same value of in the
curve of vertices. It is therefore necessary that we should study the question
from this point of view.
On thinking of the relative forms of the curves of vertices in fig. 2; the
first of which gives only one image, the second and third (in certain cases)
three :—I saw that the point of inflexion, on which the triple value of y
depends, is due to the gradual diminution of curvature of the ray near the eye
(for rays of a given inclination to the vertical) as the eye is placed lower in the
medium. Hence any arrangement which lessens the curvature of the lower
parts of the rays will increase this effect.
In fact, the portion ABC of the ray OB (fig. 4) is congruent with the ray
abe, if only the tangents at A and a be parallel. Hence the point B would
be shifted to 6 if the ray Oa were straight (or at all events, less curved than
OA) and the angle at a equal to that at A.
Thus it was at once obvious that the curve of vertices (fig. 5) in the
stratum above RS, might be made asymptotic to that line towards the right
of the figure (the eye being still at O), if only the stratum below it were
of uniform refractive index, or at least of a refractive index diminishing
so slowly with increased height that a ray from O could intersect RS at a
practically infinite distance. This at once showed me the general nature of
one mode of explanation. The curve of vertices Q@PQ’ in the stratum RU will
now be asymptotic, towards the right, to both RS and TU, and therefore can
be cut in two points by a sufficiently distant vertical. These points correspond
to VINCE’s two upper images, the third and lowest is seen by rays which have
not reached the upper stratum, and for which the corresponding branch of the
curve of vertices is the horizontal line OM, passing through the eye.
8. To repeat :—the conditions requisite for the production of Vincr’s pheno-
menon, at least in the way conjectured by him, are, a stratum in which the
refractive index diminishes upwards to a minimum (or, at all events, nearly to
a stationary state) ; and, below it, a stratum in which the upward diminution
is either considerably less or vanishes altogether. The former condition (the
558 PROFESSOR TAIT ON MIRAGE.
fall to a nearly stationary state) secures the upper erect image, the latter the
inverted image. When the former is not present, we have the phenomenon so
often observed and figured by Scorespy. This requires merely a change from
a slowly diminishing refractive index to a more quickly diminishing one, and
may occur simultaneously in more than one horizontal layer. Turned upside
down, this arrangement gives the ordinary mirage of the desert. When this
condition is not present, but only the stationary state, we have VINCE’s upper
erect image without the inverted one. This is figured several times by
SCORESBY.
9. If, instead of a plane of minimum, we have a plane of maximum, refrac-
tive index, we may assume
pw2=a?—y?,
An investigation precisely similar to the preceding gives for a ray passing
through 0, 6 the equation
—1 y -1 b
a= J/a?—7? (sin “—sin -) :
” ”
Each ray therefore is a harmonic curve, whose level line is in the maximum
stratum, and which passes through that stratum an infinite number of times.
The locus of vertices is
si
e= Ja—n? (cos ~+n7) :
Here 7 is to be taken positive when m (any integer) is even, and negative when
it is odd.
The following rough table suffices to determine the general form of this
curve in the particular case a=6d. It is shown in fig. 6; and it has been
foreshortened for convenience of representation.
-1
i. —cos 2 £
7 o) b
n=0 n=1
iow aa |
1:0 0:0 +0:°0 98 9°8
0°95 0:2 +0:98 8:8 10°76
0:9 0:29 +1°39 8°35 1113
0°8 0°41 +1:98 7:70 11°66
0-7 0°51 +2°42 716 12:0
0°6 0°59 +2°78 6°64 UA
0°5 0°67 +3°05 6:11 be 2a
0°4 0°74 +3:'20 5°46 11°86
03 0:80 +2:97 4-47 10°41
0°25 0°84 +1°9 2°5 63
0:2 0°87 0:0 0:0 0:0
01 0:93 oe
PROFESSOR TAIT ON MIRAGE. 559
The general problem of determining the images is, in this case, a very
complicated, though not difficult, one; but it becomes much simplified if we
assume as before the object and eye to be at the same level. It is obvious
that a vertical line, midway between the eye and the object, will cut the curve
_of vertices an infinite number of times, both above and below the maximum
stratum. Thus there is in such a case an infinite number of images, which are
seen by rays which have crossed the maximum stratum an even number of
times, in which zero may be included. These must each have one, or some
other odd number, of vertices between the eye and the object, and the hori-
zontal distance between two such vertices is
7 Va—7? ;
which is therefore less for that one of two rays which intersects the maximum
plane at the greater angle. .
In nature, of course, the number of images depending on a law like this
must always be finite, because the utmost percentage change of refractive index
in the lower atmosphere is very small. But, independent of equilibrium
considerations, there is the farther objection that it cannot be reconciled with
the appearances seen by VINCE and Scoressy. For these were, in the main,
very similar to one another for all distances of the object beyond certain
limits ; while with the present assumption, the appearances presented by an
object moving to successively greater distances would exhibit a species of
guast periodic change which I have nowhere seen described. And, if we keep
to probable changes in the refractive index of the atmosphere, this law will give
only one image :—not, of course, in the true direction of the object :—but
erect, and therefore not properly coming under the designation of “mirage.”
10. After trying a number of assumptions as to the law of refractive index in
the transition stratum, I finally chose for detailed examination the following :—
pe=a?-+ecos ;
This seemed to me particularly worthy of investigation, for it must be at
least a fair approximation to the state of matters near the common boundary
of two inter-diffusing fluids, or of two masses of the same fluid at different
temperatures. This follows from the facts that :—it gives a stationary state at
y=0, with a maximum refractive index ; and another at y=0, with a minimum
index. Near y= = there is a stratum of greatest rapidity of change of index.
This hypothesis has also the advantage of leading to equations which can be
treated by the ordinary elliptic integrals.
VOL. XXX. PART I. BES
560 PROFESSOR TAIT ON MIRAGE.
With this law it follows that, if the eye be in the plane y=0, the equation
of the curve of vertices is
e&= gener f ae ae 2
™
gh cos = eGg——
b
2.0
— f2-b [2-4 toos™ a +0008" F (sing a)
The equation of the path of a ray is
=) Fe as al
Jeane — cos
ey 2 TB (sing? }
7 ore Aa at pt
where sing? =sing? sing .
We have also
TY — ogi
iy mA Coss" — cos;
Ge a ra
; eA a? 4+ cos
b
and, for y=0, this takes the value
x 2h sin
o, at ecost
For the application of these formule the following little table has been
prepared :—
1 . E,(&
7 5 =cosecay C3) i a6 -
T T
0:0 2 5 5
01 6°39 1:58 1:60
0:2 3°24 161 1:69
0°3 2°20 1:66 1:87
0°4 70 1°74 2°18
05 141 1:85 2°70
0°6 1:24 2°01 3°67
0°7 1:12 2°24 5°74
0°8 1:05 2°60 11:53
0-9 1:012 3:26 42°24
0°95 1-003 3°94 16417
0-975 1:00077 4°62 650°85
1:0 1:000 co oo
PROFESSOR TAIT ON MIRAGE. 561
The headings explain themselves. The last column is required, as will
soon be seen, for the determination of the magnitudes of the images, as
compared with that of the object when seen (at its true distance) through
uniform air.
11. Let us now extend the formule of § 4 to the case of a stratum of depth
ec, in which the refractive index is constant (=,//(c) ); surmounted by
another of thickness 6, in which the index is .//(y).
The equation of a ray, passing from the origin, which we now take in the
lower surface of the inferior stratum, is
While y is not greater than c, this is the straight line
Pt ae
~ NF) a
But when y is greater than c, we have
1
Sapa ORT ats ain 2 oS OD
Also; for the branch of the curve of vertices which is in the upper stratum
(the other branch being, of course, the axis of 2),
_ el fm) _ ”
Oa J fc) —Kn) + Raf Toa = - oo? cal
Fig. 5 has been roughly traced from this formula and the curve of fig. 2.
12. In the next following equations, recurring to the form
w=a+ ecos se ;
we will simplify matters by making a=1, and altogether neglecting the terms
in é when they are added to others not containing e. This will be fully
justified, so far as air is concerned, in a subsequent section.
By § 11 the equation of the curve of vertices is
b,/2
ef = —jacoseesg + oe
1s = sine sint
If we write
where @ is the inclination of the straight part of the ray, this becomes
7 4 2 hy \ = jaad
C= 5. 7
564 PROFESSOR TAIT ON MIRAGE.
c c
b=10¢e b=c b=59 j= 00
U/]
7 ff © Sf G § 6 Hei to
0:0 co — ] for — 10 oe) —1:0 o — 10
O01 517 — 2°63 23:24 — 1:16 20:40 —1:02 20711 — 1:0
0:2 42:4 — 4:99 13°39 — 1:34 10:49 —1:03 10:20 — 1:0
0:3 40:2; —14°‘73 10°25 — 1:58 725 —1:05 695 — 1:01
0-4 402 +11°95 8:83 — 1:97 569 —1:08 5°38 — 1:01
0°5 415 + 3:32 815 — 2:97 481 —113 448 — 1:01
0°6 441 + 1°51 791 —13°91 4:29 —1:21 3°92 — 1:02
0°7 484 + 0°73 801 + 2:31 397 —1°41 3°57 — 1:03
0°8 553 + 0:32 850 + 0°58 3°82 —2:52 3:36 — 1:07
0:9 68:3 + 0:09 969 + 013 383 +0°83 3:25 —: 1°35
0°95 81:9 + 0:026 11:02 + 0:03 394 +014 3°23 +60°59
0:975 956 + 0:007 12:39 + .0:01 407 +0:03 3°24 + 0°33
1:0 re) 0:0 ore) + 0:0 fo) +0:0 ao + 00
16. We must now consider, so far as is necessary, the physical properties of
air :—and observations which have been made as to actual changes of temper-
ature at different elevations above the earth’s surface. There is no necessity
for dealing with very exact physical data, because we must make assumptions
as to distribution of temperature which cannot, at the best, be more than rough
approximations. All that we can attempt to show is, that the observed pheno-
mena are of a character and ona scale compatible with the known properties
of air, with observed changes of temperature in the atmosphere, and with the
arrangement we have suggested for the production of these phenomena.
Thus, although aqueous vapour diminishes the refractive index of air, the
practical effect is so minute at its utmost that we neglect it :—a very slight
change in our assumption as to temperature would be sufficient to make up for
it.
Assume, then, for air at 0°C. and 760 mm.,
1
f= 1.000294— 1 +3700 .
Assume farther, what is only approximately true, that the refractive power
depends on the density alone, and is proportional to it :—-2¢.,
1
nae (pera ee 2
tl 3400%pi!
The next assumption :—that the air is practically in hydrostatic equilibrium,
when such phenomena are observed :—is probably not far from the truth, except
in the case of the mirage of the desert. It gives
dp _
dy —J9JP;
PROFESSOR TAIT ON MIRAGE. 565
or, with the laws of BoyLE and CHARLES,
d(pt
Now if H=26,000 feet, be the “height of the homogeneous atmosphere,” we
have
Po= Rpoto =Jpoll ,
so that the hydrostatic equation becomes
Instability occurs when f is positive. Hence the greatest rate of fall of
temperature, per foot of ascent, which is consistent with stability is
WG. a 274°
is: 26,000°" ,
dy +H
or —1°:05 C. per hundred feet.
GLAISHER,* in a captive balloon, on two occasions out of twenty-seven, .
observed the fall of temperature in the first hundred feet to be 1°°8 F. and 1°:9 F.
respectively. On other three of these occasions it was 1°°7 F., 1°°5 F. and 1°°3 F.
respectively. The first two correspond almost exactly to the 1°°05 C. above
computed for a stratum of uniform refractiveindex. The temperature near the
earth’s surface was on these occasions 73°°6 F. and 76°2 F. ; or, roughly 24° C.
The greatest 77se of temperature per 100 feet of ascent, which he observed on
any of these twenty-seven occasions was 0°3 F. only. It seems from what
follows, therefore, that on none of these occasions would Vince's phenomena
have been possible.
17. To fix the ideas, let us now assume that the first 50 feet of air is of
uniform density, and that next there is a stratum of 50 feet thick in which the
-refractive index is given by
298 + 68 cos MH 50), |
pe =a +e cos 50
* B. A. Report, 1869, p. 37.
566 PROFESSOR TAIT ON MIRAGE.
y being measured from the surface of the earth. Since we may look on p as
practically unity, we have by the formule above
idp__1 t= — sate a)
pw dy 3400p, dy 3400\ HZ, dy)’
Hence, by our assumed law of refractive index,
1 1 dt_34007e? . a(y—50) |
Hig = oo
Hence the greatest rate of change of temperature per foot of ascent (at
y=75 feet) is
274 x 342re®—0:0105.
The whole change of temperature, from the bottom to the top of the
stratum, is
274 x 3400e?—0°53.
Both of these quantities are in degrees centigrade.
18. To get an idea of the magnitude of e’, we note that, by ScoRESBY’s obser-
vations, the elevation of the images above the horizon is usually about 10 or 15
minutes of arc at the utmost. Hence, by the value of = in § 10, we may
assume as an upper limit, j
1
Rc 550 >
or
e?=0:000008 .
With this, the greatest rate of rise of temperature in the assumed stratum is
0°22 C. per foot of ascent, and the whole rise is about 6°°9 C. These quantities,
moderate as they are, would be greatly diminished by our relinquishing the
assumption that the density in the lower stratum is constant.
But even this indicated rise of temperature with elevation has been actually
observed. Thus GLAISHER® gives, for July 17th, 1862,
Time. Altitude. Temperature. By Gridiron Thermometer.
10.30 A.M. 19,415 feet. 38°1 F. 337-1 B,
10.35 AM. 19,435 feet. 43°-0 F. 42°-2 F.
10.39 A.M. 19,380 feet. 37°-0 F. 36°°5 F.
The greatest difference here observed is as much as 5° F. in 20 feet ; 7.¢., at
the rate of 12°°5 F. or 7° C. per 50 feet, precisely what is required above.
* B. A. Report, 1862.
PROFESSOR TAIT ON MIRAGE. | 567
19. We have another and independent mode of testing whether this value of
é accords with observation. For Scoressy tells us that, only on rare occasions
and then only slightly, were objects at four miles’ distance affected. The usual
distance was 10 to 15miles. Now, by the table in § 15 we see that the nearest
object of which an image can be formed is distant
ae T-Gfeck:
uO
or, with the above value of e, about 12 miles.
There is thus a fair agreement, so far at least as these tests can tell us,
between the results of our hypothesis and observation.
The table in § 15 shows that, with the same value of e, and the same thick-
ness of the lower stratum, as before, but with the assumption of a transition
stratum of a thickness of five feet only; the distance of the nearest object of
which an image could be formed would be about six miles only. A still farther
reduction of the thickness of the transition stratum reduces this least distance
still farther; but it is clear from the table that there is a limit somewhere
about five miles. This would be still farther reduced if we supposed the lower
uniform stratum to have a depth of less than 50 feet. On the other hand, we
see that an increase of thickness of the transition stratum introduces distances
greater than are consistent with observation; unless indeed, the thickness of
the lower stratum be at the same time reduced. In the table # and @ depend
upon the ratio of 6 to ¢; € is proportional to c.
20. The columns headed & in the table of § 15 give, as shown in § 12, the
magnitudes of the images relative to that of the object seen directly. They
show that the inverted image is always taller than the object. This is consistent
with Scoressy’s observations. When the object is not near the critical
distance, however, this magnification is not considerable :—even if we assume
a 50-foot transition stratum. On the other hand, the erect image, except when
the object is not far beyond the critical distance, is much smaller than the
object. Moreover, as is obvious from §§ 12, 15, this image is seen by converging
rays. No doubt they are so nearly parallel as to be capable of producing
distinct vision in a normal eye; but the remark is necessary as showing how
different, in some respects, is the phenomenon from one of WOLLASTON’Ss imita-
tions of it. Both images become infinite :—7.e., there is simply ‘“ looming ”:—
when the object is situated at the critical distance. And, as the tables show
from the result of § 13, the ratio of the distance between the images to the
apparent size of the object seen directly, increases as the object recedes
beyond the critical distance. All this seems to accord completely with V1ncE’s
and ScoREsBY’s observations. The only additional remark I need make is that
VOL. XXX. PART II. 4T
568 PROFESSOR TAIT ON MIRAGE.
possibly Scoresby, from insufficient telescopic power, failed to see (or at least to
recognise as part of the phenomenon) the upper erect image, when the object
was much beyond the critical distance. The table shows the great rapidity
with which its height diminishes as the object recedes. The disparity between
the images depends of course upon the fact that we have assumed a law which
places the plane of most rapid change in the middle of the stratum. This may
often not be the case in nature. It might be useful to work out the whole
again, assuming a law (for the transition stratum) which would place the plane
of most rapid change considerably out of the middle of the stratum. But I
cannot attempt this at present. The results of § 14 seem also to be in com- .
plete accord with ScorgEsBy’s observations at Bridlington Quay, which are the
only detailed ones I have met with in which the point of view was shifted to
or from the transition stratum.
21. For an approximate estimate of the effect of the earth’s curvature on
these phenomena, let us suppose the same law of density as before ; but let the
strata be now J/evel, 7.¢., spheres concentric with the earth. The path of a ray
in the lower stratum will still be straight, but the angle at which it meets the
transition stratum (9+ 7, suppose) will now be necessarily greater than its
original inclination (@) to the horizon. See fig. 7.
If R be the radius of the earth, we find to a sufficient approximation,
(R+c)cosp—R=Rw,
or
Ca
aa » .
As @ cannot be negative, the greatest value of w is
2c 1
R~ 460
nearly ; ¢ being 50 feet, as before. If we write - for this quantity, we have
ites
2p0= ’
ae py
whence, by giving py the values 1, 0°9, 0°8, &c., we easily obtain the following
table :—
6 1 0+
0:0000 0:0022
0:0002 0:0022
0:0005 0:0022
0:0008 0:0023
0-0012 0:0025
0:0016 0:0027
0:0023 0:0032
0:0033 0:0040
0:0053 0:0057
00110 00112
PROFESSOR TAIT ON MIRAGE. 569
Now if we take the value of ¢ as in § 18, we have 0:004 for the greatest
value of 6+, which is consistent with the rays not passing through the transi-
tion stratum. This corresponds to
6=0:0033=45,=12/ nearly.
Hence, with this value of ¢, other assumptions remaining the same, even the
upper erect image could not (on account of the earth’s curvature) be elevated
more than about 12’ above the horizon, and the nearest object of which mul-
tiple images could be formed would be at a distance of about 13 miles.
Greater values of ¢ might remove this difficulty, but they would introduce
greater changes of temperature. This shows, therefore, that the assumption
of a lower stratum of uniform density is untenable. If there is to be a s¢mple
arrangement in that stratum, it must therefore be such that the refractive
index diminishes with elevation, but, of course, less rapidly than in the lower
half of the transition stratum. The effect of this would be to slightly raise the
images, and to reduce the critical distance.
Instead of the upper image, consider the lower one. ‘This would be, at its
Jarthest, within the distance of the visible horizon as seen from an elevation of
50 feet. Hence no inverted image of the hull of a vessel could be seen if it
were more than 18 miles’ distant ; and even then it would be seen horizontally.
The only ways of reconciling this with ScorEssy’s observations are (1) to
assume that the lower uniform stratum is much more than 50 feet thick ; (2)
to assume that it is not uniform, but gives rays a concavity downwards. The
former alternative is inadmissible on several of the grounds already mentioned ;
so we are again forced to assume the latter, which certainly holds if the tem-
perature throughout the lower stratum be constant.
22. In order that the above calculations may be applicable to the phenomena
.shown by inter-diffusing solutions, it is necessary that the length of the vessel
in which the solutions are contained be great enough to allow all rays (by
which the images are seen) to enter and escape from the transition-stratum by
one of its horizontal surfaces, and not by its ends. By using a vessel nearly 4
feet long, containing a layer of weak brine diffusing into pure water above, I
have verified the general accuracy of the results just given. For those rays
which enter or escape by an end, the calculation is by no means so simple, and
trial shows that the law determining the relative magnitudes of the images is
considerably modified. On the other hand, when the vessel is so short and
the rays so nearly horizontal, that each ray, while passing through the vessel, may
be supposed practically to move in a stratum of uniform rate of change of
refractive index, a very simple calculation suffices to give the general nature of
the phenomena produced. For the curvature of a ray, in the vessel, may now
570 PROFESSOR TAIT ON MIRAGE.
be regarded as constant throughout. Here J. THomson’s formula* is imme-
diately and usefully applicable. For, if 0,,—0,, be the angles the ray makes
with the horizon just after entering and just before escaping, we have
WWE ot dp
are a gg?
where ¢ is the length of the vessel. But, if 6;,—0;, be its directions before
entering and after escaping, we have approximately,
O,=10,, 0,=pb,.
Thus the whole change of direction is
6! +0; = — i,
depending only on the rate of change, not on the value, of the refractive index.
Parallel rays, passing nearly horizontally through such a vessel, will all be bent
in the direction in which the refractive index increases :-—but that which passes
through the stratum of most rapid change of index will be the most bent, so
that the illuninated portion of a sufficiently distant screen on which the rays
fall will be terminated by a spectral band of which the violet is outermost.
Measurements of the position of this band, from day to day, from hour to hour,
or even (in some cases) from minute to minute, will give an extremely accurate
mode of measuring the rate of diffusion. To interpret their indications,
however, a determination must be made of the law which connects the
refractive index of a mixture of the two fluids with the relative proportions
in which they are mixed. And it may not always, or even usually, be the case
that the stratum of greatest rapidity of change of refractive index is necessarily
coincident with that of most rapid diffusion. From the former, however, the
latter can always be found; and, so long as the original layers of the fluids
remain in part unaltered by the diffusion, the knowledge of the plane and rate
of greatest diffusion is sufficient for the complete determination of the other
circumstances. I believe that many important questions connected with
diffusion may be speedily and accurately investigated by this very simple
method. I propose to give a detailed account of it, with experimental results,
to the Society on a future occasion.
* B. A. Report, 1870. Tomson finds by a simple process, for the curvature of a ray in a non-
homogeneous medium, the expression
where m is measured towards the centre of curvature. The result is seen to follow immediately from
the corpuscular theory (in which =v) by multiplying both sides by py, for it is thus found to be merely
the equation of acceleration of a corpuscle in the direction perpendicular to its path. It is really in-
volved in Prop. I. of Wottaston’s paper (Phil. Trans., 1800).
PROFESSOR TAIT ON MIRAGE. 571
23. In order to calculate roughly the number, position, and dimensions of the
images visible to an eye looking through the media nearly horizontally at a
distant object, all that is necessary is to draw the caustic, as in fig. 8. It
consists, so far as the transition stratum is concerned, of the two (practically)
equal and similar curves AB, A’B’ ; which touch the stratum above and below,
and have as common asymptote the path of the most deflected ray. So long as
the eye is not within the region BAC, only one image is seen. But from any
point within this region two tangents can be drawn to the caustic, and a line
can be drawn to the object so as to pass altogether below the stratum. Thus
there are three images. In order that the middle one may be distinctly visible,
the eye must be 10 inches or so beyond the point of contact of the corre-
sponding ray with the lower caustic. Then the image is an inverted one. The
others are always direct. [It may be remarked, in passing, that the intersection
of the ray AC with the screen is always definite and measurable. |
Here the upper image is always seen by diverging rays, the middle one by
diverging or converging rays according to the position of the eye. Contrast this
with the results givenin § 20. This middle image changes its direction far more
rapidly than the others when the eye is moved vertically. It coincides with the
upper image when the eye, gradually moved downwards, reaches the line DB.
When they meet, both become blue and then disappear by moving the eye
farther down. On moving the eye upwards, the middle image approaches the
lower one, and they unite and disappear when the eye reaches the line DC.
These results are easily verified by trial, and I have mentioned them only with
the view of bearing out my statement, that this form of experiment, unless the
tank be long enough, does not give results the same as those of Mirage.
4 (Read 19th June 1882.)
A few days ago, while finally preparing the above pages for press, I had
occasion once more to consult WoLLAsTon’s paper, and inadvertently took down
the wrong volume of the Phil. Trans. Init (the vol. for 1803) I found another
paper on Mirage by Wo.taston, in which he speaks of certain articles by
WOLTMANN and GRUBER, and regrets his inability to read German. ‘This led
me to consult the Register-band of Gilbert's Annalen; and I thus learned the
existence of a very elaborate memoir by Biot* which I had never seen referred
to, and in which the subject of mirage is exhaustively treated both by calcula-
* Mém. de l'Institut, 1809; Récherches sur les Réfractions extraordinaires qui ont lieu prés de
Vhorizon. I presume that my having been altogether ignorant of the existence of this memoir is con-
nected with the fact that itis unintelligible without the plates, and that these were not issued along with
it. For in each of the three first libraries which I consulted, that of the Society being one, this volume
of the Mém. de l'Institut is devoid of plates. Bror’s memoir, however, was issued also as a separate
volume, and a copy of this, containing the plates, I procured at last from the Cambridge University
Library.
572 PROFESSOR TAIT ON MIRAGE.
tion and by long series of exact measurements of the phenomena as seen by
Marutev and Brot at Dunkirk, and by Araco and Biot at Majorca. The
previous work of GRUBER, WOLTMANN, Buscu, and others, is carefully sum-
marised by GILBERT in vol, xi. of his Annalen (1802) in notes to his translation
of WoLLAsTON’S great paper of 1800. A good deal of Brot’s work is thus seen
to have been anticipated. It may be well to quote here GiLBeRt’s remark as
to the priority of explanation of some of these phenomena—think of it now as
we may :-—
“In der That ist WoLLAsSToN der Erste und Einzige, der die Spieglung aufwarts mit
Gliick zu erkliren unternommen hat, ob er gleich auch hierin noch sehr viel zu thun iibrig lasst.”
Biot, on the other hand, gives WoLLAsToN credit only for the physical, as dis-
tinguished from the mathematical, parts of his paper. He says :—
“Sous le rapport de la physique, son travail ne laisse rien & désirer.”
Brot has considered the subject from a point of view somewhat similar to
that which I had adopted, and anticipated of course the great majority of the
more general results at which I had arrived. I was occasionally almost
startled as I looked through his memoir, to find how closely (even in mode of
stating them) I had reproduced some of his main ideas. His whole treatment,
for instance, of the ordinary mirage of the desert:—on the assumption that the
square of the velocity of a luminous corpuscle is proportional to the height
above the ground, but only through a limited stratum, together with the
important effects of limitation of the stratum:—-is almost the same as mine,
except that he (inconveniently I think) uses the caustics in preference to the
curve of vertices, though he also notices the latter as the courbe des minima.
In consequence, I had all but made up my mind to withdraw my paper, before
I had looked more than half-way through Bror’s long memoir ; for, though I
found here and there statements which I think inaccurate, these are of very
small consequence compared with the whole. But it was otherwise when I
read farther, where Biot gives his tentative explanation of VINCE’s observation.
There I found our assumptions to be so entirely different in character that,
being fairly satisfied with my own, I thought I might still reasonably produce
them with their results. My paper, therefore, appears as it was presented to
the Society, except in so far as (a) a part of the introduction, (0) the detailed
examination of the ordinary mirage of the desert, (¢) a discussion of the
singular outline sometimes presented by the setting sun, and (d) a few minor
remarks, are concerned. These parts have been simply struck out, the first as
historically imperfect, the others as practically a mere reproduction of what
had already been satisfactorily done by Brot, who had many opportunities of
observing and measuring the phenomena. As to the ordinary mirage, however,
there can be no doubt that the discovery of the existence of fou images, when
PROFESSOR TAIT ON MIRAGE. 573
the eye and object are both above the hot stratum, is far more easy by means
of the curve of vertices than by the caustics employed by Bror.
I transcribe some of the more important parts of Biot’s remarks on VINCE’s
phenomenon, premising that it was of course impossible for him to have been
acquainted with ScorEsBy’s observations, at least at the time when his memoir
was written. I fancy that, if he had seen these, he might have felt some
doubts as to the accuracy of his inference that the rays, in their course to
VINCE’s eye, were probably at first concave upwards ; and this to such an extent
as to make a vessel, which was situated close to the ordinary horizon, show
only its top-masts above the apparent horizon. He does not advert to the
certainty that, had this law held over the nearer parts of the sea, VINCE would
have seen inverted images wnder ships within the visible horizon. None such
are described. After quoting the passages in question, I shall add a few
comments onthem. To make them as intelligible as possible, I have reproduced
Bror’s hypothetical figure; it is numbered as fig. 9 in the plate. In many
respects the following passages are obscure, but to clear them up (if it can be
done at all) would require a thoroughly careful perusal of the whole minute
details of Biot’s volume, and for this I have not been able to find leisure.
Je crois pouvoir expliquer par la méme théorie les phénomenes des triples images observés
par M. Vincz et dont j’ai déja parlé plus haut. Quand je dis expliquer, j’entends ramener ces
phénoménes 4 une méme cause, 4 une méme forme de caustique, telle que la disposition des
images, et leur marche relative quand elles s’ abaissent ou qu elles s’ élévent, soient des
conséquences nécessaires de la forme supposée. Car admettre, comme l’a fait M. VINCE,
autant de lois différentes de densité quil y a d'images visibles, ne me paroit point une
explication satisfaisante, puisque les mouvements respectifs des images restent arbitraires ;
tandis que, d’aprés la description qu'il en donne, ces mouvements avoient entre eux des rapports
déterminés. :
Malheureusement M. VINCE n’ a pas observé ]’élément le plus nécessaire pour l’expli-
cation de ces phénoménes, je veux dire la dépression apparente de l’horizon dela mer. De
sorte que l’on ne peut pas affirmer a priori, si les trajectoires, dans leur partie inférieure
étoient concaves ou convexes vers la surface des eaux. Cependant je crois pouvoir conclure
qu’elles étoient convexes d’ aprés plusieurs raisons que je vais développer.
Ainsi, pendant l’observation du phénoméne, qui se fit depuis 4 heures } du soir jusqu a
8 heures, la température de l’air devoit avoir considérablement diminué, surtout dans les
couches supérieures, par l’effet de l’abaissement du soleil. Mais la surface de la mer n’avoit
pas da se refroidir aussi vite. Elle pouvoit donc alors et devoit probablement se trouver plus
chaude que l’air, ce qui donne des trajectoires convexes dans leur partie inférieure, et une
densité croissante du bas en haut, jusqu’ & une petite hauteur; aprés quoi linfluence de la
mer devenant moins sensible, la densité devoit aller de nouveau en diminuant comme a
Vordinaire, et probablement suivant une loi beaucoup plus rapide, tant 4 cause de l’abaissement
subit de la temperature, qu’ & cause de la chute des vapeurs aqueuses qui devoit en résulter
et qui par leur accumulation et par le froid qu’elles produisoient en se précipitant pouvoient
574 PROFESSOR TAIT ON MIRAGE.
contribuer 4 augmenter la réfraction dans les couches quw’elles traversoient. Ces conjectures sont
confirmées par plusieurs remarques de M. VINCE lui-méme.
. . . . . . . .
Je tire encore des observations mémes une autre preuve que les trajectoires n’ étoient pas
convexes dans toute l’étendue de leur cours, comme cela auroit eu lieu s’ il n’ y avoit eu dans
Lair qu'un seul état de densité décroissante de haut en bas. Cette preuve consiste en ce que
les deux images supérieures dont la plus haute ¢toit directe et lautre renversée, ont été
plusieurs fois completes, c’est-d-dire que la vaisseau y étoit représenté tout entier depuis le
sommet des mits jusqu’ au corps méme du batiment. Or, d’aprés les expériences que nous
avons faites sur le sable 4 Dunkerque, si ces deux images eussent ¢té données par des
trajectoires entiérement convexes vers la mer, ces trajectoires eussent nécessairement formé une
caustique qui se seroit élévée au-dessus de la surface de la mer 4 mesure quelle s’ eloignoit
de l’observateur. Cette caustique auroit done caché de plus en plus les parties inférieures du
vaisseau & mesure qu il s’ éloignoit, et par conséquent les deux images de ce vaisseau n’
auroient pas été complétes . . . . . On peut encore prouver par les observations de
M. VINCE que la caustique n’ étoit pas formée d’ une branche unique, mais de deux branches
distinctes réunies par un point de rebroussement et dont la plus basse alloit continuellement
en s’ approchant de la surface de la mer 4 mesure qu elle s’ éloignoit de Vobservateur. Car
puisque M. VINCE a vu des images completes de vaisseaux qui se touchoient par le corps méme
du batiment, il falloit bien qu’alors le vaisseau reposat sur la caustique; et comme il en a vu
aussi d’autres qui se touchoient par le sommet des mats, il failoit bien qu’ alors le vaisseau se
trouvat sous la caustique et la touchat par le sommet de ses mats. Enfin, puisque les images
d'un méme vaisseau données par ces deux branches s’ écartoient continuellement l'une de
Yautre, 4 mesure que le vaisseau s’ eloignoit, les deux branches de la caustique s’ eloignoient
done aussi lune de autre; ce qui indique une forme . . . . . qui seroit donnée par
la combinaison de deux décroissemens de densité contraires. .
Cette conséquence déduite immédiatement des observations s’ accordant avec l'état
décroissant de la température, et avec toutes les apparences que nous avons discutées, je crois
pouvoir admettre comme une chose trés-probable que, par exces de chaleur de la mer, &
l’époque ot a observé M. VINCE, les couches inférieures de lair se trouvoient dans un état de
densité croissante de bas en haut, jusqu’ 4 une petite hauteur, au-dessus de laquelle les
densités alloient de nouveau en décroissant par suite de l’abaissement de la température, avec .
assez de rapidité pour donner des images par en haut. 1D’ aprés les élévations données par M,
VINCE, nous devons placer ’observateur dans ces couches supérieures, car il dit avoir observé
le phénomeéne a 25 et 4 80 pieds de hauteur. Nous avons déja examiné précédemment les
combinaisons de ces deux états contraires, et lon a vu qu’ elle explique trés-aisément les
images multiples observées au Desierto de las Palmas et & Cullera, phénoménes qui paroissent
avoir le plus grand rapport avec ceux que M. ViINncE a deécrits. Nous supposerons donc
conformément a Vendroit cité, que la caustique avoit une forme VRV (fig. 9).
Soit AMH la circonférence de la terre, O lobservateur, OMV la trajectoire limite tangente 4
la surface de la mer. I] s’ agit d’examiner les phénoménes résultans de cette loi.
La supposition que nous venons de faire sur la non-sphéricité des couches n’est point
gratuite, car M. VINCE rémarque que des vaisseaux également élevés au-dessus de V’horizon
apparent présentoient des apparences trés-diverses, souvent plusieurs images comme nous
PROFESSOR TAIT ON MIRAGE. _ 575
venons de le dire, quelquefois deux seulement, l’inférieure constamment droite, la supérieure
renversée, d’autrefois enfin on n’ en apercevoit qu'une seule directe et reposant sur l’horizon.
Les cétes de Calais qui présentoient aussi des phénoménes analogues, offroient aussi les mémes
variétés, quelquefois on les voyoit doubles un instant aprés elles étoient invisibles. Toutes ces
apparences sont contraires 4 lidée d’ une sphéricité parfaite des couches dair qui produisoient
ces phénoménes, et l’on concoit en effet qu’étant le résultat d'une équilibre non stable, ils
peuvent difficilement s’ accorder avec une forme constante.
On this I would remark, generally, that I think VincE is here rather hardly
treated. It seems to me, on comparing the two explanations, that the
reproach of ‘‘ autant des lois différentes qwil y a @images visibles” is not
merited by ViNcE, and would perhaps more justly apply to his censor. It is
certainly most unfortunate that Vince did not note the level of the apparent
horizon ; though, unless he had done so from a great many different heights
above the sea, I fail to see how the observation would have helped to decide
- between the various possible explanations. Bror evidently expected a depres-
sion, for he states as much in reference to the elevated patches of sea and the
“heavy fog” which VincE observed ; yet this is inconsistent with his own
figure! But the following passage from VINCE’s paper (in which I have itali-
cised some words) seems to have escaped the notice of Bror.
“The usual refraction at the same time was uncommonly great; for the tide was high,
and at the very edge of the water I could see the cliffs of Calais a very considerable height
above the horizon; whereas they are frequently not to be seen in clear weather from the high
lands about the place. The Vrench coast also appeared both ways, to a much greater distance
than I ever observed it at any other time: s
Now, one of the most striking of ViNce’s observations was that of a ship
(hull down) with an inverted image above it, both projected on the confused
image of the French cliffs as a background. If Buiot’s explanation were
correct, this background must have been visible by rays of a truly schlangen-
Jormg character (as GILBERT calls them), for they must have been at least twice
(more probably thrice) concave downwards; with a convexity downwards,
somewhere between the spectator and the ship (and probably another between
the ship and the French coast). It seems much more likely that the ship’s hull
was really beyond the ordinary horizon, and that the French cliffs were visible
by rays originally concave upwards so as to rise up, as it were, behind the ship ;
and then concave downwards, according to the theory I have propounded, from
the ship to the spectator.
Biot’s memoir shows, throughout, the pervading influence of his almost
daily observations of rays which were concave upwards, because passing very
close to the ground over extensive surfaces of hot sand. If his explanation
of VINcE’s observation were correct, there would have been an inverted image
VOL XXX. PART II. a6
576 PROFESSOR TAIT ON MIRAGE.
(of a part of the top-mast) wrder the lowest of the three images, and objects
comparatively near hand would have been affected as well as those at a con-
siderable distance.
But there is much more to urge against Brot’s view of the phenomena in
question. VINCE expressly states that ‘the evening was very sultry.” As his
observations were made at heights above the sea, varying from twenty-five to
eighty feet, it is pretty clear that this sultriness was not due to the exceptionally
high temperature of the surface of the sea. Buror, in fact, allows that the
effects of this were only sensible “jusqu’ & une petite hauteur.” But then he
assumes (contrary to VINCE’s statement) a rapid descent of temperature at.
higher levels. This he looks on as developed, how he does not tell us, by the
cold produced by vapour in condensing! Besides, if this were true, it would
make the diminution of density upwards /ess, instead of greater than usual, and
the optical results of such an arrangement would be in contradiction to his
explanation.
It is much to be regretted that Vince's description, like his drawings, is of
the very roughest character. It is quite otherwise with those of ScorEsBy.
There can be no doubt whatever that Bior’s mode of explanation is alto-
gether inapplicable to the majority of ScorEsBy’s observations.
I quote a single passage,* which is apparently decisive.
“A dense appearance in the atmosphere arose to the southward of us . . . . When
it came to the S.W. of us, I first noticed that the horizon, under this apparent density, was
considerably elevated. . . . . . Two ships lying beset about fourteen miles off, the hulls
of which, before the density came on, could not be wholly seen, seemed now from the mast-head
not to be above half the distance, as the horizon was visible considerably beyond them.”
Had the arrangement of strata here been as Bror supposes in VINCE’s case,
only the top-masts would have remained visible, the apparent horizon would
have come in front of the hulls, and there would have been inverted images
of nearer objects visible wnder the objects themselves.
It will be observed that these observations were taken over a surface of ice
in which the vessels were “beset.” The sun is said to have been “ powerful,”
but the lowest strata of air, in contact with ice or ice-cold water, must have
been colder than those above them. The haze, or “ density” as ScoREsBy
calls it, probably consisted of minute drops of water, and would thus be much
raised in temperature by the sun. In connection with this I may mention that
when a trough, in which brine has been diffusing for some time into water, is
suddenly and roughly stirred for a short period, it settles in a few minutes into
a large number of strata of different densities. Something similar must hold
* Scornssy’s Arctic Regions, i, 387 (1820).
PROFESSOR TAIT ON MIRAGE. 577
in the case of air irregularly heated, and thus we have a very probable explana-
tion of the series of inverted images figured by Scorressy. The strata which
produced these, in all likelihood produced direct images also, but (except on
very rare occasions) so small in vertical dimensions as to have escaped
observation. In the absence of wind such strata, once formed, would last for
a long time, in consequence of the very small thermal conductivity of air. I
might also refer to an interesting case of inverted images seen from a balloon by
TISSANDIER.* The height at which the balloon was situated is not stated
expressly, but from the context it must have been somewhere about 6000
feet. This, of course, proves the existence, at a great elevation, of a stratum
in which there was a comparatively rapid diminution of refractive index
with increasing height.
I will quote, in conclusion, ScorEsBy’s account of his remarkable observa-
tion of an isolated inverted image of a ship, which was situated far beyond the
horizon. His drawing is reproduced as the second of the series in fig. 1. The
obvious and simple explanation of this is what has already been mentioned for
TISSANDIER’S observation, though, of course, it could also be accounted for by
an infinite number of different laws of refractive index, all of more or less
ingenious complexity.
“The atmosphere, in consequence of the warmth, being in a highly refractive state, a
great many curious appearances were presented by the land and icebergs. The most extra-
ordinary effect of this state of the atmosphere, however, was the distinct inverted image of a
ship in the clearsky, . . . . the ship itself being entirely beyond the horizon.
It was so extremely well defined, that when examined with a telescope by DoLtonp, I pal
distinguish every sail, the general ‘rig of the ship, and its particular character; insomuch
that I confidently pronounced it to be my Father’s ship, the ‘ Fame,’ which it afterwards proved
to be; though, on comparing notes with my Father, I found that our relative position at the
time gave our distance from one another very nearly thirty miles, and some leagues beyond
the limit of direct vision.” +
It seems hard to reconcile the clearness of definition in this case with any
other than a stable state of equilibrium of a transition stratum. The mirage
of the desert, where the equilibrium is essentially unstable, is always exceed-
ingly unsteady.
Brot makes a point, to which I have not yet alluded, from Vuincr’s state-
ment that the inverted image appeared to rise as the object moved farther
away. His mode of explaining this, however, savours of the “ autant des lois
différentes,” &c. ; and, besides, the result follows quite as directly from my ex-
* GLAISHER’S Tvavels in the Air, p. 297 (1871).
+ Scorzspy’s Journal of a Voyage to the Northern Whale Fishery (1823), p. 189.
578 PROFESSOR TAIT ON MIRAGE.
planation as from his. VINcr’s observations were by no means precise enough
to make this point certain ; besides, he speaks of the top-masts and not of the
hulls ; and, from the diminution of the image as the distance increases, it may
be quite true that the top-masts appear to rise in the inverted image while the
hull really sks. At any rate it isassuredly not so in the majority of ScORESBY’s
careful figures. In fig. 1 several examples are shown of multiple images of
ships at different distances in nearly the same direction ; and in all it will be
observed that the inverted image of the hull is lower as the vessel is farther
off. Also that in the upper direct image the hull appears to rise as the vessel
recedes.
[#eb. 10, 1883.—I have to acknowledge the kindness of Mr. J. W. L.
GLAISHER in verifying, and in some important instances correcting, the numerical
values given in {$10 and 15. My own original calculations, made for the most
part with four-place logarithms only, were insufficient to give accurately the
values of 6 close to the critical point. The reason is obvious from the form
of the expression for that quantity as given in § 12, above. |
oy: Soc Ladin” Vol XX PL AAAI
J. Rextholamew, Bam
( 579 )
XXIV. -—Description of Mimaster, a new Genus of Asteroidea from the Faeroe
Channel. By W. Percy Suaven, F.L.S., F.G.S. (Plate XXXIV.)
(Read May 15, 1882.)
The area lying between the north of Britain and the Faerée Islands is
classical in the annals of Marine Zoology, not only from the fact that the first
systematic deep-sea investigations undertaken by this country were carried out
there, but also from the number of new and remarkable types of animal life
which have been first found in that region. Speaking only of the Echinoderm
fauna, in justification of these remarks, it will suffice to mention the discovery
of such forms as Phormosoma and Porocidaris amongst Echinoids, and of
Hymenaster, Korethraster and Zoroaster amongst Asteroids.
The object of the present communication is to describe another new and
important generic type, which has been added to the last-mentioned group
during the dredging operations of H.M. hired ship “ Knight Errant,” whilst
engaged during the autumn of 1880 in further investigating the area referred
to. The results of that survey, including the discovery of the “ Wyville
Thomson ” ridge, which was found to form the barrier that separates the ~
“ warm ” and the ‘‘cold” areas, have already been laid before this Society in a
detailed account by Staff-Commander Tizarp, R.N., and Mr. Joun Murray.*
I desire to express here my hearty thanks to Mr. Murray for placing the
starfishes obtained during the cruise in my hands for determination.
A list of the different species, with notes thereon, is appended to the paper
previously cited. The following is a description in detail of the new form.
Genus Mimaster, Sladen.
Mimaster, Sladen, 1882, Proc. Roy. Soc. Edin., vol. xi. p. 702.
Marginal contour stellato-pentagonal; dorsal area subject to inflation ;
ventral area more or less convex. Abactinal floor composed entirely of inde-
pendent paxille, without subjacent calcareous reticulated skeleton. Paxille
small and compact. Numerous papule in the interspaces.
Marginal plates arranged in dorsal and ventral series, small and covered with
very numerous spinelets similar to those of the paxille.
* Exploration of the Faerée Channel during the summer of 1880, in H.M. hired ship “ Knight
Errant,” by Staff-Commander Tizarp, R.N., and Mr Jonn Murray ; with subsidiary Reports by various
scientific men (Prvc. Roy. Soc. Edin., vol. xi. pp. 638-719).
VOL, XXX. PART II. 4x
580 MR. W. PERCY SLADEN ON
Actinal floor extensive, and occupied by imbricating ventral plates, arranged
in isolated transverse columns, running from the adambulacral plates to the
marginal plates ; the whole area covered by a uniform epidermal layer of
membrane. Each ventral plate bears a single well-developed naked paxilla.
Adambulacral plates broader than long. Ambulacral spines delicate, taper,
numerous, irregular in disposition, forming a group which occupies the surface of
the plate, the size of the spines increasing towards the furrow-margin of the
plate.
Mouth-plates forming a pointed mouth-angle, superficies prominent,
covered with spines similar in form and character to the ambulacral spines, but
larger.
Ambulacral sucker-feet with a well-developed fleshy disk, devoid of
spicules.
Madreporiform body concealed by paxille. No pedicellarie.
Mimaster Tizardi, Sladen.
Mimaster Tizardi, Sladen, 1882, Proc. Roy. Soc. Edin., vol. xi. p. 702.
Description of an Individual.—F¥orm large and robust ; marginal contour
stellato-pentagonal. adii five, short and triangular, tapering continuously
from the base to the extremity, the breadth at the base of a ray greater than
the lesser radius of the disk, the interbrachial angle being subacute. The
lesser radius is in the proportion of 45 per cent., R=120 mm., r=54 mm. ;
R=2-27; breadth of a ray at the base, 58 mm.
The abactinal surface is high and inflated over the disk, very gibbous at the
base of the rays but flattening towards the extremities. A deep furrow is
formed along the median interradial line in consequence of the gibbosity, but
disappears before reaching the centre of the disk. The actinal surface is more
or less convex, but in a regular and comparatively slight degree, although the
feature is probably largely emphasized in the specimen under notice by the
upward turning of the extremities of the rays, which took place during the rigor
mortis. Consequent on the curvature of the actinal and abactinal surfaces,
the margins are very thin and of small dimensions, and are occupied entirely
by the double series of small marginal plates. The thickness or perpendicular
height of these two series of marginal plates together is only 4 mm.
The dorsal area is covered with a great number of small, uniform paxille,
closely and equidistantly placed, and with a well-defined space between each,
and presenting no definite order of arrangement, excepting in the immediate
neighbourhood of the arm-angle, where a certain amount of obliquely transverse ©
lineal disposition may be observed. The whole of the calcareous portion of the
MIMASTER, A NEW GENUS OF ASTEROIDEA. 581
abactinal skeleton is composed entirely of paxillee, as in Astropectinide. The
paxillz consist of a cylindrical pedicel, about twice as high as broad, expanding
slightly at the base, and with the distal extremity rounded and clavate, and
surmounted by a crown of 15 to 20 spinelets, which radiate apart very slightly
and produce a compact form of paxilla. The spinelets are short, delicate, and
slightly taper, about equal in length to the pedicel, and sometimes less,
probably owing, to a certain extent, to abrasion. The base of the paxilla is
quite small and thin at the margin, where a faint tendency to develop rudi-
ments of two or three very short radiating processes may be noticed. No
calcareous union or connection exists between individual paxille. Numerous
small papule occur in the interspaces, three to five being present in the quad-
rangle formed by four neighbouring paxille. Their membrane is very delicate,
and they taper somewhat rapidly towards the tip, which is thickened intoa
small knob. Owing to the manner in which the papule taper, a comparatively
swollen appearance is given to their lower part.
The marginal plates are small and subtubercular in appearance, and are
arranged in ventral and dorsal series, 37 to 38 plates being present in
each, between the interbrachial angle and the extremity of the ray. Each
plate is rounded or boss-like externally, and covered with a great number
of small spinelets similar to those of the paxillee, which gives them a prominent,
cushion-like appearance. The infero-marginal (or ventro-marginal) plates are
the largest, transversely sub-oval in form—the length increasing towards the
interbrachial angle—and bear not less than 100 spinelets. The supero-
marginal (or dorso-marginal) plates are smaller, usually round, and are placed
rather more aborally than the companion plate of the lower series, the pairs
standing consequently slightly oblique.
The ventral plates occupy a great space on the actinal surface, and extend
up to the very extremity of the ray. The plates are oblong and are arranged
in regular transverse and slightly oblique lines between the adambulacral
plates and the marginal plates. Each series or column thus formed is isolated,
being separated from the neighbouring column by a narrow space; and each
plate in a column overlaps or imbricates upon the next innermost plate. The
number of the columns corresponds exactly with that of the adambulacral
plates, and is not in relation with that of the marginal plates. The whole
ventral area is overlaid by a uniform layer of membrane, by which the shape of
the individual ventral plates is hidden from superficial observation. Each
ventral plate bears a single paxilla near its free extremity, which is rather more
robust than those on the dorsal surface, and carries rather fewer spinelets,
which are somewhat longer and more widely expanded. The paxillee, like
those on the dorsal area, are naked and not invested in membrane. In
582 MR. W. PERCY SLADEN ON
consequence of the size and arrangement of the ventral plates, the ventral
paxille are more widely spaced than the dorsal ones, and are disposed in
regular lines which run from the adambulacral plate to the margin, the lines
or columns being marked off by straight furrows or wrinkles in the membrane.
As the paxille are equidistantly spaced in each of these transverse rows,
equally regular and uniform longitudinal lines are also traceable along the ray.
In the arm-angle nine to ten paxillz stand in each transverse series, the same
number being maintained until about the outer fifth of the furrow.
The adambulacral plates are broader than long, and appear to stand on
the furrow margin as the terminal plates of the transverse series of ventral
plates ; about 75 adambulacral plates may be counted along the furrow. The
ambulacral spines are delicate and taper, irregular in number and disposition,
forming a compact group, transversely elongate in form, in relation to the
direction of the ray, which occupies the whole surface of the plate, and re-
sembles a compressed and enlarged paxilla. There are 15 to 20 spinelets in each
group. Two of the spinelets (sometimes three) larger than the rest, slightly
flattened and tapering to a point, stand at the margin of the furrow, their rela-
tive individual position being generally slightly oblique. The succeeding spine-
lets are less robust, and pass in gradation to the group of outermost spinelets,
which are about equal in size to those of the ventral paxille. The five or six
innermost adambulacral plates have much larger spinelets than the others.
The united mouth-plates form a sharp angle inwardly, and a large elongately
ovoid, sub-tubercular swelling is developed on their superficies,—the whole
surface being covered with spinelets arranged in somewhat similar series to the
ambulacral spinelets, standing perpendicular, seven to eight along each side of
the mouth-angle. The aboral portion of each plate is occupied by a compressed
paxilliform group, similar to those on the adambulacral plates. The madre.
poriform body is obscure and concealed by paxille.
The ambulacral sucket-feet are arranged in pairs ; they are robust and large,
with a well-developed fleshy disk, devoid of spicules.
No traces of any form of pedicellarize are present.
Remarks.—This magnificent starfish is entirely distinct from any of its
northern congeners ; and its structure is very remarkable, especially on account
of presenting an association of characters which belong to several independent
groups of Asteroids.
The arrangement and appearance of the paxille, and the numerous papule
interspersed, recall in a striking manner the habit of Solaster. On dissection,
however, it is found that this appearance is deceptive and not real; and that
the true structural resemblance lies in a very different and unexpected direction.
In Solaster endeca (Linn.), the form which at first sight is most nearly suggested
MIMASTER, A NEW GENUS OF ASTEROIDEA. 583
by the dorsal covering of the new species, the abactinal portion of the skeleton
consists of a rather closely reticulated calcareous framework, built up of small
imbricating plates, upon certain of which the paxillz are borne. The skeleton
of Mimaster, on the other hand, is constructed quite differently ; the whole
abactinal floor being composed of paxillee alone, each of the paxillee consisting
of a pedicel, with a slightly expanded base and a rounded clavate extremity, on
which the spinelets that form the crown are articulated. The expansion of the
base of the paxillz is very slight, subcircular, or irregular in outline, and usually
exhibiting two or three faint prolongations. The bases of the paxille are
closely placed, and occasionally a trace of overlapping may be found here and
there. This structure is identical with that met within Astropectinide, and has
hitherto been looked upon as specially characteristic of that group.
The adambulacral plates, the ambulacral spines, and the mouth-plates have
strictly the characters of the Gonzasteride. The marginal plates are likewise
suggestive of the same group, and, notwithstanding their inequality and in-
significant development, approach the habit of such forms as Astrogonium
pazillosum (Gray), from which also the general outline of the body is not far
removed.
The ventral plates recall in their character the ventral plates of Asterinide,
- whilst their arrangement also approaches in a certain degree that of some of
the Gontasteride.
Possessing such a great complexity of structural character, Mimaster natu-
rally stands in a very isolated position. For the present I propose to rank the
genus provisionally amongst the Gonzasteride, but reserve any expression of
opinion as to its definite position in that group until an opportunity is afforded by
a further supply of material for studying more closely the anatomy and general
structure. We may even say that the structural formula of the genus does not
appear to admit of close association with any form at present known. Radi-
aster, a genus established by M. PErrier* (from a specimen obtained by the
U. S. Coast Survey steamer “Blake,” in the dredgings in the Gulf of Mexico
and the Carribean Sea), appears to possess characters in common with our form,
and may probably prove to be one of its nearest allies. As far as their indi-
vidual relations are concerned, the description given by M. PErrirr indicates
important differences, which separate the forms widely. Without drawing any
closer comparison than that afforded by the short description of my learned
colleague, the following points may be mentioned. Radiaster possesses only
one series of marginal plates; each marginal plate carries two separate tufts
(“bouquets”) of spines, which somewhat resemble those of So/aster ; dorsal
plates are present, and these bear tufts of spines; and the tufts of spines are
* Bull. Mus. Comp. Zool., Harvard, vol. ix. No. 1, p. 17.
VOL. XXX. PART II.. 4y
584 MR. W. PERCY SLADEN ON MIMASTER.
enveloped in membrane. The structure of the abactinal floor and of the mar-
ginal girdle is thus quite distinct in the two forms. Respecting the structure
of the actinal floor, the description of Radiaster does not enable a comparison
to be made. It is quite possible that the forms may be even more widely
separated than I have supposed.
I have named this very interesting species after Staff-Commander Tizarp,
R.N., under whose command the “Knight Errant” cruise was conducted,
and to whom science is largely indebted for many valuable services and con-
tributions.
Habitat.—Faeroe Channel, lat. 59° 33’ N., long. 7° 14' W. (“ Knight Errant”
Dredging Station No. 4, August 10, 1880.) Depth, 555 fathoms. Bottom
temperature, 45°°4 Fahr.; surface temperature, 57° Fahr. Sea bottom, mud.
A single example.
DESCRIPTION OF PLATE XXXIV.
Fig. 1. Abactinal aspect of a ray of Mimaster Tizardi ; natural size.
» 2. Actinal aspect of the same; natural size.
, 3 Outline sketch of the whole starfish, seen from above, to show the marginal contour;
one-third natural size.
, 4. Outline sketch of the starfish, seen in profile; one-third natural size.
, 5. Three adambulacral plates, showing the ambulacral spines, together with a portion of
the adjacent ventral plates and their paxille ; magnified 5 diameters.
6. A portion of the dorsal surface, showing the dorsal paxille and papulle; magnified 5
diameters,
, 7. A mouth-plate, seen in profile; magnified 5 diameters.
4 Royal Soo Trans: Edin. VoL IKK -PLATE XXXIV
W & A K Jobnston Lithographers,
MIMASTER TIZARDI, — Sladen
-
XX V. Observations on Vegetable and Animal Cells ; their Structure, Division,
and History. By J. M. Macrarzane, B.Sc. (Plate XX XV.)
Part I.—THE VEGETABLE CELL.
(Communicated by Professor Dickson.)
In the present paper I propose exteuding my previous observations ‘“ On the
Structure and Division of the Vegetable Cell.”* I have shown that a nucleolus
and nucleolo-nucleus (at Professor Rutherford’s suggestion I now propose terming
this the endonucleolus) are essential,.and in most cases evident, parts of every
growing vegetable cell, and that the division of the endonucleolus very probably
precedes that of the nucleolus, just.as division of the latter undoubtedly pre-
cedes that of the nucleus, in all the cases investigated.
Chara fragilis, which I will now specially deal with, is eminently suited, in
many respects, for confirming the views above stated.. Since all the. tissues are
produced, directly or indirectly, from.a single apical cell by repeated division,
the complete life-history of each cell. can pretty easily be ascertained. My
observations have been made principally on specimens prepared by the. osmic
acid process. Buds especially, prepared in. this way and. mounted in balsam,
have a clear appearance and pleasing effect. .
Bravun,t PrinesHeim,{ Tuuret,§ De Bary,|| Sacus,1 and others, have
contributed to our knowledge of the history of Chara, while recently Srras-
BURGER ** and Jonow ft have studied cell.division in it. Reference will be
made to their results as we proceed.
In all our recent text-books illustrations of the terminal bud of Chara are
given with great accuracy, if we deal only with cell wall, protoplasm, and
nucleus ; but when we come to the nucleolus, appearances are figured such as
I have never seen in the numerous specimens by me. This is not surprising, if
we remember that the nucleolus has generally been regarded as a very doubtful
structure, even in spite of laboured protests in the shape of careful observations
by NagceELI and others. It will be seen as we advance that in Chara the
* Trans. Bot. Soe. Edin., vol. xiv. part ii.
+ Monatsberichte der Berliner Akad. der Wiss., 1852.
t Jahr. fiir Wiss. Bot. 1864, vol. iii.
§ Annales des Se. Nat. 1851, vol. xvi.
|| Monats. der Ber. Akad. 1871.
J A Text-book of Botany (Eng. ed. 1875).
** Ueber Zellbildung und Zelltheilung (3rd ed.).
++ Bot. Zeitung, 1881.
VOL. XXX. PART II. 42z
588 J. M. MACFARLANE ON VEGETABLE AND ANIMAL CELLS.
internode was cut off, its nucleolus showed continued activity, so here also,
when the three cells of the cortical node have been formed, the internodal
nucleolus may have proliferated once or twice. But the cortical nodal cells
themselves do not further multiply. Curiously enough, however, their nucleoli
follow the example of that of the internode, though necessarily at a somewhat
later period ; the consequence being that the cortical internodal, and soon after
the cortical nodal cells, become multinucleolar (figs. 6 and 7) ; and this multi-
plication of the nucleoli may not unfrequently be succeeded by breaking up of
the nucleus.
This remarkable continued activity without ‘new cell formation holds
throughout the development of all the vegetative parts.
We turn now to leaf devélopment. Each leaf originates as a lateral out-
growth from the stem node, the first portion cut off from it forming a leaf apical
cell, which by repeated transverse divisions forms a row typically of nine cells.
Of these, the three ‘terminal, as a rule, do not further divide. Each of the
lower six divide into an upper, the nodal, and a lower, the internodal, leaf
cells. The nodal cell and its contents proliferate till it forms a peripheral
layer of from six to ten cells surrounding an inner central cell. These peripheral
cells bulge out, their nucleoli divide, the nuclei then divide, a very delicate
spindle or barrel can now and again be detected (fig. 8), and along its centre
the new cell wall is deposited. The outer cells thus cut off are the so-called
stipules. In succession an inner layer, ‘“‘the uniting cells” (Sacus), are simi-
larly produced. Lastly, the cells of what may now be called the middle layer
divide, first transversely, then longitudinally. The progress of the latter stage
is well seen in fig. 9, where, after transverse division, the nucleoli of the cells
are in every phase of preparation for it.
But during this time the leaf internodes have been exhibiting the same
tendency to continued nucleolar proliferation which we have already noticed
in the stem, but in this respect even they have been outstripped by the three
terminal cells, whose nuclei, even while the stipules were being developed,
have greatly enlarged, and their nucleoli have broken up into many portions.
This again is followed at times by breaking up of the nucleus. A little later
the internodal leaf cells exhibit similar proliferation (figs. 8 and 9). But
just as we found that the nodes of the stem cortex after finishing their tissue-
producing work passed into this state, so also the nodal leaf cells exhibit similar
phenomena. But in saying so I must except the central, uniting, and stipular
cells, which, while becoming always multinucleolar, never, to my knowledge,
become multinuclear. The fact of these cells always remaining relatively
small, give us a probable explanation of this circumstance.
In tracing the later or multinuclear stages I have found that staining in
eosin, &c., with previous decolorising of the preparations, enables me more
J. M, MACFARLANE ON VEGETABLE AND ANIMAL CELLS, 589
easily to notice the nuclei than if prepared by the osmic acid process. It is to
be understood that while the multinucleolar phase has been seen in all cells,
the same cannot be said of the multinuclear phase, except in the internode of
the stem, which invariably has a greater or less number of nuclei. Only here
and there in the other parts of the plant have I detected multinucleated cells.
Whether this be due to imperfect histological examination or to the more
common presence of one nucleus only, cannot as yet be fixed.
Having studied Chara, I examined the genus Natella, which, while closely
allied to the former, is much simpler in structure. The internodal cells both
of the stem and leaf elongate greatly after their formation, while the nodal cells
scarcely increase at all. Though they all alike become multinucleolar, the inter-
nodal cells only progress to the multinuclear condition, but this is of a most
pronounced character, since in internodes still elongating I have counted thirty
to seventy nuclei.
These observations enable us to understand and group together facts which
have been more or less isolated. To do so we will take up the structurai parts
in detail.
Endonucleolus.—Though I have not been able always to follow the fate of
the endonucleolus in Chara, owing to many of my preparations being pretty
deeply stained, from all that I have seen of it Iam led to conclude that division
begins with it.
Nucleolus.—The nucleolus has been shown to pass through a most precise
and very remarkable series of changes, which force upon us the conclusion
that it isa most important part of the cell. But, as Dr Hamitron has remarked
in going over some of these points, a belief in its reality and importance is, to
a great extent, a return to former ideas. If we refer to SCHLEIDEN’S classic
paper on cell structure,* we learn that he regarded it as “a small sharply
defined body.” But to Narcexrt is due the merit of pointing out its very wide
occurrence and definite nature, for, after an examination of many Cryptogams
and Phanerogams, he is ‘inclined to set forth generally and to claim as an
essential character of the nuclear vesicle, that it contains one or more nucleoli.”
Again, he says, “as to the structure of the nucleolus, in my opinion, nothing
universal or precise can as yet be said. In some cases they appear to be merely
accumulations of mucilage. In others a membrane which surrounds them is
wholly unmistakable. In every case it is certain that they always appear with a
clearly defined margin. This circumstance speaks strongly in favour of the
assumption that they, like the nuclei, are enclosed ina utricle. Since if they
were merely agglomerated mucilage, we should have nucleoli, the substance of
which would pass gradually into the mucilage of the nuclear vesicle, and which
* MU.uer’s Archiv., part ii, 1838.
+ Ray Society Bot, Papers, 1845 (Trans.).
590 J. M. MACFARLANE ON VEGETABLE AND ANIMAL CELLS.
would generally possess an irregular periphery. Or, if they originated by
deposition of layers from without, this lamellar structure would be perceptible
in large and perfect nucleoli.”
NAEGELI regarded it functionally as a centre round which protoplasm
gathered to form the nucleus. Recent botanical authors have either greatly
neglected it or supposed it to result from a firming or segregation of the
nucleoplasm.
The conelusions-expressed in my previous paper have been amply confirmed
in studying Chara. In every active embryonic cell one nucleolus only is present
in the resting state.
In very rare cases, and only where it had attained a large size, have I noticed
a clear homogeneous liquid-like globule enclosed. Whether this resulted from
degradation of the endonucleolus, or whether the latter was enclosed in it, I
cannot definitely say, though, judging from appearances in Spirogyra, Rheum,
&c., the former view seems most probable..
From the action of chemical reagents, and the impression which it gives during
division of being thick and viscid, it seems to be a vesicle containing richly
differentiated protoplasm.
All reagents used, such as carmine, logwood, iodine solution, osmic acid,
eosin, and the various aniline dyes agree in this, that they invariably, or with
but few exceptions, stain the nucleolus more deeply than the nucleus.
During division the nucleolus elongates, becomes constricted rather sharply
in dumb-bell fashion, but during the whole period retains its dense consistence,
and then separates into daughter nucleoli. In Spirogyra, even before division,
I have pointed out that it is the centre of two opposing forces acting along the
length of the cell. The reason of this seems to be that a large nuclear spindle
has to-be formed in order to bring the daughter nuclei into the middle of the
two forming daughter cells. In Chara no such necessity exists, so that even
if similar forces be acting in it before division, these do not, since they need
not, exert themselves in the same pronounced way. But that the daughter
nucleoli are new centres of influence, determining greatly the future division
of the cell, cannot well be doubted in. view of what has been seen to take
place.
JoHow, in regarding the daughter nucleoli of cells as formed from the
chromatin granules, states that the latter are at first numerous, but gradually
unite to form the nucleoli. We might expect then to find preparations with
aggregating masses of four, five, or more. I have never found such in multi-
plying cells, and further, the idea is opposed to all that we know of cell division
where an increase and not a decrease in number occurs.
Nucleus.—I come now to a matter of great importance in view of recent
J. M. MACFARLANE ON VEGETABLE AND ANIMAL CELLS. 591
research, viz., the formation of the nuclear spindle or barrel, and the transfor-
mations of the nuclear substance during the process. No one could venture to
doubt that these are often complex, in view of the beautiful investigations of
STRASBURGER ; but the question is, Do these occur to an equal extent in all
plants, and in all the tissues of them? Before answering this, let us ascertain
for what end they exist. Setting aside SrTRASBURGER’s nuclear plate and disc
phase as something which, though occasionally, is not always present, the
study of various plants has convinced me that the spindle or barrel is merely
a scaffolding thrown across the space between the halves of the dividing
nucleus, the equator of this barrel, as its outward bulging progresses, coming
ultimately to span the inner surface of the cell wall. It thus helps the
protoplasm in its work of depositing the septum, and its presence is most
definite and marked where vacuolation has most occurred. In cells filled with
protoplasm, such as those of Chara, near the apex, no need exists for a: complex
structure of this kind, and while StrasBurcer figures, and TREuB and ScHMIDT
believe in, indirect division, I have, like Jonow, only seen such an appearance
as would result from the separation of.a rather viscid body like the nucleus,,
whose substance is traversed probably by delicate intranuclear threads. There
seems undoubtedly to be a fibrous network ramifying through the nuclear. sub-
stance of vegetable cells, judging from their appearance in the resting state,
both when fresh and stained, as also in the dividing state, when these fibres are
the most evident parts of the nuclear spindle.
In division they must of necessity be apparent if present, and the less dense
the medium by which they are surrounded the more strongly will they stand
out to view. Thus we have the very sharply defined spindles in the vacuolated.
cells of Lqguisetum limosum and Spirogyra nitida, but if the enveloping medium
be nearly or quite as dense as the fibrils, the less evident will these appear, and
as proof of this I would cite the cortical cells at the apex of the stem in
Equisetum limosum, which are filled with protoplasm, and in which either
fresh or stained spindles can be observed, but only by careful shading of the
light. In young Chara cells this is even more striking, for it is only by skilful
adjustment and shading of the light that between two nuclei pretty widely
separated, but with no cell wall, or but a mere trace of it, between, delicate
radiating strize could be detected.
PROTOPLASM, CELL WALL.—In the formation of the cellulose septum N AEGELI’s
conclusion, long ago expressed, that “ the cell membrane is an investment lying
upon the surface of the contents, and secreted by them,” is being surely
verified, though, as we have seen, it may be in a more complicated manner
than he imagined, particularly in vacuolated ‘cells.
Multinucleolar and Multinuclear State.—We will now deal with the very
peculiar phenomenon, which I hope to show occurs more or less in all plants,
592 J. M. MACFARLANE ON VEGETABLE AND ANIMAL CELLS.
but is so strikingly exemplified in Chara, of a multinucleolar succeeded by a
multinuclear condition.
As we have already seen, it can be said of all the vegetative cells of Chara,
that sooner or later, after a more or less prolonged period of proliferating
activity, further multiplication seems impossible, and the cells, while mostly
increasing greatly in length, all pass into a dormant multinucleolar and not
infrequently into a multinuclear state. Now, in studying the tissue systems of
Ornithogalum and Scilla (op. cit., pp. 198-99), exactly the same phenomenon,
though not so striking in its regularity arrested my attention, causing me to
conclude “that the nucleolus, or more probably the nucleolo-nucleus is the
centre of germinal activity, and that. as we pass outwards to the periphery of
the cell, this reproductive activity becomes less and less. Soon after, when
studying Chara, I was so struck with the similarity of the process, though on
a more exaggerated scale; that: an examination of many plants, and a wider
comparison with other observers, seemed desirable. The result is that in all
plants thus examined, after cell formation has ceased, continued division of
the cell contents from the endonucleolus outwards goes on, though in a varying
degree. Further, not.only does this seem true in the vegetable but also in the
animal cells, of which more anon.
But to bring out the phenomenon in Chara more strongly, if we commence
with a sub-apical cell, this, on division, forms a lower internodal cell, which is
at once arrested. The upper cell forms the nodal layer of cells which, after
giving off the cortical and leaf portions, is also arrested. The latter portions
continue to form many cells till, in the leaf, the three terminal cells and leaf inter- -
nodes are arrested, and in the cortex the internodes. The cells of the cortical
nodes and leaf nodes multiply till the former and then the latter are arrested,
and with their arrest the series of developmental stages is completed.
We see therefore from this that the general structural peculiarities of |
Chara result from the different cells being arrested at successive periods, the
arrest being most complete in the cells as a whole, less so in the nucleus, and least
of all in the nucleolus and endonucleolus, which, as we have seen, may undergo
proliferation to a large extent unaccompanied by any change in the nucleus or
cell as a whole. In this way, two, three, or more nucleoli may soon be formed
inside one nucleus. This is the usual condition of plant cells which have lost the
power of division. ‘These may serve to some extent for the conveyance of mate-
rial in the nutritive process, but seem principally to act as a kind of connective
tissue through which the fibro-vascular bundles ramify, and outside of which the
chlorophyll-bearing cells are borne. But in many plants, recorded by observers
or examined by me, the nucleus in turn divides in a few of the cells at least.
With such division there is no attempt at the formation of a cell plate, but
the nuclear membrane either grows into the nuclear substance till separa-
J. M. MACFARLANE ON VEGETABLE AND ANIMAL CELLS. 593
tion into parts is effected, or the nucleus elongates greatly and becomes con-
stricted in the middle, as figured by Jonow, one or more nucleoli being enclosed
in each part. When the nucleus and nucleolus are large, as in the young growing
peduncle of Hemanthus coccineus and stem of Fritillaria imperialis, one can
trace this ingrowth towards separation with ease; and it is to be noted that the
size and number of nucleoli enclosed greatly determine the size of each resulting
nucleus. Thus we may get, as ingrowth proceeds, a portion with three well-
formed nucleoli being cut off from a smaller portion with two lesser nucleoli,
and so on, the nucleoli seeming to act as centres round which the nucleoplasm
gathered (fig. 10).
STRASBURGER, in terming this breaking up of the nucleus “ fragmentation,”
does not regard the nucleoli as. of marked importance. He also holds that it is
in old cells that this phenomenon is exhibited.; but in very many cases this is
not so, since even the second, but usually the fourth or fifth internode from the
apex in Chara, may have two or three large nuclei, and yet be surrounded by
dividing cells which have been derived from the nodal cell that was cut off con-
temporaneously with the internode under consideration. The same is. true in
other plants. But while it may form in comparatively young cells, it remains
as the permanent condition of old cells ; that: is, the nuclei formed thus: may
after a time become dormant, and be found in old cells.. This is especially true
of those which are elongating to form. bast. cells in the more succulent plants.
After an examination of many plants, I find that the most gradual transi-
tion in this continued activity can be traced. Thus, in Spirogyra nitida, one
frequently finds two to five endonucleoli, though rarely two nucleoli; but in S-.
majuscula two nucleoli are very common. In the succulent parts of most plants,
one nucleus, with two or at most three nucleoli, each enclosing one to two endo-
nucleoli, is the rule. In the elongating cells of the internodes of Eguisetum
limosum the condition is one nucleus with three to six nucleoli, and two to three
endonucleoli in each.. In a few cells of some succulent plants, as Diclytira
spectabile, young peduncle of Haemanthus coccineus, Orchis mascula, &c., two to
three nuclei each, with one to four nucleoli, can be noticed. But in rather long
cells round the fibro-vascular bundles in Hamanthus coccineus, as many as seven
nuclei, each with two to three nucleoli, have been detected.. Chara may have
even more, specially in the internodal cells, each filled with dozens of small
nucleoli. Again, HEGELMAIER has described the multinuclear suspensor cells
of some Leguminose as having thirty or more nuclei, with one or two nucleoli
in each. As already stated, thirty to seventy nuclei, each with several nucleoli,
is the rule in the internodal cells of Nitella ; while, according to ScumiTz, there
may be several hundred in the seaweed Valonia, and in other alge and fungi.
TREUB observed great numbers in bast cells and laticiferous vessels.
VOL. XXX. PART II. oA
594 J. M. MACFARLANE ON VEGETABLE AND aNIMAL CELLS,
I venture, therefore, to regard it as a general principle that after cell forma-
tion has ceased, the cell contents (specially the endonucleolus and nucleolus)
persist in their activity for a shorter or longer period.
In studying these relative progressions, one or two features strike us :—
1. The cell wall is growing rapidly in length.
2. The amount of progression seems to depend greatly on relative nutrition.
(a) Those which only become multinucleolar are supplied, as far as can be
judged, with a moderate supply of pabulum, and are still able, in their earlier
stages at least, to form cells, as proved in Lquisetwm limosum, Heamanthus
coccineus, &c., where there may be three or four nucleoli in a nucleus which is
participating in cell division. The multinucleolar (two to seven) is the usual
condition of parenchymatous cells after cessation of germinal activity.
(b) Those which progress to the multinuclear state have an abundant
pabulum ; thus, in large cells round the fibro-vascular bundles, in bast cells and
laticiferous vessels, there is abundant elaborated material, and I should suppose
that the same applies in the suspensor of leguminous plants. In the long cells
of Chara, whose walls are covered ‘by chlorophyll bodies, as also in Yalonia,
&c., great nutritive supplies must be ever forming.
3. That wherever we have multinucleated cells these are never forming new
cells, but, though helping greatly perhaps in general nutrition, are themselves
the consumers of much elaborated material wherewith to increase the area of
the cell wall, and to maintain a certain quantity of protoplasm within it.
4. That multinucleolar and multinuclear cells are not the result of patholo
gical change, but ensue naturally when cell formation is stopped, the amount of
progression being to some degree proportionate to the nutritive supply. When
we say that the change is not pathological, we mean that it neither originates
new cells nor destroys old ones, so as to interfere with the normal vital func-
tions of the plant. Further, in stating that the progression is proportionate to
the nutritive supply, we do not assert that nutrition is the cause of division of
the nucleolus or nucleus, but simply that material is provided by which the
energy of the nucleolus is kept up.
It will thus be seen that I regard the building up of cells to form a definite
plant or the parts of it, as the result of a force radiating from the cell centre,
stimulating to division; and either that the energy giving rise to this force is
equal to producing only a certain amount of tissue, or that it is inhibited or
resisted by some external force, which prevents it forming an excess of tissue
when this would tend to pathological change, or to loss of individuality in the
plant. Also that the most exalted type of cell is one with abundant pro-
toplasm containing a single nucleus, nucleolus, and endonucleolus; that a
cell with vacuolated protoplasm, one nucleus, and two to four nucleoli is less
exalted, while the multinuclear state is the most degraded form of cell,
J. M, MACFARLANE ON VEGETABLE AND ANIMAL CELLS. 595
EXPLANATION OF PLATE XXXvV.
Fig. 1. Division of the apical cell of Chara fragilis.
Figs. 2 and 3. Section of the terminal bud. In fig, 2 the second and third internodal cells
have had their nuclei removed in eutting.
Fig. 4. Down-growing cortical lobes, covering in an internodal cell.
Figs, 5, 6, and 7. Further stages in the development of the cortical lobes.
Fig. 8. Upper portion of young leaf. Some of the.cells are in process of division, the
daughter nuclei exhibiting very delicate spindles,
Fig. 9. More advanced leaf development.
Fig, 10. Cell from the rapidly growing peduncle of Hamanthus coccineus. Though -eell
division has ceased,. the nuclei, &c., have continued dividing.
ile}
Gln P
2a #3 =
Trans. Roy. Soc. Edin? Vol. XXX, Plate XXXV.
J.M.Macfarilane, del.
M¢Farlane & Erskine, Lith’ Edin?
CHARA FRAGILIS, Etc.
Bay AG ou hein,
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TRANSACTIONS
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ROYAL SOCIETY OF EDINBURGH.
VOL. XXX. PART III.—FOR THE SESSION 1882-83.
~7 OSL, -
CONTENTS.
Art. XXVI. On the Nature of Solution. Part IL—On the Solubility of Chlorine in Water,
and in Aqueous Solutions.of Soluble Chlorides. By Wixi1am Lawton Goopwin,
B.Se. (London and Edinburgh), Demonstrator of Chemistry in University
College, Bristol. Communicated by Dr Crum Brown. (Plate XXXVI),
XXVII. The Dragon’s Blood Tree of Socotra (Dracena Cinnabari, Balf. jil.). By Baytuy
Baxrour, Sc.D., M.D., Regius Professor of Botany, University of Glasgow,
XXVIIL. On a Red Resin from Dracena Cinnabari (Balf. fil.), Socotra. By J.J. Dossrs,
M.A., D.Sc., Assistant to the Professor of Chemistry, eo of Cee
and G. G. Henperson, B.Sc., :
APPENDIX.
The Council of the Society, ; : -¥
Alphabetical List of the Ordinary Fellows, ‘ :
List of Honorary Fellows,
List of Ordinary Fellows Elected during Sessions 1880-81—1882-83,
List of Fellows Deceased, Resigned, and Cancelled from November 1880 to November 1883,
Page
619
624
(597)
XXVI.—On the Nature of Solution. Part I—On the Solubility of Chlorine
in Water, and in Aqueous Solutions of Soluble Chlorides. By WiLu1am
Lawton Goopwin, B.Sc. (London and Edinburgh), Demonstrator of
Chemistry in University College, Bristol. Communicated by Dr Crum
Brown. (Plate XXXVI.)
Thesis for the Degree of Doctor of Science in the University of Edinburgh.
(Read July 17, 1882.)
This research was undertaken with a view to ascertaining if metallic chlo-
rides have any tendency to combine with a further quantity of chlorine. The
well-known fact that potassium iodide unites with iodine to form a tri-iodide
suggested that potassium chloride might, under suitable conditions, form a
similar compound with chlorine. The method of investigation which first pre-
sented itself was to expose crystals of various chlorides to the action of dry
chlorine gas at low temperatures, when any chemical action taking place would
be expected to show itself in changes in the appearance of the crystals. A few
experiments were made with no apparent result, and the method finally adopted
was to determine the quantity of chlorine absorbed by solutions of the salts.
It was thought that in this way quantitative results could be obtained which
would reveal any tendency towards the formation of perchlorides. If a body
having the formula KCl, could be shown to exist, it would strengthen the
position of those chemists who contend that the generally accepted ideas
regarding atomicity need modifying. The discovery of a compound having the
formula KCl, would be a still stronger argument. At an early stage, however,
the research resolved itself into an investigation of the solubility of chlorine
gas in solutions of metallic chlorides in water, the question of the existence of
perchlorides becoming a side issue. The influence of salts in solution on the
solubility of gases in water is a subject of considerable interest, as throwing
light on the nature of solution in general. Of late, certain chemists are inclin-
ing to adopt the old view that solution should be included under the general
head of Chemical Action. ‘This view was generally held by chemists about the
beginning of this century, and in Thomson’s System. of Chemistry (1817)
we read at p. 92 :—
“The second species of combination into which water enters with solid bodies has been
usually termed the solution of these bodies in that liquid.”
VOL. XXX. PART III. 5B
598 WILLIAM LAWTON GOODWIN ON THE
And Berthollet, in his Statigue Chimique (i. 35), explains solution as
follows :—
“Water has obviously an affinity for all those bodies with which it is capable of uniting.
But affinity is mutual. We may say with as much propriety that the solid acts on the liquid
as that the liquid acts on the solid. Both act upon each other reciprocally, and at the same
time ; but the force exerted by each will be proportional to its mass. Now, there is this peculi-
arity in the action of liquids upon solids, that they can only act at the point of contact, or
at least near it, Hence, as far as the mass is concerned, it is quite the same thing whether a
solid be acted on by a large quantity of liquid or by a small quantity, since the points of con-
tact, and of course the sphere of the liquid’s activity, must in both the cases be the same.
When a solid body, then, is plunged into a liquid for which it has an affinity, whatever the
quantity of liquid may be, the action is always limited to a very small portion. Hence the
liquid is not capable at first of destroying the cohesion of the solid; the latter imbibes it and
combines with it, while new portions of liquid come into contact, and begin to exert their action.
If the affinity between the solid and the liquid be weak, the combination proceeds only till the
force of affinity is so far weakened by the quantity of water united, that it is no longer able to
overcome the cohesion of the particles of the solid, and then it necessarily stops. The com-
pound continues solid. With such solids water is capable only of forming a hydrate ; it does
not dissolve them. If the affinity be strong, new doses of water continue to combine with the
atoms of the solid, and thus these atoms are separated farther and farther from each other ;
but as this distance increases the force of cohesion continually diminishes, while the liquid, by
its increased mass, is enabled to act with greater and greater energy. Hence the cohesion of
the solid is gradually destroyed; the particles of it are separated to too great a distance, and
are dispersed equally through the liquid. This is what is termed solution. If we continue to
add more of the solid after a portion has been dissolved in this manner by the liquid, it will
be dissolved in the same way. But by this new portion the particles of the dissolved solid are
brought nearer each other in the solution; their mass is increased in proportion to that of the
liquid. Hence they exert a greater force on it, and of course the liquid is enabled to exert
only a smaller force upon new portions of the solid. If we continue to add new portions of
the solid, a time will come when the action of the liquid will be so much weakened that it will
no longer be able to overcome the cohesion of the solid, and it will then refuse to dissolve any
more of it. When a liquid has come to this state, it is said to be saturated with the solid.
Were we to suppose the solution to go on, the particles of the solid in solution would be
brought so near each other that their force of cohesion would overbalance the affinity of the
liquid for them, They would, in part, cohere, and form again a new portion of the solid. The
saturation of a fluid, then, does not mean that its affinity for the solid is satisfied, but that it
is not greater than the tendency of the combined particles to cohere. Now, when a liquid is
saturated with a solid, if by any means we can abstract part of that liquid, the cohesive force
of the particles of the solid must gain the superiority, and the consequence will be, that they
will unite and form solid bodies anew, till their number be so diminished that their mutual
attraction is again counterbalanced by the attraction of the liquid. Hence the reason that
evaporation occasions the crystallisation of those bodies which are held in solution by liquids.
If the affinity between water and the solid be not sufficiently great to enable it to overcome
any part of the cohesion of the particles of the solid, in that case none of it combines with that
body, it only moistens its surface. If the affinity is even weaker than the cohesion of the
particles of the liquid, in that case the surface of the solid is not even wetted.”
NATURE OF SOLUTION. 099
This extremely lucid explanation of the phenomena of solution evidently
is based on the assumption that solution in general is a species of chemical
action, and in Turner’s Elements of Chemistry (1842) the same assumption
is made. At p. 139, in discussing “affinity,” he says :-—
“The most simple instance of the exercise of chemical attraction is afforded by the admix-
ture of two substances. Water and sulphuric acid, or water and alcohol, combine readily. On
the contrary, water shows little disposition to unite with ether, still less with oil. .... Sugar
dissolves very sparingly in alcohol, to any extent in water; while camphor is dissolved in a
very small degree by water, and abundantly by alcohol. It appears from these examples that
chemical attraction is exerted between different bodies with different degrees of force... ..
Simple combination of two substances is a common occurrence, of which the solution of salts
in water, the combustion of phosphorus in oxygen gas, and the neutralisation of a pure alkali
by an acid, are instances.”
The opinion at present generally held is thus formulated in Roscoe and
Schorlemmer’s Treatise on Chemistry (vol. i. p. 232) :—
“Concerning the nature of solution, whether of solids, liquids, or gases, we know at present
but little. The phenomena of solution differ, however, essentially from those of chemical com-
bination, inasmuch as in the former we have to do with gradual increase up to a given limit,
termed the pnint of saturation, whereas in the latter we observe the occurrence of constant
definite proportions in which, and in no others, combination occurs. Solution obeys a law of
continuity, chemical combination one of sudden change or discontinuity.”
But on closer examination this distinction disappears. A mixture of
chlorine gas with excess of hydrogen would be a precise analogue of a solution
of a salt in excess of water. The chlorine would combine with its equivalent
of hydrogen, and then the hydrochloric acid so formed would mix with the
excess of hydrogen. Similarly, the salt would dissolve in its “ equivalent” of
water, and then the saturated solution would mix with the excess of water.
This would go on in the one case till a// the hydrogen had combined with its
equivalent of chlorine, when any excess of chlorine added would remain uncom-
bined and show its presence as free chlorine by its colour, &c.; in the other
case, till all the water had united with as much salt as it could take up, after
which any excess of salt added would remain undissolved. The same con-
tinuity appears in the one case as in the other. In one case, excess of gas
mixes with combined gases; in the other, excess of salt is visibly separate
from the combined salt and liquid, and this constitutes an apparent difference,
but that it is apparent only is seen in the fact that solids can be so finely
divided as to remain mixed with liquids for an almost indefinite period. And
the analogy holds when we compare a compound such as peroxide of hydrogen
with a supersaturated solution of a salt. A change of conditions interferes
with the stability in both cases. Pickerine has lately shown that basic
600 WILLIAM LAWTON GOODWIN ON THE
sulphates of alumina have no definite composition. An essential difference
between solution and combination seems at first sight to lie in the fact that
solubility is a function of temperature. Thus, the quantity of a salt which will
dissolve in water generally increases with the temperature regularly and appar-
ently without a limit. It is possible that at low temperatures the molecules of
water are associated together in groups, and that a molecule of salt attaches itself
to a whole group. When the temperature is raised these groups are broken
up, and molecules of water are broken off and ready to unite with farther
molecules of the salt. Or, on the supposition that the molecules of salt occupy
the interspaces, it is easy to see how arise of temperature would increase the
solubility by increasing the number of interspaces. This supposition is
strengthened by the observed decrease of the coefficient of viscosity of water
with rise of temperature, and the increased coefficient of solutions of salts.
Gases certainly mix irrespective of anything like chemical attraction, but when
liquids and solids are considered, a different set of phenomena is observed.
Some liquids “mix” in all proportions, others only within a limit. If solution
is a mere interpenetration of the particles of the two bodies, how can it be
explained that oil does not dissolve in water, but does dissolve in ether? It
may be that the particles of oil are too large to find their way into the inter-
stices of water, otherwise the kinetic theory is as favourable to interpenetra-
tion between oil and water as between alcohol and water. The case of water
and ether may be cited as an example of a limit to the solution of each liquid
by the other. The molecules of ether must be either very large or very far
apart, for with a molecular weight of 74 it has a specific gravity of only ‘723.
Its great mobility would seem to point to the latter as probable. If this be
the case the molecules of water should have no difficulty in finding room among
the molecules of ether. It can be generally stated that bodies which are like
each other in chemical constitution dissolve in each other, and it seems as if
something like chemical action between bodies must be assumed to explain
this fact. There is no definite boundary between solutions and chemical com-
pounds.* Alloys occupy a sort of middle-ground, but many of these can be
obtained in definite crystals ; but this is no more a proof of chemical combina-
tion than the production of definite crystals of isomorphous salts. It is pro-
bable that there is a gradual progression from simple mixture to the most
stable chemical combination, and for any particular case by a change of tem-
perature we may pass from a state of chemical combination to one of simple
mixture. Substances resembling each other chemically tend to mix merely,
* Dr Ramsay has shown (Jour. Chem. Soc., Oct. 1877) that hydrates of alumina and ferric oxide
give off their water at a regular rate depending on the temperature, while salts containing water of
crystallisation show different rates corresponding to definite hydrates. Something very like this is seen
in the phenomena of solution.
NATURE OF SOLUTION. 601
but may be made to combine in definite proportions by lowering the tempera-
ture or otherwise varying the conditions. Examples of this are seen in the
compounds of chlorine, bromine, and iodine with each other. The mixing of
water with sulphuric acid, as is well known, gives out decreasing quantities of
heat as dilution goes on, and the point at which no more heat is given out on
further dilution cannot be determined. We may suppose that the molecules
of water are associated together in groups, and that when the first portion of
water is added to the sulphuric acid these groups are completely broken up,
and each molecule of sulphuric acid attaches to itself a molecule of water to
form a monohydrate. If another molecule of water be added, the attraction of
the sulphuric acid, being less, can only partially disintegrate the groups of
molecules. It could be imagined that the former molecule of water prevents
the second from getting completely within the sphere of attraction of the mole-
cule of sulphuric acid. A third molecule would be still less attracted, the
groups still more incompletely broken up.
Solution probably depends on the kinetic condition of the bodies, on the
distances between their molecules, and on the attractions of molecules on each
other, or rather chemical action between the bodies.
There are, then, two theories put forward to explain the phenomena of
solution—one, that stated by BERTHOLLET, may be called the Chemical Theory,
for it assumes a chemical action between the solvent and the body dissolved ;
the other may be termed the Physical Theory, since it supposes the molecules
tu “dissolve” by finding their way into the molecular interspaces of the solvent.
It is probable that solutions are to be explained by a reference to both theories,
that some solutions take place in exactly the same way as the diffusion of gases
into each other, but that others require chemical action to bring them about by
breaking up congeries of molecules. (The word “solutions” is, of course, not
intended to include obvious chemical action.) An examination of the effect of
salts in solution on the solubility of gases might throw some light on the
subject, if the effect of an equal number of molecules of various salts be studied.
The solubility of carbonic acid gas in solutions of salts has been studied by
J. J. Mackenzie (Ann. Chem. Phys. [2] i. 438), who arrived at the following
results :—
1. Saline solutions absorb less carbonic acid than an equal volume of water.
2. The volume of the gas absorbed decreases as the concentration of the
solution increases.
3. The coefficient of absorption for solution of potassium chloride lies, like
its molecular weight, between those of ammonium and sodium chlorides ;
similarly for strontium, calcium, and barium chlorides.
As salts, in dissolving in water, generally increase the bulk, a volume of
saline solution contains less water than an equal volume of pure water. The
602 WILLIAM LAWTON GOODWIN ON THE
question then arises, Is the solubility in the water decreased by the presence of
the salt ?
SETSCHENOW (Deut. Chem. Ges. Ber., vi. 1461) has examined the effect of
magnesium, aluminium, and zine sulphates on the solubility of carbonic acid.
He concludes from his results that in salts of similar structure and amount of
water of crystallisation, the chemical equivalents are likewise the absorptio-
metric equivalents. He has also experimented with sodium salts, and finds
that they fall into two groups with regard to their action on the solubility of
carbonic acid. (1.) Those which do not combine with carbonic acid, as sodium
chloride. Solutions of these absorb the gas according to DAuron’s law. (2.)
Salts which combine with carbonic acid—for example, phosphate of sodium.
With these absorption increases with strength of solution, but is not propor-
tional to pressure.
SETSCHENOW’s examination of sulphuric acid (Peterb. Acad. Bull., xxii. 102)
gives the following results :—-The coefficient of absorption of the pure acid
for carbonic acid is almost identical with that of water. On dilution, the
coefficient diminishes rapidly till an acid of a strength represented by the
formula H,SO,+H,0 is obtained, after which further dilution slowly increases
the coefficient. ,
The solubility of ammonia gas has been studied by Raovutt (Compt. Rend.,
Ixvii. 1078), who has obtained the following results :—
The coefficient for solutions of caustic potash is less than that for water.
Thus, at 16° C. and 760 mm. pressure—
100 c.c. water absorbs 60 gms, ammonia.
, 2425 per cent. potash solution 30 gms. ammonia.
saturated potash solution 1 gm. ammonia.
»
»” red
From which it appears that the solvent power of the water is decreased by the.
presence of caustic potash, since 100 c.c. of the 24°25 per cent. solution
contains more than 50 c.c. of pure water.
Soda solutions have the same coefficient as potash solutions of the same
strength (equivalent ?).
Solutions of sodium nitrate and of ammonium nitrate absorb the same
volume as equal volumes of pure water. On the other hand, dry sodium nitrate
absorbs none, while dry ammonium nitrate absorbs a considerable volume.
Solution of potassium nitrate absorbs more ammonia than pure water, but
there is no ammonia in the evaporated residue. He formulates his results in
the general statement: The difference between the coefficient of absorption of -
ammonia in water and in solutions of a salt is proportional to the weight of the
salt in a constant volume measured before the absorption of the gas.
The solubility of chlorine gas in saline solutions does not appear to have
NATURE OF SOLUTION. 603
been heretofore determined, and the following pages give the results of my
determination of the coefficients for solutions of chlorides. The solutions were
made to contain quantities of salt proportional to the molecular weights of
the anhydrous chlorides, so as to secure an equal number of molecules in equal
volumes. By this method it was hoped that any influence due to the number
of molecules would become apparent.
The method at first adopted was to saturate 10 c.c. of the solution with
chlorine, read the temperature of a thermometer placed in the test-tube con-
taining the solution, blow off the atmosphere of chlorine, run in excess of
iodide of potassium, and titrate with hyposulphate solution. This method
did not give concordant results, owing to the difficulty of getting rid of the
superposed atmosphere of chlorine. A slight modification of ScHONFELD’s
method was then adopted. This chemist has determined the solubility of
chlorine in water at temperatures between 10° C. and 40° C. He passed the
chlorine through boiled water contained in a flask fitted with a stopper having
four holes bored in it—one each for the entrance and exit tubes, one for a
thermometer, and a fourth for a bent tube through which the chlorine water
was forced out, when required, by stopping the exit of the gas. To estimate
the amount of chlorine dissolved at any temperature, a given volume of liquid
was drawn off, diluted to a known volume, of which an aliquot part was
titrated by the iodometric method (Ann. Ch. Pharm., xevi. 8). The
apparatus employed in the present research is sketched in Plate XX XVL., fig.
vil. Chlorine evolved in A from a mixture of potassium bichromate, and strong
hydrochloric acid is washed in B, and led through G into the solution con-
tained in E, thence away by F, a rubber tube, which can be closed at will by a
pinch-cock. E was surrounded by a freezing mixture, after the liquid had
been saturated at the ordinary temperature, and determinations were made as
the temperature rose from the lowest point attained, by closing the tube F and
receiving the liquid forced out through D in a specific gravity flask (10 c.c.),
which was quickly stoppered, washed, immersed in a solution of potassium
iodide, and opened to allow the solution to escape. The iodine set free was
titrated with standard solution of sodium thiosulphate. The stream of chlorine
was easily regulated by means of a burner under the flask A, and formed a
most efficient stirrer for the solution in E. The temperature was accurately
marked by a thermometer T, graduated in tenths of a degree.
The solubility in water was first examined. The flask E was partially filled
with water, and the chlorine passed through for some time at ordinary tempera-
ture. The bath was then filled with ice, and the end of the tube D, which
dipped below the surface of the water in E, was loosely plugged with asbestos,
to act as a filter for the chlorine hydrate. As soon as the thermometer was
604 WILLIAM LAWTON GOODWIN ON THE
steady, 10 c.c. of the solution was drawn off and the chlorine estimated. As
the temperature rose, determinations were made as rapidly as possible. After
the maximum solubility had been attained and passed, the chlorine was
estimated at intervals of 5 to 10 degrees. The temperature was raised above
that of the laboratory by pouring hot water into the bath till a thermometer
marked a temperature two or three degrees above that required. As soon as
the thermometer in E was steady, the chlorine was estimated.
Then, if ~ represent the number of cubic centimetres of sltioaniiihict
employed, a the equivalent of 1 c.c. in iodine, p the pressure of the atmosphere,
and a the coefficient of absorption,
na X 22:33 x 760 x 100
“a ep
The results are tabulated below. H,0O.
i
Made with a common thermometer, and not so reliable below 12° (part of
stem within E) as the other series made with a delicate thermometer.
te p e.c. of Na,S,0, a
4 761°9 20°6 IG Sy ly
5 21-0 1:9080
7:5 23:2 2:1079
8:9 26°8 2°4350
9:6 28'7 26077
10°3 29°9 2°7104
10°8 32-4 2:9438
Ass 32°9 2°9894
14:3 27°9 25350
23:5 23°7 2°1534
32°5 19st 1:7354
39'0 15°5 14083
45:0 12°8 11636
50:0 eo) 1:0812
1 c.c, thiosulphate = 0:10537 gm. iodine.
Ti,
t p Na,S,0, a
69 750 20°7 2:2931
84 230 25469
9°3 24'5 2°7135
10:2 26:2 29012
13:3 265 2'9344
15°2 23°6 2°6133
20:9 20:9 2:3143
1 c.c. = 0°01243 gm. iodine.
NATURE OF SOLUTION. 605
NOE
a p Na,S,0, a a (Schonfeld)
10-1 756°2 25°6 2°8741 2°59
11:2 24:3 2°7267 2°53
11:3 24:05 2°7001 2°54
13°7 22°35 25079 2°42
af 18-2 2:0422 2°21
32:1 14:05 15766 1°67
32°2 14°35 16111 1:66
36°7 12°3 1:3802 1:48
1 c.c.=0°0127 gm. iodine.
These results are expressed in curves H,O (1), (2), and (3) of Diagram. It
will be seen that these curves are not identical, but show a regular variation too
great to be ascribed to experimental error. Experiment I. was begun when
only a small quantity of chlorine hydrate had been formed ; in Experiment II.
the water was allowed to become semi-solid before beginning the determina-
tions ; Experiment III. was begun at 10° without formation of chlorine hydrate.
The curves show that the solubility of chlorine in water, or at least the action
on potassium iodide, is greater in proportion to the amount of chlorine hydrate
previously formed. This applies only to the solubility after the decomposition
of the hydrate, for several sets of determinations show that the solubility
before the maximum point is reached is constant, and represented by the curve
H,O (2), this part of curve H,O (1) being somewhat irregular on account of a
circumstance mentioned above.“ An explanation may be found if it is supposed
that hydrate of chlorine in decomposing forms a small quantity of hydrochloric
or hypochlorous acid. The presence of hydrochloric acid would increase the
solubility of chlorine in water (see p. 612). With a. view to ascertaining if
hydrochloric acid is really formed, the reaction was tested after titration in a
series of estimations made for another purpose (p. 603), and found to be neutral
until the chlorine hydrate was decomposed, then distinctly acid.
Curve H,O (Sch.) was drawn from ScHONFELD’s numbers, and it appears
that the maximum as determined by him is too low, and indeed an initial rapid
fall as seen in H,0 (3) is more probable than a gradual descent ; for it may be
safely assumed that some chlorine hydrate is formed at 10°, but remains
in solution. Its decomposition between 10° and 15° would produce the sudden
descent. Ifthe temperature be reduced below 10° the hydrant crystallises out.
The question then arises—Why does the remaining liquid dissolve less chlorine
at low than at high temperatures? The answer to this is plain. The ascending
part of the curve represents the solubility of a solid (chlorine hydrate) in water,
and this solubility follows the general law. The descending portion represents
VOL. XXX. PART III. 5 C
606 WILLIAM LAWTON GOODWIN ON THE
the solubility of a gas in water, and this solubility as usual decreases with rise
of temperature.
Potassium Chloride.—A solution of pure potassium chloride was made, so as
to contain 20 gms. salt in 100 ¢.c. solution. The chloride was recrystallised to
insure its purity, and the absence of bromine, iodine, and oxidising agents was
proved. When the solution was exposed to a current of chlorine at low
temperatures, chlorine hydrate did not appear until the thermometer marked
2°. As the solution had been saturated at the ordinary temperature before
cooling, it is evident that the presence of potassium chloride prevents the
formation of solid chlorine hydrate between 2° and 10°. The maximum
solubility is at 9°, the hydrate beginning to decompose rapidly between 7° and
8°, and disappearing completely at 9°. Potassium chloride in solution then
hastens the decomposition of chlorine hydrate, and decreases the solubility of
the gas in water. It will be noticed that the ascending part of the curve is
almost identical with the prolongation of the corresponding part of the curve
for water. In other words, chlorine hydrate has the same solubility in this
solution of potassium chloride as in pure water until a temperature of 7° is
reached. The descent from the maximum is at first rapid, and then more
gradual.
KCl.
: p Na,$,0, a
— 30 741-0 116 1-0812
— 07 14:1 13142
Beales 7 1-6497
2-2 19-1 1:7802
55 22'8 21251
8-0 23°3 21717
LVI 735°5 12-9 12114
+ 0:0 141 1:3243
3-0 19-9 18687
4-0 20-1 18875
5-2 21-6 2-0283
75 22-7 21316
105 23-5 22067
18-0 143 13428
24-0 10°5 0:9860
31:8 9°5 08921
35:0 8°7 0:8170
1 c.c. Na,S,O,=0-010337 gm. iodine.
Sodium Chloride.—A solution was made containing 15°71 gms. in every 100
c.c., ae. molecule for molecule with the solution of potassium chloride.
NATURE OF SOLUTION. 607
The curve of solubility is almost identical with that of potassium chloride
solution.
NaCl .
s p Na,8,0, a
— 3 763'2 10°3 0°9321
ts 14:0 1:2669
2G) 17 es 15656
3:0 20°5 1-837
5:5 21°5 1:9455
6:7 22°6 2°0452
9:2 24:3 2°1990
10:0 21°9 1:9818
15:2 16°1 1:4570
21:0 12:9 11674
25°5 10°3 0:9321
29°5 9-4 0°8507
1 ec. Na,S,0,=0°010337 gm. iodine.
Barium Chloride.—On account of its sparing solubility it was necessary to
make the solution of this salt only half as strong as the preceding. Its curve
therefore appears above the curves for potassium and sodium chlorides.
Chlorine hydrate formed readily below 10° and decomposed rapidly between
8° and 10°.
BaCl, .
ie p Na,S,0, a
207 766 ay 11651
30 15:0 1:3981
Blo 15°6 1:4540
4:2 16°95 1:5799
UL ager 1:6497
61 19°4 1:8082
T2 26°5 1:9107
9:1 21:3 1:9853
10°9 20°3 1°8921
12:0 19:0 LTS
13°5 16°9 1:5238
17:0 16:0 1:4426
21:0 Pay 1:3254
26:5 12:1 1:0910
34:0 9°5 0°8566
Under Strontium Chloride will be found a comparative experiment with that
salt, the solution being diluted to half strength. The curve so obtained lies
above that for barium chloride.
608 WILLIAM LAWTON GOODWIN ON THE
Strontium Chloride.—With a solution of this salt of an equivalent strength
to that of potassium and sodium chlorides, only a very small quantity of
chlorine hydrate was formed at about 0°. Determinations were made with a
solution diluted to double its volume for comparison with barium chloride.
SrCl, .
Lise. = 001234,
- p Na,8,0, a
05 752 9°75 1:0768
2°9 105 11596
5:0 es 1:0933
68 9°5 1:0492
17, 8-4 09277
18:8 73 0°8062
2°) 6-1 0°6737
324 5°6 0°6185
II. (half strength).
1:0 750 12°6 1°3915
2:2 13°6 15020
4:2 150 16566
70 17:2 18966
1071 18:0 1:9879:
An accident here interrupted the experiment. Hydrate formed abundantly
at 0°, and began to decompose rapidly at about 9°.
Calcium Chloride.—No chlorine hydrate was formed even at 7°:0, and when
the solution at this temperature came in contact with some chlorine hydrate
which had formed in the tube delivering the chlorine, decomposition took place
with strong effervescence.
CaCl, .
e p Na,S,03 a
—55 7577 12°75 1:42'79
—3°'5 15°45 1°7302
—2'8 15.5 17358
eat) 15°55 17414
+0°3 14°55 16294
4:2 13-9 15567
10°4 119 LaZr
15'9 10°8 1:2095
21:4 9:2 1:0303
278 (args) 0:8679
354 6:2 0°6943
1 ec. =0:0127 iodine.
The curve constructed from these results is remarkable for its flat summit.
It shows a maximum point, although there is no formation of chlorine hydrate.
It might be supposed that this was due to non-saturation, but the same
NATURE OF SOLUTION. 609
phenomenon appeared in an earlier set of experiments, and indeed the chlorine
was in each case passed through the solution for about two hours before any
determinations were made. An explanation of this and other maxima, occurring
without formation of hydrate, will be suggested further on.
Calcium, strontium, and barium form a series, the solubility of chlorine in
solutions of their chlorides decreasing with increase of atomic weight.
Magnesium Chloride.—With this solution no chlorine hydrate was obtained
even at —7°°5, and a maximum of solubility appeared at about 2°.
Mg(Cl, .
t p Na,S,0, a
—7°5 #69 11-2 10059
—5'6 14:1 1:2664
—4°7 16:2 14550
—32 17-4 15627
—08 17°7 15897
+14 18:1 16256
3°5 17°8 15987
57 174 1:5627
85 16:2 1:4550
12'8 15°7 14101
1917 13°8 12394
26:1 11°9 1:0688
31'3 10°6 0:9520
37°3 8°7 07814
1 cc. =0°010337 iodine.
Ferric Chloride.—A neutral solution of this salt was obtained by dissolving
pure iron wire in hydrochloric acid, keeping the iron in excess, estimating the
iron and diluting to the required strength. The solution did not allow the
formation of chlorine hydrate, but on the contrary decomposed it when previ-
ously formed (Cf Calcium Chloride). As ferric chloride slowly sets free iodine
from iodide of potassium, the usual method of estimating the dissolved chlorine
was varied. The solution was poured into excess of Mohr’s salt, and the
excess titrated with permanganate of potash. It was found extremely difficult
to prevent loss of chlorine unless an enormously large excess of Mohr’s salt
was used. The results are, however, sufficiently accurate to show that there is
a maximum also in this case, although not very well defined.
He Cl...
i ay
— 6:0 1:2748
—54 1:3038
—3°0 1:33.28
610 WILLIAM LAWTON GOODWIN ON THE
Fe, Cl, .
ti a
+11 13618
+21 rains
+52 13618
14:9 1:2169
32:0 05795
38:1 0:4636
From 1°:1 to 4°2 the solubility is constant.
Cobalt Chloride.—No chlorine hydrate was formed in this case, and the
solution decomposed solid chlorine hydrate with effervescence, but not so
quickly as ferric and calcium chlorides.
CoCl,.
i p Na,8,0, a
—5:0° 766°6 13:0 14084
—40 14:0 15167
—155 16:1 17442
+0°7 16:0 17334
1-9 15-9 1°7225
55 14:7 15925
9°5 13-7 14842
159 12:0 1:3000
21:2 10°45 11312
27°3 91 0:9859
35:0 v4 08018
1 c.c.=0°01243 gm. iodine.
Nickel Chloride.—-Chlorine hydrate was formed abundantly at —4°, and
decomposed at 0°.
NiCl,.
te p Na,S,0, a
—50 754 13°9 15643
—10 fe 1:9244
+1°0 19:55 2°2001
33 19°95 2°2451
51 19°8 2:2283
11°6 18:1 2:0370
15:0 16:3 18344
22°2 13°3 14968
2974 9°5 1:0691
35'5 78 0°8778
1 c.c.=0°'0127 gm. iodine.
Manganese Chloride.—Chlorine hydrate was formed in small quantity at
5°0, and a few dark purplish crystals appeared for a short time at the lowest
NATURE OF SOLUTION. 611
temperature attained. As the temperature rose no peroxide was seen till after
the maximum was passed, when small quantities began to form. This renders
the numbers rather high between 0° and 30°, although not very much so, as the
formation of peroxide ceased shortly after the maximum point was passed.
This would seem to show that the formation of peroxide is due to the decom-
position of chlorine hydrate, and suggests hypochlorous acid as the oxidising
agent. According to SoprERO and SELMI,* no peroxide of manganese is
formed by passing chlorine through a solution of pure manganese chloride ; but
evidently the formation of hydrate of chlorine, and its subsequent decomposition
in presence of manganese chloride, causes the production of the peroxide.
MnCl,
t p Na,S,0, a
— 5:0 768°6 15:0 1:6208
— 02 21:9 2°3664
+11 27 2:3448
29 19°7 2:1287
Ser 18:5 19990
16:0 14-7 15884
24:7 12°8 13831
31:4 8:7 09401
1 c.e.=0°01243 gm. iodine.
Cadmium Chloride.—With this solution chlorine hydrate was easily formed,
and examined undecomposed up to 8”.
CdCl,
t° p Na,S,0, a
—1°5 769 57 06156
+1:3 74 0°7992
3°2 88 0°9509
12:2 12"1 13068
16:0 11°35 1:2258
25°4 Sry 1:0476
318 8°6 0:9288
1 c.c.=0°01243 gm. iodine.
Zine Chloride.—An attempt was made to estimate the solubility in solution
of zine chloride, prepared from carbonate, but it was found that a small
quantity of iron was present, and time did not permit purification. A few
determinations showed the maximum to be at about 3°.
LInthiwm Chloride.—Chlorine hydrate appeared in this solution at —5°, and
began to decompose between —5° and —4’, disappearing completely below 0°.
An inspection of the curve of solubility will show that chlorine dissolves in
* Ann. Ch. Phys. [3], xxxix. 161.
612 WILLIAM LAWTON GOODWIN ON THE
solution of lithium chloride almost as freely as in water, but that the maximum
point is nearly 10 degrees lower. Beyond the maximum the solubility greater
is than that of any other solution heretofore examined.
LiCl.
t° p Na,8,0, a
— 6:3 7645 20:0 21727
—3°5 25:3 2:7484
—0°3 26°0 2°8245
+05 24°8 2°6948
5°3 22°9 2°4877
10°5 21:2 2°3030
14:8 rat 1:9228
20:9 14:2 15426
27°4 109 111841
38:0 9°6 1-0429
1 c.c.=0°012438 gm. iodine.
Hydrochloric Acid.—A solution of hydrochloric acid was made, of specific
gravity 1:046, containing an amount of pure hydrochloric acid per 100 c.c.,
very nearly equivalent to 20 grammes of potassium chloride. In this case the
wash bottle was filled with the same solution, and the flask was cooled down
before the stream of chlorine was passed through the solution to be experi-
mented upon. The numbers below show that chlorine is much more soluble in
hydrochloric acid solution than in pure water. Of course the results at the
higher temperatures are only approximate, owing to the continual weakening
of the solution. Chlorine hydrate appeared at 0°, began to decompose at 2°,
and had completely disappeared at 7°.
HCl (sp. gr. 1:046).
ft D Na,8,0, a
—48 752 27-0 2-9819
+33 29-4 32469
4g 34-1 37660
+0°5 37°8 41746
3-2 41:8 46163
4:7 464 51244
6:9 46:0 50801
8-6 38-2 42188
16:2 815 34788
236 23-0 25403
30:1 17-1 1'8885
370 13-0 14357
41:0 10'8 11927
43'8 9-0 0:9940
1 e.c, =0°01245 om, iodine,
NATURE OF SOLUTION. 615
Stronger solutions were now tried, and the numbers below show that the
solubility increases rapidly with the concentration of the acid.
HCl (sp. gr. 1:080).
& p Na,S,0, a
—58 763°7 59-4 64596
—4:8 60-2 65466
338 592 64378
Bae! 580 63073
£3 56'1 61007
2-5 516 56113
6°8 A5‘1 49045
155. 38:1 41433
26:0 29°5 3:2080
31-0 21-2 ° 93054
35°6 16°7 18161
39°6 13:9 15116
45:2 12°3 13-376
1 c.c.=0:01243 iodine.
HCl (sp. gr. 1°125).
i p Na,S,0, a
—10°0 763°7 80:9 8:7976
— 50 83:1 9:0369
— 22 ; 745 * 81017
+ 08 65:5 71229
10:0 57-0 61843
20°7 43:8 47631
1 ¢.c.=0°012438 em. iodine.
No chlorine hydrate was formed.
It will be noticed that the points of maximum solubility occur at lower
temperatures with the stronger solutions, and if the summits of the curves be
connected so as to form a curve of maxima the latter is found to be very steep,
and it was thought that at still lower temperatures chlorine gas might be got
to combine with dry hydrochloric acid to form a perchloride of hydrogen.
The experiment was tried by passing the dry gases into a flask, cooled down to
about —10°, but no result was obtained. The high solubility of chlorine in
hydrochloric acid solutions certainly points to the formation of a perchloride,
and it is probable that under increased pressure the two gases would combine
at low temperatures.
Mixed Chlorides.—It ‘is well known that when chlorine is passed into a
solution of lead chloride and sodium chloride it is absorbed in large quantity,
and a perchloride of lead is formed. The chloride by itself does not combine
VOL. XXX. PART III. DD
614 WILLIAM LAWTON GOODWIN ON THE
with more chlorine, and the formation of a perchloride, in presence of sodium
chloride, is no doubt due to the existence of a salt PbCl,,2NaCl, analogous to
PtCl,,2NaCl. This led to the hope that other similar double chlorides might
be obtained. Accordingly, solutions were made containing two chlorides in
molecular proportions, half a molecule of each, taking the solutions used above
as containing one molecule.
4(NaC1+KCl). Plate XXXVL, Diagram 1.
. e ee Na,S,0, ¢
— AQ rie” 10:0 1:0769
0:0 13:0 1:4000
+ 1:0 14:0 : 1:5076
44 176 "18953
eo 18°1 1:9492
106 17°6 1:8953
11:8 17-0 18307
15°9 : 14:2 15292,
Doe | Acre 1:2600
25°6 F 10°6 11415
314 8-7 0:9369
1 c.c.=0-01243 gm. iodine.
This solution possesses a solubility almost identical with those of the simple
salts.
_ Manganese and Sodium Chlorides.—Chlorine hydrate was obtained easily at
0°. No peroxide of manganese was formed until the chlorine hydrate was
decomposed, but its formation was then rapid apparently, for the curve seems
to run almost horizontally instead of dipping down rapidly. Unfortunately, an-
accident stopped the experiment at 11°.
4(NaCl+Nm(l). Plate XXXVI, Diagram m1
t p Na,8,0, - a
25 761-7 12°7 13843
+19 163 17768
3°5 17-9 1:9512
5-6 18°7 2:0384
75 19-0 20711
8°8 17-9 19512
9-8 17°8 19403
111 17-4 1:8967 -
1 cc. = 001243 gm. iodine.
It is to be observed that the curve for the mixed salts takes a course
between the curves for its two components, crossing almost exactly at the point
NATURE OF SOLUTION, 615
where these latter cross each other, thus keeping its mean position on both
sides of the maximum point.
Cobalt and Sodium Chlorides.—Chlorine hydrate ae Ue at —4°, and was
completely decomposed at +4. The curve in this case also runs between
those of the single salts, crossing as in the preceding case.
3(NaCl+CoCl,). Plate XXXVI. Diagram tv.
e p Na,S,03 a
—3°5 754 12:0 13217
—1°5 14:7 16191
+10 : 15°6 17180
50 15-4 16963
12:0 - 134 14760
16°6 11:3 1:2446
254 9:7 10687
32°6 8:7 0:9583
38'2 7:2 0°7931
1 c.c, =0:01243 om. iodine.
Calcium and Sodium Chlorides.—No chlorine hydrate was formed at —5*,
and the solution caused decomposition of the hydrates with effervescence, as in
previous cases, The curve lies between those ‘of the single salts, but is below
both after passing the maximum.
3(CaCl,+ NaCl). Plate XXXVI. Diagram v.
t p Na,8,0, . a
=o 744-3 12°6 1:4059
+0°5 ; 13-0 14506
ae L227 14171
4:8 a) aes 1:3222
99 10:05 11214
15:7 . 8-7 0:9708
22:5 79 0:8815
29-1 66 0:7364
346 ale 05691
1 ¢.c.=0'01243 om. iodine.
Cadmium and Sodium Chlorides.—Hydrate of chlorine formed easily. An
accident happened at an early stage, but sufficient results were obtained to
show that the curve lies between that of the single salts, at least before the
maximum is reached.
616 WILLIAM LAWTON GOODWIN ON THE
$(C1C1,+ NaCl). :
ae p Na,8,0, a
—1-4 745 6-7 0°7842
—05 73 0°8160
+2°4 91 1:0172
58 114 1:2473
1 cc. =0:0127 gm. iodine.
Nickel and Sodium Chlorides.—Chlorine hydrate appeared at_ 2°. = ‘iite
curve falls between those of the two single salts on both sides of the maximum,
but lies nearer the curve for sodium chloride. It shows the flat top character-
istic of the nickel chloride curve. ;
1(NiCl,+NaCl). Plate XXXVL, Diagram vu.
E
p Na,S,0, a
—155 7646 11°85 315i.
—03 12-4 13761
ee 14-1 15648
3°5 17-9 1:9865
8-0 17°6 (2) 19532
11:3 17°8 1:9754
16-0 14:8 16425
24:5 11:3 12541
29-0 8:3 0-9211.
1 c.c =0:0127 gm. iodine.
Strontium and Sodium Chlorides.—Chlorine hydrate appeared at —3°, began
to decompose at 2°°6, and had completely disappeared at 5°°6. The curve lies
-above those of the single salts before the maximum, afterwards falls between
them.
2(SrCl, + NaCl).
p Na,S,0, ie F
—3'0 766°7 11°6 1:2838
—16 119 13170
0:0 13°6 15052
+2°6 14:7 16269
5°6 165 18261
7:0 15:0 16601
9°5 12°7 1:4056
14:3 10°5 11621
22°8 85 09407
28:7 72 0:7968
373 56 06198
Discussion of Results.—In discussing these results it must be premised that
the curves are not strictly comparable after the maximum point is passed in
NATURE OF SOLUTION. 617
the case of those solutions which allowed the formation of chlorine hydrate ; for
water was thus retained in the flask while a stronger solution was drawn off,
so that the solution became weaker than it was originally, after the chlorine
hydrate was decomposed. It is proposed to determine the solubilities of such
solutions at a later date, without previous formation of hydrate, so that the
second part of the curves may be strictly comparable. The principal object in
the present research has been to determine the first part of each curve, and fix
the maximum points.
. The salts which prevent the formation of ape hydrate are chlorides of
magnesium, calcium, iron, cobalt, and strontium (almost entirely).
On referring to the curves it will be found that those for these salts form a
well-defined group, having the following characteristics :—
1. The maximum point is at a temperature lower than that for water by
from 10 to 15 degrees.
2. The tops of the curves are flat, and the descent is very gradual.
_ The occurrence of maxima in the case of these salts is not to be explained
in the same way as in cases where solid chlorine hydrate appears. In seeking
for an explanation it is to be noticed that all of these chlorides have a strong
attraction for water, and tend to form definite hydrates. The anhydrous
chlorides unite with water very readily, forming definite crystalline hydrates
stable at higher temperatures than have been employed in this research.
It may be supposed that two forces come into play to determine the amount
of chlorine in the solution—(1) the solubility of chlorine in the ‘ free” water,
and (2) the attraction of calcium chloride for water, determining the amount
of “free” water. It is a case where chemical combination is a function of the
temperature. As the temperature falls the amount of free water decreases,
but at the same time its coefficient of absorption increases, and at a quicker
rate than the decrease of free water. Therefore, on the whole, the solubility
increases as the temperature falls. But as the temperature continues to fall
the rate at which the chloride goes on attaching the water increases, until it
overtakes the rate of increase of solubility, and a maximum is reached. From
this point onwards the chloride keeps and increases its ascendancy and the
solubility decreases. The gradual rise and fall of the curves favour this theory.
There is no sudden descent from the maximum, as in the case of those salts
permitting the formation of the hydrate.
The curves for the remaining solutions do not admit of classification, but
there seems a general tendency for a strong attraction for water to coincide
with a maximum at a low temperature, except in the case of cadmium chloride
where the maximum appears at 10°, very near that for water. There is also to
be remarked in the curves for those chlorides which permit the formation of
VOL. XXX. PART III. 5 E
618 WILLIAM LAWTON GOODWIN ON THE NATURE OF SOLUTION.
chlorine hydrate, a generally steep ascent to the maximum and rapid fall after
passing that point.
The coefficients in the foregoing results express the volumes of chlorine
measured at 0° and 760 millimetres pressure absorbed by unit volume of the
solution measured at the temperatures of estimation. Probably new relations
would appear if they were stated as weights of chlorine absorbed by unit
weight of the salt and its accompanying water. The data necessary for this are—
(1) amounts of chlorine absorbed at particular temperatures, and (2) the
specific gravity of the solutions containing chlorine at those temperatures. The
weight of chlorine being known, the weight of chloride could be easily found.
In a second research on this subject, it is proposed to follow the course
indicated. Such determinations were made for water, and it was found that
the absorption of chlorine increases the pews gravity of water, as the follow-
ing numbers will show :—
Sp. gr. of Chl. Water. Sp. gr. of Pure Water.
orb van. 1:004.06 0999980
8°-0 100494 0:999886
16°3 1:00424 0998954
eee) 1:00264 0997601
29°-0 1:00069 0996051
25°°5 0°99984 0°994247
Taking a general survey of the curves as grouped in the diagrams, the —
following facts are remarked :—~-
1. There is a general tendency towards coincidence at high temperatures _
(Plate XXXVI, Diagram 1.).
2. The curves for the mixed chlorides, where chlorine hydrate is formed
with both single chlorides, follow a mean course very closely ; in cases where
one of the chlorides only prevents the formation of the hydrate, the curve does
not always follow such a mean course between the curves for the single
chlorides (Plate XX XVI., Diagrams I1., IIL, Iv., V., VI., and VIL).
'3.. The solubility of Mines in watoe is | nee by the presence of
lithium chloride, hydric chloride, and, perhaps, manganese chloride (Plate
XXXVI., Diagram 1.).
4. The presence of chlorides affects the solubility of chlorine in water
chemically at low, but mechanically at high, temperatures.
This research was carried on in the Chemical Laboratory of University
College, Bristol, during the first six months of 1882, and I have to thank
Professor Ramsay for many valuable suggestions.
( 619 )
XXVII.—The Dragon's Blood Tree of Socotra (Dracena Cinnabari, Bal. jil.).
By Baytey Barrovr, Se.D., M.B., Regius Professor of Botany, University
of Glasgow.
The following remarks on the dragon’s blood tree of Socotra are intended
to serve as introduction to Dr Doxsrr’s and Mr Henperson’s paper on the red
resin obtained from the tree, and to furnish a technical description of the plant
which has not hitherto appeared. In my account of the Botany of Socotra,
which will shortly be published by the Society, further remarks upon this in-
teresting tree will be found, along with a figure.
Resina draconis (dragon’s blood resin), now only used as a varnish, has been
known as a commercial product for many centuries. Under the name xuwvdBapu,
DisocoriDEs* mentions a costly pigment brought from Africa, and under the
same designation the author of the Periplus of the Erythrean Seat speaks of a
product of the island of Dioscorida, the modern Socotra. This xwvaBapr is
undoubtedly the resin dragon’s blood, or rather one of the resins at present in
commerce under that name. Putny{ also mentions this produce. Various of
the early Arabian geographers and European travellers speak of dragon’s
blood as one of the commodities exported from the region of the incense
country about the Gulf of Aden, and we have, in the narratives of explorers
of this century, references to the production of the resin both on the Arabian
and on the African coasts of that neighbourhood.
But dragon’s blood resin has also been long known as a product of other
parts of the globe. The fame of the dragon’s blood tree of Orotava, in Teneriffe,
is world wide, and the resin of the Canary Islands tree was in former times
exported in large quantities.
Then from Sumatra and Borneo, and other islands of the Eastern Archipelago,
a dragon’s blood resin is an article of trade, though no records of its export at
an early period are extant.
In the West Indies, and also in Mexico, substances are obtained which bear
the name dragon’s blood, but, according te FLUckicEr and Hanpury, they are
not met with in European commerce.
The substances from these different regions, though bearing the same name,
= Op. lib: Vv. cap, cix, Z
+ Voyage of Nearcuus and Periplus of the Erythrean Sea, translated by Vincent, Oxford, 1809, 90.
+ Hist. Nat., xxxiii. 38.1.
VOL xXx, PART IT, 5 F
620 PROFESSOR BAYLEY BALFOUR ON THE
are not of the same character, nor are they derived from the same, or in all
cases from allied plants.
We may dismiss here the West Indian and the Mexican resins with the
remark that the former is the exudation of a leguminous plant,—Pterocarpus
Draco, Linn.,—and is, according to FLUckIGER and Hanbury, of the nature of
kino, whilst the latter is got from the euphorbiaceous Croton Draco, Schlecht.
I have not been able to obtain specimens of the resins of these.
An East Indian resin is at the present day the most common commercial
resin of dragon’s blood. It is procured from the fruits of a rotang palm,
Calamus Draco, Willd. The resin which exudes on the fruits is separated
by beating these in a sac, and then sifting out the fruit scales and other
refuse. The resin is next softened by exposure to the sun, or warming in a
vessel plunged in hot water, and then moulded into sticks or balls, which
are wrapped in a piece of palm leaf. An inferior kind is obtained by boiling
the pounded fruits. Two kinds are exported, “ Reed” and “ Lump,” of which
the former is the finer.*
Another East Indian plant, one of the Leguminose—Lcastaphyllum
Monetaria—found in Surinam, is said to yield a resin like dragon’s blood, but
of it I know nothing. . a
The dragon’s blood resins from Arabia, Africa, Socotra, and the Canary
Islands are furnished by spécies of the liliaceous genus Draceena ; but although
it is of these resins that we have the earliest records, yet the specific source of
the resin, with the exception of that from the Canary Islands, has until quite a
recent date remained unknown, The productive species are branching trees,
with large trunks, and form a very marked section of the genus.
The Canary Island tree, Dracwna Draco, Linn., has been long known, and
frequently and fully described. The large Orotava plant was 60 feet in height
and 15 feet in diameter when it was destroyed by a hurricane in 1867. The
resin is apparently not largely exported at the present time, but there is
evidence that it was formerly an article of much trade, besides being used in
early times by the Guanchos for the purposes of embalming.
Amongst the botanical results of Miss TINNr’s expedition to Bahr-el-
Ghazal river and its affluents in Nubia, was the discovery in the vicinity of
Suakim of a tree about 24 feet high, which yields a dragon’s blood. Korscuy
and Pryritscu t describe the plant under the name Dracena Ombet,—“ ombet”
meaning Mother of Earth, being the native name for it. A figure of the plant
is given in a landscape heading to the letterpress. Both description and figure
leave much to be desired. Fortunately Scuwe1nrurtH, in his Abyssinian tour,
found the same plant at an elevation of 2000 feet, growing over a few square
* See Pharmacographia, FuickicEr and Hansury, 2nd edition (1879), p. 672.
t Plante Tinneane, p. 47.
DRAGON’S BLOOD TREE OF SOCOTRA. 621
miles of country near Suakim, and he gives a representation of the tree in one
of the woodcut illustrations of his travels.* The leaf specimens sent by him to
Kew with Kotscuy and Pryritscu’s description and figure were not sufficient to
permit Mr Baker, in his revision of “‘ Asparagez,”t to take up the species, and
of it he merely remarks, under the species D. Draco, “e montibus Indie et
verisimiliter Socotre insule incola ex datis notis non potui segregare.” But
recently Dr ScHWEINFURTH has sent to Kew a portion of the panicle of this
tree, which enables me to form a more decided opinion regarding it, and shows
that the Nubian plant is a distinct species. Fruits are still wanted, and of the
resin I have seen no account, nor have I succeeded in obtaining any of it.
In 1877 Hitpesranpr found on the hills of Somali Land a tree attaining a
height of 24 feet, and known to the inhabitants as ‘“ moli,” which is said to
supply a dragon’s blood resin. It is a Draceena, and specimens sent to Kew,
though imperfect, there being only portions of flower panicles, showing specific
differences from others before known, Mr Baker described itt as D.
Schizantha. Regarding it we have as yet but little information, and of its resin
nothing is known. ,
Our expedition in the spring of 1880 to Socotra has cleared up all doubts
as to the source and character of the dragon’s blood of that island. As I have
_ noted above, the tree has been previously supposed to be identical with the
Nubian plant. But though very nearly allied to it, there are differences
between them which have led me to regard the Socotran plant as distinct
from it.
On Socotra, the dragon’s blood tree to which I, for obvious reasons, have
given the name Dracena Cinnabari, forms a small tree, attaining sometimes a
height of about 30 feet. The trunk reaches considerable dimensions. One I
measured on the Haghier hills, near the Adona Pass, at an elevation of 4000
feet, was 5 feet 3 inches in circumference at 3 feet from the ground ; another
near it was 6 feet 5 inches at 2 feet ; whilst at Hombhill, near the eastern end of
the island, I found one at an elevation of 1100 feet, which had a circumference of
9 feet at 3 feet from the ground, and a spread of branches. 29 feet 6 inches in
diameter. The tree grows only on the higher regions of the island. Nowhere did
we see it below 1000 feet elevation. It grows frequently in small groves, and the
- trees branch freely and form when well grown a dome-shaped crown, exhibiting
the feature so characteristic of screw pines. There is but one species on
the island. It has been hinted that there are two. Hunrers records that
the inhabitants recognise two distinct forms, which they speak of as being of
*
Heart of Africa, Eng. trans., i. p. 22.
+ In Jour. Linn. Soc. Lond., xiv. (1875), p. 527.
t In Trim. Jou, Bot., vi. (1877), p. 71.
§ Manuscript Journal of a Visit to Socotra in 1876.
622 PROFESSOR BAYLEY BALFOUR ON THE
different sexes. But all the forms assumed by the tree—and it does vary much
both with habitat and with age—are referable, we consider, to the one species.
The young plant has always much longer and broader leaves than the older
plants, and in these latter the inflorescences are shorter and more compact.
In unsheltered localities, too, as might be expected, the tree is frequently of a
more dwarfed size than when well protected.
The resin exudes naturally through cracks and rents in the stem, and these
are increased in size by the collector. The amount of resin produced varies
with their situation. The mode of collection is very simple. Holding below
the seat of exudation a small piece of goatskin abont a foot square, the gatherer
chips with a knife the resin from the stem, and catches it on the skin. The
time for collecting is immediately after the rains, and there are therefore two
gatherings in the year, and the resin is exported immediately after collecting
to Makullah, the Persian Gulf, and elsewhere, the Sultan taking tithe of all
export. The trees over the island are, I understand, farmed out to the inhabi-
tants, but the Sultan retains for himself a certain district.
To the tree the inhabitants give the name “kharya,” and the resin they call
‘‘edah.” WELLSTED* states that the Arabic name for the resin is ‘dum khoheil.” -
One also reads that the Arabic name for it is “ katir.”
Of the resin there are three kinds—
(a) ‘‘Edah amsello” (WELLSTED calls it “moselle”), the tears, many of
them an inch in diameter, as they exude. 2% Ibs. of this are said to fetch a a
dollar. It is the purest and most valuable kind.
(0) “ Edah dukkah” is the second best kind. It consists of the small chips
and fragments of the tears which have been broken off in separating them from
the tree, or by attrition. The fragments present a dull red powdery aspect.
It sells at one dollar for 4 lbs.
(c) “Edah mukdehah” is the cheapest kind, is very impure, and brings a
dollar for 5 lbs. It is in the form of small flat-sided masses, and consists of
fragments of the resin and refuse of the gatherings melted together into a flat
cake, which is then broken up into small portions.
We obtained a considerable supply of all these kinds of resin; and as it
appeared a matter of some interest to have an analysis made of a authentic
specimens, my friend Dr Dossiz kindly undertook the investigation, in which °
he has been assisted by Mr Henperson. They have extended their research to
the comparative analyses of the several kinds of dragon’s blood ; and through
the kindness of Sir JosepH Hooker, and those in authority at Kew, I have
been able to obtain samples of most of the resins labelled dragon’s blood in the
Kew Collection, and Mr E, M. Hoxmes, curator of the Pharmaceutical Society’s
Museum, has kindly supplied samples of like resins in the Society’s Museum.
* In Jour. Roy. Geol. Soc., v. (1835) 198.
DRAGON’S BLOOD TREE OF SOCOTRA. 623
These have been turned to good account, but much still remains to be cleared
up. Certain it is that red resins of different composition, and therefore
probably derived from different sources, are in commerce, at least have found
their way into our Museums, under the name dragon’s blood, and do not appear
to be distinguished from one another. But I must leave Dr Doppre and Mr
HeEnpeErson to tell their own story, and conclude this brief note with a technical
description of the Socotran tree.
Draceena Cinnabari, Balf fil. Arbor 25—pedalis trunco crassitiem 3 ped.
attingente apice copiose ramoso ; foliis 1-2 ped. longis 1-14 poll. latis +4 poll.
crassis sessilibus in apicem ramorum validorum confertis patenti-erectis firmis
sed in juvenilibus seepe subrecurvis basi amplexicaulibus ad similitudinem piscis
caudee expansis ibique 4 poll. latis rubescentibus, versus apicem gradatim
attenuatis, supra concavis infra jugo medio prominulo convexo extremitate
trigonis obtuse punctatis, ecostatis, glauco-viridibus margine concoloribus ;
paniculis glabris pseudo-terminalibus multiramosis 1-24 ped. longis, ramis
ramulisque divaricatis strictis, antepenultimis 9-12 poll. longis, penultimis con-
tractis 2-4—floris, pedicellis validis 4 poll. longis supra medium articulatis ;
bracteolis membranaceis longis acuminatis; perianthio sordido + poll. longo,
segmentis oblongis vix. connatis, apice uncinatis ; genitalibus inclusis, filamentis
subulatis antheris oblongis duplo-longioribus ; ovario oblongo stylum eequanti,
stigmate trilobato ; baccis aurantiacis 4 poll. diam. nitidis,
Nom. Vern. Arboris—Kharya ; Resinee draconis—Edah.
Socotra, per insulam totam in montibus ultra 1000 ped. alt. crescens. B.C.S.
No. 80. Schweinf. No. 550. Perry.
The Nubian D. Ombet is separated from the Socotran plant by its less robust
habit, more slender and shorter antepenultimate branches of the panicle, longer
pedicels, non-acuminate bracteoles, and more delicate perianth, with commonly
a stipitate ovary.
D. Schizantha, from Somali Land, is easily diagnosed by its downy panicles.
D. Draco, from the Canary Islands, differs in having compressed ensiform
leaves, smaller bracteoles, greenish perianth, the segments of which are not
uncinate at the apex, anthers relatively to the filament shorter, ovary commonly
stipitate, and stigma capitate.
( 624 )
XXVIIL—On a Red Resin from Dracena Cinnabari (Bal/f. jil.), Socotra. By
J. J. Dosaiz, M.A., D.Sc., Assistant to the Professor of Chemistry, Uni-
versity of Glasgow; and G. G. Hrenperson, B.Sc.
The resin to which the following paper refers was obtained by Professor
Baytey Batrour from a species of Dracena which he discovered in Socotra
during his visit to that island in the year 1880, and to which he has given the ©
name of Dracceena Cinnabar. In outward appearance and in general physical
properties the resin differs from the varieties known commercially under the
name of dragon’s blood. With the view of ascertaining if these differences
depend upon difference of chemical composition, we undertook, at Professor
BaLrour’s request, to make an examination of the resin,
The resin is in the form of large drops or tears of a deep red colour ; when
ground it is of the same colour as some varieties of cinnabar. At ordinary
temperatures it is brittle, and breaks with a clean fracture into transparent
fragments which transmit rich ruby-red light. It begins to soften between 50°
and 60° C, and melts at about 60°; when heated to its decomposing point
it gives off aromatic and irritating fumes. The specimens given us were ex-
ceedingly pure, leaving, after solution in ether, a residue of only 3:4 per cent.,
which appears to consist entirely of fragments of vegetable tissue. The resin is
soluble to a slight extent in boiling water, the solution being acid. It dissolves
entirely in alcohol, ether, and oil of cloves. The alcoholic solution is of a fine
blood-red colour, and has a strongly acid reaction. It is atmost entirely insoluble
in chloroform, benzene, carbon bisulphide, and petroleum ether. It contains no
benzoic acid ; at all events it yields up no extract to petroleum ether, in which
benzoic acid is fully soluble. Neither does cinnamic acid appear to be present,
because, when the resin is heated to a temperature above that at which cin-
namic acid sublimes, no trace of that acid is obtained. As much discussion has
taken place regarding the presence of cinnamic or benzoic acid in red resins,
we made artificial mixtures containing only 1 per cent. of these acids, in order
to determine whether or not they can be detected by sublimation when present
in very small quantity. On heating, in sublimation tubes, quantities of the
mixture containing not more than one-twentieth of a grain of acid, we found
that it could be detected with.certainty, whereas a much larger quantity of the
resin to which no acid had been added, gave no sublimate. Again, on digesting
the artificial mixture with benzene and with ehloroform, in both of which cin-
namic and benzoic acids are soluble, we obtained an extract which was almost
ON A RED RESIN FROM DRACAINA CINNABARI. 625
entirely sublimable, while no sublimate was given by the extract obtained by
digesting the resin to which no acid had been added. In the latter case the
extract, which is very small, appears to consist of a trace of oily matter and a
little resin. The resin, indeed, is soluble in these and in nearly every other re-
agent, with the exception of petroleum ether, to a very slight extent. When
heated the resin loses somewhat in weight, the loss being due to the expulsion
of moisture.
Caustic potash and soda completely dissolve the resin to an orange-red
coloured solution ; aqueous ammonia and lime water have nearly the same
action upon it. Cold sodium carbonate dissolves it to a blood-red solution, which
’ changes to orange red on boiling. Acetate of lead precipitates from the alcoholic
solution a mauve coloured salt, which is insoluble in boiling water but readily
soluble in alcohol. Three analyses of this salt gave the following numbers :—(1)
25°33, (2) 25°27, and (8) 25°17 per cent. of lead. The first of these determinations
was made by simply treating the salt with strong sulphuric acid, evaporating down
and igniting, the other two by acting upon the salt with strong nitric acid, and
precipitating the lead with sulphuric acid. This is the only definite salt that
we have as yet succeeded in preparing. Nitric acid completely decomposes the
resin. Hydrochloric acid dissolves it to a slight extent, ammonia reprecipitat-
ing it. Acetic acid, in which it dissolves abundantly, gives an orange-red solu-
tion, from which also the resin can be reprecipitated by ammonia. Having
carefully purified the resin by repeated solution in ether, we burned it, with the
following results :—
3) (4)
(
C 71:22 72°80 70°28 72°02
ic Re as . 5694 6:02 5°93 6°43
O 22°84 21:18 23°79 21°55
100-00 100:00 100-00 100-00
The average of these four analyses is C 71°58, H 6:08, and O 22°34.
Owing to the great difficulty in thoroughly purifying resinous bodies these
numbers can only be regarded as approximately accurate ; they correspond very
closely, however, with the formula C,;H,,0,. A substance having this formula
would contain 72°48 per cent. of carbon, 6°04 per cent. of hydrogen, and 21:47
per cent. of oxygen, and would have a combining weight of 298. This agrees
very closely with the results obtained by the analysis of the lead salt. Assum-
ing the acid to be monobasic, the composition of this salt would be (C,sH1;O,). Pb,
and a salt having this composition would contain 25°84 per cent. of lead.
The percentage of lead actually found, taking the mean of three experiments,
was 25°25.
Having ascertained the properties and ultimate composition of the resin
from Dracena Cinnabari, we proceeded to compare it with other varieties of
626 DR J. J. DOBBIE AND MR G. G. HENDERSON
red resins. We soon discovered, however, that much uncertainty prevails as
to the source of these substances, several distinct varieties of resin being
described under one name. All the published accounts of the chemical pro-
perties of dragon’s blood refer to dragon’s blood supposed to be derived from
Calamus. Draco, but it is obvious from the discrepancies in the statements of
different writers that some of them must have had in hand resins from other
sources. To place our comparison upon a sound basis, we collected specimens
of as many varieties of red resin as possible. Through the kindness of Profes-
sor BALFouR we obtained a number of specimens from Kew Gardens and from
the museum of the Pharmaceutical Society. Some of these specimens marked
“ Calamus ” have characters widely different from those ascribed by FLicki1cER
and Hanbury to the red resin from Calamus Draco. Beside the Socotra variety
we had for examination sixteen specimens. We found that all these specimens
admit of classification according to solubility and other characters into four groups.
In the first we place those resins which are entirely soluble in chloroform, car-
bon bisulphide, and benzene. This group includes two of the Kew specimens, one
marked “ Calamus Draco,” the other ‘‘Sumatra,” the species not being given,
and one of the Pharmaceutical Museum specimens, also marked “ Sumatra.”
In our second group the resins are soluble in chloroform, but insoluble in car-
hon bisulphide and benzene. This group includes two Pharmaceutical Museum
specimens, one marked ‘‘ Dutch East Indies,” the other “ Pontianak, Dutch
East Indies,” the source not being indicated. The third group contains resins
soluble in chloroform and benzene, and partially soluble in carbon bisulphide. To
this group belong three: Kew specimens, marked respectively ‘ Singapore,”
“ Penang,” and ‘Calamus Species.” The fourth group includes those resins
which are insoluble in chloroform, carbon bisulphide, and benzine. To it
belong three Kew specimens, marked respectively ‘‘ Calamus Draco, Bombay,”
“Punjab,” and “ Indian Museum,” and two Pharmaceutical Museum specimens,
one marked “ Probably from Calamus,” the other “ Dracena Draco.” The
source of the last mentioned specimen is well authenticated. The resins in the
first group have the characters ascribed by FLUckIGER and Hansury to the resin
from Calamus Draco. The resins in the fourth group agree in properties with
that from Dracena Cinnabari. All the Kew specimens are believed to have
been obtained from species of Calamus, but it is obvious from an examination
of the above list that some of them must have a different origin, unless, indeed,
as is very improbable, the same species yield different resins in different
localities, or at different seasons. Possibly, as suggested by Mr Hos, of the
Pharmaceutical Society’s Museum, some resins exported from Bombay were
imported in the first instance from the East Coast of Africa, and not from the
‘ast Indies. Thus it is easy to understand how resins derived from widely
different sources might come to be confounded with one another.
ON A RED RESIN FROM DRACAINA CINNABARI. 627
We shall now give a brief account of the chemical character of the resins
belonging to each class. The resins of all the groups are abundantly soluble in
alcohol, ether, and oil of cloves,—-the insoluble residue, which in some cases is
considerable, consisting chiefly of vegetable fibre
The resins of Group I. are, when powdered, of a brick-red colour,—the colour
of hematite rather than of cinnabar,—and transmit in thin splinters ruby-red
light. They melt about 80° C, or nearly 20° above the Socotra resin. Heated
to their decomposing point they give off highly irritatmg red coloured fumes.
The alcoholic solution is orange-red rather than blood-red in colour, but has,
like that of the Socotra resin, an acid reaction. ‘The resin of this class, which
we subjected to a more particular examination, namely, a specimen from the
Kew collection marked “ Calamus Draco, Singapore,” contains cinnamic acid,
which it yields up readily on heating in a sublimation tube. That it is not
benzoic acid is clear from the form of crystal, as well as from the fact that it
gives no extract to petroleum ether, which readily dissolves out benzoic acid
from an artificial mixture. It ought to be mentioned that cinnamic acid is only
very slightly soluble in petroleum ether. This resin is soluble only to a slight
extent in strong caustic soda, and dissolves with difficulty even on heating,
giving an orange-red coloured solution. It is hardly at all soluble in cold
ammonia and lime water, and only to a slight extent on boiling in these reagents.
It is insoluble in cold sodium carbonate, and dissolves with difficulty on boiling
to a reddish-yellow fluid, giving off a smell like rhubarb. In its behaviour,
therefore, with all these reagents, it differs in a marked manner from the Socotra
resin. With acetate of lead it gives a brownish-red coloured precipitate, soluble
in alcohol, but insoluble in boiling water. It is very slightly soluble in boiling
hydrochloric acid to an orange-yellow solution, from which it is reprecipitated
by ammonia. It is also reprecipitated by ammonia from solution in acetic acid.
It is decomposed by strong nitric acid. The ultimate composition of this resin
is very nearly the same as, if not identical with, that of the Socotra resin. Two
analyses give the following numbers :—
(1) (2) (Mean. )
C 71:03 70:08 70°55
H 6°46 6°42 6:44
O 2251 23°50 23°01
100-00 ~ 100-00 100-00
These numbers agree very closely with those given by Johnstone.
The resins of Class II. differ still more widely from the Socotra resin, both
as regards their physical and chemical characters. The specimens of the resin
which we had to work with were exceedingly pure. This variety of resin is of a
beautiful carmine-red colour, and in thin splinters transmits ruby-red light.
VOL. XXX. PART III. 5G
628 DR J. J. DOBBIE AND MR G. G. HENDERSON
The melting point of the specimen marked “ Pontianak, Dutch East Indies,
probably Calamus,” is only slightly under 100° C, nearly 40° above that of the
Socotra resin, and 20° above that of Calamus Draco. When decomposed by
heat it gives off non-irritating fumes. The alcoholic solution is of a pink-red
colour, and has an acid reaction. Benzoic acid and cinnamic acid are absent.
In cold strong caustic soda it dissolves with a magnificent purple colour, which
changes on heating or dilution to an orange-yellow. It is readily soluble in
ammonia, giving the same colour as with soda. It is also much more soluble
than either the Socotra resin or that from Calamus Draco in lime water. In cold
sodium carbonate it dissolves with effervescence to a beautiful purple-pink or
mauve-pink solution, which changes to orange-red on boiling. Acetate of lead
gives a lilac coloured precipitate, soluble in alcohol and apparently slightly
soluble in boiling water. This resin is much more soluble in hydrochloric acid
than either of the preceding, and is reprecipitated from this solution, as well as
from its solution in aeetic acid, on neutralisation with ammonia. It is decom-
posed by strong nitric acid. ‘Two combustions gave the following results :—
(1) (2) (Mean. )
C 68:18 68'22 68°20
jal 6:01 6:05 6:02
O 25°81 25°74 25°78
100 00 100-00 100:00
This resin therefore appears to contain a somewhat lower percentage of carbon
than the preceding, and would correspond better with the formula C,,H,,O; than
with that which we have assigned to the Socotra resin. A substance having the
above formula would contain 67:54 per cent. of carbon, 5°96 per cent. of
hydrogen, and 26°52 per cent. of oxygen, and would have a combining weight
of 302. Owing to the very small quantity of this resin we had to work upon,
we were not able to confirm these results by the analysis of any salts.
The resins belonging to our third class are peculiar. We selected for
examination one of the Kew specimens marked “Penang.” In common with
the other resins which we have placed in this class it is soluble for the most part
in chloroform, benzene, and carbon bisulphide. A portion, however, persistently
remains undissolved by the carbon bisulphide, and carbon bisulphide gives a
precipitate when added to the solution in chloroform. These resins therefore
would appear to be composed of a mixture of two resins, one soluble in chloro-
form, benzene, and carbon bisulphide, the other soluble in chloroform and
benzene, but insoluble in carbon bisulphide. This conclusion is confirmed by
the varying results obtained by combustion. The part of the resin soluble in
chloroform, benzene, and carbon bisulphide corresponds very closely in all its
properties with the resin from Calamus Draco, and like that resin gives a subli-
ON A RED RESIN FROM DRACAINA CINNABARI. 629
mate of cinnamic acid. We have not yet examined the other portion, which is
undoubtedly a distinct resin.
In describing the Socotra resin we have already enumerated fully the charac-
ters of the resins of Class 1V. Wecompared carefully with the Socotra resin the
specimen from the Kew collection marked “ Calamus Draco, Bombay,” and
found them to be in all points identical. Combustion gave C 71:89, H 6:17,
and O 21°74 as the ultimate composition of the Kew specimen. The specimen
from Dracena Draco belongs, as already mentioned, to our fourth class, and as
its source is well authenticated, we thought it would be interesting to compare
it also more carefully with the resin from Dracena Cinnabari, with the view of
ascertaining if there was any difference in properties answering to the difference
in species. After a very thorough examination we have come to the conclusion
that the two resins are identical, or at all events so closely allied as not to
admit of discrimination by their physical properties. The only considerable
difference which we could detect was a greater solubility of the resin from
Dracena Draco in boiling water.
The result of our work so far as it has gone has been to prove (1) that there
are several distinct and well defined varieties of resin known under the name
of dragon’s blood ; (2) that probably each variety is derived from a different
genus; and (3) that there is probably no difference in resins derived from
different species of the same genus. Little has as yet been done towards the
examination of the chemical constitution of these substances. HLastiverz and
Bartu, by oxidising with caustic potash dragon’s blood, derived presumably from
Calamus Draco, obtained a variety of aromatic products, including benzoic acid,
paraoxybenzoic acid, phloroglucin, &c. We propose to extend our investi-
gation in this direction with a view to ascertain if the resins of the different
classes yield different oxidation products, and in this way hope to gain some
insight into their chemical constitution.
%
APP ND IX,
TRANSACTIONS
ROYAL SOCIETY OF EDINBURGH.
1882-83.
VOL. XXX. PART III. 5H
CONTENTS.
THE COUNCIL OF THE SOCIETY, .
ALPHABETICAL LIST OF THE ORDINARY FELLOWS,
LIST OF HONORARY FELLOWS, : .
LIST OF ORDINARY FELLOWS ELECTED DURING SESSIONS 1880-81—1882-83,
LIST OF FELLOWS DECEASED, RESIGNED, AND CANCELLED, FROM
NOVEMBER 1880 TO NOVEMBER 1883,
PAGE
633
635
647
649
651
Pet COUN CIL
OF
THE ROYAL SOCIETY OF EDINBURGH,
NOVEMBER 1883.
THe Richt Hon. Lorpv MONCREIFF OF TULLIBOLE,
Lorp JusTIcE-CLERK, LL.D., PResipEnt.
HONORARY VICE-PRESIDENTS, HAVING FILLED THE OFFICE-OF PRESIDENT.
His Grace tHE DUKE or ARGYLL, K.T., D.C.L. Oxon., F.R.S.
Sm WILLIAM THOMSON, LL.D., ER. S., Foreign eects of the Institute of France,
Regius Professor of N: atural Philosophy i in the University of Glasgow.
VICE-PRESIDENTS.
H. C. FLEEMING JENKIN, F.R.S., Mem. Inst. Civ. Eng., Professor of Engineering
in the University of Edinburgh.
Toe Rev. W. LINDSAY ALEXANDER, M.A., D.D., Principal of the Congregational
Theological Hall, Edinburgh.
THOMAS STEVENSON, Member of the Institute of Civil Engineers.
ROBERT GRAY, Secretary of the Royal Physical Society of Edinburgh, Member
of the British Ornithologists’ Union, Corresponding Member of the “Academy of
Natural Sciences of Philadelphia.
ALEXANDER FORBES IRVINE, of Drum, Sheriff of Argyll.
EDWARD SANG, C.E., LL.D., Secretary to the Royal Scottish Society of Arts,
Honorary Member of the Royal Academy of Turin.
GENERAL SECRETARY.
P. GUTHRIE TAIT, M.A., Professor of Natural Philosophy in the University of Edinburgh.
SECRETARIES TO ORDINARY MEETINGS.
WILLIAM TURNER, M.B., F.R.C.S.E., F.R.S., Professor of Anatomy in the University
of Edinburgh.
ALEXANDER CRUM BROWN, M.D., D.Sc, F.RCP.E, F.RS., Professor of
Chemistry in the University of Edinburgh.
TREASURER.
ADAM GILLIES SMITH, C.A.
CURATOR
OF LIBRARY AND MUSEUM.
ALEXANDER BUCHAN, M.A., Secretary to the Scottish Meteorological Society.
COUNCILLORS.
Tue Rev. Dr DUNS, Professor of Natural Science
in the New College, Edinburgh,
RAMSAY H. TRAQUAIR, M.D.,F.R.S.,F.G.S.,
Keeper of the Natural History Collections in
the Museum of Science and Art, Edinburgh.
JOHN MURRAY, Director of the Challenger
Expedition Commission.
WILLIAM FERGUSON of Kinmundy, F.L.S.,
¥.G.8., Deputy-Lieutenant of Aberdeenshire,
Vice-President of the Geological Society of
Edinburgh,
JAMES COSSAR EWART, M.D., F.R.C.S.E.,
Professor of Natural History in the Uni-
versity of Edinburgh.
JAMES GEIKIE, F.R.S., F.G.S., Professor of
Geology in the University of Idin-
burgh.
Tue Rev. WILLIAM ROBERTSON SMITH,
M.A., LL.D., Lord Almoner’s Professor of
Arabic in the University of Cambridge.
STAIR A, AGNEW, M.A., Advocate, Keeper
of the Records of Scotland and Registrar-
General.
DOUGLAS MACLAGAN, M.D., F.R.C.S.E.,
Professor of Medical Jurisprudence in the
University of Edinburgh.
THE Hon. Lorp MACLAREN, one of the Sena-
tors of the College of Justice.
Tue Rey. Proressorn FLINT, DD., Correspond-
ing Member of the Institute of France.
Prorsssor JT. R. FRASER, M.D., Dean of the
Medical Faculty in the University of Edin-
burgh.
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a
ALPHABETICAL LIST
OF
THE ORDINARY FELLOWS OF THE SOCIETY,
CORRECTED TO NOVEMBER 1883.
N.B.—Those marked * are Annual Contributors.
B. prefixed to a name indicates that the Fellow has received a Makdougall-Brisbane Medal.
K. 3 rp a Keith Medal.
N ’ “i ak Neill Medal.
1e is 5 », contributed one or more Papers to the Transactions.
Date of
Election.
1879 Abernethy, James, Hon. Councillor Inst. C.E., Prince of Wales Terrace, Kensington
1871 * Agnew, Stair A., M.A., Advocate, Registrar-General, 22 Buckingham Terrace
1881 Aitchison, James. Edward Tierney, C.LE., M.D., MR.CO.P.E., F.RS., F.LS., Surgeon-
Major, H.M. Bengal Army, F.R.C.S.E., North Bank, Simla, Punjab, India
1878 * Aitken, Andrew Peebles, M.A., Sc.D., F.I.C., St Ann’s, Morningside, Edinburgh
1875 | P. |* Aitken, John, Darroch, Falkirk 5
1866 * Alexander, Lieut.-General Sir James E., of Westerton, K.C.B., K.C.L.S., 1 Esplanade,
Teignmouth, Devon
1867 * Alexander, The Rev. W. Lindsay, M.A., D.D., Principal of Congregational Theological
Hall, Edinburgh (Vicz-PRrEsipENT), Pinkie Burn, Musselburgh
1878 Allchin, W. H., M.B, (Lond.), F.R.C.P., Physician to the Westminster Hospital, 5 Chandos.
Street, Cavendish Square, London, W.
1856 | B. P.| Allman, George J., M.D., F.R.S., M.R.DA., F.L.S., Emeritus Professor of Natural History,
Univ. of Edinburgh, Ardmore, Parkstone, Dorset
1872 Anderson, Sir John, LL.D., Fairleigh, The Mount, St Leonards-on-Sea, Sussex 10
1874 Anderson, John, M.D., F.R.S., Superintendent of the Indian Museum, and Professor of
Comparative Anatomy in the Medical College, Calcutta
1883 * Anderson, Robert Rowand, A.R.S.A., 24 Hill Street, Edinburgh
1883 Andrews, Thomas, F.C.S., Mem. Inst. C.E., Ravencrag, Wortley, near Sheffield
1881 Anglin, A. Hallam, M.A., LL.B., M.R.I.A., Vice-President of Morningside College, Edinburgh.
1867 * Annandale, Thomas, M.D., F.R.C.S.E.., Professor of Clinical Surgery in the University of
Edinburgh, 34 Charlotte Square 15
1862 * Archer, T. C., Director of the Museum of Science and Art, 20 Greenhill Place
1883 Archibald, John, M.B., C.M. Ed., Lynton House, Brixton Rise, London, 8.W.
1849 Argyll, His Grace the Duke of, K.T., D.C.L., F.R.S. (Hon. Vicz-Pres.), Inveraray Castle
1879 * Bailey, James Lambert, Ardrossan ;
1875 * Bain, Sir James, 3 Park Terrace, Glasgow 20:
1843 Balfour, Colonel David, of Balfour and Trenabie, Balfour Castle, Kirkwall
636 ALPHABETICAL LIST OF THE ORDINARY FELLOWS OF THE SOCIETY.
Date of
Election.
1879 | P. |* Balfour, George William, M.D., President of the Royal College of Physicians, 17 Walker Street
1877 * Balfour, I. Bayley, Sc.D., M.D., C.M., Professor of Botany in the University of Glasgow
18354° SP, Balfour, J. H., M.A., M.D., LL.D., F.R.S., F.LS., Emeritus Professor of Medicine and
| Botany in the University of Edinburgh, Inverleith House, Edinburgh.
1870 * Balfour, Thomas A. G., M.D., F.R.C.P.E., 51 George Square 25
1867 * Barbour, George F., of Bonskied, 11 George Square
1872 * Barclay, George, M.A., 17 Coates Crescent
1883 * Barclay, G.W.W., M.A., 40 Princes Street, Edinburgh
1882 Barnes, Henry, M.D., M.R.C.S., 6 Portland Square, Carlisle
1874 Barrett, William F., M.R.I.A., Professor of Physics, Royal College of Science, Dublin 30
1878 Bateman, John Hiodorich, ‘ier Inst. C.E., F.R.S., 16 Great George Street, Westminster
1857 Batten, Edmund C., M.A., Lincoln’s Inn, Tanah
1880 * Bayly, General John, C.B., R.E., F.S.A., 58 Palmerston Place
1882 | P. |* Beddard, Frank E., M. he Ola. Office of Challenger Commission, 32 Queen Street,
Edinburgh ;
1874 * Bell, Joseph, M.D., F.R.C.S.E., 20 Melville Street 3
1876 * Belcombe, Rev. F. E., 14 Merchiston Avenue
1875 Bernstein, Ludwik Stanthorpe, M.D., Lismore, Queensland, Australia
1881 * Berry, Walter, Danish Consul General, 11 Atholl Crescent, Edinburgh
1880 * Birch, De Burgh, M.D., The Dispensary, Newcastle-upon-Tyne
1850 Blackburn, Hugh, M.A., Emeritus Professor of Mathematics in the University of Glasgow,
Roshven, Fort-William 40
1863 | P. |* Blackie, John S., Emeritus Professor of Greek in the University of Edinburgh, 9 Douglas
Crescent
1862 * Blaikie, The Rev. W. Garden, M.A., D.D., LL.D., Professor of Apologetics and Pastoral a
Theology, New College, adinbunet 9 Palinerseod Road
1878 | P. |* Blyth, James, M.A., Professor of Natural Philosophy in Anderson’s College, Glasgow
1872 * Bottomley, James ee M.A., Lecturer on Natural Philosophy in the University of
Glasgow
1869 * Bow, Robert Henry, C.E., 7 South Gray Street 45
1871 * Boyd, Sir Thomas J., President of the Scottish Fishery Board, 41 Moray Place
1873 | * Boyd, William, M.A., Peterhead
1877 * Broadrick, George, Memb. Inst. C.E., Claremont Cottage, Leith
1864 | K. B,) * Brown, Alex. Crum, M.D., D.Sc., F.R.C.P.E., F.R.S. (Secretary), Professor of Chemistry
Pp. in the University of Edinburgh, 8 Belgrave Crescent
1881 * Brown, J. A. Harvie, of Quarter, Dunipace House, Larbert, Stirlingshire 50
1883 | * Brown, J. Graham, M.D, C.M., F.R.C.P.E., 16 Ainslie Place, Edinburgh
1861 | P. | * Brown, Rev. Thomas, 16 Carlton Street
1835 | Brown, William, F.R.C.S.E., 25 Dublin Street
1870 Browne, James Crichton, M.D., LL.D., 7 Cumberland Terrace, Regent’s Park, London, N. W.
1883 * Bruce, Alexander, M.A., M.B., M.R.C.P.E., 16 Alva Street, Edinburgh 55
1878 Brunlees, James, President Inst. C.E., 5 Victoria Street, Westminster
1867 * Bryce, A. H., D.C.L., LL.D., 42 Moray Place
1833 Buccleuch, His Grace the Duke of, K.G., LL.D., D.C.L., F.R.S., F.L.S., Dalkeith Palace
1869 | B. P.| * Buchan, Alexander, M.A., Secretary to the Scottish Meteorologieal Society (CURATOR OF
Lisrary), 72 Northumberland Street
1870 | P. |* Buchanan, John Young, M.A., 10 Moray Place 60
1882 | * Buchanan, T. Ryburn, M.A., M.P. for the City of Edinburgh, 10 Moray Place
ALPHABETICAL LIST OF THE ORDINARY FELLOWS OF THE SOCIETY. 637
Date of
Election.
1883 * Butcher, S. H., M.A., Professor of Greek in the University of Edinburgh, 27 Palmerston
Place
1869 * Calderwood, Rev. H., LL.D., Professor of Moral Philosophy in the University of Edin-
burgh, Napier Road, Merchiston
1879 * Calderwood, John, F.I.C., Battersea, London
188] Cameron, Augustus J. D., Memb. Inst. C.E., 9 Victoria Chambers, Westminster, S.W. 65
1878 Campbell, John Archibald, M.D., Garland’s Asylum, Carlisle
1874 Carrington, Benjamin, M.D., Eccles, Lancashire
1882 * Cay, W. Dyce, Memb. Inst. C.E., 107 Princes Street, Edinburgh
1876 * Cazenove, The Rev. John Gibson, M.A., D.D., 22 Alva Street, Chancellor of St Mary’s
Cathedral, Edinburgh
1866 .|* Chalmers, David, Redhall, Slateford 70
1874 * Chiene, John, M.D., F.R.C.S.E., Professor of Surgery in the University of Edinburgh,
21 Ainslie Place
1875 * Christie, John, 19 Buckingham Terrace
1872 Christie, Thomas B., M.D., F.R.C.P.E., Royal India Asylum, Ealing, London
1880 | K. P.| * Chrystal, George, M.A., Professor of Mathematics in the University of Edinburgh, 5 Bel-
grave Crescent
1875 * Clark, Robert, 7 Learmonth Terrace 75
1863 | P. Cleghorn, Hugh F. C., of Stravithie, M.D., F.L.S., St Andrews
1875 * Clouston, T. S., M.D., F.R.C.P.E., Tipperlin House, Morningside
1882 * Coats, Sir Peter, of Auchendrane, President of the Glasgow and West of Scotland Horti-
cultural Society, Auchendrane, Ayr
1872 * Constable, Archibald, 11 Thistle Street
1872 * Cotterill, The Right Rev. Bishop, D.D., 10 North Manor Place 8&0
1863 Cowan, Charles, of Westerlea, Murrayfield, Edinburgh
1879 * Cox, Robert, of Gorgie, M.A., Gorgie House, Murrayfield
1830 Craig, J. T. Gibson-, W.S., 24 York Place
1875 * Craig, William, M.D., F.R.C.S.E., 7 Lothian Road
1873 * Crawford, Donald, M.A., Advocate, 18 Melville Street 85
1878 * Cunningham, Daniel John, M.D., Professor of Anatomy in Trinity College, Dublin
1877 | * Cunningham, George, 2 Ainslie Place
1871 | * Cunynghame, R. J. Blair, M.D., 6 Walker Street
1841 | P. Dalmahoy, James, 9 Forres Street, Edinburgh
1878 * Dalziel, John Grahame, 2 Melville Terrace, Pollokshields, Glasgow 90
1867 * Davidson, David, Somerset Lodge, Wimbledon Common, Wimbledon
1848 | Davidson, Henry, Muirhouse, Davidson’s Mains
1870 * Day, St John Vincent, C.E., 115 St Vincent Street, Glasgow
1876 * Denny, Peter, Memb. Inst. C.E., Dumbarton
1879 * Denny, William, Bellfield Dumbarton 95
1869 | P. | * Dewar, James, M.A., F.R.S., Jacksonian Professor of Natural and Experimental Philosodhy
in the University of Cambridge, and Fullerian Professor of Chemistry at the Royal
| Institution of Great Britain, London
1869 | P. | * Dickson, Alex., M.D., Professor of Botany in the University of Edinburgh, 11 Royal Circus
1876 * Dickson, J. D. Hamilton, M.A., Fellow and Tutor, St Peter’s College, Cambridge
1869 _* Dickson, William, 38 York Place
1863 * Dittmar, W., F.R.S., Lecturer on Chemistry, Anderson’s College, Glasgow 100
as
638 ALPHABETICAL LIST OF THE ORDINARY FELLOWS OF THE SOCIETY:
Date of
Election.)
1881
1867
1882
1866
1839
1878
1880
1860
1863
1870
1876
1878
1859
1866
1874
1869
1875
1880
1856
1855
1863
1879
1878
1875
1866
1859
1883
1868
1874
1858
1852
1876
1880
1872
1859
1828
* Dobbin, Leonard, Ph.D., 4 Oxford Street, Edinburgh
2. * Donaldson, J., M.A., LL.D., Regius paolo e aces in the University, of
Aberdeen ©
* Dott, D. B., Memb. Pharm. Soc., 24 Castle Street, Eainbuigh
* Douglas, David, 22 Drummond Place
Douglas, Francis Brown, Advocate, 21 Moray Places , 2106.
Drew, Samuel, M.D., D.Sc., Chapelton, near Sheffield
* Drummond, Henry, F.G.S., Free Church College, Glasgow
P. | * Dudgeon, Patrick, of Cargen, Dumfries
| Duncan, J. Matthews, M.A., M.D., F.R.C.P.E., LL.D., 71 Brook Street, London
* Duncan, John, M.D., FROP.E, HRCS.E, 8 ‘Minis Place , ste
* Duncan, James, of Benmore, Kilmun, 9 Mincing Lane, London, E.
* Duncanson, J. J. Kirk, M.D., F.R.C.P.E., 22 Drumsheugh Gardens |
Duns, Rev. Professor, D.D., N ew College, Edinburgh, 14 Greenhill Eine
* Dunsmure, James, M.D., EROSE, 53 Queen Street
* Durham, William, ee Portobello - 115
* Elder, George, Knock Castle, Wemyss Bay, Greenock
Elliot, Daniel G., New York
* Elliot, T. Armstrong, M.A., Fettes. Oalees Edinburgh
Ellis, W. Mitchell, 49 Minto Street, Edinburgh
Etheridge, Robert, F.R.S., Assistant-Keeper of the Geological Department at the British
Museum of Natural History, 19 Halsey Street, Cadogan Place, Chelsea, London 120
Jey Everett, J. D., M.A., D.C.L., F.R.S., Professor of Natural Philosophy, Queen’s College,
Belfast
* Ewart, James Cossar, M.D., F.R.C.S.E., Professor of Natural History, University of Edin.
P. | * Ewing, James Alfred, B.Sc., Professor of Engineering and Drawing in University College,
Dundee
Fairley, Thomas, Lecturer on Chemistry, 8 Newton Grove, Leeds
* Falshaw, Sir James, Bart., Assoc. Inst. C.E., 14 Belgrave Crescent 125
Fayrer, Sir Joseph, K.C.S8.L, M.D., F.R.C.P.L., F.R.C.S.L. and E., LL.D., F.R.S., Honorary
Physician to the Queen, 53 Wimpole Street, London, W.
* Felkin, Robert W., F.R.G.S., Fellow of the Anthropological Society of Berlin, 5 Marchhall
Crescent, Edinburgh
* Ferguson, Robert M., Ph.D., 12 Moray Place
* Ferguson, William, of Kinmundy, F.L.S., F.G.8., Vice-President of the Geological and
Royal Physical Societies of Edinburgh, and Deputy-Lieutenant of Aberdeenshire, 21
Manor Place
Field, Frederick, Chili 130
Fleming, Andrew, M.D., Deputy Surgeon-General, 3 Napier Road
* Fleming, J. 8., 16 Grosvenor Crescent
* Flint, Robert, D.D., Corresponding Member of Institute of France, Professor of Divinity
in the University of Edinburgh, Johnstone Terrace, Craigmillar Park
* Forbes, G., Professor, M.A., F.R.A.S., M.S.T.E. and E., 34 Great George Street, West-
minster
Forlong, Major-Gen. J. G., 11 Douglas Crescent, F.R.G.S., R.A.S., Assoc. C.E., &e. 135
Foster, John, Liverpool
Date of
Election.
1858
1867
1878
1867
1868
1880
1861
1871
1881
1877
1870
1879
1880
1850
1867
1880
1869
1851
1883
1875
1880
1872
1883
1860
1867
1867
1833
1881
1876
1869
1877
1870
1880
ALPHABETICAL LIST OF THE ORDINARY FELLOWS OF THE SOCIETY. 639
B, P:
BE:
iz
Fraser, A. Campbell, M.A., D.C.L. Oxon., LL.D.; Professor of Logic and Metaphysics in
the University of Edinburgh, 20 Chester Street
* Fraser, Thomas R., M.D., F.R.C.P.E., F.R.S., Professor of Materia Medica in the University
of Edinburgh, 37 Melville Street
* Galloway, R. K., B.A., Advocate, 42 Northumberland Street
Gayner, Charles, M.D., Oxford 149°
Gamgee, J. Samson, Birmingham
* Geddes, Patrick, Assistant to the Professor of Botany in the University of Edinburgh,
and Lecturer on Zoology at Minto House, 81a Princes Street
* Geikie, Archibald, LL.D., F.R.S., F.G.S., Director of the Geological Surveys of: Great:
Britain, and Head of the Geological Museum) 28 Jermyn Street, London
* Geikie, James, F.R.S., F.G.S., Professor of Geology in the University of Edinburgh,,
10 Bright Crescent, Newington:
* Gibson, G. A., D.Sc, M.B., F.R.C.P.E., F.G.S.,.1 Randolph Cliff 145
* Gibson, John, Ph.D., 10 Ethel Terrace
* Gifford, Hon. Lord, late one of the Senators of the College of Justice, Granton House
* Gilray, Thomas, M.A.. Professor of English Language and Literature and Modern History
in University College, Dundee
* Gilruth, George Ritchie, 67 York Place, Edinburgh
Gosset, Major-General W. D., R.E., 70 Edith Road, West Kensington, ,London 150
* Graham, Andrew, M.D., R.N., Army and Navy Club, 36 Pall Mall, London, 8.W.
* Graham, James, 195 Bath Street, Glasgow
* Grant, Sir Alexander, Bart., M.A., LUL.D., Principal of the University of Edinburgh,
21 Lansdowne Crescent
Grant, The Rev. James, D.D., D.C.L., 15 Palmerston. Place
* Gray, Andrew, M.A., Chief Assistant to the Professor of Natural Philosophy in. the
University of Glasgow, 21 Hayburn Crescent, Partick 155
* Gray, Robert, Secretary to the Royal Physical Society (Vicz-Presipent), Bank of Scotland.
House, Edinburgh
Gray, Thomas, B.Se., 17 Hayburn Crescent, Partick Hill, Glasgow
* Grieve, David, Lockharton Gardens, Colinton Road, Slateford, Edinburgh
Gunning, R. H., M.D., 28 Bloomfield Road; Shepherd’s Bush, London
* Guthrie, Frederick, M.A., Ph.D., F.R.S., Professor of Physics, Science Sehool, South
Kensington, London, W. 160
* Haldane, D. R., M.D., Vice-President of the Royal. College of Physicians, 22 Charlotte
Square
* Hallen, James H. B., F.R.P.S.E., Inspecting Veterinary Surgeon in H.M. Indian Army,
1 Lauriston Gardens, Edinburgh
Hamilton, Alexander, LL.B., W.S., The Elms, Whitehouse Loan
* Hamilton, D. J., M.B., F.R.C.S.E., Professor of Pathological) Anatomy in the University
of Aberdeen, 1a Albyn Place, Aberdeen
* Hannay, J. Ballantyne, Cove Castle, Loch Long, N.B. 165
Hartley, Sir Charles A., Memb. Inst. C.E., 26 Pall Mall, London
Hartley, Walter Noel, Professor of Chemistry, Royal College of Science for Ireland, Dublin
* Harvey, Thomas, M.A., LL.D., Rector of the Edinburgh Academy, 32 George Square
* Haycraft, J. Berry, M.B., B.Sc., Professor of Physiologyin Sir Josiah Mason’s Science College,
Birmingham
VOL. XXX, PART III. 51
640 ALPHABETICAL LIST OF THE ORDINARY FELLOWS OF THE SOCIETY.
Date of
Klectiou.
1875
1870
1862
1876 | K.P.
1869
1881
1871
1859
1879
1828
1879
1581
1869
1883
1872
1864
1855
1882
1874
1875
1882
1860
1880
1869
1865
1869
1867
1874
1877
1866
1877
1880
1883
1878
1875
1880
P.
Hawkshaw, Sir John, Memb, Inst. C.E., F.RS., F.G.S., 33 Great George Street,
Westminster 170
Heathfield, W. E., Alexandra Villa, Brighton
* Hector, James, C.M.G., M.D., F.R.S., Director of the Geological Survey, Wellington,
New Zealand
* Heddle, M. Forster, M.D., Professor of Chemistry in the University of St Andrews”
* Henry, Isaac Anderson-, of Woodend, Hay Lodge, Trinity
* Herdman, W, A., D.Sc., Professor of Natural History in University College, Liverpool 175
Higgins, Charles Hayes, LL,D., Alfred House, Birkenhead
Hills, John, Liewtenant-Colonel, Bombay Engineers, C,B., United Service Club, London
Hislop, John, Secretary to the Department of Education, Wellington, New Zealand
Home, David Milne, of Milne Graden, LL.D., F.G.S., President of the Geological Society
of Edinburgh, 10 York Place
* Hood, Thomas H. Cockburn, F.G.S., Walton Hall, Kelso 180
*Horne, John, F.G.S., Paleontologist to Geological Survey of Scotland, Huntly,
Aberdeenshire
* Howe, Alexander, W.S., 17 Moray Place
* Hoyle, William Evans, M.A., M.R.C.S., Office of Challenger Commission, 32 Queen Street,
Edinburgh
* Hunter, Captain Charles, Pliis Céch, Anglesea, and 17 St George’s Square, London, 8, W.
* Hutchison, Robert (Carlowrie Castle), and 29 Chester Street 185
Inglis, Right Hon, John, LL.D., D.C.L., Lord Justice-General of Scotland, and Chancellor
of the University of Hdinbash, 30 Abercromby Place
* Inglis, J. W., Memb, Inst. C.E., Myrtle Bank, Trinity
* Irvine, Alex. Forbes, of Drum, Advocate, Sheriff of Argyll (Vicz-PrEsmEnT), 25 Castle Terrace
Jack, William, M.A., Professor of Mathematics in the University of Glasgow
* Jamieson, A., Assoc. Memb, Inst, C.E., Principal of College of Science and Arts, Glasgow 190
* Jamieson, George A., 24 St Andrew Square
Japp, A. H., LL.D., 13 Albion Square, Dalston, London
.|* Jenkin, H. C. Fleeming, F.R.S., Memb, Inst, C.E., Professor of Engineering in the
University of Edinburgh (Vicz-Preswent), 3 Great Stuart Street
* Jenner, Charles, Easter Duddingston Lodge
Johnston, John Wilson, M.D., Bengal 195
* Johnston, T. B., F.R.G.S., 9 Claremont Crescent
Jones, Francis, Lecturer on Chemistry, Monton Place, Manchester
* Jolly, William, H.M, Inspector of Schools, F,G.S., Ardgowan, Pollokshields
* Keiller, Alexander, M.D., F.R.C.P.E., 21 Queen Street
* King, James, of Campsie, Dean of Faculty of Glasgow University, 12 Claremont Terrace,
Glasgow 200
* King, W, F., Lonend, Trinity, Edinburgh
* Kinnear, the Hon, Lord, one of the Senators of the College of Justice, 2 Moray Place -
* Kintore, the Right Hon, the Earl of, M.A, Cantab., Keith Hall, Inverurie, Aberdeenshire
* Kirkwood, Anderson, LL.D., 7 Melville Terrace, Stirling
* Knott, C. G., D,Se., Professor of Natural Philosophy in the Imperial University of
Tokio, Japan 208
ALPHABETICAL LIST OF THE ORDINARY FELLOWS OF THE SOCIETY. 641
lection
1868 * Laidlay, J. W., of Seacliffe, North Berwick
1875 *L’Amy, John Ramsay, of Dunkenny, Forfarshire, 107 Cromwell Road, London,
S.W.
1878 * Lang, P. R. Scott, M.A., B.Sc., Professor of Mathematics in the University of St Andrews
1870 * Laurie, Simon S., M.A., Professor of Education in the University of Edinburgh, Nairn
Lodge, Duddingston
1881 * Lawson, Robert, M.D., Deputy-Commissioner in Lunacy, 33 Drumearn Ter., Grange
Loans ‘ 210
1872 * Lee, Alexander H., C.E., Blairhoyle, Stirling
1872 * Lee, the Hon. Lord, one of the Senators of the College of Justice, 26 Charlotte Square
1882 * Leslie, Alexander, Memb. Inst. C.E., 12 Greenhill Terrace, Edinburgh
1883 * Leslie George, M.B., C.M.Ed., Old Manse, Falkirk
1863 * Leslie, Hon. G. Waldegrave, Leslie House, Leslie 215
1858 Leslie, James, Memb. Inst, C.E., 2 Charlotte Square
1874 | P. |* Letts, E. A., Ph.D., F.LC., F.C.S., Professor of Chemistry, Queen’s College, Belfast
1864 * Lindsay, William, Hermitage-Hill House, Leith
1870 | B. P.| * Lister, Sir Joseph, Bart., M.D., F.R.C.S.L., F.R.C.S.E., LL.D., F.R.S., Professor of Clinical
Surgery, King’s College, Surgeon Extraordinary to the Queen, 12 Park Crescent, Port-
land Place, London, N.W.
1882 * Livingston, Josiah, 4 Minto Street 220
1871 * Logie, Cosmo Gordon, M.D., Deputy Surgeon-General, Royal Horse Guards, 47 Queens-
: borough Terrace, Kensington Gardens, London, W.
1861 | P. | * Lorimer, James, M.A., Advocate, Professor of Public Law in the University of Edinburgh,
1 Bruntsfield Crescent
1849 Lowe, W. H., M.D., F.R.C.P.E., Woodcote, Inner Park, Wimbledon
1855 ~ | Macadam, Stevenson, Ph.D., Lecturer on Chemistry, Surgeons’ Hall, Edinburgh, 11 East
, Brighton Crescent, Portobello
1883 _ |* M'‘Bride, P., M.D., F.R.C.P.Ed., 16 Chester Street 225
1867 * M‘Candlish, John M., W.S., 27 Drumsheugh Gardens
1871 * Macdonald, Angus, M.D., F.R.C.P.E., F.R.C.S.E., 29 Charlotte Square
1847 Macdonald, W. Macdonald, of St Martin’s, Perth
1878 * MacDougall, Alan, Memb. Inst. C.E., Mail Building, 52 King Street West, Toronto, Canada
1878 | P. | * Macfarlane, Alexander, M.A., D.Sc., Examiner in Mathematics in the University of Edin-
burgh, 4 Gladstone Terrace 230
1877 * Macfie, Robert A., Dreghorn Castle, Colinton
1878 + M‘Gowan, George, F.I.C., 22 East Claremont Street
1880 | P. MacGregor, J. Gordon, M.A., D.Se., Professor of Physics in Dalhousie College, Halifax,
Nova Scotia
1879 * M‘Grigor, Alexander Bennett, LL.D., 19 Woodside Terrace, Glasgow
1869 | N. P.| * MIntosh, William Carmichael, M.D., LL.D., F.R.S., F.L.8., Professor of Natural History
: in the University of St Andrews, 2 Abbotsford Crescent, St Andrews 235
1882 * Mackay, John Sturgeon, M.A., Mathematical Master in the Edinburgh Academy
1873 | P. | *M‘Kendrick, John G., M.D., F.R.C.P.E., Professor of the Institutes of Medicine in the
University of Glasgow
1840 Mackenzie, John, New Club, Princes Street
tsz3 | E- Maclagan, Douglas, M.D., F.R.C.P.E. and F.R.C.S.E., Professor of Medical Jurisprudence
in the University of Edinburgh, 28 Heriot Row
1853 Maclagan, General R., Royal Engineers, 37 Lexham Gardens, Kensington, W, 240
642 ALPHABETICAL LIST OF THE ORDINARY FELLOWS OF THE SOCIETY.
s
rection.
1869 * Maclagan, R. Craig, M.D., 5 Coates Crescent 9
1864 * M‘Lagan, Peter, of Pumpherston, M.P., Clifton Hall, Ratho
1869 * M‘Laren, The Hon. Lord, one of the Senators of the College of Justice, 46 Moray Place
1870 * Macleod, George H. B., M.D., F.R.C.S.E., Regius, Professor of Surgery in the University
of Glasgow, and Surgeon in Ordinary to the Queen in Scotland, 10 Woodside Crescent, .
Glasgow
1876 * Macleod, Rey. Norman, 7 Royal Circus 245.
1883 * Macleod, W. Bowman, L.D.S., 43 George Square, Edinburgh
1872 * Macmillan, Rev. Hugh, D.D., LL.D., Seafield, Greenock
1876 * Macmillan, John, M.A., B.Se., Mathematical Master, Perth Academy
1866 + Macnair, John, 33 Moray Place
1883 * M‘Roberts, George, F.C.S., Ardeer, Stevenston 250
1858 Malcolm, R. B., M.D., F.R.C.P.E.,.126 George Street
1880 | P. Marsden, R. Sydney, D.Sc., F.L.C., F.C.S., South-Gate House, Eckington, near Chesterfield, |
Derbyshire, and 14 Lothian Road, Edinburgh
1882 | P. Marshall, D. H., M.A, Professor of Physics in Queen’s University and College, Kingston,
Ontario, Canada r ‘
1869 Marshall, Henry, M.D., Clifton, Bristel
» 1864 * Marwick, James David, LL.D., Town-Clerk, Glasgow 255
1866 * Masson, David, LL.D., Professor of Rhetoric and English Literature in the University of ©
.Edinburgh, 58 Great King Street
1883 * Matthews, James Duncan, 10 Lonsdale Terrace, Edinburgh
1853 Mercer, Graeme Reid, of Gorthie, Ceylon Civil Service
1875 * Millar, C. H., of Blaircastle, 5 Palmerston Place
1852 Miller, Thorias, Mi A., LL.D., Emeritus Rector of Perth ‘Academy, Tnchbank House, Perth 260 —
1833 Milne, Admiral Sir Alexander, Bart., G.C.B., Inveresk
1878 * Milne, John, Trinity Grove, Edinburgh
1875 * Milroy, John, C.E., Torsonce, Stow
1866 * Mitchell, Arthur, M. A.,.M.D., LL.D., Commissioner in Lunacy, 34: penne Place
1843 Mitchell, Joseph, Memb. Inst. C.E., Viewhill, Inverness 265
1879 * Moinet, Francis W., M.D., F.R.C.P.E., 13 Alva Street
1865 * Moir, John J. A., M.D., F.R.C.P.E,,.52 Castle Street
1870 * Monereiff, the Right Hon. Lord, of Tullibole, Lord Justice-Clerk, LL.D. (PRESIDENT), Lat
Great Stuart Street
1871 * Moncrieff, Rev. William Scott, of Fossaway, Bishop-Wearmouth, Sunderland TH
1868 * Montgomery, Very Rev. Dean, M.A., D.D., 17 Atholl Crescent 270
1879 * Morrison, J. B. Brown, of. Finderlie and Murie, Perthshire 7
1877 | P. |* Morrison, Robert Milner, D.Sc., F.I.C., Senior Demonstrator of Chemistry in the ‘University
of Edinburgh, 20 Pentland ‘iifads
1873 * Muir, M. M. Pattison, Pralector on Chemistry, Caius College, Cambridge }
1874 | P. |* Muir, Thomas, M.A., High School, Glasgow
1870 * Munn, David, M.A,, Mathematical Master, Royal High School, Edinburgh 275
1857 Murray, John Iver, 8 Huntriss Row, Scarborough €
1877 | N. P.|* Murray, John, Director of the Challenger Expedition Commission, 32 Queen Street, nae
United Service Club, Edinburgh
1877 * Napier, John, 23 Portman Square, London
1874 * Napier, James, Maryfield House, Bothwell
1866 * Nelson, Thomas, St Leonard’s, Dalkeith Road : , 280 --
ALPHABETICAL LIST OF THE ORDINARY FELLOWS OF THE SOCIETY. 643
Date of
Election.
1883
1880
1878
1877
1881
1863
1868 |
1869
1883
1859
1877
1874
1852
1880
1875
1849
1882
1880
1882
1869
1883
1865
1875
1872
1883
1877
1880
1879
1872
1859
1877
1881
1862
1881
1880
1852
1880
1869
* Newcombe, Henry, F.R.C.S.E., 5 Dalrymple Crescent, Edinburgh
* Nicol, W. W. J., M.A., B.Sc., Lecturer on Chemistry, Mason College, Birmingham
Norris, Richard, M.D., Professor of Physiology, Queen’s College, Birmingham
Panton, George A., 95 Colmore Row, Birmingham
* Peach, B. N., F.G.S., Acting Palzontologist of the Geological Survey of Scotland,
8 (SE Street 285
* Peddie, Alexander, M.D., F.R.C.P.E., 15 Rutland Street
* Peddie, John Dick, M.P., Architect, 33 Buckingham Terrace
Pender, John, M.P., Manchester
Phillips, Charles D. F., M.D., 10 Henrietta Street, Cavendish Square, London, W.
Playfair, The Right Hon. Sir Lyon, C.B., LL.D., F.R.S., M.P. for the Universities of
Edinburgh and St Andrews, 68 Onslow Gardens, London 290
Pole, William, Memb. Inst. C.E., F.R.S., Mus. Doc., 31 Parliament Street, West-
minster, 8. W.
Powell, Baden Henry Baden-, Forest Department, India
Powell, Eyre B., C.S.I., M.A., Victoria Villa, Weston Road, Bath
* Prentice, Charles, C.A., Actuary, 8 St Bernard’s Crescent
Prevost, E. W., Ph.D, Ellesmere, Salop 295
Primrose, Hon. B. F., C.B., 22 Moray Place
* Pryde, David, M.A., LL.D., Head Master of the Ladies’ College, 10 Fettes Row,
Edinburgh
* Pullar, Robert, Tayside, Perth
* Rattray, James Clerk, M.D., 61 Grange Loan, Edinburgh
Raven, Rev. Thomas Milville, M.A., The Vicarage, Crakehall, Bedale 300
* Readman, J. B., 9 Moray Place, Edinburgh
* Redford, Rev. Francis, M.A., The Rectory, Silloth
* Richardson, Ralph, W.S., Vice-Pres. of the Geological Society, 10 Magdala Place
Ricarde-Seaver, Major F. Ignacio, Conservative Club, St James’ Street, London, S.W.,
and 2 Rue Lafitte, Boulevard des Italiens, Paris
* Ritchie, R. Peel, M.D., F.R.C.P.E., 1 Melville Crescent 305
* Roberton, James, LL.D., Professor of Conveyancing in the University of Glasgow, 1 Park
Terrace East, Glasgow
Roberts, D. Lloyd, M.D., F.R.C.P.L., 23 St John Street, Manchester
* Robertson, Major-General A. Cuningham, 86 Great King Street
* Robertson, D. M. C. L. Argyll, M.D., F.R.C.S.E., 18 Charlotte Square
Robertson, George, Memb. Inst. C.E., 47 Albany Street 310
* Robinson, George Carr, F.I.C., Lecturer on Chemistry in the Royal Institution, Hull
* Rogerson, John Johnston, B.A., LL.B., Merchiston Castle Academy, Edinburgh
* Ronalds, Edmund, LL.D., Bonnington House, Bonnington Road, Edinburgh
Rosebery, The Right Hon. the Earl of, LL.D., Dalmeny :
Rowland, L. L., M.A., M.D., President of the Oregon State Medical Society, and Professor
of Physiology and Microscopy in Williamette University, Salem, Oregon 315
Russell, Alexander James, C.S., 9 Shandwick Place ;
* Russell, J. A., M.A., B.Sc., M.B., Woodville, Canaan Lane, Edinburgh
* Rutherford, Wm., M.D., F.R.C.P.E., F.R.S., Professor of. the Institutes of Medicine in
the University of Edinburgh, 14 Douglas Crescent
644 ALPHABETICAL LIST OF THE ORDINARY FELLOWS OF THE SOCIETY.
Date of
Election
1863 * Sanderson, James, Deputy Inspector-General of Hospitals, F.R.C.S.E., 41 Manor Place .
1864 Sandford, The Right Rev, D. F., LL.D., Bishop of Tasmania 320
1849 P. | Sang, Edward, C.E., LL.D., Secretary to the Royal Scottish Society of Arts (Vick-PRESIDEN?),
6 Mollendo Terrace
1846 Schmitz, Leonard, LL.D., 26 Belsize Park Gardens, London, N.W.
1880 Scott, J. H., M.B., C.M., M.R.C.S., Professor of Anatomy in the University of Otago,
New Zealand
1875 Scott, Michael, Memb, Inst. C.E., 9 Great Queen Street, Westminster, London
1864 * Sellar, W. Y., M.A., LL.D., Professor of Humanity in the University of Edinburgh,
15 Buckingham Terrace 325
1872 * Seton, George, M.A., Advocate, 42 Greenhill Gardens
1872 * Sibbald, John, M.D., Commissioner in Lunacy, 3 St Margaret’s Road, Whitehouse Loan
1870 * Sime, James, M.A., South Park, Fountainhall Road, Edinburgh
1871 * Simpson, A. R., M.D., F.R.C.P.E., Professor of Midwifery in the University of Edinburgh,
52 Queen Street
1859 | P. | Skene, Wm. F., W.S., LL.D., D.C.L., Historiographer-Royal for Scotland, 27 Inverleith
Row 330
1876 * Skinner, William, W.S., Town-Clerk of Edinburgh, 35 George Square
1868 * Smith, Adam Gillies, C.A. (TrEasurER), 64 Princes Street
1882 | P Smith, C. Michie, B.Se., Professor of Physical Science, Christian College, Madras, Tata
1883 Smith, James Greig, M.A., M.B., 16 Victoria Square, Clifton
1871 * Smith, John, M.D., ERC. S.E., President of the Royal College of Surgeons, Edinburgh,
11 Wemyss eae 335
1855 Smith, R. M., 4 Bellevue Crescent
1871 | P. |* Smith, Rev. W. Robertson, M.A., LL.D., Lord Almoner’s Professor of Arabic in the
University of Cambridge, 20 Duke Street, Edinburgh
1880 Smith, W. Robert, M.D., Bayshill Villa, Cheltenham
1846 |K.B.| Smyth, Piazzi, Professor of Practical Astronomy in the University of Edinburgh, and
P. Astronomer-Royal for Scotland, 15 Royal Terrace
1880 Sollas, W. J., M.A., Fellow of St John’s College, Cambridge, and Professor of Geology
and Zoology in University College, Bristol 340
1882 * Sorley, James, F.F.A., C.A., 26 George Street, Edinburgh
1874 | P. |*Sprague, T. B., M.A., 29 Buckingham Terrace
1850 | P. Stark, James, M.D., F.R.C.P.E., of Huntfield, Underwood, Bridge of Allan
1844 Stevenson, David, Memb. Inst. C.E., 45 Melville Street
1877 * Stevenson, James, F.R.G.S., 4 Woodside Crescent, Glasgow . 345
1868 Stevenson, John J., Red House, Bayswater Hill, London, W,
1848 | P, Stevenson, Thomas, Memb. Inst. C.E., F.G.S. (Vicu-Presipmnt), 84 George Street
1868 Stewart, Colonel J. H. M. Shaw, Royal Engineers, Madras
1878 * Stewart, James R., M.A., 10 Minto Street ;
1866 * Stewart, T. Grainger, M.D., F.R.C.P.E., Professor of the Practice of Physic in ine
University of iene 19 Charlotte Square 350
1873 * Stewart, Walter, 22 Torphichen Street
1848 Stirling, Patrick J., LL.D., Kippendavie House, Dunblane
1877 | * Stirling, William, M.D., Se.D., Professor of Institutes of Medicine in the University of
Aberdeen
1823 Stuart, Captain T. D., H.M.LS.
1870 * Swan, Patrick Don, Provost of Kirkcaldy 355
ALPHABETICAL LIST OF THE ORDINARY FELLOWS OF THE SOCIETY. 645
Date of
Election.
1848 | P, Swan, Wm., LL.D., Emeritus Professor of Natural Philosophy in the University’ of St
Andrews, President of the Royal Scottish Society of Arts, Ardchapel, Helensburgh
1844 Swinton, A. Campbell, of Kimmerghame, LL.D., Dunse
1875 * Syme, James, 10 Buckingham Terrace
1872 Tait, the Rev, A., LL.D,, Canon of Tuam, Moylough Rectory, Ballinasloe, Ireland
186] | K.P. }* Tait, P. Guthrie, M.A., Professor of Natural Philosophy in the University of Edinburgh
(GENERAL Secretary), 38 George Square 360
1870 * Tatlock, Robert R., City Analyst’s Office, 138 Bath Street, Glasgow
1872 * Teape, Rev. Charles R., M.A., Ph.D., 15 Findhorn Place
1873 * Tennent, Robert, 23 Buckingham Terrace
1843 Thomson, Allen, M.D., F.R.C.S.E., F.R.S., Emeritus Professor of Anatomy in the University
of Glasgow, 66 Palace Garden Terrace, London, W,
1870 * Thomson, Rev. Andrew, D.D., 63 Northumberland Street 365
1875 * Thomson, James, LL.D., F.R.S,, Professor of Engineering in the University of Glasgow,
2 Florentine Gardens, Hillhead, Glasgow
1880 Thomson, John Millar, King’s College, London, W.C,
1863 * Thomson, Murray, M.D., Professor of Chemistry, Thomason College, Roorkee, India
1870 * Thomson, Spencer C,, Actuary, 10 Chester Street
1847 |K.P.| Thomson, Sir William, LL.D., D.C.L., F.R.S. (Hon, Vicz-Presipent), Regius Professor’ of
Natural Philosophy in Univ. of Glasgow, Foreign Associate of Institute of France 370
1882 Thomson, William, M.A., B.Sc., Professor of Mathematics in University College, Stellen-
bosch, Cape Colony
1870 * Thomson, William Burns, F.R.C.P.E., F.R.C.S.E., Maison Flory, Route de Grasse,
Cannes, France
1876 Thomson, William, Royal Institution, Manchester
1878 Thorburn, Robert Macfie, Uddevalla, Sweden
1874 | N.P.| * Traquair, R. H., M.D., F.R.S., F.G.S., Keeper of the Natural History Collections in the
Museum of Science and Art, Edinburgh, 8 Dean Park Crescent 375
1874 * Tuke, J. Batty, M.D., F.R.C.P.E., 20 Charlotte Square
1879 * Turnbull, John, of Abbey St Bathans, W.S., 49 George Square
1867 * Turnbull, William, Menslaws, Jedburgh
1861 | N.P.|* Turner, William, M.B., F.R.C.S.E., F.RS., Beaiessay of Anatomy in the University
of Edinburgh erciuee) 6 Eton Terrace
1877 * Underhill, Charles E., B.A., M.B., F.R.C.P.E., F.R.C.S.E., 8 Coates Crescent 380
1875 Vincent, Charles Wilson, Royal Institution, Albemarle Street, London
1867 * Waddell, Peter, 5 Claremont Park, Leith
1873 * Walker, Robert, M.A., University, Aberdeen
1864 * Wallace, William, Ph.D., City Analyst’s Office, 138 Bath Street, Glasgow
1883 * Watson, Charles, Redhall, Slateford 385
1870 * Watson, James, C.A., 45 Charlotte Square
1866 * Watson, John K., 14 Blackford Road
1873 | P. |* Watson, Morrison, M.D., F.R.C.P.E., Professor of Anatomy, Owens College, Mnehenten
1866 * Watson, Patrick Heron, M.D., F.R.C.P.E., F.R.C.S.E., 16 Charlotte Square
s862'| P. Watson, Rev, Robert Boog, B.A., Free Church Manse, Cardross, Dumbartonshire 390
646 ALPHABETICAL LIST OF THE ORDINARY FELLOWS OF THE SOCIETY.
Election. |
1877 Weldon, Walter, F.C.S., Rede Hall, Burstow, Surrey
1873 Welsh, David, Major-General, R.E., R.A., 1 Barton Terrace, Dawlish
1840 Welwood, Allan A. Maconochie, LL.D., of Meadowbank and Garvoch, Kirknewton
1882 * Wenley, James, Treasurer of the Bank of Scotland, 5 Drumsheugh Gardens ;
1876 White, Rev. Francis Le Grix, M.A., F.G.S., Leaming-on-Ulleswater, Penrith 395
1881 Whitehead, Walter, F.R.C.S.E., 202 Oxford Road, Manchester
1883 Wickham, R. H. B., F.R.C.S.E., Borough Lunatic Asylum, Newecastle-on-Tyne
1879 * Will, John Charles Ogilvie, M.D., 12 Union Terrace, Aberdeen
1868 * Williams, W., Principal and Professor of Veterinary Medicine and Surgery, New Veterinary
College, Gayfield House
1858 Williamson, Thomas, M.D., F.R.C.S.E., 28 Charlotte Street, Leith 400
1879 * Wilson, Andrew, Ph.D., Lecturer on Zoology and Comparative Anatomy in the Edinburgh
Medical School, 118 Gilmore Place
1877 * Wilson, Charles E., M.A., LL.D., H. M. Senior Inspector of Schools for Scotland,
; 19 Palmerston Place
1878 * Wilson, Rev. John, M.A., Bannockburn Academy
1875 Wilson, Daniel, LL.D., President of the University of Toronto, and Professor of English
Literature in that University
1882 Wilson, George, M.A., M.D., 23 Claremont Road, Leamington ’ 405
“1834 Wilson, Isaac, M.D.
1847 Wilson, John, Professor of Agriculture in the University of Edinburgh
1870 Winzer, John, Chief Surveyor, Civil Service, Ceylon, 7 Dryden Place, Newington, Edinburgh
1880 * Wise, Thomas Alexander, M.D., F.R.C.P.E., Inchrye Abbey, Newburgh, Fife
1864 * Wood, Alexander, M.D., FROPE, 12 Strathearn Place 410
1855 Wright, Thomas, M.D., F.R.S., Cheltenham
1864 * Wyld, Robert S., LL.D., 19 Inverleith Row
1882 * Young, Andrew, 22 Elm Row ©
1882 * Young, Frank W., F.C.S., Lecturer on Natural Science, High School, Dundee, 4 Airlie
Terrace, Dundee
1882 * Young, Thomas Graham, Limefield, West Calder 415
>
APPENDIX.—LIST OF HONORARY FELLOWS.
LIST OF HONORARY FELLOWS
AT NOVEMBER 1883.
His Royal Highness The PRINCE OF WALES.
FOREIGNERS (LIMITED TO THIRTY-SIX BY LAW X.).
Elected.
1864
1867
Robert Wilhelm Bunsen,
Michel Eugéne Chevreul,
1858 James D. Dana,
1877
Alphonse De Candolle,
1883 Luigi Cremona,
1879 Franz Cornelius Donders,
1855
1877
Jean Baptiste Dumas,
Carl Gegenbaur,
1879 Asa Gray,
1883 Julius Hann,
1864 Hermann Ludwig Ferdinand Helmholtz,
1879 Jules Janssen,
1875 August Kekulé,
1868 Gustav Robert Kirchhoff,
1875 Hermann Kolbe,
1864 Albert Kolliker,
1875 Ernst Eduard Kummer,
1864 Richard Lepsius,
1876 Ferdinand de Lesseps,
1864 Rudolph Leuckart,
1881
1876
1878
Sven Lovén,
Carl Ludwig,
J. N. Madvig,
1855 Henry Milne-Edwards,
1864 Theodore Mommsen,
1881
1874
Simon Newcomb,
Louis Pasteur,
1864 Karl Theodor von Siebold,
1881
1878
Johannes Iapetus Smith Steenstrup,
Otto Wilhelm Struve,
1855 Bernard Studer,
1874 Otto Torell,
1868
1874
1883
Rudolph Virchow,
Wilhelm Eduard Weber,
Charles Adolphe Wurtz,
Total, 35.
VOL, XXX. PART III,
Heidelberg.
Paris.
New Haven, Conn., United States.
Geneva.
Rome.
Utrecht.
Paris.
Heidelberg.
Harvard University, United States.
Vienna.
Berlin.
Paris.
Bonn.
Berlin.
Leipzig.
Wiirzburg.
Berlin.
Berlin.
Paris.
Leipzig.
Stockholm.
Leipzig.
Copenhagen.
Paris.
Berlin.
Washington.
Paris.
Munich.
Copenhagen
Pulkowa.
Bern.
Inmd.
Berlin.
Gottingen.
Paris.
647
648
APPENDIX.—LIST OF HONORARY. FELLOWS.
BRITISH SUBJECTS (LIMITED TO TWENTY BY LAW X.).
Elected.
1849 John Couch Adams, LL.D., F.R.S., Corresp. Mem. Inst. France,
1835 Sir George Biddell Airy, K.C.B., M.A., LL.D., D.C.L., F.B.S.,
Foreign Associate Inst., France,
1870 Thomas Andrews, M.D., LL.D., F.R.S.,
1865 Arthur Cayley, LL.D., F.RB.S., ieee Mem. Inst. France,
1874 John Anthony imate LL.D., ‘
1881 The Hon. Justice Sir William Robert Grove, M.A., LL.D.,
D.C.L., F.B.S.,
1883 Sir Joseph Dalton Hooker, K.C.S.I., C.B., M.D., D.C.L., LL.D.,
F.R.S., F.G.S., Corresp. Mem. ‘tes tes: Director of the
Royal Gardens, Kew,
1876 Thomas Henry Huxley, LL.D., D.C.L., President of the Royal
Society, F.L.S., F.Z.S., F.G.S., Cotes Mem. Inst. France,
1867 James Prescott Joule, LL.D., D.C.L., F.R.S., Corresp. Mem.
Inst. France,
1845 Richard Owen, C.B., M.D., LL.D., D.C.L., F.R.S., Foreign
Associate Inst. France,
1881 The Rev. George Salmon, D.D., LL.D., D.C.L., F.R.S.,
1878 Balfour Stewart, M.A., LL.D., F.R.S.,
1864 George Gabriel Stokes, M.A., LL.D., D.C.L., Sec.
Corresp. Mem. Inst. France,
1874 James Joseph Sylvester, M.A., LL.D., F.R.S., Corresp. Mem.
Inst. France,
1864 Alfred Tennyson, D.C.L., F.R.S., Poet Laureate,
1883 Alexander William Williamson, LL.D., F.R.S., V.P.C.S., Corresp.
Mem. Inst. France,
1883 Colonel Henry Yule, C.B., Member of the Council of India,
Total, 17.
B.S.,
Cambridge.
Greenwich.
Belfast.
Cambridge.
‘London.
London.
‘London.
London.
’ Manchester
London.
Dublin.
Manchester.
Cambridge.
Baltimore.
Isle of Wight.
London.
London.
APPENDIX.—LIST OF MEMBERS ELECTED. 649
LIST OF ORDINARY FELLOWS.
ELECTED DURING SESSION 1880-81, ARRANGED ACCORDING TO THE DaTE OF
THEIR ELECTION,
6th December 1880.
Tuomas ALEXANDER Wisz, M.D, (re- Tuomas Gray, B.Sc.
admitted). °
3d January 1881..
G. A. Gipson, D.Sc., F.R.C.P.E.
7th February 1881.
Water Waitenead, F.R.C.S,E. W. A. Herpman, D.Sc.
A. H. Anew, M.A., M.R.IA. Tuomas WiLu1aM Rumsuz, Memb, Inst. C.E.
J. A. Harvir Brown, of Quarter. Rosert Lawson, M.B.
7th March 1881.
JouN Hornz, F.G.S. B. N. Peacu, F.G.S
4th April 1881.
Lronarp Dossy, Ph.D. D. J. Hamitton, M.B. Prof. of Pathology,
Univ. of Aberdeen.
6th June 1881.
The Right Hon, the Ear or Rosepery, LL.D, Watter Berry, Danish Consul-General.
Avueustus J. D. Cameron, Memb. Inst. C.E. JoHN JOHNSTON Rogerson, A.B., LL.B.
J. EK. Tierney Artcuison, M.D.
ELECTED puRING SESSION 1881-82.
5th December 1881.
Sir Perer Coats, ANDREW YOUNG.
16th January 1882.
D. B. Dorr. : James CuerK Rattray, M.D.
6th February 1882.
ALEXANDER Lesiiz, Memb. Inst. C.E. Joun Sturczon Macgay, M.A.
Henry Barnss, M.D.
6th Murch 1882.
James Soruey, Actuary. THomas GRAHAM YOUNG,
Witiiam THomson, M.A. W. Dycs Cay, Memb. Inst. C.E.
3d April 1882.
J. A. Drxon. D. H. MarsnHatt, M.A.
Prof, C. Micurt Suita, B.Sc. JOSIAH LivinasTon.
lst May 1882.
Davin Pryps, M.A., LL.D. Frank W. Youna, F.C.S.
J. W. Ines, Memb. Inst. C.E. T. R. Bucuanan, M.A., M.P.
5th June 1882.
Grorce Wi1son, M.A., M.D. Frank E. Bepparp, B.A.
3d July 1882.
ANDREW JAMIESON, Memb. Inst. C.E. J. A. Wentey, Treasurer, Bank of Scotland.
(=r)
Or
—)
APPENDIX.—LIST OF MEMBERS ELECTED.
ELECTED DURING SESSION 1882-83.
4th December 1882.
R H. Gunnine, M.D. ALEXANDER Bruce, M.A., M.B.
Cuartes D, F, Puruuirs, M.D.
15th January 1883.
R. Peet Rrrcars, M.D.
5th February 1883. -
The Hon. Lorp Kinngar. W. Bowman Mactsop, L.D.S.
Rk. H. B. Wioxuam, F.R.C.S. Ed.
5th March 1883.
Wim FE. Hoye, M.A., M.R.C.S. Joun ARCHIBALD, M.B., C.ML.
James Duncan MatTHeEws. Rozsert Rowanp ANDERSON,
James Grete Suitu, M.A., M.B. Anprew Gray, M.A.
2d April 1883.
P. M‘Bring, M.D. ; G. W. W. Barcray, M.A.
Tuomas AnprREws, F.C.S.
7th May 1883.
Professor S. H. Burcusr, M.A. Rosert W. Fevkin, F.R.G.S.
GrorGE M‘Roserts, F.C.S. Groree Lesiiz, M.B., C.M.
4th June 1883.
J. R. READMAN. Henry Newcomss, F.R.C.S.E.
CHARLES WATSON.
2d July 1883.
J. GraHam Brown, M.D.
ELECTIONS OF HONORARY FELLOWS.
BRITISH HONORARY FELLOWS.
Elected from November 1880 to November 1881.
The Hon. Justice Sir Witt1am Ropert Grove, M.A., D.C.L., LL.D., London.
The Rev. Grorcr Satmon, D.D., D.C.L., LL.D., Reg. Prof. of Divinity, Trinity College, Dublin.
Elected from November 1882 to November 1883.
Sir JosepH Datron Hooker, K.C.S.1., M.D., D.C.L., LL.D., Director of the Royal
Gardens, Kew, Corresp. Mem, Inst. France, London.
Witu1aM Spottiswoope, D.C.L., LL.D., Pres. Royal Society, Corresp. Mem. Inst. France, London.
ALEXANDER WiLiiaAM Witiiamson, LL.D., Corresp. Mem. Inst. France, London.
Colonel Henry Youre, ©.B., Member of Council of India, i. London.
FOREIGN HONORARY FELLOWS. °
Elected from November 1878 to November 1879.
Frank Cornetius Donpers, Professor of Physiology, Utrecht.
Asa Gray, Professor of Botany, Cambridge, U.S.
JuxLes JANSSEN, Director of the Observatory, Meudon Paris.
Jouann Benepict Listine, Professor of Natural Philosophy, Gottingen.
Elected from November 1880 to November 1881.
Sven Lovin, Professor of Physiology, Stockholm.
Smion Newcoms, Professor of Astronomy, Washington.
Emite Prantamour, Professor of Astronomy, Geneva.
JOHANNES JAPETUS SmitH SteenstRuP, Professor of Zoology, Copenhagen.
Elected from November 1882 to November 1883.
Luiat Cremona, Professor of Mathematics, Rome.
Junius Hann, Director of Meteorological Institute, Vienna
Caarites Apotpae Wurtz, Professor of Chemistry, Paris.
(esl)
LIST OF FELLOWS DECEASED, RESIGNED, AND CANCELLED.
HONORARY FELLOWS (BRITISH) DECEASED.
From Novemser 1880 to NovemBer 1881.
Tuomas CARLYLE.
HONORARY FELLOWS (BRITISH) DECEASED.
From Novemser 1881 to NovemsBer 1882.
Dr Cartes Darwin, F.R.S. : Rey. Dr Romney Rosrnson.
From NovemBer 1882 to Novemser 1883.
Dr Henry Jonny SterHen Suita, F.R.S. Dr Wintiam Sporttiswoops, P.R.S.
General Sir Epwarp Sasing, R.A., F.R.S.
HONORARY FELLOWS (FOREIGN) DECEASED.
From Novemper 1880 to NovempBer 1882.
JosEPH LIOUVILLE. Emite PLaNnTAMour.
FRriepRicH WOHLER.
From November 1882 to NovemBer 1883.
JOHANN BENEDICT LISTING.
ORDINARY FELLOWS DECEASED.
From NovemBer 1880 to Novemper 1881.
Dr Joun Hiti Bourton. Davin Situ.
Dy JoHN CUMMING. Sir ALEXANDER Taytor, M.D.
Dr Hanpystbe. James Waker, W.S.
Dr Lauper Linpsay, Dr J. G. Witson.
Professor SANDERS. Dr ANDREW Woop.
From Novemper 1881 to NovemBer 1882.
Davin AnpErRson of Moredun. Sir Danie, MacNue.
CuHarLES Davipson BELt. CuaruLEs Morresean, M.D.
Dr JoHNn Brown. Dr Joun Muir.
Sir Roprert Curistison, M.D. RicHARD PARNELL.
Sir Jonn Rose Cormack, M.D. SamveL Raueiaeu, C.A.
JosepH ANTHONY Dixon. WixiramM Rosertson, M.D.
Sheriff Frepsrick Hatnanrp. JoHN Scott RUSSELL.
Wiuram Kine. Professor SPENCE.
Joun M‘Cuttoca. Sir Wyvitte THomson.
Rogsert WILSON,
APPENDIX.—LIST OF MEMBERS DECEASED, ETC.
From November 1882 to November 1883.
Warren Hastincs ANDERSON (death only Professor Pirrim.
intimated in November 1883). ANDREW PriTcHaRD.
Dr Witii1am CHAMBERS. Davin Rup.
Dr James ScartH Compe. Downatp Ross, M.A.
Witi1am Jamieson, Surgeon-Major (death THomas Witt1am Rumsre, Memb. Inst. C.E.
only intimated in February 1883). - Jon ALExanpeER Situ, M.D.
Davin Macraean, F.8.A., Actuary. - Wit11am Toomas Tuomson, Actuary.
Right Hon. Sir Jonn M‘Nertt, G.C.B. James Youne of Kellie, F.R.S.
Joun MitiEer, Memb. Inst. C.E.
FELLOWS RESIGNED.
Durine Szssion 1879-80.
Dr A. Bruce BREMNER. Davin MacGiszon.
Professor J. Bett Prrticrew, F.R.S.
Durine Session 1880-81.
The Rev. JosepH Goopsir.
Durine Szsston 1882-83.
JAMES Buaikip, M.A. Professor H. ALLEYNE NicHoLson.
FELLOWS CANCELLED.
Dvurine Session 1880-81.
G. W. Hay. JAMES PowRIE.
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TRANSACTIONS
OF THE
ROYAL SOCIETY OF EDINBURGH.
VOL. XXX. PART IV.—FOR THE SESSION 1882-83.
CONTENTS.
Laws OF THE SOCIETY, .
Tue Kern, Brispane, AND Nein Prizss,
PROCEEDINGS oF StaTuTORY GENERAL MEETINGS,
INDEX,
Six PLatEs to accompany Dr Traquarr’s Paper on Fossit Fisuxs, issued with Part I.
Page
653
660
665
675
LAWS
OF THE
ROYAL SOCIETY OF EDINBURGH,
AS REVISED 20TH FEBRUARY 1882.
VOL XXX. PART“ IV. By Ib
PAWS.
[ By the Charter of the Society (printed in the Transactions, Vol. VI. p. 5), the Laws cannot
be altered, except at a Meeting held one month after that at which the Motion for
alteration shall have been proposed. |
I.
THE ROYAL SOCIETY OF EDINBURGH shall consist of Ordinary and
Honorary Fellows.
i:
Every Ordinary Fellow, within three months after his election, shall pay Two
Guineas as the fee of admission, and Three Guineas as his contribution for the
Session in which he has been elected ; and annually at the commencement of every
Session, Three Guineas into the hands of the Treasurer. This annual contribution
shall continue for ten years after his admission, and it shall be limited to Two
Guineas for fifteen years thereafter.*
III.
All Fellows who shall have paid Twenty-five years’ annual contribution shall
be exempted from farther payment.
IV.
The fees of admission of an Ordinary Non-Resident Fellow shall be £26, 5s.,
payable on his admission ; and in case of any Non-Resident Fellow coming to
reside at any time in Scotland, he shall, during each year of his residence, pay
the usual annual contribution of £3, 3s., payable by each Resident Fellow ; but
after payment of such annual contribution for eight years, he shall be exempt
* A modification of this rule, in certain cases, was agreed to at a Meeting of the Society held on
the 3rd January 1831.
At the Meeting of the Society, on the 5th January 1857, when the reduction of the Contribu-
tions from £3, 3s. to £2, 2s,, from the 11th to the 25th year of membership, was adopted, it was
resolved that the existing Members shall share in this reduction, so far as regards their future annual
Contributions.
Title.
The fees of Ordi-
nary Fellows resid-
ing in Scotland.
Payment to cease
after 25 years.
Fees of Non-Resi-
dent Ordinary
Fellows.
Fellows
g Non-
Ge
es of
y Fellows.
3 Un-
entitled
sactions.
f Recom-
¢ Ordinary
656 LAWS OF THE SOCIETY.
from any farther payment. In the case of any Resident Fellow ceasing to reside
in Scotland, and wishing to continue a Fellow of the Society, it shall be in the
power of the Council to determine on what terms, in the circumstances of each
case, the privilege of remaining a Fellow of the Society shall be continued to
such Fellow while out of Scotland.
V.
Members failing to pay their contributions for three successive years (due
application having been made to them by the Treasurer) shall be reported to
the Council, and, if they see fit, shall be declared from that period to be no
longer Fellows, and the legal means for recovering such arrears shall be
employed.
Walls
None but Ordinary Fellows shall bear any office in the Society, or vote in
the choice of Fellows or Office-Bearers, or interfere in the patrimonial interests
of the Society.
VIL.
The number of Ordinary Fellows shall be unlimited.
VIL.
The Ordinary Fellows, upon producing an order from the TREASURER, shall
be entitled to receive from the Publisher, gratis, the Parts of the Society’s
Transactions which shall be published subsequent to their admission.
IX.
Candidates for admission as Ordinary Fellows shall make an application in
writing, and shall produce along with it a certificate of recommendation to the
purport below,* signed by at least fowr Ordinary Fellows, two of whom shall
certify their recommendation from personal knowledge. This recommendation
shall be delivered to the Secretary, and by him laid before the Council, and
shall afterwards be printed in the circulars for three Ordinary Meetings of
the Society, previous to the day of election, and shall lie upon the table during
that time. ;
* “A. B., a gentleman well versed in Science (or Polite Literature, as the case may be), being
“to our knowledge desirous of becoming a Fellow of the Royal Society of Edinburgh, we hereby
“ recommend him as deserving of that honour, and as likely to prove a useful and valuable Member,”
LAWS OF THE SOCIETY. 657
X.
Honorary Fellows shall not be subject to any contribution. This class shall
consist of persons eminently distinguished for science or literature. Its number
shall not exceed Fifty-six, of whom Twenty may be British subjects, and Thirty-
six may be subjects of foreign states.
XI.
Personages of Royal Blood may be elected Honorary Fellows, without regard
to the limitation of numbers specified in Law X.
XII.
Honorary Fellows may be proposed by the Council, or by a recommenda-
tion (in the form given below*) subscribed by three Ordinary Fellows ; and in
case the Council shall decline to bring this recommendation before the Society,
it shall be competent for the proposers to bring the same before a General
Meeting. The election shall be by ballot, after the proposal has been commu-
nicated viva voce from the Chair at one meeting, and printed in the circulars
for two ordinary meetings of the Society, previous to the day of election.
XIII.
The election of Ordinary Fellows shall only take place at the first Ordinary
Meeting of each month during the Session. The election shall be by ballot,
and shall be determined by a majority of at least two-thirds of the votes, pro-
vided Twenty-four Fellows be present and vote.
XIV.
The Ordinary Meetings shall be held on the first and third Mondays of
every month from December to July inclusively ; excepting when there are
five Mondays in January, in which case the Meetings for that month shall
be held on its third and fifth Mondays. Regular Minutes shall be kept of
the proceedings, and the Secretaries shall do the duty alternately, or
according to such agreement as they may find it convenient to make.
* We hereby recommend
for the distinction of being made an Honorary Fellow of this Society, declaring that each of us from
our own knowledge of his services to (Literature or Science, as the case may be) believe him to be
worthy of that honour.
(To be signed by three Ordinary Fellows.)
To the President and Council of the Royal Society
of Edinburgh.
Honorary Fellows,
British and
Foreign.
Royal Personages.
Recommendation
of Honorary Fel-
lows.
Mode of Election.
Election of Ordi-
nary Fellows.
Ordinary Meet-
ings.
actions.
ished.
cil.
Jouncil-
of Office-
feetings ;
d.
r’s Duties.
658 LAWS OF THE SOCIETY.
xvi.
The Society shall from time to time publish its Transactions and Proceed-
ings. For this purpose the Council shall select and arrange the papers which
they shall deem it expedient to publish in the Z’ransactions of the Society, and
shall superintend the printing of the same.
The Council shall have power to regulate the private business of the Society.
At any Meeting of the Council the Chairman shall have a casting as well as a
deliberative vote.
XVI.
The Transactions shall be published in parts or Fascicult at the close of
each Session, and the expense shall be defrayed by the Society.
XVII.
That there shall be formed a Council, consisting—First, of such gentlemen
as may have filled the office of President ; and Secondly, of the following to be
annually elected, viz. :—a President, Six Vice-Presidents (two at least of whom
shall be resident), Twelve Ordinary Fellows as Councillors, a General Secretary,
Two Secretaries to the Ordinary Meetings, a Treasurer, and a Curator of the
Museum and Library.
XVIII.
Four Councillors shall go out annually, to be taken according to the order |
in which they stand on the list of the Council.
XIX.
An Extraordinary Meeting for the Election of Oftice-Bearers shall be held
on the fourth Monday of November annually.
XX.
Special Meetings of the Society may be called by the Secretary, by direction
of the Council; or on a requisition signed by six or more Ordinary Fellows.
Notice of not less than two days must be given of such Meetings.
XXY.
The Treasurer shall receive and disburse the money belonging to the Society,
granting the necessary receipts, and collecting the money when due.
He shall keep regular accounts of all the cash received and expended, which
shall be made up and balanced annually ; and at the Extraordinary Meeting in
November, he shall present the accounts for the preceding year, duly audited.
LAWS OF THE SOCIETY. 659
At this Meeting, the Treasurer shall also lay before the Council a list of all
arrears due above two years, and the Council shall thereupon give such direc-
tions as they may deem necessary for recovery thereof.
9, O.S 06
At the Extraordinary Meeting in November, a professional accountant shall
be chosen to audit the Treasurer’s accounts for that year, and to give the neces-
sary discharge of his intromissions.
XXITI.
The General Secretary shall keep Minutes of the Extraordinary Meetings of
the Society, and of the Meetings of the Council, in two distinct books. He
shall, under the direction of the Council, conduct the correspondence of the
Society, and superintend its publications. For these purposes he shall, when
necessary, employ a clerk, to be paid by the Society.
AXLV..
The Secretaries to the Ordinary Meetings shall keep a regular Minute-book,
in which a full account of the proceedings of these Meetings shall be entered ;
they shall specify all the Donations received, and furnish a list of them, and of
the Donors’ names, to the Curator of the Library and Museum ; they shall like-
wise furnish the Treasurer with notes of all admissions of Ordinary Fellows.
They shall assist the General Secretary in superintending the publications, and
in his absence shall take his duty.
XXYV.
The Curator of the Museum and Library shall have the custody and charge
of all the Books, Manuscripts, objects of Natural History, Scientific Produc-
tions, and other articles of a similar description belonging to the Society ; he
shall take an account of these when received, and keep a regular catalogue of
the whole, which shall lie in the Hall, for the inspection of the Fellows.
XXVI.
All Articles of the above description shall be open to the inspection of the
Fellows at the Hall of the Society, at such times and under such regulations,
as the Council from time to time shall appoint.
XXVIT.
A Register shall be kept, in which the names of the Fellows shall be
enrolled at their admission, with the date.
Auditor.
General Secretary’s
Duties.
Secretaries to
Ordinary Meetings.
Curator of Museum
and Library.
Use of Museum
and Library.
Register Book.
( 660 )
THE KEITH, BRISBANE, AND NEILL PRIZES.
The above Prizes will be awarded by the Council in the following manner :—
I. KEITH PRIZE.
The Keirn Prize, consisting of a Gold Medal and from £40 to £50 in
Money, will be awarded in the Session 1881-82 for the “best communication
on a scientific subject, communicated, in the first instance, to the Royal Society
during the Sessions 1879-80 and 1880-81.” Preference will be given to a
paper containing a discovery.
II. MAKDOUGALL-BRISBANE PRIZE.
This Prize is to be awarded biennially by the Council of the Royal Society
of Edinburgh to such person, for such purposes, for such objects, and in such
manner as shall appear to them the most conducive to the promotion of the
interests of science ; with the proviso that the Council shall not be compelled
to award the Prize unless there shall be some individual engaged in scientific
pursuit, or some paper written on a scientific subject, or some discovery in
science made during the biennial period, of sufficient merit or importance in
the opinion of the Council to be entitled to the Prize.
1. The Prize, consisting of a Gold Medal and a sum of Money, will be
awarded at the commencement of the Session 1882-83, for an Essay or Paper
having reference to any branch of scientific inquiry, whether Material or
Mental.
2. Competing Essays to be addressed to the Secretary of the Society, and
transmitted not later than 1st June 1882.
3. The Competition is open to all men of science.
APPENDIX.—KEITH, MAKDOUGALL-BRISBANE, AND NEILL PRIZES. 661
4. The Essays may be either anonymous or otherwise. In the former case,
they must be distinguished by mottoes, with corresponding sealed billets, super-
scribed with the same motto, and containing the name of the Author,
5. The Council impose no restriction as to the length of the Essays, which
may be, at the discretion of the Council, read at the Ordinary Meetings of the
Society. They wish also to leave the property and free disposal of the manu-
scripts to the Authors; a copy, however, being deposited in the Archives of
the Society, unless the paper shall be published in the Transactions.
6. In awarding the Prize, the Council will also take into consideration any
scientific papers presented to the Society during the Sessions 1882-83 and
1883-84, whether they may have been given in with a view to the prize or not.
iI. NEILL PRIZE.
The Council of the Royal Society of Edinburgh having received the bequest
of the late Dr Patrick Neri of the sum of £500, for the purpose of “the
interest thereof being applied in furnishing a’ Medal or other reward every
second or third year to any distinguished Scottish Naturalist, according as such
Medal or reward shail be voted by the Council of the said Society,” hereby
intimate,
1. The Neti Prize, consisting of a Gold Medal and a sum of Money, will
be awarded during the Session 1883-84.
2. The Prize will be given for a Paper of distinguished merit, on a subject
of Natural History, by a Scottish Naturalist, which shall have been presented
to the Society during the three years preceding the Ist May 1883,—or failing
presentation of a paper sufficiently meritorious, it will be awarded for a work
or publication by some distinguished Scottish Naturalist, on some branch of
Natural History, bearing date within five years of the time of award.
VOL. XXX, PART TV. 5M
( 662 )
AWARDS OF THE KEITH, MAKDOUGALL-BRISBANE, AND NEILL PRIZES,
FROM 1827 TO 1879.
IJ. KEITH PRIZE.
lst Brenn1au Periop, 1827—29.—Dr Brewster, for his papers “on his Discovery of Two New Immis-
cible Fluids in the Cavities of certain Minerals,” published in
the Transactions of the Society.
2np Brenniat Pertop, 1829-31.—Dr Brewster, for his paper “fon a New Analysis of Solar
Light,” published in the Transactions of the Society.
3rD Bienniau Periop, 1831—-33.—THomas Grauam, Esq., for his paper “on the Law of the Diffusion
of Gases,” published in the Transactions of the Society.
47H Biennial Peniop, 1833-—35.—Professor J. D. Forsss, for his paper “ on the Refraction and Polari-
zation of Heat,” published in the Transactions of the Society.
57H Brennrau Periop, 1835-37.—Joun Scorr Russet, Esq.,for his Researches “on Hydrodynamics,”
published in the Transactions of the Society.
67TH Brennrat Periop, 1837-39.—Mr Jonun Suaw, for his experiments “on the Development and
Growth of the Salmon,” published in the Transactions of the
Society.
7TH Brpnntat Periop, 1839—41.—Not awarded.
87H Brennrat Periop, 1841-43.—Professor James Davip Forbes, for his Papers “on Glaciers,”
published in the Proceedings of the Society.
9TH Brenniat Parton, 1843-45.—Not awarded.
107TH Brennraut Periop, 1845-47.—General Sir Tuomas BrisBane, Bart., for the Makerstoun Observa-
tions on Magnetic Phenomena, made at his expense, and
published in the Transactions of the Society.
lira Brennrau Perrop, 1847—49.—Not awarded.
127TH BrenniaL Periop, 1849-51.—Professor Ketuanp, for his papers “on General Differentiation,
including his more recent communication on a process of the
Differential Calculus, and its application to the solution of
certain Differential Equations,” published in the Transactions
of the Society.
137H BrenniaL Periop, 1851-53.—W. J. Macquorn Ranxrne, Esq., for his series of papers “ on the
Mechanical Action of Heat,” published in the Transactions
of the Society.
147 Brenntau Periop, 1853-55;—Dr Tuomas Anpmrson, for his papers “on the Crystalline Con-
stituents of Opium, and on the Products of the Destructive
Distillation of Animal Substances,” published in the Trans-
actions of the Society.
15TH BrenntaL Periop, 1855-57,—Professor Boots, for his Memoir “ on the Application of the Theory
of Probabilities to Questions of the Combination of Testimonies
and Judgments,” published in the Transactions of the Society,
16TH BrENNrIAL Periop, 1857—59.—Not awarded.
177H Brenniat Perron, 1859-61.—Jonn Atuan Broun, Esq., F.R.S., Director of the Trevandrum
Observatory, for his papers “on the Horizontal Force of the
Earth’s Magnetism, on the Correction of the Bifilar Magnet-
ometer, and on Terrestrial Magnetism generally,” published in
the Transactions of the Society.
APPENDIX.—KEITH, MAKDOUGALL-BRISBANE, AND NEILL PRIZES. 663
18TH Brenniat Pertop, 1861—63.—Professor Witt1am THomson, of the University of Glasgow, for his
Communication “on some Kinematical and Dynamical
Theorems.”
197H Brenntat Periop, 1863—65.—Principal Forsus, St Andrews, for his “Experimental Inquiry into
the Laws of Conduction of Heat in Iron Bars,” published in
the Transactions of the Society,
20TH BrenniaL Periop, 1865—67.—Professor C. Prazzt Smyrg, for his paper “on Recent Measures at
the Great Pyramid,’ published in the Transactions of the
Society.
21st Brenniat Pertop, 1867—69.—Professor P. G. Tart, for his paper “on the Rotation of a Rigid
Body about a Fixed Point,” published in the Transactions of
the Society.
22ND BrenntaL Periop, 1869—71.—Professor Crerk Maxwett, for his paper “on Figures, Frames,
and Diagrams of Forces,’ published in the Transactions of the
Society.
23rp BrenntaL Perron, 1871—73.—Professor P. G. Tair for his paper entitled “ First Approximation
to a Thermo-electric Diagram,” published in the Transactions
of the Society.
247H BIENNIAL PeRiop, 1873—75.—Professor Crum Brown, for his Researches “ on the sense of Rota-
tion, and on the Anatomical Relations of the Semicireular
Canals of the Internal Ear.”
25TH Brenniau Periop, 1875-77.—Professor M. Forster Heppis, for his papers “on the Rhom-
bohedral Carbonates,’ and “on the Felspars of Scotland,’’
published in the Transactions of the Society.
26TH Brennrau Periop, 1877—79.—Professor H. C. Frermine Jenkin, for his paper “on the Appli-
cation of Graphie Methods to the Determination of the Effi-
cieney of Machinery,” published in the Transactions of the
Society; Part IT. having appeared in the volume for 1877-78.
277H Brenniat Pertop, 1879—81.—Professor Grorcn Curystat, for his paper “on the Differential
Telephone,” published in the Transactions of the Society.
28TH Brenniat Pertop, 1881—-83.—Tusomas Muir, Esq., LL.D., for his “ Researches into the Theory
of Determinants and Continued Fractions,” published in the
Proceedings of the Society.
Il. MAKDOUGALL-BRISBANE PRIZE.
Ist BreyniaL Periop, 1859,—Sir Roprricx Impry Murcuison, on account of his Contributions to
the Geology of Scotland.
2npD Brenniat Periop, 1860—62.—Winiiam Sevier, M.D., F.R.C.P.E., for his ‘‘ Memoir of the Life
and Writings of Dr Robert Whytt,” published in the Trans-
actions of the Society.
3RD BIENNIAL Periop, 1862-—64.—Jonn Dunts Macponaxp, Esq., R.N., F.R.S., Surgeon of H.M.S.
“Tearus,” for his paper “on the Representative Relationships
of the Fixed and Free Tunicata, regarded as Two Sub-classes
of equivalent value; with some General Remarks on their
Morphology,” published in the Transactions of the Society.
4¢H Brenntat Perron, 1864—66.—Not awarded.
57H Brenniau Pertop, 1866-68.—Dr Atrxanper Crum Brown and Dr Taomas Ricnarp Fraser,
for their conjoint paper “on the Connection between
Chemical Constitution and Physiological Action,” published
in the Transactions of the Society.
6TH BrenntAt Periop, 1868—70.—Not awarded.
664. APPENDIX.—KEITH, MAKDOUGALL-BRISBANE, AND NEILL PRIZES.
Tru Brennrau Pertop, 1870—72.—Grorcet James ALtMAN, M.D., F.R.S., Emeritus Professor of Natural
History, for his paper “on the Homological Relations of the
Ceelenterata,” published in the Transactions, which forms a
leading chapter of his Monograph of Gymnoblastic or Tubu-
larian Hydroids—since published.
8TH Brenniat Periop, 1872—-74.—Professor Listrr, for his paper “fon the Germ Theory of Putre-
faction and the Fermentive Changes,” communicated to the
Society, 7th April 1873.
Orn Brenntat Periop, 1874—76.—Atexanprr Bucnay, A. M., for his paper “on the Diurnal Oscillation
of the Barometer,’ published in the Transactions of the Society.
107 BienntAL Periop, 1876—78.—Professor ArcHiBALD Gerkig, for his paper “on the Old Red
Sandstone of Western Europe,” published in the Transactions
of the Society.
1]ra Brenniat Periop, 1878—80.—Professor Piazz1 Smytun, Astronomer-Royal for Scotland, for his
paper “fon the Solar Spectrum in 1877-78, with some
Practical Idea of its probable Temperature of Origination,”
published in the Transactions of the Society.
127H Brenniat Perrop, 1880—82.— Professor James Gerrxin, for his “ Contributions to the Geology of
the North-West of Europe,” including his paper “on the
Geology of the Farées,” published in the Transactions of the
Society.
It. THE NEILL PRIZE.
1st Trrennrau Periop, 1856-59.—Dr W. Lauper Linpsay, for his paper “ on the Spermogones and
Pycnides of Filamentous, Fruticulose, and Foliaceous Lichens,”
published in the Transactions of the Society.
2np TRIENNIAL Pertop, 1859-62.—Ropert Kay Grevitie, LL.D., for his Contributions to Scottish
Natural History, more especially in the department of Cryp-
togamic Botany, including his recent papers on Diatomacez.
3RD TRIBNNIAL Periop, 1862—65.—Anprew Crompiz Ramsay, F.R.S., Professor of Geology in the
Government School of Mines, and Local Director of the
Geological Survey of Great Britain, for his various works and
Memoirs published during the last five years, in which he
has applied the large experience acquired by him in the
Direction of the ardous work of the Geographical Survey of
Great Britain to the elucidation of important questions bear-
ing on Geological Science.
47H Trienntat Pertop, 1865-68.—Dr Witt1am Carmicuart M‘Intosu, for his paper “on the Struc-
ture of the British Nemerteans, and on some New British
Annelids,” published in the Transactions of the Society.
57TH TrienNIAL Periop, 1868--71.—Professor Witt1am Turner, for his papers “on the great Finner
Whale ; and on the Gravid Uterus, and the Arrangement of
the Foetal Membranes in the Cetacea,’ published in the
Transactions of the Society. 7
6TH TRIENNIAL Periov, 1871—74.—Cuartes Witti1AM Praca, for his Contributions to Scottish Zoology
and Geology, and for his recent contributions to Fossil Botany.
77H TRIENNIAL Periop, 1874—77.—Dr Ramsay H. Traquair, for his paper “on the Structure and
Affinities of Tvistichopterus alatus (Egerton),” published in
the Transactions of the Society, and also for his contributions
to the Knowledge of the Structure of Recent and Fossil Fishes.
8TH TrimnniaL Pertop, 1877-80.—Joun Murray, for his paper “on the Structure and Origin of
Coral Reefs and Islands,” published (in abstract) in the
Proceedings of the Society.
97TH TRIENNIAL Peron, 1880—83,—Professor Hurpman, for his papers “on the Tunicata,” published
in the Proceedings and Transactions of the Society.
PROCEEDINGS
OF THE
STATUTORY GENERAL MEETINGS,
AND
LIST OF MEMBERS ELECTED AT THE ORDINARY MEETINGS
FROM NOVEMBER 1881 TO NOVEMBER 1882,
i
+
m -«£
fa
ry cr
vEvi
P > 7
CVesunit
SUN
TAT
( 667 )
STATUTORY MEETINGS.
NINETY-NINTH SESSION.
Monday, 28th November 1881.
At a Statutory Meeting, Professor MAcLAGAN, Vice-President, in the Chair, the Minutes of
last General Statutory Meeting of 22nd November 1880 were read, approved, and signed.
The Ballot for the new Council was then taken, Messrs TENNANT and MAccULLOCH being
requested to act as Scrutineers. The following Council was elected :—
The Right Hon. Lorp Moncrzirr, President.
Davin Minne Home, LL.D.
Sir C. Wyvitte THomson, LL.D.
Professor Dovetas Mactaean, M.D.
Professor H. C, Firemine JENKIN, F.R.S.
Rey. W. Linpsay ALExanper, D.D.
J. H. Batrour, M.D., F.R.S.
Professor Tait, General Secretary,
Vice-Presidents.,
Professor TurnER, F.R.S.
Professor Crum Brown, F.R.S.
Apam Gruss Samira, C.A., Treasurer.
ALEXANDER Bucuan, M.A., Curator of Library and Museum.
\ Scoretaries to Ordinary Meetings.
COUNCILLORS.
Professor CAMPBELL FRASER, Professor A. Dickson.
Professor GErk14, F.R.S, The Right Rey. Bisnop Correritt.
Rey. Dr CazEnove. The Rey. Professor Duns.
Davin STEVENSON. Dr Ramsay Traquair, F.R.S.
Professor CHRYSTAL. JouHn Murray,
Sheriff Forsss Irvine, of Drum. Wit1am Ferevson, of Kinmundy.
The TREASURER’S Accounts were submitted and approved,
On the motion of Professor Tart, seconded by Mr Maccuttocn, the Auditor was re-
appointed.
Professor CRUM BROWN gave notice of the following motion for alteration of a part of the
Laws, viz., To change in Law XIV. the words “ November to June” into “ December to July.”
668 APPENDIX.—PROCEEDINGS OF STATUTORY MEETINGS.
HUNDREDTH SESSION.
Monday, 27th November 1882.
At a Statutory Meeting, Professor MACLAGAN, Vice-President, in the Chair, the Minutes of
last General Statutory Meeting of 28th November 1881 were read, approved, and signed.
The Ballot for the new Council was then taken, Professor SwAN and Professor DIcKsON
being requested to act as Scrutineers. The following Council was elected :—
The Right Hon. Lorp Moncrerrr, President.
Professor Dovetas Mactacan, M.D.
Professor H. C. Fizemine Jenin, F.R.S.
The Rey. W. Linpsay ALExanpeER, D.D.
J. H. Batrour, M.D.
Tuomas Stevenson, M. Inst. C.E.
Rogert Gray, Sec. Roy. Phys. Soc.
Professor Tart, M.A., General Secretary.
Professor TuRNER, F.R.S.
Professor Crum Brown, F.R.S.,
Apam Gitties Suitu, C.A., Treasurer.
ALEXANDER Bucuan, M.A., Curator of Library and Museum.
Vice-Presidents.
| Secretaries to Ordinary Meetings.
COUNCILLORS.
Professor GrorcE Curystat, M.A. Wi1aM Frereuson, of Kinmundy.
ALEXANDER Forbes Irving, of Drum. Professor James Cossar Ewart, M.D.
Professor AtexanDER Dickson, M.D. Professor James Gurxre, F.R.S.
The Right Rev. Bisnor Correrim, D.D. Professor WiLL1AM Robertson SMITH,
The Rey. Professor Duns. LL.D.
Ramsay H. Traquair, M.D., F.R.S. Starr A, Aanew, M.A.
Joun Murray, Director of “ Challenger”
Comniission.
Read Letter from the Treasurer apologising for absence on account of illness, and explain-
ing the apparent surplus shown by the Financial Statement.
The Auditor’s Report on the Treasurer’s Accounts was read and approved.
On the motion of Dr Crum Brown, the Auditor was reappointed.
( 669 )
The following Public Institutions and Individuals are entitled to receive Copies of
the Transactions and Proceedings of the Royal Society of Edinburgh :—
London, British Museum.
Royal Society,
London.
Anthropological Institute of Great Bri-
tain and Ireland, 3 Hanover Square,
Burlington House,
London.
British Association for the Advancement
of Science, 22 Albemarle Street,
London.
Society of Antiquaries, Burlington
House.
Royal Astronomical Society, Burlington
House.
Royal Asiatic Society, 22 Albemarle
Street.
Society of Arts, John Street, Adelphi.
Atheneum Club.
Chemical Society, Burlington House.
Institution of Civil Engineers, 25 Great
George Street.
Royal Geographical Society, Burlington
Gardens.
Geological Society, Burlington House.
Royal Horticultural Society, South Ken-
sington.
Hydrographic Office, Admiralty.
Royal Institution, Albemarle Street, W.
Linnean Society, Burlington House.
Royal Society of Literature, 4 St Mar-
tin’s Place.
Medical and Chirurgical Society, 53
Berners Street, Oxford Street.
Royal Microscopical Society, King’s
College.
Museum of Economic Geology, Jermyn
Street.
Royal Observatory, Greenwich.
Pathological Society, 53 Berners Street.
Statistical Society, 9 Adelphi Terrace,
Strand, London.
Royal College of Surgeons of England,
40 Lincoln’s Inn Fields,
VOL. XXX. PART IV.
London, United Service Institution, Whitehall
Yard.
University College, Gower Street,
London.
Zoological Society, 11 Hanover Square.
The Editor of Nature, 29 Bedford
Street, Covent Garden.
The Editor of the Electrician, 396
Strand.
Cambridge Philosophical Society.
University Library.
Historic Society of Lancashire and Cheshire.
Leeds Philosophical and Literary Society.
Manchester Literary and Philosophical Society.
Oxford, Bodleian Library.
Yorkshire Philosophical Society.
SCOTLAND.
Edinburgh, Advocates Library.
University Library.
College of Physicians.
Highland and Agricultural Society.
Royal Medical Society, 7 Melbourne
Place, Edinburgh.
Royal Physical Society, 40 Castle
Street.
Royal Scottish Society of Arts, 117
George Street.
Royal Botanic Garden, Inverleith
Row.
Aberdeen, University Library.
Dundee, University College Library.
Glasgow, University Library.
Philosophical Society, 207 Bath Street.
St Andrews, University Library.
IRELAND.
Royal Dublin Society.
Royal Irish Academy, 19 Dawson Street,
Dublin.
Library of Trinity College, Dublin.
5N
670 APPENDIX.
COLONIES, DEPENDENCIES, &c.
Bombay, Royal Asiatic Society.
Calcutta, Asiatic Society of Bengal.
Madras, Literary Society.
Canada, Library of Geological Survey.
Queen’s University, Kingston.
Montreal, Royal Society of Canada.
Quebec, Literary and Philosophical
Society.
Toronto, Literary and Historical Society.
Ne The Canadian Institute.
Cape of Good Hope, The Observatory.
Melbourne, University Library,
Sydney, University Library.
Linnean Society of New South Wales.
Royal Society of New South Wales.
Wellington, New Zealand Institute.
CONTINENT OF EUROPE.
Amsterdam, De Koninklijke Akademie van We-
tenschappen
: Koninklijk Zoologisch Genootschap.
Basle, Die Schweizerische Naturforschende Gesell-
schaft.
Bergen, Museum.
Berlin, Kénigliche Akademie der Wissenschaften,
Physicalische Gessellschaft.
Bern, Allgemeine Schweizerische Gesellschaft fiir
die gesammten Naturwissenschaften.
Bologna, Accademia delle Scienze dell’ Istituto.
Bordeaux, Société des Sciences Physiques et
Naturelles.
Brussels, Académie Royale des Sciences, des Let-
tres et des Beaux-arts.
L’Observatoire Royal.
La Société Scientifique.
Bucharest, Academia Romana.
Buda, A Magyar Tudés Tarsasag—Die Ungarische
Akademie der Wissenschaften.
... Konigliche Ungarische Naturwissenschaft-
lische Gesellschaft.
Catania, Accademia Gioenia di Scienze Naturali.
Christiania, University Library.
Meteorological Institute.
Coimbra, University Library.
Copenhagen, Royal Academy of Sciences,
Danzig, Naturforschende Gesellschaft
Dorpat, University Library.
Ekatherinebourg, LaSociétéOuralienned’Amateurs
des Sciences Naturelles,
Erlangen, University Library.
Frankfurt-am-Main, Senckenbergische Naturfor-
schende Gesellschaft.
Geneva, Société de Physique et d’ Histoire
Naturelle,
Genoa, Museo Civico di Storia Naturale
Giessen, University Library.
Gottingen, Konigliche Gesellschaft der Wissen-
schaften.
Graz, Naturwissenschaftlicher Verein fiir Steier-
mark
Haarlem, Société Hollandaise des Sciences
Exactes et Naturelles.
Musée Teyler,
Kaiserliche Leopoldino - Carolinische
deutsche Akademie der Naturforscher.
Halle, Naturforschende Gesellschaft,
Helsingfors, Sallskapet pro Fauna et Flora
Fennica.
Halle,
Societas Scientiarum Fennica (Société
des Sciences de Finlande).
Jena, Medicinisch-Naturwissenschaftliche Gesell-
schaft,
Kasan, University Library,
Kiel, University Library.
Ministerial-Kommission zur Untersuchung
der Deutschen Meere.
Kiev, University of St Vladimir.
Leyden, Tijdschrift der Neerlandsch Dierkundige
Vereeniging
The University Library.
Leipzig, Prof. Wiedemann, Konigliche Siichsische
Akademie.
Lille, Société des Sciences,
Lisbon, Academia Real das Sciencias de Lisboa.
Sociedade de Geographia.
Louvain, University Library.
Lucca, M. Michelotti.
Lund, University Library.
Lyons, Académie des Sciences, Belles Lettres et
Arts.
Musée Guimet.
Société d’Agriculture.
Madrid, Real Academia de Ciencias,
Comision del Mapa Geologico de Espafia.
APPENDIX. | 671
Milan, Reale Istituto Lomhardo di Scienze, Lettere,
ed
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672
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674 APPENDIX.
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( 26R5u1)
INDEX TO
VOL. XXX.
Acanthocaris, 511.
Acanthodes, 18.
Adiantites, 540.
Aitken (Jon), F.R.S.E. On Dust, Fogs, and
Clouds, 337.
Alethopteridew, 547.
Anthrapalemon (Fossil), 75, 512.
Arachnida of the Carboniferous Rocks of the Scottish
Border. By B. N. Pracu, F.R.S.E. Order
Merosomata, Glyptoscorpius, gen. nov., 516.
Genus Prestwichia, 525. Genus Cyclus, 526.
Archachthys, 18.
Asteroidea, a new Genus of (Mimaster).
Prroy Siapen, 579,
B
Batrour (Professor Baytey), F.R.S.E. On the
Dragon’s Blood of Socotra, Dracena Cinna-
bari, 619.
Bepparp (Frank E.), F.R.S.E., and GEppEs
(Patrick), F.R.S.E. On the Histology of the
Pedicellariea, and the Muscles of Echinus
sphera (Forbes), 383.
On the Anatomy and Histology of Plewro-
cheeta Moseleyt, 481.
Betaines, See Phosphorus-Betaines.
Bythotrephis, A Fossil Alga, 534.
C
Canonbie, Fossil Plants of.
Calamites, 547.
Canobius, 46, 68.
Cardiocarpus, 545.
Caulopteris, 541.
Cells, The Vegetable Cell. By J. M. Macrar-
LANE, 585. The Endonucleolus, 589. The
Nucleolus, 589. Nucleus. 590. Protoplasm,
cell wall, 591. Multinucleolar and multinu-
clear state, 591.
By W.
See Fossil Plants.
Ceratiocaris scorpioides, 73.
Cheirodopsis, 56.
Chlorine, its Solubility in Water and in Aqueous
Solutions of Soluble Chlorides. By Wituam
Lawton Goopwin, B.Sc., 597.
Chondrites, 532, 548.
Chromite, 460.
Chromium, Ores of (Mineralogy of Scotland). By
Professor Huppie, 456.
CurystaL (Professor), F.R.S.E. Note on Mr
THomas Mutir’s Transformation of a Deter-
minant into a Continuant, 13.
On a Special Class of Sturmians, 161.
Clouds. By Joun ArrKen, F.R.S.E., 337.
Coclacanthus, 20.
Cotte (N.) and Lerrs (Professor), F.R.S.E. On
the Action of Phosphide of Sodium on Haloid
Ethers and on the Salts of Tetrabenzyl-Phos-
phonium, 181.
Complementaries in Determinants, The Law of.
By Tsomas Murr, F.R.S.E. If the Comple-
mentary of (A) with respect to a certain Deter-
minant be (B), its Complementary with respect
to a Determinant of a higher order is the
Extensional of (B), 4.
Continuants. On some Transformations connecting
General Determinants with Continuants. By
Toomas Muir, F.R.S.E., 5. Note on Mr
Mutr’s Transformation of a Determinant into a
Continuant. By Professor Curystat, F.R.S.E.,
13.
Cordaites (Fossil), 544.
Crossochorda. A Fossil Alga, 533,
Crustaceans. Some new Crustaceans from the Lower
Carboniferous Rocks of Eskdale and Liddes-
dale. By B. N. Psacu, F.RB.S.E.
carts scorpioides, nov. spec., 73.
elongatus, nov, spec, 74.
Etheridgii, nov. spec., 76.
Ceratio-
Ceratiocaris
Anthrapalemon
Anthrapalemon
676
INDEX.
Parki, nov. spec., 78. Anthrapalemon Tra- | Elongation (Permanent), its Effect on the Specific
quairii, nov. spec., 80. Anthrapalemon Mac-
oonnochii, 82. Anthrapalemon formosus, nov.
spec., 83. Paleocrangon LEskdalensis, nov.
spec., 84. Paleocaris Scoticus, nov. spec., 85.
Crustacea of the Carboniferous Rocks of the Scottish
Border. By B. N. Peaon, F.R.S.E. Order
I. Phyllopoda, Acanthocaris, gen. nov., 511.
Order II. Decapoda. Genus Anthrapalemon,
512. Genus Pseudo-Galathea, gen. nov., 513.
Genus Paleocaris, 515.
Resistance of Metallic Wires, 369.
Eoscorpius. See Scorpions.
Equisetaceee (Fossil), 542, 547.
Eremopteris, 540.
Eskdale and Liddesdale, Fossil Fishes of, collected
by the Geological Survey of Scotland. See
Fossil Fishes.
Fossil Plants of Eskdale and Liddesdale. See
Fossil Plants.
Hurynotus, 54.
Curves whose Intersections give the Imaginary Roots | Eurypterida, 516.
of an Algebraic Equation. By Tuomas Bonp
Sprague, F.R.S.E., 467.
Cycloptychius concentricus, 37.
Cyclus, 526.
D
Decapoda (Fossil), 512.
Determinants, The Law of Extensible Minors in,
1, 2. The Law of Complementaries, 1,2, On
some Transformations connecting General De-
terminants with .Continuants, 5. Note on Mr
Murr’s Transformation of a Determinant into a
Continuant. By Professor CurystaL, F.R.S.E.,
13.
Dosstz (J. J.), D.Se., and G. G. Henperson, B.Sc.
On a Red Resin from Dracena Cinnabari, 624,
Dracena Cinnabari (Balf. jil.). On the Dragon’s
Blood of the Socotra, Dracena Cinnabari. By
Professor BayLtry Baurour, F.R.S.E., 619.
— Chemical Examination of a Red Resin from
Dracena Cinnabaria. By J.J. Dossts, D.Sc.,
and G. G. Henperson, B.Sc., 624.
Dust, Fogs, and Clouds. By Joun ArrKen, F.R.S8.E.,
337. 1. When water vapour condenses in the
atmosphere, it always does so on some solid
nucleus. 2. Dust particles form the nuclei on
which it condenses. 3. If there were no dust
there would be no fogs, no clouds, and probably
no rain, 342.
E
Echinus sphera (Forbes), The Muscles of. By
Patrick Gerpprs, F.R.S.E., and Frank E.
Bepparp, F.R.S.E., 383.
Electric Conductivity, The Effect of Strain on.
Aveust WitrkowskI, 413.
Electricity. Researches in Contact Electricity. By
Carcitt G. Knorr, D.Sc., F.R.S.E., 271.
—— Effects of Strain on Electric Conductivity.
By Aveust WirKowskl, 413.
Llonichthys, 22.
By
F
Feroe Islands, The Geology of. By Jamus GrIxin,
LL.D., F.R.S.E., 217. I. Introduction, 218,
II. Physical Features of the Islands, 220. III.
Geological Structure of the Islands, 223. IV.
Thickness of the Strata: Conditions under
which they were Amassed, 237. V. Glacial
Phenomena of the Islands, 243. VI. Origin
of the Valleys and Fiords: Subaerial and
Glacial Erosion, 253. VII. Marine Erosion,
263. VIII. Peat and Buried Trees, 266.
Filicacew, 535, 546.
Fogs and Clouds. By Joun ArrKen, F.R.S.E., 337.
Fossil Fishes collected by the Geological Survey of
Scotland in Eskdale and Liddesdale. Part I.
Ganoidei. By Ramsay H. Traquair, M.D.,
15. List of Genera and species collected, 16.
Out of twenty-eight species at least twenty are
new. Of fourteen genera five are new, 17.
See Ganoidet.
Fossil Plants of Eskdale, Liddesdale, and Canonbie.
By Roxsert Kinston, 531. Thallophyta, Atcx
(Chondrites, Crossochorda, Bythotrephis), 532.
Filicaceze (Sphenopteridez), 535, 546. Pale-
opteridee, 540. Neuropteridew, 541, 547.
Stipes Filicinz, 541. Equisetacee, 542, 547.
Lycopodiacez, 543,548. Fruits, Cardiocarpus
and Schutzia, 545. Alethopteridee, 547.
Pecopteridez, 547.
Fossil Scorpions, Some new Species of, from the
Carboniferous. Rocks of Scotland and the
English Borders. By B. N. Praca, F.R.S.E.,
397.
G
Ganoidei found among Fossil Fishes, collected by
the Geological Survey in Eskdale and Liddes-
dale, 15. By Dr R. H. Traquair. New
Genera and Species, 16, 17. Genus Acan-
thodes, 18. Genus Strepsodus, 18. Genus
INDEX.
Genus Megalichthys
Genus Ccelacanthus,
Genus Rhadi-
Archichthys, 18.
(Saurodepteride), 20.
20. Genus Elonichthys, 22.
nichthys, 25. Genus Cycloptychius, 37.
Phanerosteon, gen. nov., 39. Holurus, gen.
nov., 43, 66. Canobius, gen. nov., 46, 68.
Wardichthys, 55. Cheiro-
Platysomus, 58. Tar-
Eurynotus, 54.
dopsis, gen. nov., 56.
rarius, gen. nov., 61.
Gaseous Spectra. See Spectra.
GeEpprs (Patrick), F.R.S.E., and Bepparp (FRANK),
FE.R.S.E. On the Histology of the Pedicellariz
and the Muscles of Echinus sphera (FORBES),
383.
Geixiz (James), LL.D., F.R.S.L. and E. On the
Geology of the Feroe Islands, 217. See
Feroe Islands.
Glyptoscorpius, 516.
Goopwin (Wit14m Lawton), B.Sc. On the Nature
of Solution. Part I—On the Solubility of
Chlorine in Water and in Aqueous Solutions
of Soluble Chlorides, 597.
Gothite (Mineralogy of Scotland).
Hepptie, F.R.S.E., 462.
Gray (THomas), B.Sc. The Effect of Permanent
Elongation on the Specific Resistance of
Metallic Wires, 369.
H
HeEpDLE (Professor), F.R.S.E. Chapters on the
Mineralogy of Scotland. Chap. VII.—Ores of
Manganese, Iron, Chromium, and Titanium, 427.
Henperson (G. G.), B.Se., and J. J. Dossin, D.Se.
On a Red Resin from Draceena Cinnabarri, 624.
Herscuet (Professor Anex. §.). Magnificent
Features exhibited by End-on Views of Gas-
Spectra under High Dispersion, 150.
Holurus, 48, 66.
By Professor
I
Ilmenite, 438.
Imaginary Roots. Nature of the Curves whose
Intersections give the Imaginary Roots of
an Algebraic Equation. By Tuomas Bonp
Sprague, F.R.S.E., 467.
Tron, Ores of (Mineralogy of Scotland).
fessor Hrppiz, F.R.S.E., 435, 437.
Iron Sand, 446.
Tserine, 446.
By Pro-
K
Kipston (Rozert). Report on Fossil Plants, col-
lected by the Geological Survey in Eskdale and
Liddesdale, 531.
VOL, XXX. PART IV.
677
Knorr (Carat G.), D.Sc. Researches iu Contact
Electricity, 271.
L
Lepidodendron (Fossil), 543, 548.
Lepidophyllum (Fossil), 544, 548.
Lepidostrobus, 543, 548.
Letts (Professor), F.R.S.E., and Mr N. Cotuin.
On the Action of Phosphide of Sodium on
Haloid Ethers and on the Salts of Tetrabenzyl-
Phosphonium, 181.
Lerrs (Professor), F.R.S.E. On Phosphorus
Betaines, 285. See Phosphorus-Betaines.
Liddesdale and Eskdale, Fossil Fishes of, collected
by the Geological Survey of Scotland. See
Lossil Fishes.
, Fossil Plants of. See Fossil Plants.
Lycopodiaceee (Fossil), 543, 548.
M
Macrartane (J. M.). Observations on Vegetable
and Animal Cells; their Structure, Division,
and History, 585.
Magnetite, 452. Chromiferous Magnetites (Miner-
alogy of Scotland). By Professor HEppDLE,
F.R.S.E., 456.
Manganese, Ores of (Mineralogy of Scotland).
Professor Huppin, F.R.S.E., 427.
Martite (Mineralogy of Scotland). By Professor
Hepvte, F.R.S.E., 437.
Mazonia Woodiana, of Munk and WortuHen, 408.
Megalichthys, 20.
Merosomata, 516.
By
Mimaster. A new Genus of Asteroidea from the
Feroe Channel. By W. Percy Swapen,
579.
Mineralogy of Scotland. Chap. VII.—Ores of
Manganese, Iron, Chromium, and Titanium.
By Professor Heppie, F.R.S.E., 427.
Minors (Extensible) in Determinants, The Law of.
By Tuomas Moir, F.R.S.E., 1, 2.
Mirage. By Professor Tart, 551.
Morir (THomas), F.R.S.E. The Law of Extensible
Minors in Determinants, 1. The Law of
Complementaries in Determinants, 1, 2. On
some Transformations connecting General
Determinants with Continuants, 5.
N
Neuropteridece, 541.
Nucleolus of Vegetable Cell, 599.
Nucleus of Vegetable Cell, 590.
5 @
678
O
Oxygen, Spectrum of. By Prazzi Sayru, F.R.S.E.,
Astronomer-Royal for Scotland. On the Con-
stitution of the Lines forming the Low-
Temperature Spectrum of Oxygen, 419.
Oxygen in the Sun, 422. Oxygen of the
Earth’s Atmosphere in the Tellurie Solar
Spectrum, 423.
E
Paleocaris, 85, 515.
Paleocrangon, 84, 515.
Palceopteridee, 540.
Pracu (B. N.), F.R.S.E. On some new Crustaceans
from the Lower Carboniferous Rocks of Esk-
dale and Liddesdale, 73. ~~
— Further Researches amore Mie womiiere and
Ayraconida of the Carboniferous Rocks of the
Scottish Border, 511.
Pecopteridex, 547.
Pedicellarie, The Histology of. By Patrick GEDDES,
F.R.S.E., and Frank E. Bepparp, F.R.S.E.
383.
Phanerosteon, 39.
Phosphines, Prepared from Phosphide of Sodium,
189. Phosphine products, — Tetrabenzyl-
Phosphonium: Chloride and its compounds,
191. Action of Heat on Salts of Tetrabenzyl-
Phosphonium, 213, Tribenzyl-Phosphine and
its compounds, 203. Preparation of, 211.
Action of Heat on, 215.
Phosphorus-Betaines. By Professor Lerts, F.R.S.E.
A comparison of the Properties of Nitrogen,
Phosphorus, and Sulphur, 285. Action of Chlor-
acetic Acid on Triethyl-Phosphine, 301. Hydro-
bromate of Triethyl-Phosphorus-Betaine, 304,
Hydriodate of Triethyl-Phosphorus-Betaine,
305, Hydrate of Triethyl-Phosphorus-Betaine,
306. Sulphate of Triethyl-Phosphorus-Betaine,
307. Chloroplatinate of Ethyl-Chlorate of
Triethyl-Phosphorus-Betaine, 308. Action of
Oxide of Silver on the Ethyl-Chlorate, 309.
Action of Heat on the Compounds of Triethyl-
Phosphorus-Betaines, 310, Action of Caustic
Potash on these Compounds, 318. Action of
Bromacetic Acid on Triethyl-Phosphine, 321.
Action of Hydrobromic Acid on Oxide of
Triethyl-Phosphine, 332.
Phyllopoda (Fossil), 511.
Platysomus superbus, 58.
Pleurochaeta Moseley’. By ¥. E. Bepparp, F.R.S.E.,
481. Its Tegumentary System, 483. Muscular
Coats, 484, Clitellum, 488. Peritoneal Mem-
INDEX.
brane, 489, Body Cavity, 490, Alimentary
Tract, 490. Circulatory system, 495. Nervous
system, 499. Generative system, 501. Cocoon
and Embryos, 504,
Pothocites, 548.
Prestwichia, 525.
Pseudo-Galathea, 513.
Psilomelane, 432.
Pycnophyllum, 544.
Pyrolusite, 427,
R
Racopteris Machaneki, 540.
Red Resin, from Dracena Cinnabari.
Rhacophyllum Lactuca, 540,
Rhadinichthys, 25, 34.
Rhizodopsis. On the Cranial Osteology of. By
Ramsay A. Traquair, M.D., F.R.S.E., 167.
Rhizodopsis sauroides, 169.
See Draccena.
8
Schutaia (Fossil), 545.
Scorpions. Some new Species of Fossil Scorpions.
By B. N. Peacu, F.R.S.E. oscorpius tuber-
culatus, n, sp., 398. Loscorpius glaber, n. sp.,
400. oscorpius euglyptus, nu. sp., 402. Ho-
scorpius inflatus, n. sp., 405. Genus Eoscorpius,
Merrx and Worruen, 408.
StapEen (W. Percy), F.L.S. Description of Mi-
master, a new Genus of Asteroidea from the
Feroe Channel, 579.
Smyta (Piazzt), F.R.S.E., Astronomer-Royal for
Scotland. Gaseous Spectra in Vacuum Tubes,
under small Dispersion, and at low Electric
Temperature. General Introduction, 93.
Practical commencement described, 96. On
the Tables of 20 Gas-Vacuum Tubes, 97 and
Appendix I. Examination of the Observed
Quantities,"and Elimination of Impurity Effects,
97, Search for New Lines and their Gaseous
Identifications, 99 and Appendix II, Standard
Tables of the Principal Gaseous Lines and
Bands, 99, Of Changes with Time and Use,
100. On Recent Observations in Belgium, 103.
On Professor A. S. Herscue’s Contribution of
Appendix ITI., 104.
Appendix I, Separate Tables of Observa-
tions of each of 20 Gases, pp. 105-
141. Appendix II. Tables of Gaseous
Impurities, pp. 142-149,
Socotra. See Dracena Cinnabari.
Solubility of Chlorine in Water, and in Aqueous
INDEX.
Solutions of Soluble Chlorine.
Lawton Goopwin, B.Sce., 597.
Solution, The Nature of. By Wiuturam Lawron
Goopwin, B.Sc., 597.
Spectra. Gaseous Spectra in Vacuum Tubes, under
small Dispersion and at low Electric Tempera-
ture. See SmyrH (Prazzi), F.R.S.E., and
Astronomer-Royal for Scotland, 93.
— Magnificent Features exhibited by End-on
Views of Gaseous Spectra under High Disper-
sion. By Professor ALEXANDER S, HERSCHEL,
M.A., 150,
—— On the Constitution of the Lines forming the
Low-Temperature Spectrum of Oxygen, and on
the Oxygen of the Earth’s Atmosphere in the
Telluric Solar Spectrum, By Priazzt Smytu,
F.R.S.E., Astronomer-Royal for Scotland, 419,
423,
Sphenopteridew, 535, 541, 546.
Spracusz (Tuomas Bonp), M.A., F.R.S.E On the
nature of the Curves whose Intersections gives
Imaginary Roots of an Algebraic Equation, 467.
Staphylopteris, 539, 546.
Stigmaria ficoides, 544.
Strepsodus, 18.
Sturmians, A special class of Sturmians,
fessor Corystat, F.R.S.E., 161.
Strain. Its effect on Electric Conductivity.
Aveust Witkowsk], 413.
By Witt1aM
By Pro-
By
679
T
Tair (Professor), Sec. R.S.E., on Mirage, 551.
Tarrasius, 61.
Tetrabenzyl-Phosphonium, 191.
Thallophyta (Fossil), 531.
Titanium, Ores of (Mineralogy of Scotland).
Professor Heppu, F.R.S.E., 427.
Traquair (Ramsay H.), M.D., F.R.S.E, Report on
Fossil Fishes collected by the Geological Survey
of Scotland in Eskdale and Liddesdale. Part I.
Ganoidei, 15-71. See Ganoidei Fossil Fishes,
TraquaiR (Ramsay H.), M.D., F.R.S.E. On the
Crannial Osteology of Rhizodopsis, 167.
Tribenzyl-Phosphine, 203, 211,
T'riethyl-Phosphine, 301, 321.
Triethyl-Phosphorus-Betaine, 304,
Turgite (Mineralogy of Scotland).
Heppie, F.R.S,E., 462.
By
By Professor
Vv
Volkmannia, 542.
W
Wardichthys Cyclosoma, 55,
Wires. The effect of Permanent Elongation on the
Specific Resistance of Metallic Wires, By
THomas Gray, B.Se., 369.
Witkowski (Aveust). Effects of Strain on Electric
Conductivity, 413.
98 JUN 1887
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