PROCEEDINGS OF THB AMERICAN ACADEMY OP AETS AND SCIENCESc NEW SERIES. Vol. X. WHOLE SERIES. Vol. XVIII. FROM MAY, 1882, TO MAY, 1883. SELECTED FROM THE RECORDS. BOSTON: UNIVERSITY PRESS: JOHN WILSON AND SON. 1883. 2 if ^' 7 CONTENTS. PAGE I. On certain Substances obtained from Turmeric. — II. Cur- cumin. By C. LoRiNG Jackson and A. E. Menke . 1 n. Observations of the Transit of Venus, December 5 and 6, 1882, 7nade at the Harvard College Observatory. By Ed- ward C. PiCKERlMG 15 ni. On certain substituted Acrylic and Propionic Acids. By C. F. Mabery and F. C. Robinson 41 IV. On the Products of the Dry Distillation of Wood at low Tem- peratures. By Charles F. Mabery 47 V. A simple method of Correcting the Weight of a body for the buoyancy of the Atmosphere ivhen the Volum-j is unknown. By JosiAH Parsons Cooke 55 VI. On the Vapor Density of the Chloride, the Bromide, and the Iodide of Antimony. By C. P. Worcester, A. B., Harv., 1883 61 VII. Notes on some Species in the third and eleventh centuries of Ellis's North American Fungi. By W. G, Farlow . . 65 VIII. On certain Parabrombenzyl Compounds. By C. Lorxng Jackson and G. T. Hartshorn 86 IX. A new method of preparing Borneol from Camphor. By C. LoRiNG Jackson and A. E. Menke 93 iv CONTENTS. PAGE X. Contributions to American Botany. By Sereno Watson 9(j XI. On the Heat produced in Iron and Steel by Reversals of Magnetization. By John Trowbridge and Walter N. Hill 197 XII. On the Heat produced in Iron and Steel by Reversals of Mdc/netization. By John Trowbridge and Charles Bingham Penrose 205 XIII. Influence of Magnetism upon Thermal Conductivity. By John Trowbridge and Charles Bingham Penrose 210 XIV. Papers on Thermo- Electricity. — No. I. By John Trow- bridge and Charles Bingham Penrose .... 214 XV. The Electromotive Foi-ce of Alloys. By John Trowbridge and E. K. Stevens 221 XVI. The Potential of a Shell bounded by Confocal Ellipsoidal Surfaces. By Frank Nelson Cole 226 XVII. Researches on the Complex Inorganic Acids. Hypophospho- Moly.lates. By Wolcott Gibbs, M.U 232 XVIII. The Volumetric Determination of Combined Nitrous Acid. By Leonard P. Kinnicutt and John U. Nef . . 275 XIX. The ^ Phemjltribrompropionic Acid. By Leonard P. Kinnicutt and George M. Palmer 277 XX. On the Crystalline Form of Chlordibromacryllc Acid. By Oliver W. Huntington, Assistant 282 XXI. On a Method of Determining the Index Error of a Meridian Circle. By William A. Rogers 284 XXII. Studies in Metrology. First Paper. By William A. Rogers 287 XXIII. On the Reduction of different Star Catalogues to a Common System. By William A. Rogers 399 CONTENTS. V PAGE Proceedings 409 Memoirs : — John Bacon 419 Augustus Allen Hayes . 422 Chandler Robbins 427 William Barton Rogers 428 J^athaniel Thayer 438 Charles Avery 442 Henry Draper 444 George Perkins Marsh 447 Isaac Ray 457 Theodore Ludwig Wilhelm von Bischoff 458 Joseph Liouville 460 Emile Plautamour 461 Friedrich Wohler 463 List of the Fellows and Foreign Honorary Members . . 467 Index 475 PROCEEDINGS OF THE AMERICAN ACADEMY OF ARTS AND SCIENCES. VOL. XVIII. PAPERS READ BEFORE THE ACADEMY. I. DF HAR- MARINE BIOLOGICAL LABORATORY. ly. IQ \ / rf ^y Received Accession No. 9 .x~^ Given by <^vP~~ ..d'^rr?::^^^ Place, *;^*rlo book or pamphlet is to be pemoved tpom the liab- oratopy tuithout the permission of the Trustees. [ TUR- fore the nascent lade by 'he best , hoi, and strong sodium amalgam was allowed to stand for somewhat more than a week. The alcohol, though not absolutely necessary, as the sodic hydrate formed gradually brings the curcumin into solution, accel- erates the action, which at best is extremely slow. After the dark- red color of the sodic salt of curcumin had given place to a blackish tinge, the liquid was poured off from the mercury, acidified with hydro- * The first paper was published in these Proceedings, Vol. XVII. p. 110. VOL. XVIII. (n. S. X.) 1 2 PKOCEEDINGS OF THE AMERICAN ACADEMY chloric acid, the fawn-colored precipitate thus obtained washed till free from acid, and dried in vacuo. A combustion gave the following results : — 0.2290 g. of substance gave 0.5678 g. of CO2 and 0.1312 g. of Hp. Calculated for C^fiyfi^. Found. Carbon 67.74 67.63 Hydrogen 6.49 6.36 Properties. It forms a brownish white powder melting in the neigh- borhood of 100°, but with no definite melting-point; it is insoluble in water, freely soluble in alcohol and glacial acetic acid, slightly in ether, and insoluble in ligroine and benzol. Strong sulphuric acid dissolves it with a reddish-brown color, very different from the purple produced by curcumin. Sodic hydrate dissolves it on warming, and so does sodic carbonate ; but the latter solution becomes turbid, and throws down a brownish precipitate on cooling. The adilition of hydrogen to curcumin by sodium amalgam and dilute alcohol is a tedious process occupying more than a week and giving a very bad yield, the product being frequently accompanied by a viscous substance, probably formed by the action of air on the alka- line solution of the hydride. A much better method of adding hydro- gen to curcumin consisted in treatingf it with zinc dust and acetic acid, although in this case tlie hydride at first produced was further modified in the course of the reaction. Anhydride of Curcumin Dihydride, (C^^^^O^.,0. Curcumin was warmed with acetic acid of 85 per cent and a large quantity of zinc dust, the temperature being kept below the boiling-point of the acetic acid. After some hours the yellow color of the solution had become replaced by a dark brown, and if then a little of the substance gave a yellow instead of a red color with sodic hydrate, the heating was discontinued, and the liquid filtered into water, which precipitated fawn-colored flocks similar to those of the preceding compound. After we had satisfied ourselves that it was impossible to crystallize the substance, we purified it by resolution in glacial acetic acid and precipitation with water ; but even this treatment did not remove the whole of the zinc salt, as was shown by the appearance of a slight ash on combus- tion. This has been subtracted from the weight of the substance taken in calculating the percentages. The same substance was obtained when curcumin was heated with zinc dust and a solution of ammonic hydrate. The combustion marked III. was of a product made in this way : — OP ARTS AND SCIENCES. 6 The substance after thorough washing with water was in each case dried on a steam-radiator at a temperature of about 60°. I. 0.2552 g. of substance gave 0.6460 g. of COg. 0.1476 g. of H.p. Ash = 0.004. 11. 0.2449 g. of substance gave 0.6183 g. of CO^. 0.1368 g. of U.p. Ash = 0.0061. III. 0.2357 g. of substance gave 0.6001 g. of COj. 0.1365 g. of up. Ash = 0.002. Calculated for CjgHaoO,. Found. I. II. in. Carbon 70.42 70.14* 70.61* 70.03* Hydrogen 6.25 6.53 6.36 6.48 Properties. It resembles the dihydride closely, like it forming a dirty white powder with no definite melting-point, since it melts gradually in the neighborhood of 120°. The best solvents for it are alcohol and glacial acetic acid, but it is deposited on evaporation of the solvent as a varnish. It is essentially insoluble in ether, ligro- ine, and benzol, slightly soluble iu chloroform. A solution of potassic hydrate dissolves it with a yellow color, while potassic carbonate forms a dark-brown solution if boiled with it, but as this solution cools, brownish flocks are deposited, which we supposed to be a potas- sium salt, until two analyses of the substance showed that it did not contain more than 2.5 per cent of potassium, whereas the salt with the least possible amount of the metal contains 7.5 per cent. It is evident, therefore, that the potassium was an impurity, which could well be, since we were able to find no satisfactory method of purifi- cation. An attempt to make a potassium salt with alcoholic potassic hydrate gave a black liquid, insoluble in a mixture of alcohol and ether, and of the most unpromising appearance. The fact that the substance forms no salt with potassic carbonate indicates that the two molecules of the dihydride are connected by the removal of water from their carboxyl groups ; but we did not consider the nature of the substance satisfactorily explained until we succeeded in making it from the dihydride, Cj^HjgO^, by the action of an acetic- acid solution of zincic acetate. After warming the two substances * If the ash is not subtracted the percentages are, — I. II. III. 69 04 68.85 69.44 6.43 6.20 6.43 4 PROCEEDINGS OP THE AMERICAN ACADEMY together for some time, the product was treated with water, and the precipitate washed, dried, and anal); zed, with the following result: — 0.1430 g. of substance gave 0.36G6 g. of CO^ and 0.0868 g. of U.f>. Calculated for C28H30O7. Found. Carbon 70.42 69.92 Hydrogen 6.25 6.68 Whereas before this treatment a portion of the same samjjle gave carbon 67.63, hydrogen 6.36, as on page 2. This experiment proves, therefore, that the nascent hydrogen given off by zinc dust and acetic acid first converts the curcumin into the dihydride, from which the zincic acetate afterward removes one molecule of water. The anhy- dride is broken up only incompletely by the action of water at high temperatures or by boiling with sodic hydrate, the product in each case being a mixture of the dihydride and its anhydride. In order to study the oxidation of the dihydi'ide, some diethylcur- cumin, prepared according to the method given in our first paper, was treated with zinc dust and acetic acid. The product thus obtained gave the following results on analysis, which indicate that it is a mix- ture of di- and monoethylcurcumin dihydride : — I. 0.2130 g. of substance gave 0.5484 g. of CO^ and 0.1415 g. of H.,0. Ash 0.0004. 11. 0.1 938 g. of substance gave 0.4986 g. of COg and 0.1336 g. of H,0. Calculated for Found. Calculated for (C,H,)ChU,504. I. II. (CiU,),C,tU,,0^. Carbon 69.56 70.35 70.15 71.05 Hydrogen 7.25 7.40 7.66 7.89 Some of this substance was mixed with a saturated neutral solution of potassic permanganate and allowed to stand at the ordinary tem- perature. The oxidation took place very slowly, several weeks' standing being necessary to complete the reaction. The principal product was proved by its melting-point to be ethylvanillic acid, while the presence of a small quantity of ethylvanilliu was indicated by its characteristic smell. The most striking fact in connection with this reaction was that the dihydride was oxidized with so much more difficulty than curcumin itself. Action of JBromine on the Anhydride of Curcumin Dihydride. When the hydride, dissolved in glacial acetic acid, was mixed with an excess of bromine and allowed to stand over night, the liquid OF ARTS AND SCIENCES. turned black, and upon addition of water, a red precipitate was thrown down, which was washed with water, dried, and analyzed, — I. 0.6652 g. of substance gave 0.7160 g. of CO2 and 0.1122 g. of up. 0.3100 g. gave according to Carius 0.4125 g. of AgBr. II. 0.3202 g. gave 0.3498 g. of CO^ and 0.0562 g. of HgO. 0.2786 g. gave 0.3730 g. of AgBr. Calculated for CuHioBr^O^. Found. I. II. Carbon 29.89 29.36 29.80 Hydrogen 1.78 1.87 1.95 Bromine 56.94 56.62 56.99 The substance is red and amorphous ; it does not melt under a red heat, but seems to be decomposed without melting. It is insoluble in water, ligroiue, and benzol, very slightly soluble in alcohol and ether, soluble in glacial acetic acid. Strong sulphuric acid has no action upon it. It is vigorously acted on by boiling potassic hydrate, forming a red solution, from which acids precipitate a black tarry body which we were unable to purify ; two analyses of its sodium salt, however, showed that it contained about the same percentage of oxygen as of carbon, and that most of the bromine (all but 7 per cent) had been removed, proving that the bromine in the original substance is all in the side-chain. Action of Bromine on Curcumtn. We have obtained two bromine compounds of curcumin, one con- taining four and the other seven atoms of bromine. Tetrabromide of Curcumin.^ Cj^Hj^Br^O^. When curcumin sus- pended in carbonic disulphide is allowed to stand with an excess of bromine for some hours, it is converted into a white substance, which is left as the carbonic disulphide evaporates. The carbonic disulphide can be replaced by glacial acetic acid, but in this case an excess of bromine or the use of a large quantity of glacial acetic acid must be avoided. The nature of this body could not be established satisfac- torily by analysis, as it was more or less decomposed by all its sol- vents, and therefore a thorough purification was impossible ; we have obtained one fair analysis, however, of a sample washed with carbonic disulphide. 0.2375 g. of substance gave according to Carius 0.3180 g. of AgBr, — Calculated for CiiHuBrjO^. Found. Bromine 56.66 56.99 6 PROCEEDINGS OF THE AMERICAN ACADEMY Other specimens contained the following percentages : — Bromine 54.87 58.51 58.57 To confirm this result, which points to the taking up of four atoms of bromine, we determined the increase of weight caused by the bromine. For this purpose carbonic disulphide and bromine in excess were added to a weighed amount of curcumin, and the product weighed after drying it a little below 100°. I. 0.252 g. of curcumin gained 0.354 g. II. 0.218 g. gained 0.300 g. These results correspond to the following percentages of bromine in the product, — Calculated for Ci^UuBr^O^. Found. I. n. Bromine 56.66 58.41 57.91 And there is therefore no doubt that the substance contains four atoms of bromine. To decide whether it was an addition or substitution product, we determined the amount of hydrobromic acid given off, as in every preparation an evolution of this gas was observed. For this purpose the gases formed in the reaction were allowed to pass through water, and finally the carbonic disulphide and excess of bromine were removed, at first from the curcumin, and afterward from the absorbing water, by a sti'eam of air ; the hydrobromic acid collected in the water was then determined as argentic bromide. One gramme of curcumin was used in each case, and in the following com- parison of results the amounts found are compared with the calculated amount if the curcumin had given off two molecules of hydrobromic acid, — Two Molecules HBr. I. II. 0.66 0.185 0.28 From this it appears that the hydrobromic acid is produced by an insignificant secondary reaction, and that the substance is an addition product, and therefore has the formula Cj^Hj^Br^O^.* We may add that some experiments to determine directly the number of molecules of bromine added pointed to two molecules as the probable amount, but the results are not definite enough to make them worth publishing. Properties. It is a white or whitish amorphous substance, melting in the neighborhood of 185° with decomposition, but it has no definite *The high percentages of bromine obtained in the analyses may be ac- counted for by this secondary reaction. OF AETS AND SCIENCES. 7 melting-point. It is insoluble in water, soluble with decomposition in alcohol and iu glacial acetic acid, which acts upon it, however, less rapidly than the alcohol, very slightly soluble in ether, chloroform, and carbonic disulphide, insoluble in ligroine and benzol. Its be- havior with various reagents was taken up, but no results were obtained which promised to repay further study. The following observations, however, are of some interest. Potassic hydrate and also argentic oxide convert it in part into vanillin, to judge from the smell, while both anilin and zinc cleaned with sulphuric acid act upon it, the former with considerable evolution of heat, — thus confirming the inference that it is an addition-product. The principal products from these reactions, as well as those from the action of sodic carbon- ate and water, and of reducing-agents, are ill-defined bodies which we could find no means of purifying. Pentabromcurcumindibromide, Cj^HgBr^O^. If curcumin in glacial acetic acid is treated with an excess of bromine, or the solid tetra- bromide treated with bromine, a red substance is formed, which, after washing with water and drying in vacuo, gave the following results : — 0.2898 g. of substance gave 0.2230 g. of CO^ and 0.0304 g. of Hp, 0.2G66 g. of substance gave according to Carius 0.9323 g. of AgBr. Calculated for Ci4H9Br704. Found. Carbon 20.97 20.98 Hydrogen 1.12 1.16 Bromine 69.91 69.02 Properties. A red amorphous substance melting near 120°, but without definite melting-point ; insoluble in water, soluble in alcohol apparently with decomposition, easily soluble in ether and glacial acetic acid, leaving a varnish, slightly soluble in benzol, insoluble in ligroine. Strong sulphuric acid acts on it very slowly, finally turning it a more brilliant red. Our study of the behavior of this substance has led to no more definite results than in the case of the tetra- bromide. Heated alone, it gives off bromine and hydrobromic acid, leaving a black tar, from which a yellow substance containing bromine can be extracted by alcohol ; we may study this experiment more carefully hereafter. Sodic hydrate, sodic carbonate and water, sodic alcohol- ate, and argentic oxide all act upon it, but no smell of vanillin was observed in any case. The same is true of several oxidation experi- ments we have tried upon it, and this would seem to indicate the presence of a portion of the bromine in the benzol ring. It is an 8 PROCEEDINGS OP THE AMERICAN ACADEMY interesting fact that potassic dichromate and sulphuric acid, and also neutral potassic permanganate, attack this substance only with extreme difficulty, whereas they both act vigorously on curcumin. Summary. 1. Curcumin takes up two atoms of hydrogen when treated with nascent hydrogen. 2. The dihydride thus formed passes over easily into an anhydride by losing one molecule of water. 3. The anhydride of diethylcurcumin dihydride is much less easily attacked by oxidizing agents than diethylcurcumin, but the products are the same, — ethylvanillic acid with a trace of ethylvanillin. 4. Bromine removes two atoms of hydrogen from the dihydride, and replaces four more, forming Cj^Hj^Br^O^. 5. Only four atoms of bromine can be added to curcumin. 6. The tetrabromide has a great tendency to form vanillin when treated with substances which remove bromine. 7. With an excess of bromine a substance, Cj^HgBr^O^, is formed. 8. The pentabromcurcumindibromide is oxidized in neutral or acid solutions only with great difficulty. The observations just described throw some light upon the nature of the side-chain of curcumin, but as the inferences to be drawn from them are at best extremely doubtful, we shall postpone all discussion of the structure of curcumin until our further study of it has put the subject on a more secure basis. III. TURMERIC OIL — TURMEROL. The oil obtained from turmeric, which amounts to about 11 per cent of its whole weight, has naturally attracted the attention of chem- ists much less than curcumin, the yellow coloring-matter of the root ; we find consequently only a few analyses and some meagre statements about the action of reagents upon the oil, in place of the much fuller study to which curcumin had been submitted. The most important of these will be found in the papers of Ivanow-Gajewsky * and Kachler,t but as they all refer to mixtures, it is not necessary to repeat them here. The oil, however, is not without practical interest, as to it the turmeric (and therefore curry powder) owes its aromatic taste and smell. * Ber. d. ch. G. 172, p. 1103. t Ber. d. ch. G. 170, p. 713, OP ARTS AND SCIENCES. 9 The crude product with which we started in the following study of the oil was extracted, from ground Bengal turmeric with ligroine, in the way already described iu the first paper* of this series. After being freed from the higher boiling portions of the ligroine by heating to 150° in a boiling- flask, it formed a rather thick oily liquid, with a yellow color, and pleasant aromatic smell. The purification offered some difiiculty, because it was decomposed by distillation under ordin- ary pressure, giving distillates with a rank, disagreeable smell ; and distillation with steam, although effecting a partial purification, was an extremely tedious process, owing to the difiiculty with which the oil was driven over. We were therefore obliged to resort to fractional distillation under diminished pressure, and in this way at last suc- ceeded in sejDarating the oil into three fractions, — the first, boiling below 193° under 60 mm. of pressure; the second, from 193°-198°; and the third, the retort residue, a viscous, semi-solid body of extremely unin- viting appearance. We have up to this time confined our attention to the middle fraction, although a few experiments on the fraction below 193° would indicate that it consists of the middle fraction con- taminated with hydrocarbons from the ligroine used in the extraction of the oil, — a view which is borne out by the very small amount of this fraction. For the fraction from 193°-198°, which is the subject of this paper, we would propose the name turmerol. Composition of Turmerol. I. 0.1924 g. of the oil gave 0.5903 g. of CO2 and 0.1814 g. of H,0. 11. 0.3126 g. gave 0.9588 g. of CO^ and 0.3010 g. of H,0. III. 0.2354 g. gave 0.7157 g. of CO^ and 0.2190 g. of lip. IV. 0.2002 g. gave 0.6123 g. of CO^ and 0.1818 g. of H.^. V. 0.2448 g. gave 0.7492 g. of COg and 0.2306 g. of l\0. I. II. III. IV. V. Mean. Carbon 83.68 83.66 82.90 83.43 83.47 83.62 Hydrogen 10.47 10.70 10.34 10.10 10.47 10.42 I. -III. are analyses of the same sample ; IV. and V. analyses of a different sample. To test the purity of the oil, the original sample was distilled again in vacuo, and collected in three equal fractions. Of the analyses which follow, VI. was made with the portion which came over first ; VII. and VIII. with that which came over last. * These Proceedings, Vol. XVII. p. 110. 10 PROCEEDINGS OP THE AMERICAN ACADEMY VI. 0.3315 g. gave 1.0194 g. of C0„ and 0.3145 g. of Hp. VII. 0.2837 g. gave 0.8G75 g. of CO,' and 0.2604 g. of H^O. VIII. 0.2706 g. gave 0.8228 g. of COl and 0.2474 g. of Up. Lower Fraction. Higher Fractions. TI. VII. vni. Carbon 83.86 83.39 82.92 Hydrogen 10.54 10.20 10.16 From this it appears that the substance is essentially pure and homogeneous. As has been stated already, the turmerol can be purified to a certain extent by distillation with steam ; analysis IX. was made with a sample prepared in this way, while X. was made with some of the same sample after it had been distilled once under ordinary pressure. These speci- mens were extracted with carbonic disulphide instead of ligroine. IX. 0.2260 g. gave 0.6860 g. of CO, and 0.2195 g. of H,0. X. 0.2636 g. gave 0.8038 g. of CO, and 0.2546 g. of H^O. IX. X. Carbon 82.78 83.16 Hydrogen 10.77 10.73 The analyses unfortunately are not capable of establishing the for- mula of turmerol with certainty, since the difference between the members of the homologous series is very small, as is shown by the following comparison : — Mean of the Preceding Analyses. CisH^oO. C19H23O. 020^300- Carbon 83.62 83.73 83.81 83.90 Hydrogen 10.42 10.08 10.29 10.49 Taking both the hydrogen and the carbon into consideration, our results agree best with the formula CjgHgyO, as shown above in the case of the mean, and a comparison of the separate analyses with the calculated percentages also declares in favor of this formula. But it is evident that it is impossible to decide definitely from these data in favor of this formula, nor can the derivatives we have prepared from the oil settle this question, as a thorough purification of these bodies has proved impossible on account of their ill-defiued properties and slight stability. We are inclined to ascribe the differences between analyses VI. and VII. and VIII. to the presence of a trace of some hydrocarbon from the ligroine, but did not attempt to purify the substance further, as it is slightly decomposed, even by distillation, under a pressure of 60 mm. OP ARTS AND SCIENCES. 11 Properties of Turmerol. The substance analyzed by us had a pale yellow color, an agreeable, not very strong aromatic smell, and a specific gravity of 0.9016 at 17°. It turns a ray of polarized light to the right with the following specific rotary power for sodium light : — [a] = 33.52. Under ordinary pressure it boils at 285°-290°, but decomposes apparently with formation of water, giving a substance with a lower boiling-point. At a pressure of 60 mm. it boils from 193° - 198°, but even under this pressure suffers a slight decomposition. It is essentially insoluble in water, but mixes easily with all other common solvents. Acid sodic sulphite in aqueous solution has no action upon it. In order to determine the nature of turmerol, its behavior with various reagents was next studied. Action of Hydrochloric Acid. Turmerylchloride. "When turmerol was heated with aqueous hydrochloric acid satur- ated at 0° to 150° in a sealed tube for some hours, a brown oily liquid was formed having a different smell from the original substance, which, when washed until free from acid and dried in vacuo, gave the follow- ing results on analysis : — I. 0.2938 g. of substance gave 0.8464 g. of CO^ and 0.2530 g. of H,0. 0.4434 g. of substance gave according to Carius 0.2190 g. of AgCl. 11. 0.3179 g. of substance gave 0.1518 g. of AgCl. Calculated for OiaHjjCl. I. Carbon 78.48 78.57 Hydrogen 9.30 9.57 Chloride 12.22 12.21 Found. IL 11.80 100.00 100.35 Analyses I. and II. were made with specimens from different prepara- tions. The substance was a pale brownish oil with an agreeable smell, different from that of turmerol ; it decomposed on distillation, and also lost chlorine when distilled with steam or even with fuming hydro- chloric acid. The same compound was formed by the action of phosphorous 12 PROCEEDINGS OF THE AMERICAN ACADEMY trichloride on turmerol, but much less neatly. Phosphoric penta- chloride, on the other hand, seemed to add chlorine also, as the product from its action on turmerol contained about 15 per cent of chlorine. "We have postponed the study of this substance for the present. Tlie formation of the turmerylchloride described above indicates that turmerol is an alcohol, and to confirm this view we next treated the turmerylchloride with various reagents, and found that its chlorine was removed, in part, at least, by boiling water or by alcoholic solu- tions of sodic acetate, potassic cyanide, or ammonia, — a substance being formed in each case with the characteristic smell of the class to which it should belong. The regenerated alcohol and the acetate we were unable to purify, while the nitrile and its corresponding acid and the amine were formed in very small quantities and did not give crystal- line compounds, so that their further study, which we had at first hoped would establish the formula of turmerol, did not jiromise to repay the labor. To still further confirm the alcoholic nature of turmerol, we prepared the sodium compound as follows, — Action of Sodium on Turmerol. Some of the turmerol mixed with high boiling ligroine was warmed with sodium in a flask with a return cooler for twelve hours, during which time hydrogen was given off ; the liquid was then filtered, and the ligroine evaporated off from the viscous filtrate. I. 0.1456 g. of substance gave 0.0374 g. of Na2S0^. II. 0.9820 g. gave 0.2342 g. of Na^SO^. Calculated for C,QlI,,0Na. Found. I. n. Sodium 7.82 8.32 7.72 The substance forms a viscous semi-solid mass. Sodic hydrate seemed not to act upon turrperol. An attempt to convert turmerol into its acetate by heating it with acetic anhydride and sodic acetate on the water-bath gave a product having the same smell as that from the reaction of sodic acetate on turmerylchloride, but no means could be found of separ- ating it from the unaltered turmerol, as it was decomposed by distil- lation even in vacuo. We accordingly turned our attention to the ethers of turmerol, and selected for study the isobutylether, as the difference between the percentage composition of this and that of the alcohol would be greater than in the case of the methyl- or ethyl- ethers. OP ARTS AND SCIENCES. 13 Isohutylether of Turmerol. This body was prepared by boiling the sodium compound with iso- butyliodide in a flask with a return-condenser for some time ; the product was purified by distillation in vacuo. I. 0.2110 g. of substance gave 0.6524 g. of COg and 0.2039 g. of 11. 0.2742 g. of substance gave 0.8520 g. of COg and 0.2646 g. of H,0. Calculated for Cj5,H270CiH9. Found. I. II. Carbon 84.14 84.45 84.71 Hydrogen 10.97 10.73 10.83 It is a heavy yellowish oil with a pleasant smell. The ethylether is a similar substance. From the observations described there can be no doubt that tur- merol is an alcohol. Oxidation of Turmerol. When turmerol was treated with a hot aqueous solution of potassic permanganate until it was no longer decolorized, and after destroying the slight excess of permanganate with sodic sulphite the liquid was filtered from the brown hydrate of manganese, upon adding sulphuric acid a yellowish-white precipitate was thrown down, which, purified by washing with alcohol, became perfectly white, and volatilized without melting, indicating that it was terephthalic acid. To prove that this was the case, the acid was converted into the methylester by passing hydrochloric acid through methylalcohol, in which it was suspended. The solid gradually dissolved, and upon allowing the alcohol to evapor- ate, long prisms were deposited, which, after two crystallizations from hot alcohol, melted at 139°-140°. Melting-point of methylester of terephthalic acid 140°. Another sample of the acid was analyzed, — 0.1782 g. of substance gave 0.3798 g. of COg and 0.0641 of Hp. Calculated for CgllgOi. Found. Carbon 57.83 58.12 Hydrogen 3.62 4.00 The product in this case, therefore, is terephthalic acid, and turmerol must stand in close relationship to the para series of aromatic com- pounds. It is probably a derivative of the terpenes. The formation of terephthalic acid from turmeric oil also explains 14" PROCEEDINGS OF THE AMERICAN ACADEMY the results of Tvanow-Gajewsky in regard to the oxidation of curcu- min, as it renders it almost certain that the terephthalic acid obtained by him, but of which we could find no trace, proceeded from an im- purity of turmeric oil in his curcumin. When cold potassic permanganate not in excess is used, turmerol yields one or more apparently new acids, with the investigation of which we are at present occupied. Summary. The formula of turmerol (the fraction of turmeric oil boiling from 193° to 198° under 60 mm. of pressure) is CjgHogO, or one of its adjacent homologues. Its alcoholic nature is proved by the following observations : — 1. Conversion into CigHg-Cl by hydrochloric acid or phosphorous trichloride. The chlorine can be removed by ordinary reagents. 2. The formation of a compound, CjaH^i^ONa, by the action of sodium. 3. The formation of its isobutylether, CjgHg^OC^Hg. That it is related to the para compounds of the aromatic series is proved by its conversion into terephthalic acid by treatment with a hot aqueous solution of potassic permanganate in excess. OF ARTS AND SCIENCES. 15 II. OBSERVATIONS OF THE TRANSIT OF VENUS, DE- CEMBER 5 AND 6, 1882, MADE AT THE HARVARD COLLEGE OBSERVATORY. By Edward C. Pickering. Presented December 13th. 1882. The chances of cloudy weather at this Observatory early in Decem- ber are large, and Cambridge was not selected by the United States Commission on the Transit of Venus as a station for observations of the phenomenon. It therefore seemed injudicious to make any exten- sive preparations for the occasion. The available telescopes at the Observatory, however, were employed in observing the contacts. Photometric and spectroscopic observations were also obtained with the East Equatorial, and measurements of the diameter of Venus were made with the telescope of Mr. Chandler, mounted in the West Dome, and also with the East Equatorial. The morning of the transit was so cloudy that there seemed little prospect of observing the contacts ; but the sua gradually became vis- ible, and the clouds were thin enough at the time of ingress to allow observation of both the first and the second contacts. The first part of the afternoon was nearly clear, and the third contact was well seen. A few minutes later the sun entered a mass of thin clouds, but was still sufficiently well seen for observation of the last contact. Arrangements had been made before the day of the transit with the "Western Union Telegraph Company for the distribution of the time signals of this Observatory among those who might desire to obtain them on December 6. The clock at which these si"-nals oriorinate was carefully compared with the standard sidereal clock of the Obser- vatory at frequent intervals, and also with the signals furnished by the United States Naval Observatory at Washington, which were received here by telegraph. To determine the error of the sidereal clock, ob- servations were made with the meridian circle by Professor W. A. Rogers, the results of which are given below. Since the transit, in order to remove any doubts with regard to the error of the sidereal clock as determined by a large fixed instrument, Professor Rogers has 16 PROCEEDINGS OP THE AMERICAN ACADEMY made a special series of observations, in which he used both the merid- ian circle and the portable transit instrument on each of eight even- ings, determining the clock error independently with each instrument. The result confirms the correctness of the form of level employed with the meridian circle, and shows that the instrument furnishes trustworthy results for the absolute as well as the relative clock error. The mean correction to be applied to the error found by the meridian circle in order to reduce it to that found by the portable transit in- strument, according to these observations, is -}-0^08 ; the eight sep- arate results are 4-0^20, -f0^06, -]-0^09, +0'.07, -[-0^06, -f-OMl, -|-0\09, -|-0^-05, the first having a weight of one third. As the mag- nifying powers and the reticules used with the two instruments differ materially, the amount of the correction is not surprising. The results for the error of the sidereal clock obtained from the observations with the meridian circle near the time of the transit are exhibited in Table I. The first two columns contain the date of the observations in mean solar days and tenths, and the sidereal time, to hundredths of an hour, for which the error was determined. The third column gives the number of stars on which each result for clock error depends. The next two columns give the amount by which the clock was slow at the time of each set of observations, and the corre- sponding error for noon of December 6, corrected by means of the hourly rate -)-0'.023. The last two columns contain the values of the instrumental constants n and h (angle at pole, and inclination of axis). TABLE I. — Observed Clock Errors. Date. 1882. Sid. Time. No. of Stars. Clock Slow. n 6 Observed. Red. to Dec. 6.0 Dec. 4.2 Dec. 4.8 Dec. 5.4 Dec. 6.2 2P.92 12.63 3.07 22.05 5 4 4 7 +2" 21».25 +2 21.69 +2 22.05 +2 22.36 +2" 22'.24 +2 22.46 +2 22.37 +2 22.24 — IMO — 1.03 — 1.05 — 1.05 +0'.77 + 0.77 + 0.77 + 0.77 The mean result for noon of December 6 is -j-S™ 22'.33. Re- ducing this to the result to be expected from the portable transit instrument, by adding -|-0'.08 as above, we have -j-^"" 22'. 41, with an hourly increase of -[-^'•023. OF ARTS AND SCIENCES. 17 On December 5, 6, and 7, at noon, the Washington signals were received at Cambridge, and compared by chronograph with our sidereal clock. The result, after allowing for the difference in longitude, was that the Washington clock was fast 0'.6, 0'.4, and 0'.3 on the three days respectively. The signals were promised for December 4 also, but were not received, as the lines were occupied in transmitting po- litical news. A good example is thus afforded of the importance of depending on the local observatories for supplying the public with time. The clock distributing the mean-time signals from the Harvard College Observatory is kept as nearly as may be 15'.5 fast. The time is therefore that of the meridian passing through the State House in Boston, and 4*^ 44" lo^5 west of Greenwich. On the day of the transit the deviation of the Washington signals was noted, and, to avoid the confusion arising from two systems, our signals were brought to an approximate agreement with them, rather than with our own determination of the local time. Frequent comparisons were made with our sidereal clock, and showed that at December 5.8 our signals were 0'.6 fast ; at December 6.0, 0^5 fast ; at December 6.3, 0'.5 fast ; and at December 6.8, 0'.2 fast. Allowing for the difference of longi- tude, these signals therefore did not differ more than a tenth of a second from the Washington signals, but to reduce them to the true time both should be regarded as about 0'.5 fast. In other words, in reducing to Greenwich mean time, the longitude for the Washington and Boston signals should be taken as 5^ 8™ 11^7 and 4'' 44"" 15\0 respectively. Since the observed times of contact are known to be liable to variations of several seconds, these corrections in any case are small, and may be neglected without serious error, especially as it is useless to give the resulting times of contact more closely than to sinole seconds. O' Contacts. A statement of the results of the contact observations is given below, in Table 11. The upper part of the Table contains in successive columns the names of the observers and recorders, the apertures and focal lengths of the telescopes in centimeters, their magnifying powers in diameters, and the corrections required at ingress and at egress to reduce the observed times to Cambridge mean or sidereal time according to the timepiece employed. These corrections are given in accordance with the assumption that the signals furnished by the mean-time clock give the time of a meridian 4'' 44™ 15\5 west of VOL. xviii. (n. s. X.) 2 18 PROCEEDINGS OF THE AMERICAN ACADEMY Greenwich, The second part of the Table gives the observed times of the four contacts, without any corrections. The third jiart contains the concluded Greenwich mean times of the contacts noted by each TABLE II. — Contacts. Observer. Recorder. Aperture in cm. Focal Length in cm. Power in Diame- ters. Corrections of Time-piece. E. C. Pickering A. W. Cutler 14.5 682.5 206 +9S.0, +10S.3 Arthur Searle W. A. Rogers 13.2 230 220 — 76S.2 0. C. WeiKlell A. W. Cutler 10.2 141.4 40,90 -l-g^.O, +10S.3 J. R. Edmands R. G. Saunders 10.2 140 150 +82S.3, -4-82S.3 S.C. Chandler, Jr. \V. V. Brown 152 244 180 — 26S.8, — 24S.7 W. II. Pickering R. G. Saunders 6.4,10.2 71,84 20,110 -1-82S.3, +82S.3 Observer. Observed Times of Contacts. I. II. III. IV. E. C. P. 21'' IQ-" 43S.4 21" 39™ 51S.3 3" 3'" 3s.8 3'' 23"> lOs.O A. S. 20 6 23.4 20 26 28 0. C. W. J. R. E. 21 20 8.2 3 3 8.2 20 3 40 3 23 14.2 20 23 40 14 40 1 s. C. C. 21 20 22 21 40 30 3 3 30 3 24 10 W. H. P. 14 40 9 20 3 33 20 24 0 Observer. Greenwich Mean Time of Contacts. Difference from Mean. I. II. III. IV. I. 11. III. IV. E. C. P. 2'' 4°' 23^ 2h 24ra 31s 7h 47m 45s 8h 7m 51s —9s —12s +5s —Is A. S. . . . . 7 47 41 8 7 42 . . . +1 —10 0. C. W. 2 4 48 ■ • • 7 47 49 8 7 55 + 16 +9 +3 J. R. E. . 2 24 50 7 47 36 8 7 33 +7 4 —19 S. C. C. 2 4 26 2 24 34 7 47 36 8 8 16 —6 —9 4 +24 W. H. P. . . . 2 24 58 7 47 30 8 7 54 -fl5 —10 +2 Mean 2 4 32 2 24 43 7 47 40 8 7 52 OF ARTS AND SCIENCES. 19 observer, obtained by adding 4'' 44™ 3P to each of the Cambridge mean times. The mean result for each contact is given in the last line of the Table. At the right are given the differences of each observer's result from the mean of all. The following notes contain, under the name of each observer, the details of his work. E. C. Pickering. The instrument employed was the East Equatorial. Its full aper- ture is 1 5 inches, which on this occasion was reduced to about 6 inches by a cap over the object-glass. An audible signal was given to the recorder at the time of each phenomenon noted. The recorder took the time of each signal from the chronometer, and recorded it, with any subsequent remarks by ihe observer. The wedge of shade glass placed between the eyepiece and the eye was of a greenish tint. In observing the first contact, the last time recorded before the appear- ance of the notch was ^^ 19"" 29^6 by the chronometer. Venus was first seen at ^^ 19" 44^2 by the chronometer. The edge of the sun was wavy, rendering it difficult to decide whether an indentation was real. At 9^ 19™ 49^0 the interval between the cusps was estimated at 9" ; two parallel lines 6" apart served as the unit of measure. From a reduction of this observation the time of first contact appears to be 9*^ 19™ 42'. 6 ; the mean of this and of the time directly observed is here assumed to be the time of the first contact, which is therefore gh jQm 4334 jjy ^}jg chronometer. A scale in the eyepiece would allow the observer of phenomena like these to make estimates of the inter- val of the cusps without removing his eye from the telescope, and would accordingly afford him many of the advantages of a double-image micrometer without its disadvantages. The images at the second contact were unusually well defined, and the contact was recorded as occurring at 9^ 39™ 5r.3. Eight seconds later it was clearly past. The third contact was recorded as occurring at 3^ 3™ 3'.8. At gh 3m 2is_4 tijg interval between the cusps was estimated as double that between the lines in the field, and consequently as 12". A reduction of this observation would make the time of contact 3'' 3™ 0^0. The fourth contact was recorded as occurring at 3'' 23™ lO'.O. At 3*^ 23™ 3^4 it had not occurred, at 3'^ 23™ 19^4 it was certainly past. The chronometer used by the recorder, who also recorded for Mr. 20 PROCEEDINGS OP THE AMERICAN ACADEMY Wendell, was Bliss & Creighton 1182; it is regulated to mean time, and has been in frequent use at the Observatory. Arthur Searle. The instrument was the five-inch telescope formerly mounted in the "West Dome. As it was not provided with any stand, and as economy was an object kept strictly in view during the preparations for the transit, the best plan for using this telescope seemed to be to lay it horizontally upon a rough frame, at a height of three feet from the ground, before the south entrance of the Observatory. A plane mir- ror of unsilvered glass, formerly used in photographing the sun, was placed upon the block of stone at the east side of the steps of the entrance. This mirror was attached to the frame originally prepared for it, which is provided with screws for moving it approximately in altitude and in azimuth. The dimensions of the mirror are 7^ by 6 inches, so that the sunlight reflected from it at moderate hour angles was thrown upon the whole surface of the object-glass before it. The two surfaces of the mirror are inclined to each other, so that only one image of the sun is seen. In order to keep this image of the sun in the field, the services of an assistant were necessary. Unfortunately, the assistant who had accustomed himself before the transit to the management of the mirror, considering the morning too cloudy for any observation, did not arrive at the Observatory in season to take part in the observations at ingress. No other assistant having the necessary skill was available, and an attempt made to use the tele- scope at ingress was therefore unsuccessful. At egress, the mirror was very successfully managed so as to keep the required part of the sun's limb in view, and Professor W. A. Rogers kindly undertook to record the times at which the observer gave his signals. The observation of the third contact was accordingly a satisfiictory one. Nine seconds before the time recorded as that of the contact, the sun's limb became noticeably darkened at the place of egress, but the shade was lighter than the tint of the planet itself. The shade gradually darkened as the planet advanced, and at the time recorded as that of contact a darkness equal to that of the planet's disk had reached the limb of the sun. This phenomenon could not be distinguished from that of geometrical contact. If the limb of the sun had been steadier, it is possible that such a distinction might have been made. The image, in fact, was by no means bad, but there was sufficient nndulation to make a very exact observation of geometrical contact impossible. Thirteen seconds after the recorded time it had OF ARTS AND SCIENCES. 21 become evident that the cusps were separated by a part of the planet's limb, and that geometrical contact was past. Tiiese observations were made through a dark red shade-glass be- tween the eyepiece and the eyestop. The limb of the sun was dis- tinctly seen, and was free from glare. As the sun entered the thin clouds mentioned in the introductory remarks above, the red glass was replaced by a blue one, which admitted much more light. The part of the planet exterior to the limb of the sun was then certainly, though indistinctly, seen. Its outline seemed to be part of a smaller circle than that bounding the portion of the disk interior to the sun's limb. The increasing cloudiness soon put an end to this appear- ance, the Greenwich mean time of which, derived from the record, 23 7" 57™ 3 P. The fourth contact was observed with some difficulty, owing to the clouds and to the necessity of an occasional movement of the mirror to keep the image in the field. The time given is that of a signal accompanied by the remark " Notch doubtful " ; the notch was not afterwards seen. During the transit, the disk of the planet was uniformly dark, ex- cept that at times it seemed to be crossed by faint streaks of light, very likely due to slight defects in the shade-glass or other parts of the optical apparatus employed. The eyepiece used was positive, No. 5 of the set of eyepieces be- longing to the large filar micrometer of the East Equatorial, and, with that instrument, having a nominal magnifying power of 688. Its power, with the telescope used during the transit, has been deter- mined by two methods, and the approximate mean result 220 is given in the Table. The chronometer employed was Bond 236, regulated to sidereal time ; it has been in constant use at the Observatory for many years. 0. a Wendell. The instrument employed was the finder of the East Equatorial. The object-glass was silvered to reduce the light, and an additional reduction was effected by a shade-glass. Between the first and second contacts the silvering was partially removed, owing to an apprehension that the clouds would grow thicker ; but as the sky actually became clearer, the second contact could not be observed. Before the third con- tact, the film of silver was entirely removed, and the object-glass was smoked by Mr. Clacey's method, which sufficed, with the aid of one shade-glass, to reduce the light. 22 PROCEEDINGS OF THE AMERICAN ACADEMY The first contact was well observed, but the recorder did not notice the signal, and the time is derived by estimate. According to the observer, the signal was given half-way between the last two signals of Professor Pickering, whose own estimate, however, placed it six seconds later. The mean of these estimates was adopted. The third and fourth contacts were well seen and recorded. The time given for the third contact is that when the diminishing thread of light at the place of egress definitely broke. Eighteen seconds earlier contact had certainly not yet occurred. Eight seconds previous to the time of fourth contact it was evident that the egress had not been completed. J. R. Edmands. The telescope was one borrowed from Dr. E. T. Caswell, of Provi- dence, R. I., and originally owned by Dr. Alexis Caswell, of Brown University. It was attached to a portable equatorial mounting (with- out clock) belonging to the Observatory. The observations at ingress were made on the east balcony of the dome, and at egress on the west balcony. The eyepiece was negative, and the light was reduced by one shade-glass placed near the focus of this eyepiece at second con- tact, and by three shade-glasses, one on each side of the focus and one next the eye, at the third and fourth contacts. The chronometer used in recording these observations, as well as for those of Mr. W. H, Pickering, was Frodsham 3451, regulated to sidereal time. This is an excellent instrument, of much value in the work of the Observatory Time Service. At first contact the rapid changes in the opacity of the clouds pre- vented observation of the phenomenon, as the observer had no wedge of shade-glass, and could not readily control the brightness of the field. At second contact, the recorder found it impracticable to note the times from the signals of the two observers, and the assumed times are derived by estimate. The original estimate of the time of the signal " Past " was derived from an inspection of the chronometer made immediately after the observer learned that no record had been secured. But he was satisfied, on consideration, that this first estimate allowed too little for the interval between the signal and his inspection of the chronometer ; besides which, his signal " Past " must have been given an appreciable time after the contact itself. His last signal, " Not yet," preceded the signal " Past " by about ten seconds. On these accounts, he estimated the observed time of contact, which has been entered in the Table, as five seconds earlier than the original OP ARTS AND SCIENCES. 23 estimate of the time of the signal " Past," This decision was made before correcting the result for error of chronometer, and before com- paring it with any other observation. At the third and fourth contacts, the recorder counted the seconds from the chronometer, and the observers recorded the times of their observations. At the third contact, the seeing was good, and the fol- lowing note was made : " No black drop seen. Purposely used faint image." The clouds impeded any similar observation at the second contact. The telescope was somewhat disturbed by wind during the observations at egress, which prevented the observation of additional phenomena. S. C. Chandler, Jr. The first contact was looked for at a part of the limb estimated to be 3° to 5° to the right of the apparent vertex. The notch was sud- denly noticed still nearer the apparent vertex at the time given as that of contact. Nineteen seconds later the notch had increased, confirming the first observation with regard to the place of ingress. The time given as that of second contact is that of geometrical contact in the opinion of the observer. Seven seconds before the recorded time the contact had not occurred. Four seconds after the recorded time it was still uncertain whether the contact was past. Nine seconds after the recorded time the contact was certainly past. No "black drop" was seen. Thirty-five seconds before the recorded time of third contact a shade appeared on the sun's limb, very much fainter than the disk of Venus. This shade increased in darkness, but did not seem to confuse the de- termination of the time of geometrical contact, which is that recorded for this phase of the transit. The recorded time must be as early as that of geometrical contact, which might possibly, however, have been thought to occur ten seconds later than the recorded time. Twenty- two seconds after the recorded time, contact was certainly past by sev- eral seconds. The fourth contact was very satisfactorily observed. Eight seconds before the recorded time the notch was still certainly visible ; at the recorded time it was certainly gone. The telescope was one belonging to the observer, and lately placed on the equatorial mounting in the West Dome. No shade-glasses were used. The necessary reduction of the light was effected by pre- viously smoking the front surface of the crown and the back surface of the flint lens of the object-glass. This was done by Mr. John Clacey, 24 PROCEEDINGS OP THE AMERICAN ACADEMY the maker of the telescope, and the result proved very satisfactory. A negative eyepiece was used iu observing the contacts. The timepiece used was the pocket-chronometer Patek, Phillipe, & Cie. 34,807. W. H. Pickering. The instrument selected for the observations was the Bowditch Comet-seeker ; but as dew upon its reflecting prism prevented obser- vations with it at ingress, the Quincy Comet-seeker, a smaller instru- ment, was employed in observing the second contact. No complete record of these observations was secured, owing to the circumstances explained in the notes relating to Mr. Edmands's observations. The estimate of the time of contact is based upon the circumstance that the observer's signal " Past " was given one second later than the cor- responding signal by Mr. Edmands, according to the judgment of both observers. But on consideration, previous to any comparison with other observations, it appeared likely that this signal " Past " was given a little too early. The observer, therefore,, assigned for his observation of contact a time three seconds later than the original estimate of Mr. Edmands for the time of his own signal. The Bowditch Comet-seeker was used at egress. Observers at other Stations. The following observations of the transit have been communicated to me for publication, and are here inserted. 1. Station, the establishment of Messrs. Alvan Clark & Sons in Cambridgeport, Massachusetts. Approximate latitude, -|-42° 21' 16" ; approximate longitude, west of Greenwich, 4'' 44" 26^7. The times are given according to the clock signals of this Observatory. Observer, Alvan G. Clark. Second contact, 2P 40" 3'; third, 3*^ 2" 30' (the observer has no doubt that the minute should be 3 instead of 2) ; fourth, 3'' 23" 54^5. Observer, C. A. R. Lundin. Third contact, 3*^ 3" 13'; fourth, 3h 23m 34s_ Reducing these observations to Greenwich mean time by the ad- dition of i^ 44" 15^5, we have, for Mr. Clark, 2*^ 24" 18% 7*^ 47'" 46% 8"^ 8" 10' ; and for Mr. Lundin, 7" 47" 28% 8" 7" 50^ 2. Station, near St. Paul's Church, New York. Approximate latitude, -["40'^ 46'.0 ; approximate longitude, west of Greenwich, 4" 56" 0^ Observer, Rev. G. M. Searle. Telescope by Dollond ; aperture, 2.65 inches ; focal length, 44 inches ; magnifying power, 60. OF ARTS AND SCIENCES. 25 Timepiece, a good watch, the errors of which were determined by sextaut observations at 22^ 16"", 22^ 34 , and 1" 11™, which gave the respective corrections -|-9% -\-S% -\-3\ No " black drop " was seen at either internal contact. The first contact was lost; the rest were observed as follows: 21'> 28'" 2% 2^ SI"" 49% 3" ll'" 50^ The corrected mean times are 21'^ 28™ 10% 2^ 51™ 52% 3'' 11™ 53'; and the corresponding Greenwich mean times are 2** 24™ 10% 7^ 47" 52% gh ym 53s^ -pj^g sun's limb was remarkably steady at egress, but some- what disturbed at ingress. 3. Station, terrace at No. 55 Habana Street, Havana, Cuba. Approximate latitude, -\-23° 9' 21" ; approximate longitude, west of Greenwich, 5** 29™ 26^ Observer, Professor Charles Hasselbrink (U. S. Signal Service observer in Havana). Telescope by Negretti and Zambra ; apertui-e, 2.5 inches ; focal length, 39 inches; magnify- ing power, 80. Chronometer Negus 582, slow 3% by comparisons furnished by the observatory of Don Jose Maria Garcia de Haro, semi-otficial observer for the Spanish Navy and the mercantile marine. The observer recorded for himself ; the telescope was shaken by wind in the afternoon. The external contacts are considered doubtful, but the internal contacts were well observed. Observed times of contacts, 20" 33™ 57% 20'' 54™ 30% 2*^ 19™ 0% 2'^ 36™ 47^ corrected mean times, 20^^ 34" 0% 20'' 54™ 33% 2'' 19-" 3% 2" 36™ 50' ; resulting Greenwich mean times, 2" 3™ 26% 2" 23™ 59% 7'' 48™ 29% 8" 6™ 16^ Just before internal contact at ingress, the observer saw a fine line of light round the disk of Venus, beyond the limb of the sun. During the transit, a delicate aureola of very white light was noticed around the planet, suggesting the illumination of its atmosphere. Patches of a dark grayish tint were noticed at times upon the deep black disk of Venus. Photometric Observations. A photometer was constructed for comparing the brightness of the disk of Venus during transit with that of the sky in immediate prox- imity to the sun's limb. In the accompanying figure, A and B are two glass prisms, the first having parallel sides, the other with sides inclined at a small angle. C is a double-image prism, D a positive eyepiece, £J a Nicol, and F an eyestop. A graduated circle, G, and an index, II, serve to measure the angle through which the eyepiece and Nicol are turned. The whole is inserted, like an eyepiece, in the tailpiece of the 15-iuch telescope of the Observatory. The light from the object-glass, striking upon the prism A, is not deviated, but is divided by the prism 26 PROCEEDINGS OF THE AMERICAN ACADEMY A B G into two pencils, one of which passes without deviation through the eyepiece and the hole in the eyestop to the eye. The other pencil is thrown to one side by C, and is cut off by the eyestop. The light passing through B is deviated about G'* by the difference in inclination of its two inclined sides. This lisht is also divided into two pencils by (7, one retaining the deviation imparted by B, and being cut off by the eye- stop. The other is deviated by C, but in such a manner as to counteract the inclination imj^arted to it by B. It therefore passes centrally through the hole in the eye- stop to the eye of the observer. The latter accordingly receives two pencils of light formed by the same object-glass, one receiving the liglit from A, the other that from B. These two pencils are polarized by G in planes at right angles, and their relative brightness may accordingly be varied at will by turning the Nicol E. The instrument in principle closely resembles the meridian photometer for some years in use at this Observatory. The same device is employed to secure two equal pencils polarized in perpendicular planes, but in that instru- ment two equal object-glasses are employed, instead of two images ot the same objective. The eyepiece is focused on the front surface of the prisms A, B, so that their adjacent edges appear as a line dividing the field into two equal parts. By turning the Nicol the brightness of either part of the field may be reduced indefinitely, so that the brighter may always be brought to equality with the fainter. Placing the whole instrument at the principal focus of the telescope, we see side by side in the two halves of the field images of objects really about 16' apart. The observations were made by placing the edge of the prism par- allel to the sun's limb at the point nearest Venus, and bringing Venus into one half of the field. A portion of the sun's disk near its centre will be seen in the other half of this field, and may be compared directly with Venus by turning the Nicol. Settings were made in the four posi- tions of the Nicol in which the images appeared equal, and the posi- tions read to tenths of a degi'ee. The observation was then repeated, moving the telescope so that the portion of the sky close to the sun's limb should be measured in the same manner. Eight settings taken OF ARTS AND SCIENCES. 27 in this way constitute a set, and give the relative light of the sky and Venus. To eliminate any difference in the prisms the photometer was rotated 180° after each set, but no perceptible difference is indi- cated in this way. To reduce the observations, the first reading was subtracted from the second, and the third from the fourth. Calling the sum of these differences A, the relative light, L = tan^ i A. It will also be convenient to use a method of expressing the light in stellar magnitudes, according to the method already used in this Ob- servatory for comparing nebulae and portions of the moon. When surfaces are thus compared, portions of equal area are selected and reduced to stellar magnitudes by the formula of Pogson. We shall then have the difference in magnitude, 31^ 2.5 log L. In Table III, the successive columns give a current number, the Cambridge mean time, the difference in light of equal areas of Venus and the sun expressed in stellar magnitudes, the corresponding quantities for the sky near the edge of the sun, and these same ratios expressed in per- centages, that is, assuming the light of the centre of the sun equal to one hundred. The last column gives the initial of the observer. TABLE III. — Photometric Observations. No. Cambridge Meau Time. Difference in Magnitude. Percentages. Observer. Venus. Sky. Venus. Sky. 1 2 3 4 5 6 7 8 9 10 1" 7'".6 1 18.4 1 24.8 1 29.4 2 48.3 2 51.6 2 54.4 Mean W. Mean P. Mean W., P. 430 4.55 4.05 4.46 5.58 4.44 4.37 4.34 4.80 4.57 2.54 2.94 2.79 2.40 3.32 2.74 806 2.67 3.04 2.85 1.0 1.5 2.4 1.6 0.6 1.7 1.8 1.8 14 1.6 9.6 6.7 7.7 11.0 4.7 8.0 6.0 8.8 6.2 7.5 W. w. w. w. p. p. p. w. p. Both. The result for the light of the sky in the first line of the table depends upon eight settings. These observations show a well-defined increase in light of the sky near the edge of the sun as compared with that received from Venus. This effect also seemed to me to be very perceptible without the pho- tometer. To confirm it, I asked Mr. Wendell which looked to him the brighter. He satisfied himself that Venus certainly appeared darker than the sky. A slight difference was to be expected, since there are instances on record of the visibility of Venus before first 28 PROCEEDINGS OF THE AMERICAN ACADEMY contact. In tlie interval between the exterior and interior contacts, the edge of the planet has sometimes been traced beyond the limb of the sun. The effect was noticed by Mr. Searle shortly after the third contact, as above stated. According to his recollection of the appear- ance of the field, the difference in darkness beween the planet's disk and the sky was obvious, and might have been expected to make the planet more distinctly visible outside of the sun's limb than was actually the case. No appreciable light could be received from Venus itself, unless that planet is incandescent or phosphorescent, an extremely improbable hypothesis. Doubtless the greater portion of the light, like that of the sky near the sun, is due to reflection of the light of the sun from the particles of the earth's atmosphere. During a total solar eclipse the interposition of the moon suffices to cut off nearly all the light near the sun, except the small portion due to the solar corona. It is therefore obvious that the light of the sky near the sun originates at no great distance from the earth, and is doubtless caused by reflection in the terrestrial atmosphere. In a communication to this Academy nine years ago {Proceedings, IX. 1), I showed that many of the phenomena of atmospheric illumination and polarization could be explained by specular reflection from the particles of the air, whose index of refrac- tion differs very slightly from unity. In this case, if the sun was reduced to a point, the light of the sky at small distances would vary inversely as the fourth power of the distance. In any case, a glance towards the sun is sufficient to show that the light increases very rap- idly as we approach the sun's limb. We should expect that the light of the portion of the atmosphere between us and the sun would be much greater than that outside of the sun's disk. Most of the light would be received from the portion of the sun at a very small angular distance. A point between us and the sun would be illuminated in all directions, that is. through the entire 3G0°. A point outside the sun's disk could at most receive light only from 180°. Moreover, the edge of the sun is much fainter than its centre, which would still farther reduce the light. "We should then expect that the light received from Venus would be greater than that of the sky near the sun's limb, the opposite result from that indicated by the observations. This effect would be modified by the solar atmosphere, which would increase the light outside of the sun. The observations of Professor Langley, however, during the eclipse of 1878, seem to prove that the light of the corona is entirely insufficient to produce this effect. The difficulty of photographing the corona confirms this view, but its spectrum in- OF ARTS AND SCIENCES. 29 dicates that it is composed of light of a wave-length to which the photographic plate is not very sensitive. An important source of error arises in almost all these measures from the diffuse reflection from dust or scratches on the object-glass. The eifect of this would be similar to an increased haziness of the sky, and would tend to increase the apparent light received both from Venus and the sky. In our measures this effect was reduced to a minimum, as the object-glass had been cleaned shortly before the transit, and the diffuse reflection was therefore very slight. A remedy for this difficulty would be found by removing the object-glass and substituting for it a minute hole. When the sky is hazy we should expect an increased relative brightness near the edge of the sun. This may account for the larger readings obtained by Mr. "Wendell, as the sky was somewhat clearer during my observations than during his. As the portion of the sky observed was only about 1' distant from Venus, irregular clouds could not produce the observed difference in light. In fact, the persistence of the phenomena under varying conditions seems to leave little doubt that the disk of Venus was really much darker than the sky near it. The solution of this problem would be greatly aided by researches of the kind described below, a portion of which will probably be under- taken at this Observatory. Measurement of the relative light of different portions of the sun's disk and of the sky at various distances from it. Measures of the sky at various distances from the moon, thus eliminat- ing any effect corresponding to that of a solar atmosphere. Measures of the light of the disk of the moon during the progress of a partial eclipse of the sun. Spectroscopic Observations. The spectrum of the light received from Venus was observed with a star spectroscope constructed by Hilger. The dispersion was such, that about one third of the spectrum was visible in the field of view at a time. Two prisms of dense flint glass were employed. This spectroscope was attached to the large Equatorial, and was focused on the limb of the sun. When Venus was brought upon the slit it appeared as a broad band traversing the spectrum lengthwise, which could be compared directly with the solar spectrum on each side of it. The slit was then broujrht tangential to the limb of Venus, so as to receive the light grazing its surface. The breadth of the dai-k band was thus reduced and flickered owing to the slight unsteadiness of the 30 PROCEEDINGS OP THE AMEEICAN ACADEMY atmosphere. No difference in the spectrum was detected either by myself or by Mr, W. H. Pickering after careful examination. This negative result should not be regarded as throwing doubt on the positive results attained by so skilful an observer as Professor Young, who is said to have detected the presence of aqueous vapor in Venus. I have not yet seen the details of his observation, but his facili- ties for making this observation were much greater than mine, and he probably used a much higher dispersion. I satisfied myself that there were no very marked absorption bands, and doubtless the phenomenon is one which requires more careful preparation than we were permitted to make without interfering with the other portions of our programme to which, in preparing our plans, we had attached more importance. Diameter of Venus. The measurements of the diameter of Venus, mentioned in the first paragraph of this communication, were made by Professor William A. Rogers and by Mr. S. C. Chandler, Jr. The subjoined reports from these gentlemen furnish the account of the work undertaken. In these reports, Mr. Chandler's telescope, mounted in the West Dome, has been called the West Equatorial. Report hy William A. Rogers. The following method for the determination of the diameter of a planet was first employed by the writer in 1877, having been used in the determination of the diameter of Mars. Let: — Xq = a line ruled upon glass and set in the direction of diurnal motion. a-j ^ a line ruled at a given angle, i, with respect toXy, and reckoned from east to west. 3-2 = a line ruled at the angk (180° — i) with respect to x^. y =^ a line ruled at right angles to x^ and bisecting the angle formed between x^ and x^. Tj = the observed time of transit of the preceding limb of the planet over x^. Tj = the time of transit of the following limb over x^. Tg, T^ = the corresponding times over x.^. D =: the diameter of the planet. Then : Z> = 15 cos 8 (tjj — Tj) sin i = 15 cos 8 (t^ — r^) sin i OF ARTS AND SCIENCES. 31 For any variation whatever of the angle i we have : ^i = T-- FT N = lo cos 0 (r, — - T-J COS I and hence, from transits over the line x^, 2) = 15 cos 8 (t2 — Tj) sin {i -\- A^) = 15 cos 8 (r, — Tj) sin i -I- — — r A ^ - ' L locos 0 (T2 Tj) COS ?J and from the transits over the line x.-^, Z> = 15 cos 8 (t, — To) sin i — -^ t—, r ; ^ ■* •^^ L lo cos 6 (r^ — Tg) cos ij If therefore the times of transit of each limb are taken over the lines a^j and x.^, any error in D due to an erroneously assumed position angle will be eliminated. It must be noted, however, that any error in A^ arising from an un- known error in the angles between a-^, x^, and x^ will be only partially eliminated. Designating by i and i' the angles which x^ and x^ make with X,,, and their variations on account of errors of graduation by Ai and Az' respectively, we have, from transits over Xj, D ■= \5 cos 8 (t^ — Tj) [sin i -\- cos i A^] and from the transits over x^-, D = 15 cos 8 (T^ — Tg) [sin ^'-{- cos i' At'] or, since i' = 180° — i nearly, Z> = 15 cos 8 (r^ — Tg) [sin z — cos i Ai'] whence X> = -V- cos 8 [[(r, — rj + (r, — r^)] sin ^ -j- cos I [(t2 Ti) At* (t^ T.) Aj']] The only case, therefore, in which the elimination will take place is that iu which (r, — tJ M = (t, — T3) A{' But since, on Dec. 6, the time required for Venus to make a complete transit over a line having i = 20° was only 24', the effect of any small error in the graduation will be practically insensible. For the equatorial diameter we have : D= 15 cos 8 (t2 — Tj) sin (90° + Ai) Unless Az, therefore, is very large, we shall have : Z) = 15 cos d (Xg Tj) Assuming the same constant of differential refraction for Venus north and for Venus south, any error in the observed value of Z> 32 PROCEEDINGS OF THE AMERICAN ACADEMY due to the differential refraction ^^f will be eliminated if we combine the observations over x^ and x.^ with corresponding observations over these lines extended below the line a:^. Designating the times of transit for Venus north of x^ by t\, t'^, t'^, and t'^, we shall have ; For Venus South. D D = V- cos 8 [(r, — rj sin {i -\- - 5 cos 6 (tj — T^) cos i ) + (ji — ^s) sin (i D 15 cos S (r^ — T3) cos i For Venus North. D = -V- cos 8 (r., — T,) sin ( « + 3-= ^^ , , ^ L^ ^ 1^ \ ' 15 cos 5 (r'i ^ 15 cos 8 (r'4 — r'g) cos i )] + ^rf D (t^ — T3) sin ^ i , — r'j) cos i )]--B. ) + Combining these equations, we shall still have, for any case except where 'A^ is due to an error in the assumed value of ^, an equation of the form : i) = 15 cos 8 (tj — Tj) sin i Two ruled plates were prepared for the observation of Dec. 6, one for the East Equatorial and one for the West Equatorial. They consist of one horizontal line, two vertical lines, and a series of lines having the inclinations 10°, 20°, 30°, 40°, 45°, and the inclinations 135°, 140°, 150°, 1G0°, and 170°, respectively, to the horizontal line. These lines were all extended below the line x^, giving the angles 225°, 230°, 240°, 250°, 260°, and the angles 315°, 320°, 330°, 340°, and 350°. In general, a complete series of observations consists of 10 transits over each of the inclined lines, and 20 transits over the vertical lines, both for Venus south and for Venus north of the horizontal line. The results for Dec. 6, arranged in the order of the times of obser- vation are as follows. TABLE IV. — East Equatorial. Position of " Venus with respect to horizontal line. i-30^ i = 45° i = 90° Kemarks. D. No. Obs. D. No. Obs. D. No. Obs. South. South. North. South. It 62.51 62.27 59.73 59.21 18 20 22 22 II 62.46 60.85 60.26 58.98 18 20 22 22 II 60.45 59.62 60.18 58.37 32 40 42 44 Seeing fair. Seeing fair. New zero of position. Seeing very bad. Image of Venus boiling. Reject. OP ARTS AND SCIENCES. 33 TABLE v. — West Equatorial. Position of Venus. 1 = 10° i = 20° i - 30° i - 45° i = 90° Kemarks. D. No. Obs D. No. Obs. D. No. Obs. D. No. Obs. D. No. Obs. South. South. North. South. North. II 60.56 56.51 • • • • '22' 22 II 61.18 61.37 59.52 24 20 22 II 60.73 60.94 60.53 24 20 22 Il 61.04 61.43 59.28 22 20 22 II 60.18 60.59 59.35 61.70 59.62 44 40 44 44 44 Seeing yery good. Seeing fair. New zero. Seeing unsteady. Seeing fair. Seeing bad. Collecting the results for each instrument, but rejecting tlie last series with the East Equatorial, we have : TABLE VL Instrument. i = 10° i = 20° J = 30° i = 45° 1 = 90° East Equatorial ] Means // // // 62.51 62.27 59.73 II 62.46 60.85 60.26 // 60.45 59.62 60.18 61.50 61.19 60.08 West Equatorial - Means • ■ • • • • • • 60.56 56.51 61.18 61.37 59.52 60.73 60.94 60.53 61.04 61.43 59.28 • • ■ • 60.18 60.59 59.35 61.70 59.62 58.54 60.69 60.78 60.58 60.29 Combining the results of the observations over the inclined lines, and assigning the same weight for each value of i, we have : TABLE VII. D for i = 90° D fori = 10°.... 45° From the East Equatorial . . . From the West Equatorial . . . Means .... Vahies of D at the distance unity 60!08 60.29 61.34 60.28 60.18 // 15.92 60.81 // 16.09 It will be seen, by an examination of Tables IV. and V. that the magnitude of D apparently depends to a certain extent upon the VOL. xviii. (n. s. X.) 3 84 PROCEEDINGS OF THE AMERICAN ACADEMY character of the atmospheric conditions under which the observa- tions were made. Arranging the resuUs according to the character of the seeing, we have : TABLE VIII. — Seeing Fair to Good. Instrument. t"=10° i=20o i = 30° 1=45° 1=90° East Equatorial ] West Equatorial } Means • • • • 60.56 61. is 61.37 62.51 62.27 60.73 60.94 // 62.46 60.85 6104 61.43 II 60.45 59.62 60.18 60.59 61.70 60.56 61.27 61.61 61.45 60.51 Seeing Bad to Very Bad, East Equatorial < West Equatorial | Means • * • • 56.5i 59.52 59.52 59.73 59.21 60.53 60.26 59-98 59.28 60.18 58.37 59.35 59.62 56.51 59.82 59.84 59.38 Combining by weights proportional to the number of observations, we have : TABLE IX. D for / = 90° DioTi = 10°... 45° For seeing fair to good . . For seeing bad to very bad // 60.51 59.38 // 61.39 59.38 From the observations made under favorable conditions, we have for the distance unity : D for i = 90° 16".01 D for i = 10° . . . . 45° 16".24 There is a general tendency of the observations to indicate a lesser value for the equatorial diameter, but the method of obtaining this quantity by direct transits over a vertical line is not a very reliable one. The apparent difference, therefore, between the diameter determined at different angles of inclination, is probably fictitious rather than real. In order to determine the difference in the amount of the irradiation OP ARTS AND SCIENCES. 35 of a dark disk upon a bright ground and of a bright disk upon a darker ground, observations for the diameter were continued for several days succeeding the transit. Since it was only possible to observe both points of tangency of the inclined lines with the disk of the planet on one side of the vertical lines, the elimination of the effect of an error in the position angle of the line x^ does not here take place. Care was taken, however, to make the setting for the zero of position as exact as possible. The followins: results were obtained. TABLE X. Date. Instrument. i = 10° t = 20° t = 30° i = 40° i = 45° Means. 1882. Dec. 13-14 Dec. 14-15 Dec. 24-25 Dec. 26-27 1883. Jan. 1-2 V E. Equatorial < West Equatorial // 17.73 // 17.96 16.75 16.66 16.90 17.66 16.45 16.58 17.33 17.47 • • • • II 16.49 16.14 17.29 // 16.56 16.46 17.12 17.47 17.73 If these observations can be trusted we may conclude : — («.) That the difference in the value of the diameter at the dis- tance unity, due to irradiation on Dec. 6, and on the days immediately following, is not far from 0"A. (b.) That up to a certain point this difference increases with the angular increase in the distance of the planet from the sun. This in- crease, however, is probably not quite as great as the observations seem to indicate. On Dec. 26 and Jan. 1 the atmospheric conditions were not favorable to good observations. Report by S. C. Chandler, Jr. The following determinations of the diameter of Venus during the transit on Dec. 6, 1882, were made by Professor Rogers's plan of transits over inclined lines, with the "West Equatorial. The telescope had been prepared for solar observation by the maker, Mr. John Clacey, by smoking the front of the crown and the back of the flint lens of the object-glass ; a process which he finds affords a better effect than a silver film, the image being sharper and the effect of contrast with the sky more agreeable. The result in the present instance was completely satisfactory. The obscuration produced by the double smoke film was sufficient to render a shade glass unnecessary with the power used, which was about 180 diameters. 36 PROCEEDINGS OF THE AMERICAN ACADEMY The scheme of observation, and the plate, were the same as used by Professor Rogers. The transits were taken in sets consisting of an equal number of contacts of both limbs with lines ruled at equal and contrary angles with the middle transit lines, thus eliminating the error of the zero of position. The formula of reduction follows simply from equation (2) hereafter given. Thus, if we call A^j, A/g, the dif- ferences of the observed times of transit of opposite limbs, for the angles p and — p, respectively, we get D =: Y COS 8 COS p (A^i -f LQ. The corrections for proper motion and differential refraction are so far within the uncertainty of observation, in their effect on the con- cluded diameter, that they have been neglected. Table XI. gives the value of the observed diameter and the number of observations in each pair of sets arranged according to the position angle of the lines em- ployed. Table XII. gives the means, taken with reference to the number of observations, of the results of Table XI. TABLE XI. P-W p — m° p-60'^ p-bQ'^ p = 45° p = 0° II II II II // II 59.66 6 61.61 17 62.07 6 63.73 6 62.47 6 61.50 6 62.36 6 59.17 4 61.03 6 61.28 6 61.13 6 60.87 6 61.30 6 63.11 6 61.03 6 62.76 6 62.76 6 61.03 17 61.06 17 62.18 17 61.03 4 60.67 4 62.51 4 59.91 61.23 6 6 61.64 8 TABLE XIL Position Angle ObserTed No of Diameter reduced of Lines. Diameter. Observations. to Mean Distance. // // 80° 61.01 12 10 14 70° 61.09 27 16.16 60° 61.41 45 16.24 50° 68.73 6 16.85 45° 62.33 45 16.49 0° Mean 62.09 59 194 16.42 61.83 16.35 The mean value of the diameter from the 194 observations is, D= 16''.35. OF ARTS AND SCIENCES. 37 It is uoteworthy that the results over the different lines, with the exception of that at 50°, which is based on only 6 observations, all give values less than that of 1G".61, adopted in the Berlin Jahrbuch, Nautical Almanac, and Connaissauce des Temps, and that the lines of greatest position angle, which by this method would be expected to afford the most accurate results, give the smallest values of the series. It appears to me that the method of Professor Rogers is not limited, in its application to the interior planets, to their transits over the sun's disk, or to times when the conditions permit the whole disk to be seen ; but that it may, by an appropriate construction of the plate and arrangement of the observations, be employed at any time when they are near inferior conjunction, and that determinations both before and after conjunction will eliminate any errors peculiar to each elongation. Let p be the position angle, counted from an assumed zero, of a line on the plate drawn from some point taken as a centre; the true position angle being p -\- Ap. Let D and 8 be the diameter and declination of the planet ; AS the difference of declination from the centre of the plate when it passes north, and A'S when it passes south of that centre ; and t and t\ the corresponding observed times when the planet's limb in its diurnal motion is tangent to the line. Then in the triangle formed by the planet's centre, the intersection of its path with the line, and the observed point of taugency, the distance be- tween the first two points is, \D sec {p -\- A;?) = \D sec p -{- \D tan p sec p Aj» where, A/) being small, the terms involving its squares are neglected. If we imagine a line drawn from the centre of the plate at the angle p from the true position zero, we have, from the triangle formed by the actual and imaginary lines and the portion of the path of the planet's centre between them, the length of the intercepted path : AS A^ secj9 sec {p -\- A/)) = AS Ap sec^jo If now we call T the time when the centre of the planet is on this imaginary line when the planet passes north, and T' the time for a corresponding position when the planet passes south of the centre, we have the general equations : T=:t -\- ^ \±\D&ecp± \D tan p sec p Ap -f- ^^ soc^p ^p\ (1) T'=.t' -\- r^ r =F |Z) sec p :p ^D tan p sec^ A/) -|- A'S sec^^ Ajo J 38 PROCEEDINGS OP THE AMERICAN ACADEMY p being reckoned as usual from 0° to 360° in the direction n. f. s. p. ; the upper sign being used for the preceding, and the lower sign for the following limb. Let #1 and t^ be the observed times when the planet, passing north of the centre, has either limb tangent to lines at the angles p and — p from the assumed zero. Then the 1st equation of (1) gives : Tj^z=t^-\- — ± \D seep ± \D tan jo sec jo Ap -|- AS sec^jo Ajo | (2) Tj = #2 + rE ^ ± \D seep =F iZ) tan p sec p A/> -|- AS sec^jo A^? | If ^0 be the corresponding time for a third line drawn through the intersection of the other two and bisecting the angle between them, we shall have p = 0, and But we have T^ — ^o = ^o — ^i- Hence, putting t =: ^^ ~l~ 'i — ^ — T (10) Ap = -rj-z,eoip + OF ARTS AND SCIENCES. 39 The last term in equation (9) disappears when the planet passes at equal distances north and south, and in general is inappreciable ex- cept when the error of i^osition zero is large, or when the planet passes at very unequal distances north or south of the centre, which in practice need never occur. Equation (9) consequently permits the determination of the diameter by observations on one limb only. As has been remarked, observations on the preceding limb before inferior conjunction, and on the following limb after it, may be expected to eliminate errors pe- culiar to the elongation. It should be remarked that the quantity cot p cot \ p becomes unity for p = 60°, and for larger angles rapidly increases. In general the advantageous application of the method requires the use of lines at greater position angles than 60°. In what precedes it has been assumed that the line corresponding to the time t^ bisects the angle formed by the others, and also passes through their intersection. In ruling the plates for the observations of the diameter during the transit of Yenus, these conditions may possibly not have been exactly fulfilled ; since, as they did not affect the observations then contemplated. Professor Rogers did not especially attend to those points in the preparation of the plates. Any such errors may, however, be eliminated. Thus, if we put a = the dis- tance between the transit line on the plate from an imaginary line parallel to it passing through the point of intersection of the inclined lines, and A^ the inclination to a line bisecting the angle of the in- clined lines, equation (3) becomes, ^» = '«+ IT^ [± i^ + ^^ i^P + ^i) +-] and equation (9), Z> = =F V- cos 8 cot jo cot 1 JO Ft -f t' — 2 a — 2 (AS — A'S) At Since Ai changes sign by turning the plate 180° in position angle, and a changes sign by turning the other side of the plate toward the eye these sources of error may be determined or eliminated by arran- ging the observations with appropriate reversals. To exemplify partially the use of this method, I avail myself of some observations of the following limb of Venus, on various days succeeding the recent transit, by Professor Rogers and myself. As 40 PROCEEDINGS OF THE AMERICAN ACADEMY these were not arranged with a view to eliminate the possible errors involved in a and Az", as it is the intention to do in the future, the results cannot be considered as having other than an illustrative value. The angle, 60°, was less than should properly be used for advan- tageous results, and the record gives no means of knowing in which series the plate was in the direct, and in which it was in the reversed position. The results are as follows. TABLE XIII. Date. Number of Observations Diameter. Observer. 1882 Dec. 13-14 " 14-15 " 24-25 « a " 26-27 25 20 22 21 17 // 16.39 17.06 17.58 18.30 17.89 W. A. R. H t< s. c. c. (1 These results are of interest for comparison with those obtained on the same days by Professor Rogers from different observations. The series is not sufficient to determine the " irradiation constant." In conclusion, the results may be summarized as follows : — 1. Observations of the four contacts by six observers. 2. The determination, by a photometer esiDecially devised for the purpose, of the relative amounts of light received from the disk of Venus, from the sky near the sun's edge, and from the sun's centre. Denoting the last amount by 100.0, that received from Venus was 1.6, and that received from the sky 7.5. Contrary to expectation, Venus was thus shown to be distinctly darker than the adjacent sky, and this result was confirmed by direct observation. 3. The spectroscojoic observations. These gave negative results, and showed that no marked absorption was caused by the atmosjihere of Venus. 4. A careful determination of the diameter of Venus by a method not previously attempted, and the suggestion of an application of this method to planets when both limbs cannot be observed. The result obtained by Professor Rogers was 16".10 from transits over inclined lines, and that obtained by Mr. Chandler was 1 6".35, which would be reduced 0".02 by using only the transits over inclined lines. OP ARTS AND SCIENCES. 41 HI. CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF HAR- VARD COLLEGE* 1. ON CERTAIN SUBSTITUTED ACRYLIC AND PROPIONIC ACIDS. By C. F. Mabery and F. C. Robinson. Presented January 10th, 1883. /S-DiBROMACRTLic acid, unlike the isomeric a-acid, will not unite with bromine at ordinary temperatures. After standing twelve days, a solution of the acid with bromine in chloroform was not bleached, and by slow evaporation of the solution crystals were deposited which melted at SG'^, the melting-point of dibromacrylic acid. At 100*^ the addition of bromine was easily accomplished. When pure dibrom- acrylic acid was heated in a closed tube with undiluted bromine in slight excess over the calculated amount for one or two hours, tetrabrom- propiouic acid was formed in nearly the theoretical quantity. The excess of bromine was removed by evaporation from the crude product, which was purified by pressure in filter-paper and crystallization from carbonic disuljihide and chloroform. From a concentrated solution in carbonic disulphide it crystallizes by slow evaporation in oblique prisms. It is somewhat soluble in hot water, from which it separates at first as an oil ; but on further cooling it crystallizes in thick prisms. On boil- ing an aqueous solution of the acid, it is rapidly decomposed, imparting a milky appearance to the solution, probably from the formation of tri- bromethylen. Melting point 118°-120°. Its composition was deter- mined by the following analyses. I. 0.2149 grm. of the substance gave by Carius's method 0.4169 grm. AgBr. II. 0.1639 grm. of the substance gave 0.3145 grm. AgBr. III. 0.8899 grm. of the substance gave 0.2857 grm. CO2 and 0.0478 grm. H.^0. * This work was done in connection with the summer course of instruction in chemistry for 1882. — C. F. M. 42 PROCEEDINGS OP THE AMERICAN ACADEMY Ci ilculated for C3II2B lr,0,. Pound. I. II. III. Br 82.04 82.55 81.76 C 9.23 8.76 H .51 .60 The barium, calcium, and potassium salts of this acid were made and analyzed. We were unable to prepare the silver salt in a form sufficiently pure for analysis. Argentic bromide began to separate even in the dark as soon as the salt was formed. Baric tetrabrompropionate, Ba(C3HBr^02)2 . \ H^O ? To prepare this salt, a solution of the acid was saturated with baric carbonate, filtered, and allowed to evaporate spontaneously at the ordinary tem- perature. From the concentrated solution the salt crystallized in flat prisms, which were very soluble in water. In aqueous solution the salt is per- manent when exposed to the air at ordinary temperatures, but it is rapidly decomposed by heat. In the following determinations of the water of crystallization, in each case the salt was dried to a constant weight in the air and then heated until constant at 80°. I. 1.2784 grms. of the air-dried salt lost 0.0090 grm. Ylf> at 80°. 11. 1.0862 grms. of the air-dried salt lost 0.0081 grm. \\p at 80°. III. 1.2403 grms. of the air-dried salt lost 0.0087 grm. HgO at 80°. Calculated for Ba(C3HBr402)2 . * HjO. Found. I. II. III. H^O .96 .7 .7 .75 1.0762 grms. of the salt dried at 80° gave 0.2747 grm. BaSO^. Calculated for Ba(C3HBri02)2. Found. Ba 14.97 • 15.01 Calcium tetrahrompropionate, Ca(CgHBr^0o)2 • H„0. When an aque- ous solution of the acid was neutralized with calcic carbonate in the cold and evaporated at the ordinary temperature, the calcium salt sep- arated from the concentrated solution in clusters of miscroscopic prisms, which were much less soluble in water than the corresponding barium salt. The air-dried salt contained one molecule of water of crystalliza- tion, which was given up at 80°. I. 1.1413 grms. of the air-dried salt gave 0.0215 grm. H.O at 80°. II. 1.1087 grms. of the air-dried salt gave 0.0205 grm. H.O at 80°. III. 1.0948 grms. of the anhydrous salt gave on ignition with HgSO^ 0.1895 grm. CaSO^. OP ARTS AND SCIENCES. 43 Calculated for CaCCaUBriOolj . II2O. Found. I. II. H,0 2.15 1.88 1.85 Calculated for CaCCaHBrjOjjj. Found. Ca 4.89 5.09 Potassic tetrabrompropionate, KCgHBr^O, . 2 HgO. By the action of an aqueous solution of potassic carbonate on the acid a neutral solution was obtained, from which by spontaneous evaporation the potassium salt was deposited in the form of clustered needles. This salt is very solu- ble in water and permanent in the air at ordinary temperatures, but rapidly decomposed by heat. The air-dried salt gave up its water of crystallization over sulphuric acid. I. 1,1571 grms. of the air-dried salt lost over HgSO^ 0.0882 grm. II.O. II. 1.1304 grms. of the air-dried salt lost over HgSO^ 0.0858 grm. H.O. III. 1.0354 grms. of the anhydrous salt gave on ignition with HgSO^ 0.2165 grm. K^SO^. Calculated for KC3HBr402 . 2 HjO. Found. I. II. H^O 7.76 7.62 7.59 Calculated for KCsHBr^O,. Found. K 9.14 9.39 When heated in aqueous solution the barium salt was easily decom- posed with the separation of an oil which distilled readily with steam. Since tribromethylen was the only substituted hydrocarbon that could be derived from tetrabrompropionic acid under these conditions, it was converted directly into pent^bromethan. The salt was distilled with an excess of baric hydrate, and the oily distillate absorbed by bromine water. A solid residue was left after evaporation of the excess of bromine, which melted at 53° when purified by crystallization from alcohol, and on analysis gave the required percentage of bromine. 0.0918 grm. of the substance gave 0.2041 grm. AgBr. Calculated for C^HBrg. Found. Br 94.12 94.61 Carbonic dioxide was evolved in this decomposition, and the retort residue contained baric bromide in large quantity. It may therefore be expressed by the following equation : Ba(C3HBr,02)2 = 2 C^HBrg + BaBrg + 2 CO.. 44 PROCEEDINGS OF THE AMERICAN ACADEMY On standing with an alcoholic solution of potassic hydrate, a molecule of bydi'obromic acid was eliminated from the acid with the formation of tribromacrylic acid, according to the equation : CgH^Br.O^ + 2 KOH = KCsBrgO^ + KBr + Hp. Tribromacrylic acid was recognized by its melting point, 118°, and by its crystalline form. If the structure of /3-dibromacrylic acid* is represented by the formula, — CBr^ II CH I COOH the bromine-addition product would have the form, — CBr3 I CHBr I COOH The above statement concerning the behavior of /3-dibromacrylic acid towards bromine, holds true with regard to chlorine. Although no action takes place at ordinary temperatures, when chlorine is passed through the melted acid the addition-product is formed without diffi- culty. The resulting dichlordibrompropionic acid will be submitted to further examination. We have also tried the action of hydrobromic acid upon y8-dibrom- acrylic acid, but as yet our results are as unsatisfactory as those of Fittig and Petri. f The product melted at about 53° and gave a percentage of bromine which showed that it contained much unaltered dibromacrylic acid. Nevertheless, by prolonged heating, we hope to obtain the tribrompropionic acid in a form sufficiently pure to enable us to study its properties. Several attempts were made to obtain an addition-product by the action of bromine monochloride on brompropiolic acid. A substance was formed which melted quite constant at 110°-112° ; but the results of analyses indicated that it was a mixture of the chlorine and bromine addition-products. In one experiment a product was obtained which melted at 102°-105°, and the percentage of bromine was very con- * H. B. Hill, these Proceedings, Vol. XVII. p. 153. t Ann. der Chem., cxcv. 73. OF ARTS AND SCIENCES. 45 siderably increased. There is little doubt that the addition would take place, provided the bromine monochloride could be obtained in a state of purity under conditions necessary to form addition-products. Wlieu brompropiolic acid is dissolved in chloroform saturated at 0'^ with chlorine, and allowed to stand for some time, the chlorine is ab- sorbed with the formation of bromdichloracrylic acid. 2. ON THE DECOMPOSITION OF CHLORTRIBROMPROPIONIC ACID BY ALKALINE HYDRATES. By C. F. Mabery. In a previous paper by H. C. Weber and myself,* some experiments were mentioned in which we had attempted to determine the decompo- sition-products of chlortribrompropionic acid. Although our results were not entirely satisfactory, we were unable to verify them on account of the limited time at our disposal. Since the necessary material could be obtained without difficulty, it seemed worth while to define this reaction with greater precision. This work was undertaken by Mr. R. D. "Wilson, who found that on prolonged heating with baric hydrate in aqueous solution chlortribrompropionic acid was completely decomposed, according to the equation, — Ba(C3HClBr„02)2 = 2 aHClBr, -j- BaBr, + 2 CO^. For ideutification the volatile product of the distillation was converted into chlortetrabromethan. It was caught in bromine water, the excess of bromine allowed to evaporate, and the oil which separated cooled to 0°. The solid thus obtained was purified by crystallization from alcohol, and its composition determined by analysis. 0.1556 grm. of the substance gave 0.3657 grm. AgBr -f- AgCl. Calculated for CinClBrj. Found. CI + 4 Br 93.42 93.30 Since this substance melted at 33°, it was probably identical with the chlortetrabromethan, melting point 32°-33", obtained by Wallach and Bischof,t from the decomposition of yS-dichloracrylic acid, CCI2 = CH — COOH. * These Proceedings, Vol. XVII. p. 209. t Ann. der Cliem., cciii. 89. 46 PROCEEDINGS OF THE AMERICAN ACADEMY This acid gave chloracetylen, CCl = CH, which by the addition of bromine formed chlortetrabroraethan, — CHBr^ I CClBr, By the action of potassic hydrate in alcoholic solution upon chlortri- brompropionic acid, the elements of hydrochloric acid were eliminated, with the formation in small quantity of tribromacrylic acid. From the evident analogy between chlorbromacrylic acid, from which chlortribrompropionic was made, and ^-dibromacrylic acid, the structure of chlorbromacrylic acid * is probably, — CBrCl II CH I COOH. Chlortribrompropionic acid would then have the form, — CBr^Cl I CHBr I COOH. * H. B. Hill, these Proceedings, Vol. XVII. p. 153. OP ARTS AND SCIENCES. 47 lY. CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF HAR- VARD COLLEGE. ON THE PRODUCTS OF THE DRY DISTILLATION OF WOOD AT LOW TEMPERATURES. By Charles F. Mabery. Presented January 10th, 1883. In the manufacture of acetic acid by the dry distillation of wood at low temperatures, as it is conducted by Dr. E. R. Squibb, of Brooklyn, N. Y., an oil heavier than water collects during the distillation in con- siderable quantities. Upon examination, Professor H. B. Hill* found that this oil contained a large percentage of furfurol, and that by the action of alkalies upon it a small quantity of pyrosanthin was formed. Further information concerning the more volatile products of the dis- tillation therefore seemed desirable ; and since different portions of the crude methyl alcohol were kindly jilaced at my disposal by Dr. Squibb, I undertook an examination of its constituents. The composition of crude wood spirit has frequently been made the subject of investigation within a few years. Beside methyl alcohol and methyl acetate, which constitute the greater part of the product in the ordinary process of distillation, acetic aldehyde, acetic acid, aceton, acetal, dimethylacetal, methylethylketone, and allyl alcohol have been found in smaller quantities. Traces of the higher ketones have been detected in the less volatile portions, and in the high boiling oils small quantities of the aromatic hydrocarbons toluol, xylol, and curaol. A study of the product under consideration shows that it has essen- tially the same composition. Its distinctive characteristic consists in different quantitative proportions of several constituents, probably due to the low temperature at which the first distillation was conducted. * These Proceedings, Vol. XVI. p. 192. 48 PROCEEDINGS OP THE AMERICAN ACADEMY It also contains methyl formiate, which has not hitherto been recog- nized as a constituent of wood spirit.* Three portions were selected for examination. The first portion (a) was collected at the beginning of the distillation, the second [b) after several hundred gallons had distilled, and the third (c) when the distillation of methyl alcohol was well advanced. Each portion was bright yellow in color, and from (a) and (b) a sharp penetrating odor Avas emitted. Since various attempts to remove the small percentage of water by desiccation were unsuccessful, the product was fractional as it was received. Anhydrous cujiric sulphate absorbed only a small fraction of the water, even after standing several weeks, and fused potassic cai-bonate produced a decomposition, as shown by the color changing to a dark brown, with the formation of a yellow precipitate on standing. In the fractional distillation very satisfactory results were obtained, botli in the separation of the different fractions and in economy of time, by the use of Hempel'sf device for condensation. The following table contains the results of the tenth fraction of each portion expressed in percentages. To insure a more complete con- (a. ) (^0 (c. ) Temperatures. Percentages. Temperatures. Percentages. Temperatures. Percentages. 20° -25° 2.1 25° -30° 1.5 30° -40° 1. 40° -50° 1. 50° - 52° 1.6 52° -54° 0.3 Below 54° 3. 54° -56° 62.8 74.1 56° -60° 7.3 3.6 Below 63° 4.7 Above 60° 6.7 60°- 70° 3.7 63° -65° 2.5 Above 70° 0.9 65° -68° Above 68° 57.9 31.4 Loss 6.7 5.7 3.5 densation of the volatile products in (a), after passing through a Lie- big's condenser, the distillate was cooled by a freezing mixture. Con- siderable gas escaped condensation at the beginning of the distillation, but it was found to consist chiefly of carbonic dioxide. * Kramer and Grodzky succeeded in isolating formic acid in small quantity from tlie oil obtained by adding sulphuric acid to the mother liquor of Holzessig, after removing the greater part of the acetic acid as sodic acetate. (Berichte deutsch. chem. Gesellsch., 1878, 1356.) t Zeitschrift fur Anal. Chem., xx. 502. OP ARTS AND SCIENCES. 49 The residue of the distillation in each case contained the greater part of the water, though in (a) it consisted chiefly of methyl alcohol. In (b) approximately one half of the residue consisted of ihe higher boiling oils, and in (c) it was composed beside water of furfurol and an oil of low specific gravity. The constituents of the various fractions will be described in detail. Acetic Aldehyde. In (a) the fraction that came over between 20° and 25° was very soluble in water, and it gave the penetrating odor characteristic of acetic aldehyde. This substance was also recognized in that portion of (b) which distilled below 54°, and in the fraction below 63° in (c). It formed a compound with acid sodic sulphite, crystallizing in flat prisms, which were very soluble in water. In order to estab- lish its identity, an aqueous solution of the fraction 20° - 25° was boiled with an excess of silver oxide, filtered, and concentrated by evaporation. On cooling, silver acetate crystallized in characteristic forms, which, on analysis, gave the required percentage of silver. I. 0.2222 grm. of the substance gave on ignition 0.1432 grm. Ag. II. 0.3167 grm. of the substance gave on ignition 0.2050 grm. Ag. Calculated for AgC^Ufii- Found. I. II, 64.68 64.43 64.' Ag According to Kramer and Grodzky,* in the manufacture of wood spirit acetic aldehyde may usually be found in the first portions of the distillate. It is rarely present in large quantities, since, as they assert, the greater part is converted into dimetbylacetal during the distillation. Methyl Formiate. This substance was isolated from the fractions 25° - 30° and 30° - 40°. On the addition of water an oil separated, which was purified by frac- tional distillation. There were thus obtained 8 grms. of a substance which distilled between 30° and 35°. It was saponified by boiling with an excess of plumbic hydrate, and the composition of the plumbic formiate determined by analysis. * Berichte deutsch. chem. Gesellsch., 1876, 1920. VOL. xviii. (n. 8. X.) 4 60 PROCEEDINGS OP THE AMERICAN ACADEMY I. 0.5214 grm. of the substance dried over HjSO^ gave on ignition with HjSO^ 0.5296 grm. PbSO^. II. 0.2900 grm. of the substance gave 0.2960 grm. PbSO^. Calculated for PbCCHOjjj. Found. I. IT. Pb 69.69 69.42 69.71 The presence of formic acid, and the quantity of the distillate which collected between 40° - 50°, suggested the possible formation of me- thylal. This fraction was therefore treated with an equal volume of water, and the oil which separated boiled with plumbic hydrate to decompose the methyl formiate. After drying with fused calcic chloride, the residue distilled above 50°. In another attempt to iso- late methylal, 2,000 grms. of (a) were fractioned, and the distillate below 50° examined according to Dancer's method* for the sepa- ration of dimethylacetal. As in the first experiment, the residue distilled at a temperature far above the boiling point of methylal, which seemed to indicate that this substance could not have been formed in any appreciable quantity. Methyl Acetate. Since the fractions 50° -52° and 52° -54° gave reactions for alde- hyde and acetone, they were evidently a mixture of these substances with methyl acetate. The greater part of the methyl acetate in (a) and {])) was collected in the fraction 54° -56°, which boiled constant at 54°. 5 -55°. 5 (Bar. 769.5 mm.). To determine approximately the percentage of methyl alcohol in this fraction, 655 grms. were saponi- fied with potassic hydrate, and distilled. After drying with fused potassic carbonate and distilling off the methyl alcohol, there were obtained 255 grms., which came over between 66° and 67° (Bar. 769.5 mm.), or 92 per cent, of the amount required from the weight taken of methyl acetate. In repeating this saponification in a dilute solution of methyl acetate, with a potassic hydrate solution of known strength, the excess of alkali was titrated with standard sulphuric acid, and the percentage of methyl acetate calculated from the amount of potassic hydrate required to decompose it. This method gave 99.2 per cent of pure methyl acetate. * Ann. Chem. Pharm., cxxxii. 240. OF ARTS AND SCIENCES. 51 Methyl Alcohol. Although a small amount of methyl alcohol was contained in the hit^her fractions of (a) and (6), it was evidently condensed foi' the most part in the fraction 65° - 68° of {c). This fraction was slightly yellow in color, but no further attempts were made to determine its purity than an estimation of the percentage of acetone, which will presently be described. Dimethylacetal. The formation of dimethylacetal during the dry distillation of wood for the preparation of methyl alcohol was not observed until 1864, probably because of the small difference between its boiling point (64°) and that of methyl alcohol. After removing the methyl alcohol and acetone, Dancer* succeeded in separating a product which proved to be identical with dimethylacetal, made by heating methyl alcohol with acetic aldehyde. Kramer and Grodzkyf state that it has since been recognized as a constant constituent of wood spirit. Its formation is probably due to the high temperature of the distillation, which enables the aldehyde to act upon the methyl alcohol. From the large per- centage of aldehyde in the product under consideration, it would seem that this reaction had not taken place to any extent. Since an exami- nation of the distillate below 65° in (c) failed to reveal the presence of dimethylacetal, a second portion of 2,000 grms. was fractioned, the lower fraction saponified and distilled over calcic oxide. The small amount of residue left after removing the methyl alcohol with calcic chloride, distilled at 57° -58°, was readily miscible with water, and its reactions in general were characteristic of acetone. Dimethyl- acetal could not therefore have been formed in quantity sufficient for identification. Acetone. The first quantitative experiments on the influence of acetone upon the commercial value of methyl alcohol were made by Kramer and Grodzky.l They determined the quantity of dimethylaniline which could be obtained from a given weight of pure methyl alcohol, and also * Ann. Chem. Pharm., cxxxii. 240. t Berichte deutsch. chem. Gesellscli., 1876, 1920. X Ibid., 1880, 1005. 62 PROCEEDINGS OF THE AMERICAN ACADEMY from methyl alcohol containing different amounts of acetone. Their results seemed to sliow that the yield was very considerably dimin- ished if the quantity of acetone exceeded one per cent. Since crude wood spirit always contains a much higher percentage, it must be specially purified for the preparation of dimethylaniline. Various methods, dependent either upon the physical or the chemical properties of methyl alcohol, have been proposed for testing its purity. Krell * suggested a determination of the amount of methyl iodide which could be obtained by treating a given quantity of the alcohol with phosphorous iodide. In the hands of a skilful analyst the per- centage of methyl alcohol may be accurately determined by this method ; but, as Kramer remarked, it does not account for the nature of the impurities, and it is not sufficiently expeditious. To overcome these objections, Kramer f took advantage of the formation of iodo- form from acetone. In his modification of Lieben's reaction, J the for- mation of iodoform from ethyl alcohol and acetic acid is avoided, and acetic acid is only partially decomposed. According to Kramer's method a mixture of 10 c.c. of a normal sodic hydrate solution, 5 c.c. of a double-normal iodine solution, and 1 c.c. of the alcohol to be tested, is shaken in a graduated cylinder with 10 c.c. of ether. 5 c.c. of the ether solution are withdrawn with a pipette, evaporated on a weighed watch-glass, and the residue we'ghed after drying in a warm desiccator. To obtain the weight of acetone in Ic.c. of the alcohol, the weight of iodoform is multiplied by ,28 if there are 9.5 c.c. of the ether solution. The percentage of acetone in several fractions, as determined by this method, is given in the following table.§ Since in each determination from 9 c.c. of the ether solution 5 c.c. were evaporated, the weight of iodoform was multiplied by .27 for the weight of acetone. * Berichte deutsch. chem. Gesellsch., 1873, 1310. t Ibid., 1880, 1000. t Ann. Cliem. Pliarm., Suppl. VII., ccxviii. 377. § In several instances the fraction was boiled with silver oxide before test- ing for acetone ; but this seemed to have no appreciable effect on the quantity of acetone indicated by the iodoform reaction. OF ARTS AND SCIENCES. 53 Fraction treated. Specific Gravity. Weight of Iodoform. Weight of Acetone. Percentage of Acetone. 54° -56° (a) Below 54° (b) 54° -50° (b) Methyl Alcohol from 54° -56° (6) 50° -60° (b) 650-68°(c) 0.935 0.930 0.935 0.805 0.830 0.820 0.0359 0.0648 0.0638 0.0914 0.0802 0.1037 0.0097 0.0175 0.0182 0.0247 0.0217 0.0280 1.04 1.88 1.95 3.07 2.66 3.41 Although the quantity of acetone in the product under consideration is sufficiently large to render further purification necessary, it is evidently much smaller than is usually observed in commercial wood spirit. Allyl Alcohol. The occurrence of allyl alcohol as a product of the distillation of wood was first mentioned by Aronlieim,* and soon afterward Kramer and Grodzkyt stated that small quantities of it may always be found in the higher fractions. In examining the aqueous part of the residue in (c) for this substance, after removing the water, a small amount of an oil was left, with a boiling point somewhat higher than that of allyl alcohol. It absorbed bromine readily, Avith the formation of a product which boiled much too low for dibromallyl alcohol, and oxidation with nitric acid gave only oxalic acid. Since from the results of Kramer and Grodzky it is usually present in wood spirit, in quantity not ex- ceeding two tenths of one per cent, it is evidently possible that the small amount contained in 2,000 grms. might escape observation. Although the determined with my attempts to i the less volatile has already been of an oil heavier composed chiefly High Boiling Oils. composition of the higher boiling fractions was not sufficiently desirable accuracy, a brief description of solate substances which have already been found in portions of wood spirit may have some interest. It mentioned, that beside water these fractions consisted and an oil lighter than water. The heavier oil was of furfurol, though, as well as the water and lighter * Bericlite deutsch. chem. Gesellsch., 1874, 1381. t Ibid., 1874, 1492. 54 PROCEEDINGS OF THE AMERICAN ACADEMY oil, it contained pyroxanthine in small quantity, which could be pre- cipitated by the addition of sodic hydrate. 2,000 grms. of (c) gave 45 grms. of the lighter oil, which was pale yellow when freshly distilled, but it turned dark brown on standing. In attempting to fraction it, a constant boiling point could not be obtained between 75° and 200°. About two grms. of a substance distilled between 75° and 85°, which formed crystals with acid sodic sulphite, indicating the presence of methylethylketone ; but the quantity obtained was insufficient for analysis. The penetrating odor observed in the distillate between 95° and 105° was characteristic of the allyl compounds. It was possibly due to a trace of allyl acetate, since after heating with sodic hydrate and neutralizing the solution a qualitative test for acetic acid was obtained with ferric chloride. This oil distilled for the most part be- tween 150° and 200°. Finding, however, that a constant boiling- point could not be obtained with the supply of substance at my com- mand, I did not consider it worth while to fraction the amount of material necessary to obtain the oil in large quantity. The important characters of this product, as they have appeared in the course of the preceding examination, may be summarized as follows : — 1. The high percentage of aldehyde in (a), of methyl acetate in (a) and (b), and of methyl alcohol in (c). 2. Presence of methyl formiate. 3. Absence of dimethylacetal. 4. Small percentage of acetone. 5. General purity of the product. OF ARTS AND SCIENCES. 55 CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF HARVARD COLLEGE. A SIMPLE METHOD OF CORRECTING THE WEIGHT OF A BODY FOR THE BUOYANCY OF THE ATMOS- PHERE WHEN THE VOLUME IS UNKNOWN. By Josiah Parsons Cooke. Presented May 9th, 1883. It is a familiar fact, that, in the usual method of accurate weighing, the buoyancy of the atmosphere produces a sensible effect, whenever the volume of the load differs materially from that of the equipoise. But, as in all the ordinary processes of chemical analysis, the analyst deals solely with relative weights, the presence of a perfectly dry atmosphere does not influence his results, unless the conditions of temperature and pressure have changed between the successive weighings ; and even then the effect is insignificant in most cases. Still, when the volume of the vessel weighed is considerable, differing from that of the weights by as little even as twenty-five cubic centimeters (for example, in weighing the absorption tubes used in "organic analysis "), the error caused by variations in the density of the atmosphere may be sufficient seriously to impair the accuracy of the result. In weighing large vessels — as in determining the density of a gas — the effect of any variation of buoyancy is eliminated by the well- known methods of calculating the results ; but the formulas usually given for that purpose involve as known quantities the volume of the vessel, the volume of the weights, the density of the air under the standard conditions, as well as the temperature and pressure at the time of the several observations ; and, since the calculations are somewhat complex, and the required data not always readily obtained, the for- mulas are seldom applied unless the volume of the load is quite large. Moreover, in these formulas the effect of each factor cannot readily 56 PROCEEDINGS OF THE AMERICAN ACADEMY be traced, and most analysts are probably not aware of the extent to which their weighings may be influenced by changes in the density of the air due to variations of temperature and pressure. In seeking to fix the weights of certain absorption tubes, (in connection with my work on the revision of the atomic weights,) I have been led to a method of correcting the weights of such tubes for variations of buoy- ancy ; which, while it does not involve the determination of any data except the temperature and tension of the air in the balance-case, and is as simple in its application as the calibration of a flask, also gives a clear conception of the effect of each variable on the weight. It is assumed that the air of the balance-case is dry ; and with one of Becker's balances I have not been able to trace any effect on the weight of a glass vessel from variations of hygrometric condition, when two open dishes of sulphuric acid (three inches in diameter) were kept in the case, which has a volume of about thirty-seven cubic decimeters. Under such circumstances, the only causes which sensibly modify the weight of a small glass vessel (like a closed potash bulb-tube) are the variations of temperature and pressure. The relative effect of these two variables will appear from the following considerations, which suggested the method I am to describe. If we assume thirty inches of mercury as the standard of barometric pressure, it is obvious that the variation of each tenth of an inch from this standard will determine a change of ^J^ in the resultant effect of the buoyancy of the air on the load and its equipoise. Again, if we assume 27° C. as our standard of temperature, — that is, 300° on the so-called '• absolute scale," — then, according to the law of Charles, the variation of each degree from this point will also cause a change of -^^■Q in the same resultant. In other words, counting from these standards, a variation of one degree in the Centigrade thermometer indicates the same effect on the density of the air, and therefore on its buoyancy, as the change of ^ of an inch in the mercurial barometer. In our climate the barometer changes slowly, and its fluctuations do not ordinarily exceed one inch. On the other hand, the balances in our chemical laboratories are liable to rapid changes of temperature, which often exceed twenty degrees, the equivalent of two inches. Hence, of the two variables the temperature is by far the more important. If we select the two standards of temperature and tension here assumed, we can easily correct for temperature by simply adding to the observed height of the barometer (in tenths of an inch) the difference between 27° C. and the temperature observed. — Of course the correction becomes negative if the temperature exceeds OF ARTS AND SCIENCES. 57 27° C. — Having thus eliminated the effect of temperature, we can (after taking a few weighings under as great a variation of temperature and pressure as we can command) easily find the difference of weight which corresponds to a variation of ^ of an inch in the barometer, and we thus obtain a constant for the vessel (or other object weighed) by means of which we can rapidly reduce the weights obtained to the standard of thirty inches' barometric pressure, having previously re- duced them to the standard of 27'' C. for temperature. The weights, having now been corrected for buoyancy, can be compared ; and, although the standards assumed may be as unusual in their associa- tion as is one of them in its value, they are as legitimate as any others, and will be found in practice more convenient. To apply this method of reduction we simply leave the load equi- poised on the balance, shifting the rider with the varying weight, and noting the corresponding temperatures and pressures, until a sufficient difference has been observed ; and a difference corresponding to 20° C, or two inches of mercury, is adequate in most cases. The process corresponds to calibrating a flask, and the constant, once obtained, can be afterwards used for the same vessel, unless the weight of its con- tents is materially altered. The following examples will show the application of the method. In each case the load was a closed absorption tube of peculiarly irregular construction, but not much larger in volume than those generally used in organic analysis. We give in the accompanying tables, first, the date ; secondly, the observed weight ; thirdly, the temperature of the balance-case ; and, fourthly, the height of the barometer at the time of weighing in tenths of an inch. These are the observed data. In the fifth column we give the reduced heights of the barometer for 27° C, and these values are obtained by simply subtracting the observed temperatures from 27°, and adding the re- mainders to the observed barometric heights. Below the table we print in each case the largest weight observed over the smallest weight observed, and on the same lines the corresponding reduced barometric heights. Dividing now the difference of weight in milli- grammes by the difference of height in tenths of an inch, we obtain the value last given, which we have called the*" constant." "With this constant we can very rapidly reduce all the weights to the common standard of thirty inches, and this we do by multiplying the difference between 300 and the reduced barometric heights by this constant, and adding or subtracting the product, as the case may be, to or from the observed weights. 58 PEOCEEDINGS OP THE AMERICAN ACADEMY TABLE OF WEIGHTS. First Series. No. 1883. Weight. C.° H. H. reduced. Result. 1 May 1 87.5304 o 17 304.0 314.0 87.5346 2 " 2 87.5303 17 304.2 314.2 87.5346 3 " 2 87.5314 19.5 303.2 310.7 87.5316 4 " 3 87.5322 20 301.0 308.0 87.5316 5 " 4 87.53205 20.5 301.9 308.4 87.5346 6 " 4 87.5320 21 302.5 308.5 87.5346 7 " 6 87.5316 18 300.8 309.8 87.5345 8 " 7 87.5320 19 300.0 308.0 87.5344 9 " 8 87.5328 19.5 298.9 306.4 87.5347 10 " 9 87.53245 22 302.2 307.2 87.5346 11 " 11 87.5333 22 299.5 304 5 87.5346 12 " 11 87.5383 19.5 296 2 303 7 87.5344 18 " 19 87.5317 21 303.5 309.5 87.5346 14 " 21 87.5345 23 296.2 300.2 87.5346 15 " 22 87.5336 22 298.0 303.0 87.5345 Gr eatest weight, 87.5345 Baromete r, 300.2 Sn nallest weight, Differences, 87.5303 it 314.2 14.0 42 Constant = 4.2 mg. -f- 14.0 = 0.3 I Tig. The balance here used is only sensitive under such a load to the tenth of a milligramme, and hence the constancy of the results obtained is very striking. There can be no question that the mean of the sev- eral weighings is accurate to the full limit of the sensibility of the instrument used. Moreover, during the course of the observations it was also evident that the slight variations observed (only j\ of a milligramme between the extreme limits) were owing to the want of exactness in the measure of temperature of the balance-case. "VYe used a common thermometer reading only to whole Centigrade degrees ; although, as afterwards appeared, a diflference of only ■j'^g of a degree caused a variation of -^^ of a milligramme in the weight, and a differ- ence of a whole degree corresponded to the extreme difference between the observations. In the Second Series (made with the same tube, but differently mounted) we used a standard thermometer (Geisler's make) reading to tenths of a degree, and the results are all that could be expected with the instruments emi)loyed. The observations were made, nevertheless, under the most unfavorable conditions, during exceedingly hot weather, when the temperature was rapidly changing ; OF ARTS AND SCIENCES. 59 and it was evident that the insignificant differences remaininsf arose from the circumstance that the thermometer was not nearly so sensi- tive as the air in the balance-case, following the changes of tempera- ture of" the air after a considerable lapse of time. It was curious to notice the slight increase of weight, caused by the radiation of the body while weighing, followed after some time by a rise of the very sensitive thermometer employed ; and this effect was obtained with a displacement of only about 75 cubic centimeters of air. TABLE OF WEIGHTS. Second Series. No. 1883. Weight. CP H. H. reduced. Result. 1 May 29 87.3447 o 23.5 297.6 301.1 87.3451 2 " 30 87.3432 23.2 302.0 305.8 87.3451 3 " 30 87.3437 24.5 301.8 304.3 87.3451 4 " 31 87.3444 23.8 298.8 302.0 87.3450 5 June 1 87.3429 22.8 302.4 306.6 87.34-50 6 " 1 87.34-32 23.75 302.4 305.65 87.-3450 7 " 2 87.3419 22.6 305.2 309.6 87.-3451 8 " 3 87.3420 21.95 304.5 309.55 87.-3450 9 " 8 87.-S427 2-3.15 303.8 307.6 87.3451 10 " 4 87.-3441 25.0 301.1 303.1 87.3451 11 " 5 87-3443 26.0 301.4 302.4 87.3451 12 " 5 87.3446 26.3 300.6 301.3 87.3450 13 " 6 87.34435 25.55 300.75 302.2 87.34.51 14 " 7 87.3452 26.7 299.0 299.3 87.34-50 15 " 8 87.3464 29.4 297.9 295.5 87.3450 Greatest weight, 87.-3464 Barometer, 295.5 Smallest weight, 87.3419 309.6 Differences, 45 14.1 Constant = 4.5 mg. -~ 1' l.l = 0.319 mg. Note. — In combining only the extreme weights, we must obviously take care that neither of them is seriously affected by any accidental errors ; and a more certain value of the constant would be obtained by combining all the observations after well-known methods. This compli- cation, however, is seldom necessary ; as such errors would render the final result irregular, and lead to a rediscussion of the observations. The limits in the accuracy of the method here described are obvi- ous ; but it will be noticed that the accuracy of the method is exactly proportional to the requirements. The greater the volume of the load, and hence the greater the effect of buoyancy, the more accu- rately can the " constant " be found, by which the correction required in any case can be calculated ; and, as the above examples abundantly 60 PROCEEDINGS OP THE AMERICAN ACADEMY prove, the accuracy is sufficient for the purpose in view. When the volume of the load is large, it becomes necessary to measure the tem- perature and pressure with great precision, and to protect the balance from radiation, and from all causes of rapid change of temperature. It was a great satisfaction to the author to find that by so simple means the relative weight of glass vessels of considerable size may be determined with accuracy to the tenth of a milligramme, — an accuracy which is fully equal to that of the most refined processes of chemical analysis. From the data given, and from the known normal density of the air, it can easily be calculated that in the first series of weighings the volume of the tube and mountings exceeded that of the weights by about 75 cubic centimeters. With this difference of volume we have a variation of ^^j of a milligramme of weight for a difference of ^^ of an inch of mercury in tension, or one degree in temperature. Hence, with a difference of volume of 100 cubic centimeters, we should have a variation of weight amounting to about four milligrammes for every difference of one inch in the barometer, or of ten degrees of the Cen- tigrade thermometer ; and these data will furnish the basis for a rude estimate of the effect in any given case. If the difference of volume amounts to 2,500 cubic centimeters, then a difference of xoVo ^^ ^^ inch in the barometer, or of y^„ of a degree in the thermometer, would cause a variation of ^g of a milligramme in the weight ; so, also, a variation in the intensity of gravity amounting to only ^qoito ^^ ^^^ whole amount would produce a similar effect, and a sensible variation would follow any marked change in the purity of the air. Hence, the balance might be used to detect exceedingly minute changes in any one of these variables, provided the others could be exactly controlled ; and although with our better methods these applications of the balance may be of no practical value, yet the considerations here adduced will serve to show how sensitive the instrument is to the slightest changes in the density of the air when loaded with vessels of large volume. The best method of controlling the weight in such cases is that adopted by Regnault in his classical work on the density of the more perma- nent gases. This consists in balancing the vessel whose contents are to be weighed with a second vessel of equal volume, the two hanging side by side in a case lined with thick felt. The balance is set over the case, and the vessels are suspended from the pans by means of platinum wires, which swing freely through holes made in the base of the instrument. OF ARTS AND SCIENCES. 61 YI. CONTRIBUTIONS FROM TOE CHEMICAL LABORATORY OF HARVARD COLLEGE. ON THE VAPOR-DENSITY OF TtlE CHLORIDE, THE BROMIDE, AND THE IODIDE OF ANTIMONY. Bt C. p. Worcester, A. B. Harv, 1883. Presented May 9th, 1883. The usual form of the tube employed in Victor Meyer's method for determining vapor-densities was found unsatisfactory, in that any slight variation in the tension or the temperature of the enclosed air — such as was caused by drawing out the stopper or dropping in the sub- stance — was apt to draw water up the delivery arm from the pneu- matic trough, and so crack the hot tube. This was remedied by enlarging the delivery arm both in length and in bore. Several modi- fications of the tube were tried, varying in capacity from 75 to 200 cubic centimeters. The tube that was found most satisfactory was of hard glass, of the usual form (with the exception just noted), and of about 150 c.c. capacity. The neck was closed with a perforated rubber stopper, into which was fitted a thin glass tube drawn out and closed at one end, the other end being thrust nearly through the bored stopper. The substance was weighed out in a small tube of the same size as that just described, and the open mouth of this weighing tube was thrust into the lower end of the same perforation ; so that the rubber stopper both held and closed it. The stopper being tightly fitted into the neck, and the ap- paratus heated to a constant temperature, the upper tube was forced downwards, pushing before it the tube holding the substance, which was thus dropped into the bulb of the apparatus. As soon as the dis- placed air ceased to come over, the closed tip of the upper tube was broken off, thus effectually preventing the back flow from the pneu- matic trough on cooling the apparatus or drawing the stopper. 62 PROCEEDINGS OF THE AMERICAN ACADEMY Bromide of Antimony, SbBrg. The substance used being a white crystalline solid, not deliquescent and not readily oxidized, no special precautions were found necessary. Results. No. 1 12.71 No. 2 12.34 No. 3 12.66 Mean 12.57 Theory 12.48 Greatest difference .... 0.14 Mean difference 0.09 Chloride of Antimony, SbClg. Since the chloride of antimony is very deliquescent, the substance was weighed in a closed tube, which was afterwards quickly transferred to the perforated stopper of the apparatus, arranged as above described so as effectually to protect the material from the atmosphere, till the tube was dropped into the heated bulb. Determinations were made in both air and nitrogen ; but the results seemed to show that no advantage was gained by using nitrogen. Results. No. 1 8.0G No. 2 8.03 No. 3 7.80 Mean 7.96 Theory 7.85 Greatest difference .... 0.16 Mean difference 0.11 Iodide of Antimony, Sblg. Pure material was prepared by subliming in a stream of carbonic dioxide a quantity of an otherwise pure substance, which, by exposure to air and light, had been partly changed into the oxyiodide. Several o OF ARTS AND SCIENCES. 6-; determinations were made in the air, but the results showed that, at the temperature of volatilization, the iodide was rapidly oxidized, and the determinations were afterwards made in an atmosphere of nitro- gen. Many unsuccessful attempts were made to obtain pure nitrogen by the well-known method described by Dr. Wolcott Gibbs. The method consists in simply mixing together and warming solutions of sodium nitrite, ammonium nitrate (or suljjhate) in excess, and potas- sium dichromate in large excess, the speed of the reaction being regu- lated by the amount of the dichromate added. It was found that red fumes always appeared in the nitrogen evolved ; and that, while no variations of proportions quite eliminated the fumes, still, when but very little bichromate was used, the resulting nitrogen was compara- tively pure. It was evident, as Dr. Gibbs pointed out, that the nitric fumes were caused by chlorine present as an impurity in the materials used, and the impurity was readily traced to the dichromate ; but, as the purification of potassium dichromate is troublesome and expensive, it was found more practicable to pass the impure nitrogen over red- hot copper filings recently reduced, and then through drying-tubes. The nitrogen thus purified gave satisfactory results. . Results. No. 1 17.25 No. 2 17.90 No. 3 17.63 Mean 17.59 Theory 17.33 Greatest difference . . . 0.31 Mean difference . . . . 0.26 It will be seen that the results do not agree very closely with the theory, or with each otlier. While we do not presume that we have obtained as accurate results as the method will allow, a ^evr trials care- fully conducted and closely watched made it evident that very close results cannot be reasonably expected from this method. An abso- lutely constant temperature — indicated by the unchanging position of the water surface in the delivery tube — it is practically impossible to maintain. Furthermore, the slight resistance to be overcome by the air in rushing out of the delivery tube is often enough to retain 64 PEOCEEDINGS OF THE AMERICAN ACADEMY the last bubbles, especially when there is any delay in the volatilization of the substance, giving time for the diffusion and partial condensa- tion of the vapor. Such variable conditions seem to preclude the possibility of uniformly accurate and consistent results from Meyer's method. OF ARTS AND SCIENCES. 65 VII. NOTES ON SOME SPECIES IN THE THIRD AND ELEVENTH CENTURIES OF ELLIS'S NORTH AMER- ICAN FUNGL By W. G. Farlow. Presented May 9th, 18S3. The third Century of Ellis's North American Fungi, issued in 1879, and the eleventh, issued in 1883, contain almost exclusively species of Uredinece and Peronosporece. As a considerable number of these were collected by me, and others were examined by me at the request of Mr. Ellis, I have taken occasion in the present paper to offer certain notes with regard to the determination and distribution of some of the species, which are either new or not sufficiently well known. In the first place, a few remarks on the nomenclature adopted are perhaps necessary. In publishing a series oi fungi exsiccati like that of Mr. Ellis, greater latitude is naturally allowed than were one pub- lishing a monograph of the UredinecB or Peronosporece. In the latter case one would be expected to give names only to what he regards as good species, and all other names would be reduced either to synonyms, or would appear under the head of species inqidrendce. In issuing a series of exsiccati, however, one is not only at liberty to distribute species the validity of which seems to him certain, but it is frequently desirable to distribute forms which have received definite names from the earlier mycologists, although their specific value is doubtful. In the latter case, all that is incumbent on the editor is, as far as possible, to be sure that the specimen distributed really corresponds to the form which originally bore the name given. In the Centuries to which we refer, several species bear the names of Schweinitz and other earlier mycologists ; and it is not to be understood that the species are really considered to be valid, but merely that, in the opinion of the editor, the specimen represents the form originally described under the name given, and that the species must be studied further. VOL. xviii. (n. s. X.) 5 66 PROCEEDINGS OF THE AMERICAN ACADEMY In the case of Peronosporece^ the nomenclature presents no excep- tional difficulty; but the case is very different with the Uredinece, which present, perhaps, greater complications than any other group of plants. Among mycologists the almost universal custom is, in case a change is made in the genus, to retain the original specific name, put the original authority in a parenthesis, and add the name of the person who first gave the correct generic name. In any work which is at all elaborate, the parenthetical name is given as well as the generic authority, and in such cases no difficulty usually arises. But in published lists or specimens distributed as exchanges, the parenthetical name is often omitted, and difficulties of interpretation arise. By retaining the parenthetical name difficulty may be avoided ; but it is too much to expect that mycologists will closely adhere to the plan in practice, because it involves a good deal of trouble. In the case of Phaenogams the parenthesis is not generally used, and it might be asked whether cryptogamic botanists had not also better abandon it. The usage, however, is so nearly general, that one can see very little hope of its discontinuance, at least for a good many years to come. But it must be admitted that in the case of the Thallophytes the use of the parenthesis has a value which it would not have in Phajnogams. The genera of Fungi, for instance, are not so definitely fixed as in Phaenogams, and the tendency seems to be to increase the number with greater and greater rapidity. A species of Fries, for instance, may during five years be dragged through no one knows how many new genera, and it is with a mildly malicious satisfaction that one sees those modern writers who adopt minute generic subdivision forced by the prevailing custom to add the {Fr.) as a slight tribute to the past. If mycologists are at times too much inclined to multiply genera, they sometimes err in another direction, and in search of an old spe- cific name pass beyond the limits of the certain, or even the probable, to what is merely vague conjecture. It is this latter tendency which has served to make the nomenclature of the Uredinece at times obscure. The connection between the a^cidial states and the teleuto- sporic states of the different species brings up the question of how this connection can be represented in the nomenclature. Shall we, in case we believe that a certain ^cidium is connected with a certain Uredo and Puccinio, take the oldest specific name, whether it belongs to the u^ridinm, Uredo, or Pucclnia'} This is in the main the plan adopted by Winter in what I would gladly acknowledge to be the most com- plete systematic account which has yet appeared of the Uredinece of any OF ARTS AND SCIENCES. 67 countrj'. Cut to abandon the oldest specific name of Puccinia, and substitute for it an older name given to the ^cidium which is sup- posed to be connected with it, is to encounter difficulties and produce a confusion which is unnecessary. Suppose, to refer to another order of Fungi, that the conidial form of a Pleos-pora had been described as a Cladosporium before the ascosporic form had been described, would mycologists suppress the original name given to the ascosporic form, and retain that given to the conidia ? Certainly not. The generic distinctions in the Uredinece are mainly derived from the characteris- tics of the teleutosporic stage, and the generic names are, as far as possible, those originally given to the teleutospores. The discovery that the so-called species of ^cidium are states of Puccinia, Uro- myces, and other genera, has not affected the generic terminology at all, and I see no reason why it should affect the specific names. As it is, the greater number of species of Uredinece, excepting of course the purely secidial forms, are recognized by the names given to the teleutosporic or Uredo condition, and if hereafter any particular secid- ial form is found to belong to them, I see no reason why the specific name should be changed because the ^cidium was described before the other stages. As soon as an ^cidium is found to be connected with another form, its name should disappear, and it should simply be called the aicidial or hymeniferous condition of the species of Puccinia, or other genus to which it belongs, unless, of course, for purposes of what may be called mechanical convenience, one retains the aecidial name unchanged in exchanges or lists. For practical reasons, if for no other, the custom of substituting an aecidial specific name for a name given to a Uredo or teleutosporic form should by all means be avoided. Of all the Uredinece described by older writers, probably none are more difficult to determine satisfac- torily at the present day than the species of ^cidium so called. Original specimens of that genus are as a rule not so well preserved as those of other genera of the order, and if one usually gets little satis- faction from examination of what is left of the original types, he is scarcely any better off on reading the older descriptions. It was not unfrequently the habit of older mycologists to describe as varieties of one ^cidium forms found on the most diverse plants, and most certainly it is going too far to substitute for the name of a Puccinia, let us say, which has passed current for many years, the name given by an old authority like Persoon or Link to what he considered a variety of an ill-defined ^cidium. It cannot be said that any want of respect to the older writers is shown by abandoning their gecidial names 68 PROCEEDINGS OF THE AMERICAN ACADEMY in such cases. In this connection we might mention one of our own species. There is a Puccinia which grows on Claytonla, whiih was described by Peck and Clinton in 1873. It is now well known that this Puccinia is often accompanied by what was described by Schweinitz in 1831 as Cceoma (^cidium) Claytoniatum. It is inferred that one form is a stage of the otlier, and, supposing that this inference is cor- rect, shall we say, instead of Puccinia Marice-Wilsoni Clinton, Puc- cinia Claytoniata (Schw.) Fallow ? I am distinctly of the opinion that such a change should not be allowed. The case mentioned is one of the strongest, and other instances are less favorable still. One more point needs to be considered. If one is not justified in going back to aecidial specific names, is he justified in going back to old Uredo names? It seems to me that one is justified in this, and that the objections urged in the case previously mentioned do not apply to any great extent here. As a matter of fact, the types of the earlier described Uredo forms are much better preserved than ^cidia^ and examinations of older herbaria frequently enable one to determine with accuracy what form was meant by an older author. Further- more, the Uredo and teleutosporic forms frequently are found together in the same soriis, or in close proximity, and examinations of authentic specimens often show the relation of an old described Uredo to a more recently described teleutosporic form. The most important considera- tion, however, is the following. Many of the forms now recognized as teleutosporic have one-celled spores, and were originally described as forms of Uredo, and in such cases one must go back to the original specific names. We may mention several of our species of Uromyces originally described by Schweinitz as species of Uredo. Whenever an examination of Schweinitz's specimens of Uredo enables us to recognize a species of Uromyces or Puccinia, we are warranted, I think, in substituting a Schweinitzian specific name for a more recent one, and placing his name as authority in a parenthesis. A number of Schweinitz's species of Uredo are so generally known to belong to Uromyces, Coleosporitim, and other genera, that the use of the paren- thesis is often omitted, until some m3^cologist desirous of adding his name to as many new species as possible gains a cheap reputation by appearing suddenly in print with his name attached as authority to an old and well-known Schweinitzian species. If I have advocated retaining the older Uredo name in cases where we know with certainty what was meant by the earlier mycologists, I have by no means intended encouraging the use of names about which there is doubt, either from the absence of typical specimens, or confu- OP ARTS AND SCIENCES. 69 sioa of several species by older writers. Rather than favor that method — if one may say so — of forcing priority, I should prefer to give up the substitution of all old Uredo names, except, possibly, in the case of species now referred to Uromyces. To make a long story short, I am of the opinion that in naming Uredlnece we should go back to the oldest specific name given to the teleutosporic form or to the Uredo form, provided sufficiently good data exist in older writings or herbaria to enable us to ascertain with certainty whether the Uredo named actually was associated with the teleutosporic form ; and this can in many cases be settled by reference to older herbaria. The connection between teleutosporic and a3cidial forms certainly was not suspected until recent years ; and, as it seldom happens that in old herbaria the two forms are found intimately asso- ciated, and, furthermore, as the whole group of ^cidia are rather va^i^uely characterized by older writers and poorly preserved in her- baria, it seems best to abandon the attempt to go back to the original secidial name. Where the practice might succeed in one case, it would produce uncertainty in many more ; and while, on the one hand, there is danger that sufficient attention may not be paid to priority, there is, on the other, still greater danger that, by attempting to do too much, the nomenclature of Uredinece may become hopelessly entangled. In the North American Fungi a considerable number of forms of ^cidium have been issued, sometimes with a reference on the label to the teleutosporic form to which they have been referred, but in most cases without such reference. In this country it seems to me that in general a conservative policy had best be adopted in regard to asso- ciating our ^cldla with teleutosporic forms. Information is always to be desired ; hasty assumption, however, is an entirely different matter. In Europe so many excellent observers have experimented on the connection between different forms, that in regard to European UredinecB one can venture to make a statement of the subject in systematic works. In this country almost nothing has been done in an experimental way, and, if one will only bear in mind the peculiar relations which ^cidia and Uromyces on Euphorhice are considered to bear to one another in Europe, he will recognize that w^e in this country cannot assume that, because an ^cidiinn and a Puccinia or a Uromyces occur on the same host, even when in close proximity, they are really stages of one species. All one can say is that such is probably the case. In papers describing our Uredinece one should of course state, as far as he knows, what ^cidia are found with teleuto- sporic forms ; but to go farther than this in our endemic species, anrJ 70 PEOCEEDINGS OF THE AMERICAN ACADEMY in several of the species which also occur in Europe, is in my opinion undesirable. To group together hastily different forms is a very easy matter ; but it is more to one's credit to be willing to wait until future study shall have shown what forms really are connected. Syncliytrium fulgens Schrt. var. decipiens Farlow, no. 201, and S. Anemones Wor., no. 203, are now known to be common in the Western as well as the Eastern States, but apparently *S'. papillatum Farlow is not known beyond the region where it was first collected by Dr. Anderson. No. 207, Peronospora ohducens Schrt., has also been found in Iowa by Professor C. E. Bessey, and in Illinois by Mr, A. B. Seymour. I at first su^jposed that this fungus appeared only in the spring on the cotyledons and occasionally the youngest leaves of Impatiens, but it was found by Professor William Trelease to be common ou the mature leaves of Impatiens collected at Wood's Holl in August, 1880. The cotyledons are generally thickly covered by the conidia, but on the leaves the spots are generally small and scattered. I have myself never found ripe oospores, and only rarely the young oospores, of this species, but they were found fully developed by Mr. Seymour in specimens on Impatiens collected in Illinois. They occur in large numbers in the petioles and young stems from just beneath the epidermis to near the vascular bundles. The oogonia measure from 38-45/x in diameter, and the oospores themselves are from 26-31/a in diameter, with an endospore about 3/x thick. The outer wall of the oospores is nearly smooth, but usually has a few ill-defined folds or ridges, not, however, to be compared with the markings on the oospores of some other species. No. 208, Peronospora viticola (B. «&; C.) De Bary. In the Bussey Bulletin, Vol. I. p. 422, March, 1876, I made the statement that practically no harm was done to the grape crop in our Northern States by this fungus, but added, " Should the fungus be introduced into Central Europe, the case might be different." Since that date, as every one knows, this parasite has been introduced into Europe, and an enormous amount has been written relating to its spread on the Continent and the harm that it has caused. On the latter point authorities differ, some going so far as to assert that it does as much harm as the Phylloxera, and others that it does perceptible harm only in exceptionally moist seasons. The majority of writers, how- ever, believe that considerable damage is done by the fungus, and the statement made in the Bussey Bulletin is not credited. While admit- ting the damage done in other regions, I have seen no reason for OF ARTS AND SCIENCES. 71 changing my opinion with regard to the harmlessness, practically speak- ing, of the Peronospora in New England. I never meant to deny that, theoretically speaking, the existence and growth of a parasite like P. viticola would weaken the vines in which it was growing ; but the fact is that I have repeatedly seen vines attacked by the Peronospora produce good crops of grapes year after year, and, whatever we might expect in theory, in practice no perceptible harm is done to the open- air grape culture in New England. In that region, as was stated in the Bulletin, the great danger to be dreaded is the occurrence of frosts before the grapes have ripened, and the Peronospora, in so far as it causes the leaves to curl up, thus exposing the grapes to the full force of the September sun, benefits rather than injures the grape crop. The position of New England and the northern parts of the United States with regard to grape culture is quite exceptional, and there is evident reason why what is true of the Peronospora here should not be true in other parts of the world. Nos. 209 and 210. Peronospora Halstedii, Farlow. This species was referred to in the Bussey Bulletin, Vol. TI. p. 235, January, 1878, where mention was made of a Peronospora found by Mr. B. D. Halsted on Eupatorium purpureum, near the Bussey Institution, in May, 1876. Since then the fungus has been collected in numerous other localities and on several different hosts, and it may now be reo-arded as one of our most widely spread and characteristically American species. It was found by Professor Bessey, in August, 1878, on Eupatorium purpureum, Bidens frondosa, and Rudheckia lacmiata, and since then it has been observed by Professor Arthur on Helianthus doronicoides in Iowa ; on Helianthus strumosus and Sil- phium terehinthinaceum in Wisconsin, by Professor Trelease ; on Helianthus tuberosus in West Chester, Pa., by Mr. J. B. Ellis; and I have myself also found it on Ambrosia artemisicEfolia in several dif- ferent localities. In short, we may expect to find it on almost any Composite, although it apparently affects principally the Tubidljiorce, while with us P. (jangliformis affects rather the Ligulijlorce. The ripe oospores of P. Halstedii are not common, as far as my experience goes ; but I have seen them in good condition on the leaves of Heli- anthus doronicoides, collected at Charles City, Iowa, by Professor Arthur. The conidia vary in their development according to the host, forming large and conspicuous patches on Rudbeckia, Silphium^ and Helianthus tuberosus, but rather inconspicuous spots on Ambrosia. The conidial spores vary very much in size, and their shape, as in all Peronosporce, depends much on their age ; when young oval, when 72 PROCEEDINGS OP THE AMERICAN ACADEMY about to germinate, elliptical and slightly papillate. In germination they produce zoospores like P. viticola. The germination I have obsei'ved in the form growing on Ambrosia at Wood's Holl, and it differs in no essential respect from what takes place in all our zoo- spore-producing species, to wliich reference will be made hereafter. The nearest ally of the present species is P. viticola, from which P. Halstedii differs but little in morphological characters ; but in P. viticola the ultimate branches are distinctly more dense, so that the tips almost appear denticulate at times, while in P. Halstedii the ultimate branches are more or less subulate and divaricate. In P. Halstedii the haustoria are numerous in the leaves, nearly glob- ular, and much more easily seen than in P. viticola. The oospores of the two species resemble one another, but those of P. Halstedii appear to be on an average larger, and the epispore more distinctly in irregular folds. As might be expected, a species appearing on so many hosts presents modifications on the different hosts. The most marked deviation from the type is seen in the form on Helianthus tuberosus from Mr. Ellis. In the type the conidial stalks consist of a main axis, from the upper part of which are given off" lateral branches nearly at right angles ; the branches then give off a second and third series of branchlets, which usually end in a prong-like projection, near the base of which are from two to four similar prongs in a divaricating tuft. The general outline of the conidial ramifications is pyramidal, while in P. viticola it is more nearly linear. In the form on species of Helianthus tlie lower branches are often much longer and more frequently divided than in those on Ambrosia and Hidens, and the branching becomes almost thyrsoitlal. In rare cases, the usually erect prong becomes recurved, and the tip of the branchlet swells so that there is an approach to P. gangliformis, from which, however, it can easily be distinguished by the different ramification. Were it not for the large series of connecting forms, one might be inclined to separate the specimens of Mr. Ellis as a distinct species. The following may serve as a description : — P. Halstedii, Farlow. Mycelium furnished with numerous oval haustoria. Oogonia 30-40/x in diameter. Oospores spherical, yellowish, 23-30/A in diameter, epispore with ill-defined folds, endospore about 3/A thick. Conidial stalks fasciculate, narrowly pyramidal in outline, with a percurrent axis, ll-15/x in diameter, 300-750/x long, two -four times pinnate, branches given off nearly at right angles, ultimate divisions approximate in clusters of three or four divaricating tips. Conidial spores colorless, oval or elliptical, with a slight papilla, 19-30/A long by 15-26/a broad, germinating by zoospores. OF ARTS AND SCIENCES. 73 Hab. Leaves of Eupatorium piirpureum L., Ambrosia artemisice- folia L., Bldens frondosa L., Rudbcckia laciniata L,, Silphlum tere- binthinaceiim L., Helianthus strumosus L., II. doromcoides Lara., and H. tuberosiis L. In the Bussey Bulletin for 1876 less than a dozen Peronosporece were enumerated as known in the United States, but since that date the number has been very much increased. Reference will be made later on to the additions to our flora, but in this connection I would call attention to the large proportion of species whose conidial spores produce zoospores. I have studied the germination in P. vlticola, P. Halstedil, P. obducens, and P. Geranii, no. 218, North American Fungi, and find that the spores all produce zoospores in germinating, although I have experienced difficulty in making those of the last named species germinate, having tried for several j-ears in vain. Besides the species just enumerated, Peronospora (^Basidiophora) entospora Cornu and Roze, which according to Cornu also germi- nates by zoospores, is now known in at least three localities in this country.* Counting also the potato-rot, we have six species which produce zoospores. Of these P. viticola and P. Halstedii are dis- tinctly, and P. entospora probably, of American origin. P. obducens was discovered almost simultaneously in Baden and in Massachusetts, and as it is about equally common on both continents on indigenous species, we have no guide to its original home. P. Geranii, it seems to me, can on morphological grounds with difficulty be distinguished from P. nivea on Umbelliferce in Europe, and I previously regarded it as a variety of that species. Certainly, if there is a difference, I was not able to express it in words. It is, however, distinct from any European form on Geranium, and as the majority of Continental botanists will not admit that the same Peronospora can .grow on * The species was originally found on Erigeron Canadense in France, and has since been found in Germany. I first received American specimens from Pro- fessor T. J. Burrill, of Champaign, III., by whom it was found on Erigeron in May, 1878. The species afterwards was described in the Thirty-first Report of the New York State Museum as Peronospora simplex Peck, on Aster Novce- AngHoe, from New York, and it has since been found by Trelease in Wisconsin, on Aster NovcB-Avglice. Although I have often searched, I have never found it near Cambridge, but instead Cercospora caiia Sacc, which to tlie naked eye resembles it. Probably the species is a native of America, and was introduced into Europe with Erigeron, following the e.xample of P. viticola. P. Halstedii, as far as I know, is not yet known in Europe, but it may be e.xpected to appear there at any time, and may do a real injury to the crops of Helianthus tuberosus, which is largely cultivated in several parts of Europe. 74 PROCEEDINGS OP THE AMERICAN ACADEMY species of orders as remote as Geraniacece and UmbelHfercB, in their sense, at least, P. Geranii must be considered peculiar to America. I once tried without success to cultivate it on an Umbellifer, but that hardly shows anything, as under all circumstances — and I have tried many times — the couidia of this species are with difficidty made to germinate at all. One naturally asks why it is that such a large pro- portion of our species produce zoospores instead of direct germinal tubes. From their close resemblance one might suppose that P. viti- cola, P. Halstedii, and, to stretch the matter somewhat, possibly P. Geranii, were derived from some common American ancestor which produced zoospores. If, in the various surviving species, we find this common peculiarity of germination preserved, we ought certainly to suppose that this form of germination is especially adapted to the climatic and hygrometric conditions of our country. Strange to say, the contrary appears to be more probable. Our climate is a continental one, subject to extremes of heat and moisture, and one would suppose that a species with spores so contrived that they could push forth germinating tubes would be more likely to survive in comparatively dry seasons than one arranged to give out a number of zoospores ; for it is the result of my experience that the tube-producing spores retain their vitality for several days, whereas those which produce zoospores lose their power of germinating in a comparatively few hours after maturing. It may be said, on the other hand, that the chances of survival are greatest if the spores usually produce zoospores, but in exceptional cases produce germinal tubes. P. infesians, which usually produces zoospores, is known occasionally to produce tubes, but of the hundreds, or even thousands, of germinating spores of P. viticola and P. Halstedii I have seen, I never met with one producing anything but zoospores. No. 228. JEcidhim Convallarice Schm. var. Lilii. This was found in June efrowiu^ on cultivated Lilium candidum, but was not followed by any uredo or teleutospores. It certainly is not JEcidium Liliacearum Ung., which is associated with Uromyces Liliacearum Ung., nor the ascidium of Puccinia Liliacearum Duby, but rather a large form of ^c. Convallarire Schm., of which no. 229 on Polygonatum is the more common form. No. 230. This is the common form of ^c. myricatum Schw. The small form distributed with Cent. XI. is only known to me from Mr. Ellis's specimen. No. 225, It is possible that there was a mixture of two species un- der this number, as in my copy I notice one leaf with j^c. punctatum P. OP ARTS AND SCIExNCES. 75 No. 1003. It may be doubted whether either the form oa Ra- nunculus abortivus or that on Anemone nemorosa is the same as the u^c. Raiiunculacearum DC, or the form associated witii Uromyces Dactylidis. The fungus on R. abortivus is the u^c. Ranunculi of Schvveiuitz's Syn. Car. no. 410, afterwards referred to ^c. Ranuncu- laceatum Lk. in the Syn. Am. Bor. The form on Anemone has the jecidia in spots, as iu -^c. Ranunculaceurum DC, but the small size of the ajcidia, as well as other peculiarities, leads one to ask whether it is not distinct from all the forms on Ranunculus. No. 1004. ^cidlum Thalictri Grev. Mr. Ellis informs me that by accident the wrong specimens were distributed with this number, and that the true species will be distributed later. No. 1007. I can see no good ground for separating this from ^cidium Violce Schm. Authentic European specimens of that spe- cies have spores as large as this. ^c. Petersii B. & C, which also occurs on violets, has slenderer and longer peridia. No. 1018. The three forms on Rudbeckia, Xanthium, and Solidago may, for want of any satisfactory information as to their relationship, be called ^c, Compositarum ; but it is perhaps going too far to give Martius as the authority. The form on Xanthium is in Massachusetts frequently followed by the Puccinia Xanthii of Schweinitz, distributed as no. 264. Nos. 1021-1026. In another paper I shall refer to the distribution of the Peridermia of the White Mountain region, and the names and authorities here given are taken from Thiimen's Blasenrost Pilze der Goniferen without criticism. The P. orientale, no. 1026, apparently common in the Southern States, is rosy flesh-colored when fresh, and is probably what is figured by Bosc in Gesell. Naturf. Freunde, Vol. V. PI. G, f. 13, as Tubercularia cornea. No. 1084. The spermogouia of this species usually appear on the leaves, while the a3cidia are more common on the fruit and smaller twigs. No. 1086. The typical form of Roestelia penicillata Fr. is well shown in the specimens on the fruit of Amelanchier. No. 1087. Apparently R. Botryapites Schw. occurs in its most luxuriant form on AmelancJner, growing near the seashore, as shown in the specimen from Magnolia, Mass. No. 1089. This is the typical R. cornuta Tul., and is abundant at Eastport, Me., where it is associated with Juniperus communis, which on the coast of Maine is infested by Gymnosporangium clavariceforme DC. no. 273. It is supposed, however, in Europe, that R. cornuta is 76 PROCEEDINGS OP THE AMERICAN ACADEMY connected with Gym. conicum DC, which does not occur with us in the region where the typical R. cornuta abounds. Nos. 277 and 278. Tiie ^cidium nitens of the Syn. Fung. Car. Sup., changed by Schweiiiitz to Cceoma luminatum in the Syn. Fung. Am. Bor., is probably the most striking and brilliant member of the Uredinca; in the Eastern United States, where it is extremely common on several wild species of Riibus, being familiar to every child. In spite of its frequency there is as yet no clue to its connection with any other form. The spermogonia are very abundant, and cover both surfaces of the leaves, and the petioles, looking to the naked eye like minute greenish-yellow glands. They cause a peculiar deformity ot the younger shoots, which become longer and slenderer than usual, and paler in color, and the leaves remain small and unexpaaded. The spermogonia, instead of being wholly or partly immersed in the leaf, as in most species, are entirely above the surface of the epidermis, which rises so as to form a cup, often contracted at the base, leaving the whole body of spermatiferous threads projecting in somewhat club-shaped glutinous masses, either quite naked or covered for a time by the cuticle only. The spermatia are nearly spherical. The spores are arranged in rows like the uredo of Coleosporium, and when fully ripe are somewhat hexagonal in outline, the wall being thinner at the angles. In germination they give off long hyphce from the angles, and not promycelia proper. The present species resembles in many respects the forms placed by Tulasne, in his Second Memoire sur les Uredinees et les Usdlaginees, in the genus C(Soma, using the name in a more restricted sense than Link and Schweinitz, and on that account the generic name Cceoma was given in the North American Fungi. On grounds of priority the specific name nitens should be kept; but, of course, in our ignorance of the connection of this form with others, no generic name can be given which it may not be required to change in a short time. One might sup{^ose that we had here the gecidium of some Phragmidium, as the ascidia of that genus as under- stood by AVinter resemble our plant. I have never been able to trace any connection, however, between our rust occurring early in the season and any subsequently appearing Phragmidium or Coleosporium, and the probabilities are that the species is heteroecious. Nos. 247 and 248. Pileolaria hrevipes B. & Rav. Mycologists have been in doubt as to the teleutosporic form of this species. The more common form is the uredo, no. 247, in which the spores are depressed-globose and covered with roughnesses, and it is to this form that the name Pileolaria brevipes was first given. The teleutospores, OF ARTS AND SCIENCES. 77 which are more frequent toward the end of the season, are short- stalked, ovate, with a distinct hyaline papilla at the npex, and are marked witli spiral lines or dots arranged in spirals. This latter stage is the Uredo Toxicodendri of Ravenel's Fung. Car. III., no. 797, described by Berkeley in Grevillea, Vol. III. p. 5G, under the name of Uromyces Toxicodendri. It seems to me that Leveille and Tulasne were ri a^ and o-^ being the effects at the planes. From thermodynamic principles, it is obvious that the absorption must take place at the higher temperature T, and the evolution at T^. The second law of thermodynamics gives This equation shows that o-^ cannot equal o-^, and in this special case of a homo<^eneous circuit there must be an electromotive force. "We ■'» OP ARTS AND SCIENCES. 215 also see that, at least for this case, the Thomson effect must be pro- portional to the absolute temperature. To look at the problem from another point of view, suppose that in the homogeneous circuit there is but one abrupt change of tempera- ture. That is, the temperature varies continuously from T^ — T'j, and then falls abruptly to T^. In this case the curve representing the change of temperature along the curve is discontinuous at T. The integral of o- tlirougliout the circuit is then not necessarily zero. The part of the integral corresponding to the fall from T — T^ has in this case the maximum or the minimum value of which it is capable. The complete effect through the circuit is represented by h To If (T varies with the temperature, this expression cannot equal zero. If the current is in such a direction as to absorb heat at the plane of abrupt variation of temperature, the part of the general integral cor- responding to the abrupt change has its maximum value ; otherwise it has its minimum value. There is nothing in the equation to deter- mine the direction of the current. Its intensity will obviously be the same in either direction, /" crdT T being a mean between its maximum and minimum values. We have tried several experiments to see if the direction of the current was related to the direction of the Thomson effect. It was soon perceived, however, that in the method employed many complicating causes masked the effect sought. From the fact that the equations show that a current can take jjlace in either direction, we must conclude that there are most probably equal currents in opposite directions, making the resultant cui-rent equal zero. This is especially so in the perfectly- symmetrical case first considered, where there are two abrupt changes of temperature. We are not aware that any experiments have been made on a circuit arranged in this way, and in fact it would be most difficult to realize the arrangement practically. In the second case, however, experiment shows that there is a current, and if there is anything in the nature of the metal which prevents the plane of ab- rupt variation of temperature from acting as the reservoir and refriger- ator at the same time, then the equations explain the current. We 216 PROCEEDINGS OF THE AMERICAN ACADEMY shall see that in special cases there is another heat effect at this plane ; it is probable, therefore, that this effect exists in every case. An abrupt variation of temperature can be produced practically in various ways. Le Roux and others have produced the currents by cutting a strip of metal in such a shape that its section varied abruptly from the broad to the narrow part. When a flame is aj^plied to the narrow part, it becomes heated so much more rapidly than the broad portion that the temperature changes abruptly. Maxwell says, in regard to these cases, that a current is produced in a homogeneous conductor when " at any part of the conductor a sensible variation of temperature occurs between points whose distance is within the limits of molecular action." Le Roux attempts to explain the phenomena by a difference of pressure caused by the heat, the current being due to heating the contact of compressed and free parts of the same metal. Becquerel produced an abrupt variation of temperature by suddenly uniting the hot and cold ends of a wire. The current in this case is, as Becquerel pointed out, at least partly due to a coating of oxide. In the case of lead the current is probably due to a coating of oxide, as the Thomson effect for lead is zero. In the experiments made by us, with the object of observing whether there was any law connecting the direction of the current with that of the Thomson effect, the method of varying the section abruptly was employed. This method gets rid of all complications due to impuri- ties at the surface of contact ; but in cutting the metal to the neces- sary shape, the parts were necessarily more or less strained, and the results sought were always masked by a permanent current between the strained and unstrained parts. The direction of this current de- pended upon the position of the point where the heat was applied. The direction could be reversed by moving the lamp a few centimeters to either side, beneath the narrow part. The best method to avoid these complications is to pass a fine wire through the non-conducting partition separating the two compartments of a vessel, each compart- ment being filled with some good thermal conductor, and kept at different temperatures. This method has not yet been tried. We have seen that the equations do not determine the direction of the thermo-electric current, and consequently that it is probable that a current exists in both directions. The Thomson effect, then, cannot alone explain the current that experiment shows to exist ; there must be some other effect at the plane of abrupt variation. That this effect does take place in certain special cases there can be no doubt. OP ARTS AND SCIENCES. 217 Tables of the values of the Thomson effect show that nickel changes twice between 17o° and 340°. There are two points of deflection in the thermo-electric line. At these points, — ■,(f,) = o. Let Tq be the temperature at which the Thomson effect equals zero, and let The a. temperature above this. Let the circuit be so heated that the temperature rises gradually from T^ — T, and then falls abruptly to T^. Any heat effect at the plane must necessarily take place at the higher temperature, if we suppose the Thomson effect alone to exist. Hence frorn thermodynamic considerations the absorption must take place here. In this case the direction of the current is completely determined. Suppose, now, we pass a current from some outside source, through the circuit, in such a direction as to absorb heat where the tempera- ture falls gradually. There can be no evolution of heat at the plane, as it can take place neither at T^ nor at T. If the whole energy of the current is expended in heat we must have EI=RP- iL'dT. : E=RI—icTdT. That is, the electromotive force of the outside current is diminished by an electromotive force peculiar to the arrangement, and due to the absorption of heat in the circuit. But if the Thomson effect is the only effect in this circuit, the current produced by it does not obey the fundamental principles of thermodynamics. We have an engine, working between finite temperatures, in which there is no loss of heat. Suppose, moreover, T < T^, and pass a current in such a direction as to evolve heat where the temperature varies continuously. There can be no absorption at TJ,, and E=RIA- la-dT. = RI-\- Co In this case the outside electromotive force is increased by a secon- dary electromotive force. But unless some effect besides the Thomson effect exists, the secondary current is produced alone by an evolution of heat. The conclusion is absurd, and there must exist some other effect at the plane of abrupt variation. If this effect exists for the 218 PROCEEDINGS OP THE AMERICAN ACADEMY special cases considered, it seems probable that it exists for all cases where there is a sensible variation of temperature between points whose distance is witliin the limits of molecular action. It obviously differs from both the Thomson and Peltier effects. Several properties of this effect can easily be deduced. In the first place, since in general the current is caused entirely by it, — the Thomson effect producing equal and opposite electromotive forces, — if the effect obeys the ordinary thermodynamic laws, it must exist so as to cause an absorption and an evolution of heat at the plane of abrupt variation. Tiiis is not the only case of a thermodynamic arrangement where the evolution and absorption take place at one plane. In a thermo-electric circuit which has two neutral points, and in one metal of which the Thomson effect is null, if the two junctions are maintained respectively at the temperatures of the neutral points, all the heat effects take place in one metal, and if the circuit is so arranged that the change of temperature takes place across a plane, then all the effects occur at this plane. If we call the new effect ^{T), the general equations for a circuit where there exists one abrupt variation of temperature become : — -[/{W-r.(^,-7;)] +f^dT+ ar,(T, - T,) + ^ {T,) T^) To Ti The first parts of these equations are identically zero : — -•i -'o The latter equation shows that ( 7^) is proportional to T. The electromotive force is then proportional to the difference of tempera- ture between the two surfaces of the plane. The chief practical uses of thermo-electricity are in the measure- ment of high and low temperatures, and in the conversion of the energy of heat into that of an electric current. The measurement of OP ARTS AND SCIENCES. 219 temperatures is much complicated by the existence of the two thermal effects, and by the fact that the direction of these effects is not con- stant for all ranges of temperature. The existence of the Thomson effect venders the curve of the electromotive forces and temperatures a parabola. The electromotive force cannot be considered propor- tional to the difference of temperatures of the junctions. Tait's in- genious method of acting on a differential galvanometer with two elements, gives an arrangement where the deflection is proportional to the difference of temperatures ; but the method is exceedingly diffi- cult in practice. We have also seen that, when an abrupt variation of temperature is produced, the electromotive force is probably pro- portional to the difference of temperatures ; but there is no obvious method of realizing this arrangement practically for the measurement of temperature. The chief difficulty, however, in using the thermo- electric element as a thermometer, is due to the reversal of the heat effects. Every element must first be tested through the ranges in which it is to be used ; and this testing necessitates the use of some other method of measuring temperatures, which is very difficult and inaccurate. In regard to the use of the thermo-electric element as a heat engine, there is always a loss of heat, from two causes, which is absolutely unavoidable unless some substance can be procured which has a ther- mal conductivity of zero, and a finite electrical conductivity. Tiiis loss must always be taken into consideration in comparing the efficiency of the thermo-electric engine with that of other heat engines. In a bar of section S, and length I, the quantity of heat lost in unit time by conduction is That generated in unit time by a current of electricity is H, = PkL^E^S^, K and .- are the thermal and specific electrical conductivities. Loss of heat by radiation from the surface of the bar is supposed to be avoided. If this bar is supposed to form part of a thermo-electric ele- ment, any increase of S throughout the bar, that is, so as to increase the surfaces of contact, will increase H -\- H^. If, however, the cur- rent strength is fixed, that is, if the current is passed through the bar from an outside circuit of large resistance compared with that of the 220 PROCEEDINGS OP THE AMERICAN ACADEMY bar, we may consider / indepeudent of S, and the sum of the heat lost is a miuimum when dH , (IH^ _ dS~^ dS —^' 8=11 K{t -0/ \. Substituting this value of >S^ in iTand H^, H= I\JcK (t^ — + ^^ 5P) («- + «'. + '?') = «' for all values of x, y, and z. =z — 2b ,2 d d(b r^iQa+Q. + Qc) Integrating, ^« + c. + ^.=^- To determine this constant we must use the surface condition dV, , dV^ .„ -y^-f- -— = 4 90-. dv^ ' a 1^2 The X force which the shell exerts on a point in its interior is +2 Qpx8{a,b^c^Q^) = + 2 QpxaJ>,c,BQ^^ + 2 QpxQ^?i{aJ),c,), so that the sum of the X components on the two sides of the shell is 7 ( dQa , dQb , dQc ) ' Resolving the sums of the components along the normal, we have 2 8/=* {s^, (e. + e. + ej ^ + ^,3 ( <3„ + ^o^^o — ~^ ' Then a V, = IJiQ^ada + Q.bdb + ^,0^4 = I Q, where dt Q J V(a^ o 230 PROCEEDINGS OP THE AMERICAN ACADEMY Also a a a 0 = 2 n Q^cdu -!- Q,hdb + Q^cdc] = 2 J--^ = 4j|f , 'i 00 00 and concequently ^ is a homogeneous function of a, h, c of degree — 1. ■ ••• a'^Qa + ^'Qb + '^'Qc^-hQ- = 1 1 {X- - a^) Q^ + {f - I') Q, + {^ - c"-) ^,} . Within the shell F = I {x'^Qa^+fQ,, + ^^^0,) - 2 9P (^. + If. + ^.) «iS«i + «^°«t- At the surface the const. = 2 Qpa^^a, + ^ ».+ e.. + <>. } - 2 Qp-M {i + i + i} So that any internal equipotential surface is an hyperboloid of one sheet of which the square of the imaginary axis is numerically the least, or an hyperboloid of two sheets of which the square of the real axis is numerically the least. The equations of the external equi- potential surfaces involve elliptic functions. 232 PROCEEDINGS OF THE AMERICAN ACADEMY XVII. RESEARCHES ON THE COMPLEX INORGANIC ACIDS. By Wolcott Gibbs, M. D., Rumford Professor in Harvard University. (Continued from Vol. XVII. p. 90.) Presented May 9th, 1883. The compounds which I have hitherto described may be embraced under the general formula 7» R 0,3 . 2 W.p, . p ^'\0. in which m may represent any even number from 10 to 48 inclusive, p the number of molecules of base (old style), R an atom of tungsten or molybdenum, and R' one of phosphorus or arsenic. I shall now proceed to show that these results may be generalized in a variety of different ways, and, further, that there are other typical formulas, per- haps less general than that above given, but still embracing many interesting and instructive special cases. HYPOPHOSPHO-MOLYBDATES. Hypophospho-molyhdate of Ammonium. — When solutions of 14:6 acid ammonic molybdate and sodic hypophosphite are mixed, no precipitate is formed, but the liquid takes a fine blue color from the partial reduction of molybdic teroxide to Mo.^O^. On addition of chlorhydric acid and stirring for a short time, a large quantity of a crystalline salt separates. This is to be filtered off, well drained by the filter-pump, and washed with cold water, in which it is not very soluble. When perfectly pure and free from Mo^Og the salt presents colorless prismatic crystals, which are readily soluble in hot water. The solution, at first pale blue, speedily assumes a deeper tint; with cold water a colorless strongly acid solution may be obtained, and OF ARTS AND SCIENCES. 233 with such the reactions here given were obtained. Baric chloride gives no precipitate alone, but after adding ammonia a colorless salt is thrown down, which is at first flocky, but which soon becomes fine- grained granular-crystalline. Strontic and calcic chlorides behave in a similar manner, but the calcic precipitate does not form so rapidly. Manganous sulphate gives no precipitate alone, but after adding am- monia a white flocky salt is formed, which becomes yellowish on stand- ing. Cupric sulphate behaves in the same manner ; the precipitate after the addition of ammonia is green and flocky. The mixture with solution of copper is not reduced on boiling, either alone or after addi- tion of chlorhydric acid. The solution of the hypophospho-molybdate gives a canary-yellow precipitate with mercurous nitrate, and a nearly white precipitate with argentic nitrate, which soon becomes gray and finally black. Thallous nitrate gives a white flocky precipitate. "When the dry salt is heated, it becomes at first black and fumes slightly, but on further heating it melts to a dark blue mass which gives off a little molybdic teroxide on heating to redness. The fused mas3 dissolves readily in hot water, forming a deep blue solution which has an acid reaction, and gives with magnesia-mixture the character- istic ammonio-magnesic phosphate. The effect of heat is represented by the equation 8 M0O3 . 2 {H, . PO . OH} 2 . (NH,)^ 0 + 2 H,0 = 8 M0O3 + P2O5 + 3 H2 + 2 (NHJ 2 0 + H,0. In the analyses the loss by ignition corresponds to 2 (NHJ^^ -f~ H.,0 + 3 H.,, and the residual mass to 8 M0O3 + P2O5, when the ignition is made with sodic tungstate. In this salt, — 1.3172 gr. lost on ignition with W0,Na2 0.1329 gr. = 10.09 % II.p, (NH,),0, and H. 1.0764 gr. lost on ignition with WO^Naa 0.1086 gr. = 10.09 % HA (NHJO, and H. 1.2369 gr. gave 0.1836 gr. NH.Cl = 7.21 % (NHJ^O. 1.2850 gr. " 0.0918 gr. (NHJ,0 by titrition = 7.15% 2.4322 gr. " 0.3860 gr. Pp.Mg^ = 9.42% PO^Hg. 1.6217 gr. " 0.2578 gr. " = 9.30% PO^Hj. The analyses lead to the formula 8 M0O3 . 2 {H2 . PO . OH^ 2 (NH,), O -f- 2 aq, which requires : — 234 PROCEEDINGS OP THE AMERICAN ACADEMY Calc'd. Mean. Foun d. 8 M0O3 1152 80.89 80.97 2 PO.Hg 132 9.27 9.36 9.42 9.30 2(NH,),0 104 7.31 7.18 7.21 7.15 2U,0 36 2.53 2.49 2.47 2.52 1424 100.00 100.00 In computing the results of the analyses the loss of weight by igni- tion, 10.09 %, is of course taken to represent 2 (NHJ.p + H^O + 3 Hg, in accordance with the equation given above. In the analyses the quantity of hypophosphorous acid was determined by dissolving the salt in a solution of sodic carbonate, and then adding bromine, which with the aid of heat readily converts the hypophosphorous into phos- phoric acid. The quantity of the former could not be determined by means of potassic hypermanganate in an acid solution. Bromine does not act sensibly upon acid solutions, and even an excess of nitric acid effects an imperfect oxidation. These facts, taken in connection with the relations of the salt to solutions of copper and silver, seem to show that the stability of hypophosphorous acid is increased by its combination with molybdic teroxide. The salt has, as stated, a strong acid reaction, and the limit of the basicity of this class of compounds still remains to be determined. The formula may also be written : — 8 M0O3 . 2 {H„ . PO . (NH,0),} 2 H„0 + 2 aq. The constitution of hypophosphorous acid was first established by Wiirtz. More recent investigations in organic chemistry have shown that it is to be regarded as dihydryl-phosphinic acid, and that it forms the initial term and type of an extensive series of organic acids, in which the two atoms of hydrogen attached to the phosphorus are replaced by methyl, phenyl, &c., and in which also arsenic may replace phosphorus. I do not propose at present to proceed further in this particular line of research, but will content myself with the statement that a solution of dimethyl-arsinic (kakodylic) acid gives immediately in one of 14:6 acid ammonic molybdate a beautiful colorless crystal- line precipitate. It can hardly be doubted that this is a dimethyl- arsino-molybdate belonging to the general type represented by the formula m M0O3 . 2 {(CHj)^ . AsO . (OH)} n (NHJp. The structural formula of the hypophospho-molybdate above de- OP ARTS AND SCIENCES. 235 scribed, or rather of the corresponding acid, may be written, in accordance with the general principles already assumed, as follows : — M0O2 = M0O2 I I O O I I M0O2 = M0O2 I I o o I I HO - M0O2 — M0O2 - OH I I HO - M0O2 — M0O2 - OH I I O O I I HO - PO OP - OH li II Hg Hg In this formula the acid is supposed to correspond to the ammonium salt described. HYPOPHOSPHO-TUNGSTATES. The salts of this series are not very well defined as regards their physical properties, and it is difficult to obtain any single one in a state of perfect purity. They are most readily prepared by boiling acid tungstates with a solution of hypophosphorous acid, and appear to be in general very soluble in water, yielding sometimes thick syrupy liquids, and sometimes gelatinous masses more or less colored by the partial reduction of tungstic teroxide. Potassic Salt. — When a strong solution of hypophosphorous acid is mixed with one of 12 : 5 acid sodic tungstate, the liquid becomes turbid and yellowish, and after a short time gelatinizes to a pale yellow mass. This is to be dissolved in boiling water, and a solution of potassic bromide added, which after a short time gives a white crystalline pre- cipitate, to be drained upon the filter-pump, redissolved in hot water, again crystallized, drained, washed with cold water, and dried on wool- len paper. As thus prepared, the salt presented small colorless granular crystals, soluble in hot water to a somewhat turbid strongly acid liquid, which effervesced with alkaline carbonates. The solution gave no precipitate with cupric sulphate, and no copper was reduced on boiling 236 PROCEEDINGS OF THE AMElilCAN ACADEMY either with or without chlorhydiic acid. Argentic nitrate gave a turbid white solution ; on boiling, silver was reduced. Mercurous nitrate gave a white flocky precipitate, which on boiling became yel- low, and finally dirty greenish yellow, without reduction of mercury. Baric chloride gave a white precipitate of indistinct feathery crystals. When heated in a porcelain crucible the salt became blue, and finally white, giving off a sharp acid smell. The residue dissolved in water, in part at least, forming a strongly acid solution. Of this salt ( 1.2295 gr. lost on ignition 0.0340 gr. ^ 2.76 % water and hydrogen. 1 1.2295 gr. gave 1.1172 gr. WO3 + PA = 90.84% 0.7272 gr. lost on ignition with W04Na2 0.0203 gr. = 2.79 % 1.5110 gr. gave 0.1921 gr. P^Mg^ = 7.57% POgHg The analyses lead to the formula 18 WO3 . 6 {H, . PO . OH} 4 K^O + 7 aq, which requires : — 90.28 Calc'd. Found. 18 WO3 6 PO2H3 4176 396 ^^•^U 90.11 7.80 i 82.71 7.57 4K,0 376 7.41 7.42 TH^O 126 2.48 2.45 5074 100.00 100.15 In the analysis the hypophosphorous acid was determined by oxida- tion with bromine in an alkaline solution and precipitation with magnesia-mixture. The formula given may be written, with equal probability, • 18 WO3 . 6 {H2 . PO . OK} Kp . 3 HP + 7 aq, since the assignment of the fixed base is purely arbitrary ; other arrangements are also possible. I am disposed to regard the salt as acid, with the formula 2 (6 WO3 . 2 {FI^ . PO . OH} 2 K,,0) + 6 WO3 .'2 {H2 . PO . OH} 2 H^O + 5 aq, so that the type of the corresponding acid, setting aside the question of basicity, will be 6 WO3 . 2 |H, . PO . OH} 2 H^O. OF ARTS AND SCIENCES. 237 The structural formula of such an acid will be similar to that already giveu ia the case of the hypophospho-molybdate described. Further investigation may, however, show that the more complex formula must be admitted. I coutent myself with proving that there is at least one class of hypophospho-tungstates. In computing the direct results of the analyses I have assumed that, as in the case of the corresponding molybdenum compounds, the complex 2 {Hj . PO . OH} is oxidized to Ffi^ wholly at the expense of two molecules of WO3 reduced to W.,05, which last is then again oxidized to 2 WO3 by heating in air. This assumption appears to be justified by the changes of color observed on heating the salt. The actual loss of weight observed then corresponds to water and hydrogen only, the percentage of hydrogen being calculated from that of P^O^Hg. When tungstic hydrate in excess is boiled with a solution of sodjc hypophosphite, it dissolves very readily, giving a pale blue solution which yields on evaporation a thick syrupy liquid. This solution gives precipitates with BaCl.,, NH^Cl, and KBr, and will furnish a con- venient starting-point for further investigation. It does not oxidize readily in the air, even after long standing. A solution of dimethyl- arsinic acid gives with one of 12:5 acid sodic tungstate a beautiful colorless crystalline precipitate. I have not studied this compound, from want of proper facilities for work of the kind. It will, I think, prove to be a dimethyl-arsino-tungstate, coming under the general formula m WO3 . 2 {(CHg), . AsO . OH} n Na,0, and we may reasonably expect an extensive series of analogous com- pounds, in which other radicals take the place of methyl. PHOSPHOROSO-MOLYBDATES. Since phosphorous acid is now to be regarded as hydryl-phosphinic acid with the formula {H.PO.(OH)J, the existence of a class of phosphoroso-molybdates and of phosphoroso- tungstates appeared, to say the least, a probable inference from that of the hypophospho-compounds already described. Phosphoroso-mohjhdate of Ammonium. — When a solution of phos- phorous acid — as prepared by the reaction of phosphorous chloride with water — is added to one of 14: 6 acid ammonic molybdate, a very pale yellow indistinctly crystalline precipitate is formed, which is insoluble 238 PROCEEDINGS OF THE AMERICAN ACADEMY in cold water. Hot water dissolves it only in a small proportion, but gives a milky emulsion, which settles very slowly. For analysis the salt was drained on a filter-pump, well washed with cold water, and finally dried on woollen paper. Of this salt, — 1.9695 gr. gave 0.0980 gr. (NHJ^O = 4.97% by titrition. 1.1425 gr. " 0.0559 gr. " =4.89% " 0.9301 gr. lost on ignition with WO^Naa 0.1225 gr. = 13.17% 1.2722 gr. gave 0.1374 gr. P^O.Mg, = 7.97% PO3H3 The analyses correspond fairly well with the formula 24 M0O3 . 4 {H . PO . (OU)^} 4 (NHJP + 17 aq, which requires : — Calc'd. 24 M0O3 80.41 4 P0,Il3 7.63 4 (MH,),0 4.84 ITH^O 7.12 } Found. 79.88 ) 88.04 ^ g^ y 87.85 4.89 4.97 7.22 100.00 The salt certainly contained a little phospho-molybdate, to which the faint yellow tint was probably due. It is very difficult to obtain a solution of phosphorous which is absolutely free from phosphoric acid. With respect to the formula I remark that the number of molecules of water may be purely accidental, and that there is at present no sxif- ficient reason for rejecting the simpler expression 12 M0O3 .2 (H . PO . (011)2} 2 (NHJ^O -f x aq. The type of the acid is then 12 MoOj . 2 {H . PO . (OH),,} 2 Kfi. A solution of baric chloride boiled with the phosphoroso-molybdate decomposes it more or less completely, giving a white very fine- grained crystalline salt. Under the same circumstances argentic ni- trate gives a nearly colorless flocky substance, which quickly becomes darker, and finally assumes a dull violet color. Mercurous nitrate yields a clear pale yellow flocky salt ; the phosphoroso-molybdate does not reduce a solution of mercuric chloride even on boiling. Cupric sulphate dissolves the salt to a clear blue liquid. Manganous sulphate also dissolves it, forming a colorless solution. Alkaline hydrates dis- solve it very readily to colorless liquids. The salt is readily decom- OF ARTS AND SCIENCES. 239 posed by heating in a porcelain crucible, and fuses at a low red heat, giving off vapors of molybdic teroxide. The fused mass on cooling is bluish gray. It dissolves readily in water to a deep blue liquid, which has a strongly acid reaction, and gives with magnesia-mixture the reaction for phosphoric acid. The structural formula of the acid corresponding to the ammonium salt may be written provisionally : — MoOj = I 0 I MoO. = '2 I o I MoO-^ I O I M0O2 I o I HO — MoO, HO — MoO, — M0O2 I O I M0O3 I O I M002 I o I M002 I o I MoO, — OH MoO„— OH HO ^ 1 0 1 ^ PO 1 0 t OP " ^ OH HO " 1 H 1 H " OH If we accept the views now generally received as to the constitution of hypophosphorous and phosphorous acids, the hypophospho-molyb- dates, hypophospho-tungstates, and phosphoroso-molybdates furnish a much needed demonstration of the fact, that in this whole class of compounds part at least of the hydroxyl is united to phosphorus di- rectly, and a part only to tungsten or molybdenum. This will appear at once from the formulas for the two acids, since these cannot be broken up into simpler expressions, {Hj . PO . OH}, and {H . PO . (OH)^, or from the structural formulas which I have given. I shall return to 210 PROCEEDINGS OF THE AMERICAN aCADEMY this point hereafter, and give additional proofs of the twofold mode of combination of hydroxyl. Further investigation will almost certainly show that the homologues of hydryl-phosphinic or phosphorous acid will also form complex acids with tungstic and molybdic teroxides. Thus methyl-phosphinic acid {CH„ . PO . (OH) J should form at least one series of each of the general types : — m M0O3 . {CH3 . PO . (0H)2} n Hp. n WO3 . {CH3 . PO . (0H)2} p HoO. In these cases arsenic, and perhaps antimony, may replace phosphorus. Phosphoroso-tungstates may be formed by the action of phosphorous acid upon acid tungstates. The only salt obtained at present appears to have the formula 12 WO3 . 2 {H . PO . (OH),} 2 Kp + 12 aq. I propose to return to this special point when describing the related groups of arsenoso-tungstates and antimonoso-tungstates and the cor- responding molybdates. In the analysis of the phosphoroso-molybdate of ammonium the phosphorous acid was determined by dissolving the salt in an excess of a solution of sodic carbonate, oxidizing with bro- mine, and precipitating with magnesia-mixture. VANADIO-MOLYBDATES. The general analogy between vanadic, arsenic, and phosphoric pen- toxides suggested to me the possibility of forming series of vanadio- molybdates and vanadio-tungstates, belonging to types of a character similar to those of the phospho-molybdates and phospho-tungstates already described. I shall now show that such compounds may readily be formed by processes identical in principle with those which yield compounds of phosphoric and arsenic oxides with molybdic teroxide. Vanadio-molybdates are formed when vanadic pentoxide VgOj is di- gested with solutions of alkaline molybdates, more especially with the acid salts of potassium, sodium, or ammonium. The solution quickly becomes yellow, then, on heating, orange, and finally passes in many cases to deep orange-red. The vanadic oxide or acid employed must be perfectly free from vanadic dioxide, as this is also readily dissolved. The resulting compound then belongs to the class of triple complex acids, and contains both oxides of vanadium united to molybdic oxide. I shall return to these compounds in due time, and meanwhile shall OP ARTS AND SCIENCES. 241 refer to them under the name of vanaclico-vanadio-molybdates. The presence even of a small quantity of vanadic dioxide may usually be detected by a peculiar greenish shade of color, easily recognized when once seen. This tint disappears when the solution is heated for a short time with bromine water or nitric acid, which readily oxidize the lower oxides of vanadium. Vanadio-molybdates are also formed when solutions of alkaline va- nadates and raolybdates are heated together, and more readily when an excess of acid is present. The mixed solution then assumes at once a deep orange-red color. The same salts are also formed when molybdic oxide, M0O3, is boiled with a solution of an alkaline vanadate or meta-vanadate. Ammonic meta-vanadate, VOgNH^, may now be had in commerce in a state of very considerable purity, and has served as the starting point for much of my work. A solution of this salt readily dissolves molybdic oxide, forming one or more vanadio-molybdates, only in this case there is a tendency to a kind of supersaturation, a large excess of molybdic oxide being dissolved and separating from the liquid on cooling. Finally, vanadio-molybdates may be formed by the decomposition of phospho-vanadio-molybdateSj a class of triple compounds also to be described. The vanadio-molybdates of the alkaline metals are in general read- ily soluble in water. They are highly crystalline, have a yellow or greenish yellow, sometimes orange-yellow or orange-red color, and give in many cases crystalline precipitates with salts of the alkaline earths, of silver, and of thallium. They are not decomposed by boiling with excess of acid, and are usually very stable, except in the pres- ence of reducing agents. Analytical Methods. — The quantitative separation of molybdenum from vanadium presented a new problem in analytical chemistry, the solution of which cost much time and labor. It may be effected in two different ways. When the vanadium is wholly or jiartially in the form of vanadic dioxide, VO, , it is to be oxidized by heating the con- centrated solution with nitric acid. An alkaline carbonate is then to be added until the solution is nearly neutral, when the vanadic and molybdic oxides may be precipitated together by means of mercurous nitrate and mercuric oxide, precisely as in the estimation of tungstic oxide already described. The precipitate of mercurous vanadate and molybdate and mercuric oxide is to be filtered upon a paper filter. After drying, the filter and contents may be heated together in a plati- num crucil)le, with free access of air. When the process is carefully VOL. XVIII. (x. s. X.) 16 242 PROCEEDINGS OF THE AMERICAN ACADEMY conducted, the filter may be completely incinerated with great ease, and without loss of molybdic oxide from volatilization. A weighed quan- tity of fused and pulverized neutral sodic tungstate is then to be added, when the crucible may be heated to redness, and the mercurous and mercuric oxides completely expelled. A second heating and weigh- mg are always advisable. In this manner the sum of the weights of molybdic and vanadic oxides is obtained. To determine the quantity of vanadic oxide alone, the same process is to be repeated ; only after burning off the filter the mass is to be carefully heated with a free sup- ply of air to act mechanically until the whole of the molybdic oxide is volatilized and vanadic oxide remains as an orange-brown liquid, and, after cooling, as a crystalline mass. The complete expulsion of the molybdic oxide requires long heating, at a full red heat. The vanadic oxide is not volatile, but it has the inconvenient habit of creeping up the sides and over the edge of the crucible, — a habit for which there appears to be no remedy. The weight of the molybdic oxide may then be determined by difference. This method gives good results, and in some cases may be used with advantage. Another method is the following, which applies directly to the vana- dio-molybdates of the alkaline metals, and to those of the alkaline earths, after the separation of the base. Ammonia is to be added in excess to the solution, which is then to be boiled for a few minutes, so as to convert the salt into a mixture of an alkaline vanadate and molybdate. A saturated solution of ammonic chloride is then added in very large excess, after which the liquid must be concentrated by continued boiling until reduced to a relatively small volume. The solution must then be allowed to stand for twenty-four hours, when a greater or less deposit of ammonic meta-vanadate will have formed in colorless crystals.* These crystals are to be brought upon an asbestos filter, and washed with a cold saturated and pure solution of ammonic chloride. The vanadic pentoxide may then be found by carefully igniting the salt with free access of air. It is, however, better to dis- solve the salt upon the filter with boiling water, reduce the solution by means of a current of sulphydric acid gas after adding a little sulphuric acid, filter, and titrate with potassic hypermanganate. The clear blue solution contains vanadic dioxide only. The end reaction is tolerably sharp in dilute solutions — say 0.25 gramme — of VO^ in 250 c. c. of * The best commercial chloride of ammonium always contains iron not pre- cipitablc by ammonia. If bromine water be added first to the boiling solution, ammonia in small quantity separates the iron completely. OF ARTS AND SCIENCES. 243 water. The reason for adopting the method of titrition is, that the ignition of amnionic meta-vanadate, even when conducted with great care, usually yields a mixture of vanadic pentoxide and dioxide, which it is difficult to oxidize completely. The precipitation of ammonic meta-vaiiadate by ammonic chloride is, as is well known, not abso- lutely complete, but the results of the analyses are on the whole fairly good. It is sometimes more advisable to employ a combination of the two methods described. After precipitating the two oxides by means of mercurous nitrate and mercuric oxide, the greater part of the molyb- dic oxide may be expelled by heat, after which the mixture of oxides, which now consists chiefly of vanadic pentoxide, may be dissolved in ammonia and treated with ammonic chloride in the manner above described. The quantity of molybdic oxide is most easily estimated by difference, the sum of the weights of the two oxides being deter- mined by the method given above. It is not possible to reduce the vanadic pentoxide in the vanadio-molybdates to vanadic dioxide by means of sulphydric acid gas, by sulphurous oxide, or by any other reagent which I have tried, without at the same time reducing a por- tion of the molybdic teroxide to the blue oxide M02O5. This difficulty may however be overcome by first adding phosphoric acid to the solution in quantity about equal to the weight of the salt analyzed. After the addition of a little sulphuric acid the reduction of the vana- dic pentoxide may be effected either by boiling with a solution of sul- phurous oxide, or by passing sulphydric acid gas for some time through the hot solution of the salt. In separating vanadic from molybdic oxide by means of ammonic chloride it is necessary to keep the solution always slightly alkaline by the occasional addition of a little ammonia, since, as soon as the liquid becomes acid by the dissociation of the ammonium salts present, a vanadio-molybdate is again formed in greater or less quantity. To resolve a vanadio-molybdate into a mixture of vanadate and molyb- date, it is necessary to employ an excess of free ammonia, and also to heat the solution. Actual boiling is most advantageous. Another method of estimating vanadic oxide in the presence of molybdic teroxide consists in boiling the compound with strong chlor- hydric acid, passing the chlorine set free into a solution of potassic iodide, and then determining the free iodine volumetrically by sodic hyposulphite and starch. I have not actually employed this method, however, though it gives excellent results in the analysis of the vana- dio-tungstates. 244 PROCEEDINGS OF THE AMERICAN ACADEMY It will be convenient to speak in this place of the best method of determining vanadium in alkaline vanadates without special reference to its separation from other elements. I find that this estimation may be effected with great accuracy by first oxidizing any lower oxide which may be present by means of nitric acid to vanadic pentoxide, and then i>recipitating the faintly acid solution by mercurous nitrate and an excess of mercui'ic oxide at a boiling heat. Precipitation by mercurous nitrate alone was long since suggested by Berzelius, but the addition of mercuric oxide to render and to keep the solution neutral makes precisely the difference between a very accurate and an only tolerably good result. The precipitate may be collected upon a paper filter, and after washing with hot water ignited with free access of air. On cooling, a fine orange-brown crystalline mass of vanadic pentoxide remains. The filtrate from the precipitated oxides contains no appre- ciable trace of vanadium. The great facility with which a solution of vanadic pentoxide containing free chlorhydric acid is reduced by fer- rous salts, suggested the possibility of determining vanadium by titri- tion with ferrous sulphate, a solution of potas.sic ferricyanide being employed to determine the point of complete reduction. A special study of this j^rocess was made in my laboratory by my assistant, Mr. Charles A. French, to whom the following details are exclusively due. The solution containing vanadic pentoxide is to be concentrated, and chlorhydric acid solution containing about one tenth of its weight of pure acid added in large excess. After nearly saturat- ing with a solution of ferrous or ammonio-ferrous sulphate of known titre, the solution is to be heated nearly to boiling, and the titrition then completed with the ferrous salt, the end reaction being deter- mined by trial drops upon a porcelain plate with a very dilute solu- tion of potassic ferricyanide. Of this solution two drops of the ordinary laboratory reagent in a test-tube full of water give an ap- propriate strength. The process may be varied by adding the ferrous solution in excess, then titrating back by means of potassic dichromate of known titre, and finally adding the ferrous salt until the end reac- tion with ferricyanide is obtained. The ferrous solution may contain with advantage 0.005 gr. of iron in one cubic centimeter. A sample of potassic di vanadate containing no other impurity than a little potas- sic nitrate gave, by the gravimetric process above described, 65.12^ V2O5. In three successive titritions with ammonio-ferrous suljihate Mr. French found G5.16, 65.27, and 64.95%. As ammonic meta-vanadate is now largely used in the manufacture of aniline black, and has become an article of commerce, the method OF ARTS AND SCIENCES. 245 of titvition described above may perhaps find useful application in technical laboratories, as the end reaction in titrating with hyperman- gauate is not very sharp. I have in my work employed it in several cases as a check upon other methods. In the analyses of vanadio-molybdates it is best to determine the alkalies by difference, as in the cases of the phospho-molybdates and phospho-tuugstates. As in these cases also ammonia and water are best determined together by ignition with a weighed portion of neutral sodic tungstate, WO^Na^, a method suggested by Dr. F. A. Gooch for the whole class of phospho-tuugstates and phospho-molybdates of ammonium ; only in the case of the vanadio-molybdates and other salts containing both molybdenum and vanadium, it is necessary to be espe- cially careful in igniting with the tungstate, because molybdic teroxide is sometimes given off before the complete fusion of the tungstate with the salt. 6:1 Series. — A solution of ammouic meta-vanadate, YOgNH^, readily dissolves molybdic teroxide on boiling, forming a deep orange- yellow solution. The liquid on standing deposits a veiy beautiful lemon-yellow salt, in sharp octahedral crystals, which are soluble in a rather large excess of cold water without sensible decomposition. The solution, on spontaneous evaporation, yields the salt without change. Of this salt, — 1.1349 gr. lost on ignition with WO.Na, 0.1806 gr. = 15.91% 1.3220 gr. " " « " ' 0.2128 gr. == 16.09% 1.5022 gr. « " « " 0.2412gr. = 16.05% 1.2477 gr. gave 0.2201 gr. NH.Cl = 8.57% (NHJ^O 1.3822 gr. " 0.2439 gr. " = 8-57% " 1.2847 gr. " 0.1893 gr. V^O. by KMnO^ = 14.73% The analyses lead to the formula 6 M0O3 . Y^O, . 2 (NH,\0 -f 5 aq, which requires : — Calc'd. Found. 6 M0O3 864 69.62 VA 183 14.74 14.73 2 (NH,),0 104 8.39 8.57 8.57 5 H,0 90 7.25 7.34 7.52 7.48 1241 100.00 246 PROCEEDINGS OF THE AMERICAN ACADEMY The reactions of a solution of this salt iu cold water are as follows. No preci^iitate with salts of copper, zinc, manganese, and cadmium. Argentic nitrate gives a flocky yellow precipitate, with a tinge of buff. Mercurous nitrate gives a bright yellow i^recipitate. Thallous nitrate gives a very pale yellow flocky precipitate, which does not become crystalline on standing. Baric chloride gives no precipitate at first, but after a short time very beautiful sharp octahedral crystals : after lono-er standing small pale yellow very distinct prismatic crystals also appear in the solution. Strontic chloride gives, after some days, very well defined pale yellow prismatic crystals. The solution of the vanadio-molybdate gives a rather dull yellow flocky precipitate with hydro-chloride of brucin, and a bright yellow one with hydro-chloride of strychnin. No precipitate is formed at first with potassic bromide, but after some days beautiful very well defined granular crystals are deposited in quantity. The solution of the salt has a strongly acid reaction. The mer- curous salt is decomposed by dilute chlorhydric acid, with formation of mercurous chloride and a yellow acid solution, doubtless of the acid of this series. The acid was decomposed by spontaneous evaporation, and did not yield crystals. It appears unnecessary to give a structural formula for the salt de- scribed, since we may regard V^O^ as simply replacing PJJ^, and with the same function as this last, so that the structural formulas already given for the phospho-tungstates will apply to the present case also. Uight Atom Series. — When acid ammouic molybdate is dissolved, and vanadic j^entoxide is added in small quantities at a time, the boil- in o- solution quickly becomes yellow, and then orange. If the vanadic oxide is not perfectly free from dioxide, VO^, a little bromine water should be employed to complete the oxidation. If a solution of baric chloride be mixed with the rather dilute and warm solution, no pre- cipitate is formed at first, but after a few seconds an abundance of beautiful yellow well-defined crystals appears. These crystals are very sharp octahedra, and strongly resemble those of one of the am- monium salts of the six-molecule series. After a time granular yellow crystals make their appearance also in large quantity. The habitus of these crystals is so different from that of the first named that the two can readily be separated when mixed. A very approximate separa- tion can also be effected by pouring off the liquid the moment that the granular crystals begin to appear. The yellow octahedral crystals are soluble in hot water, containing a little chlorhydric acid, and may be OF ARTS AND SCIENCES. 2^7 recrystallized. When heated, the salt swells up very much, and turns black, looking like coke. Of this salt, — 1.0070 gr. lost on ignition with WO^Naj 0.1310 gr. = 13.00% 0.9716 gr. " " " " 0.1280 gr. = 13.17% 1.2449 gr. " " " " 0.1637 gr. = 13.16% 0.9682 gr. gave 0.6534 gr. M0O3 + V.O, = 67.48% 1.0162 gr. " 0.3029 gr. SO.Ba ' = 19.56% 1.0343 gr. " 0.3072 gr. " = 19.50% 1.0190 gr. " 0.3023 gr. " * = 19.48% 1.0937 gr. " 0.0998 gr. V.O^ = 9.12% 1.4395 gr. " 0.1356 gr. " ^ = 9.37% These analyses lead to the formula 16 M0O3 • 2 Vp, . 5 BaO + 29 aq, or. 8 M0O3 . VA . 3 BaO + 8 M0O3 . V^O^ . 2 BaO . 11,0 -f 28 aq, which requires : — Calc'd. Found. 16 M0O3 2304 58.25 58.34 2 V,0, 364 9.21 9.12 9.37 5 BaO 765 19.35 10.48 19.56 29 H.O 522 13.19 12.06 13.00 13.16 3955 100.00 The salt is therefore to be regarded as the acid salt of the eight- atom series, and belongs to a type of which several examples have been o-iven among the phospho-tungstates and phospho-molybdates. It may also be considered as an acid sixteen-atom salt, upon the view which I have siio-gested in another place as at least possibly correct The 16:2 barium salt is also formed when baric chloride is added to a solution of the 6 : 1 vanadio-molybdate of ammonium already de- scribed. The last-named salt is therefore formed when vanadic pentoxide is dissolved in acid ammonic molybdate, as well as when molybdic oxide is dissolved in ammonic meta-vanadate. In the double decomposition with baric chloride at least three molecules of the 6 : 1 ammonium salt must take part. The barium salt is nearly insoluble in cold water, but is soluble in much hot water, with partial decomposition and deposition of baric molybdate. The solu- tion in cold water reddens litmus strongly : it gives with argentic 248 PROCEEDINGS OP THE AMERICAN ACADEMY nitrate a pale, and with mercurous nitrate a bright yellow flocky I^recipitate. The first determination of vanadic pentoxide in this salt was made by heat alone, the mixture of molybdic and vanadic oxides being ignited until a constant weight was obtained. In the second analysis the determination was made by titrition with ferrous sulphate after adding chlorhydric acid to the solution. Eighteen Atom Series. — A boiling solution of ammonic meta- vanadate readily dissolves molybdic teroxide, M0O3, forming a deep yellow or orange-yellow solution. When the oxide is added as long as it is readily dissolved, an olive-green liquid is obtained, from which after twenty-four hours hard tabular crystals of a pale greenish color are deposited. These crystals are decomposed by boiling water, beau- tiful yellow needles very slightly soluble in water, being formed, to- gether with a greenish yellow solution which soon becomes turbid. The salt could not be purified by recrystallization, and was therefore washed with a little cold water and dried on woollen paper. Of this salt, — 0.8067 gr, ignited with WO.Na, lost 0.1586 gr. = 19.66% 0.8538 gr. gave 0.2140 gr. NII^CI =12.18% (NHJP 1.0243 gr. " 0.2526 gr. " =11.99% " 0.7945 gr. " 0.0407 gr. V^O^ = 5.12% These analyses correspond to the formula 18 M0O3 . V2O5 . 8 (NH,X,0 + 15 aq. Calc'a. Found. 18 M0O3 2592 74.89 75.22 v,o, 183 5.29 5.12 8 (NHJ.O 416 12.02 11.99 12.18 15 H,0 270 7.80 7.58 3461 100.00 A more extended investigation will, undoubtedly, show that the vanadio-molybdates are, to say the least, numerous. The salts which I have described are sufficient to establish a parallelism between them and the phospho-molybdates, which is the more interesting because the chemical relations of vanadium are nearer to antimony than to phosphorus and arsenic. I shall return to this point, however, in describing and discussin"; the class of antimonio-tunijstates and anti- monio-molybdates. OP ARTS AND SCIENCES. 249 VANADIO-TUNGSTATES. Vanadio-tungstates are very readily formed under conditions pre- cisely the same as tliose which determine the formation of vanadio- molybdates, and which it is unnecessary to recapitulate. As a class, they have a yellow, orange, or orange-red color. They are, so far as examined, readily soluble in water, are crystalline and extremely stable in composition, in the sense at least that it is often difficult to separate the combined vanadio and tungstic oxides, though in many cases com- plex salts easily break up into compounds of simpler type. Analytical Methods. — When alkaline vanadates and tungstates ai-e simply mixed together under conditions which do not result in the for- mation of vanadio-tungstates, it is possible to effect the separation of the vanadic and tungstic oxides by means of a solution of amnionic chloride, which, as is well known, precipitates ammonic meta-vauadate in colorless crystals nearly insoluble in a saturated solution of ammonic chloride. This method cannot be applied directly to the separation of the two oxides when combined, as in the vanadio-tungstates, but the difficulty can be overcome by either of the following methods. An excess of ammonia is to be added to the solution, which is then to be digested, or, if necessary, boiled until the liquid becomes colorless. By tliis process, which, however, does not always perfectly succeed, the vanadio-tungstate is resolved into a mixture of ammonic tungstate and meta- vanadate. In place of ammonia, sodic or potassic hydrate in excess may be employed, and frequently with advantage. After the resolu- tion of the vanadio-tungstate, as indicated by the color of the liquid, ammonic meta-vanadate may be precipitated by boiling with an excess of ammonic chloride. From the cold solution completely saturated with ammonic chloride the meta-vanadate my be separated by filtra- tion, and the vanadic pentoxide estimated in the manner already pointed out. A variation of this process, which may often be em- ployed with advantage, consists in fusing the vanadio-tungstate with an excess of potassic or sodic carbonate in a platinum crucible. The fused mass must be boiled with a strong solution of ammonic chloride, a drop or two of ammonia being added from time to time to keep the solution distinctly alkaline. The ammonic meta-vanadate is to be sep- arated and treated as above. In applying these methods it is impor- tant in each case to be sure that the vanadium is exclusively in the form of pentoxide. It is therefore always advisable to add a little bromine water to the solution of the vanadio-tuno-state before adding the excess of ammonia. In fusing with alkaline carbonates a little 250 PROCEEDINGS OF THE AMERICAN ACADEMY potassic or soclic nitrate may be added to the mixture in the crucible. In this manner we may avoid the error which would result from the pres- ence of vanadic dioxide in the small quantity which often exists in con- sequence of the reducing agency of dust or traces of organic matter. After a great number of trials, the methods given above are the only ones by which I have found it possible to effect even an approximate separation of vanadic and tuugstic oxides in combination. In place of the actual separation of the oxides, it is much more con- venient, and I believe also in general much more accurate, to employ the following process, which permits us to estimate vanadium quanti- tatively in presence of tungstic, as well as of various other oxides. This process depends upon the fact that vanadic pentoxide, either free or in combination, when boiled with strong chlorhydric acid, evolves chlorine, which may be collected in a solution of potassic iodide. The iodine set free may then be estimated with great accuracy by means of sodic hyposulphite after adding a solution of starch. The fact that vanadic pentoxide evolves chlorine on heating with chlorhydric acid was, so far as I have been able to find, first remarked by Mohr, who in his well-known work on volumetric analysis sug- gested as possible the method of determining vanadium which I have employed, without, however, testing it in any single case. It is possible, in some cases at least, to determine vanadic pentoxide in the presence of tungstic oxide by titrition with hypermanganate. To the solution of the substance containing both metals, phosphoric and sulphuric acids are to be added, and the vanadic pentoxide is then to be reduced to dioxide by means of sulphydric acid gas passed into the boiling solution until comjjlete reduction is obtained. No appre- ciable quantity of tungstic oxide is reduced under these circumstances. The titrition with hypermanganate may then usually, though not always, be executed, and gives a fairly good result. Finally, the method of titrition by ferrous salts may often be used with success. The details have already been given, and do not need to be repeated. 5 : 1 Vanadlo-tungstate of Ammonium. — When 12:5 ammonic tunijstate is boiled with a solution of ammonic meta-vanadate an orange solution is obtained, which, on evaporation deposits orange-yellow crusts of indistinct crystals. The color of this salt is somewhat dull ; it is not very soluble in cold, but soluble in boiling water, and may be re- crystallized without sensible decomposition. The salt becomes green- ish upon the surface when dried upon woollen paper, from a slight superficial reduction of the vanadic pentoxide. Of this salt, — OF ARTS AND SCIENCES. 251 1,0558 gr. gave 0.1222 gr. (NHJ.O by titrition = 11.57% 1.1873 gr. lost on ignition 0.2922 gr. = 24.61% HgO and NH3 1.0558 gr. gave by titrition with KMnO^ 11.09% VPg The analyses lead to the formula 5 WO3 . y.fi, . 4 (NHJ,0 + 13 aq, or 5 WO3 . V,0, . 4 (NH,),0 . 2 HP + 11 aq, if we regard the acid provisionally as G-basic, which requires : — Calc'd. round. oWOg 1160 64.99 — VA 183 10.26 11.09 4 (NH,)20 208 11.65 11.57 13 H2O ' 234 13.10 13.04 1785 100.00 The percentage of vanadic oxide found is too high, but there can be no reasonable doubt as to the formula. I obtained the salt but once, and then in small quantity. The solution gives a dull yellow flocky precipitate with argentic and mercurous nitrates, and after a time a yellow crystalline precipitate with excess of potassic bromide. The ammonium salt is interesting as being probably the first term in a series. It corresponds to the phospho-molybdate 5 M0O3 . PoO^ . 3 (NHJ.O . 3 H,0 4- 4 Aq. The following may serve as starting points for further investigation. "When normal baric tungstate, WO^Ba, is boiled for a long time with a solution of ammonic meta-vanadate, it is very sl'owly dissolved to an orange-yellow solution, which on cooling gives very beautiful square tabular deep red crystals mixed with excess of baric tungstate. 12 : 5 baric tungstate dissolves more readily in the meta-vanadate, and gives a bright orange-yellow solution, which on evaporation yields fine pris- matic crystals. From the above it appears probable that the tung- states of the heavy metals, both neutral and acid, will yield vanadio- tungstates by boiling with alkaline vanadates, and possibly in this manner various new series of salts may be formed. The costliness of the material for this work has prevented a more thorough study on my own part. 10:1 Vanadio-tungstic Acid. — A solution of ammonic meta-vana- date dissolves tungstic oxide readily on boiling, giving a deep orange- 252 PROCEEDINGS OF THE AMERICAN ACADEMY yellow solution. After long boiling with an excess of the oxide, the clear deep orange filtrate gives, with a solution of chloride of trimethyl- ammonium, on standing some hours, two distinct kinds of crystals, which are respectively yellow and deep orange-red. There are there- fore, apparently at least, two different salts formed in the solution of the tungstic oxide. The solution of the ammonium salt gave with baric chloride, after some hours, sharp octahedral crystals of a yellow salt but slightly soluble even in hot water. In a second experiment, baric chlo- ride gave at once a yellow fine-grained crystalline insoluble jirecipitate ; but the precipitation was not complete. On boiling the mixture of oxides obtained by igniting amraonic meta-vanadate in air with 12:5 sodic tungstate, I obtained a greenish-orange solution. This was oxi- dized by boiling with nitric acid, when it became orange. On standing, the acid solution deposited a relatively large quantity of a sulphur- yellow crystalline body, which was but very slightly soluble in cold water, and required a large quantity of hot water for complete solu- tion. This substance was drained upon the filter-pump, washed with cold water, and dried upon woollen paper. Of this preparation, — ( 0.8331 gr. lost on ignition 0.1188 gr. = 13.42% ( 0.8331 gr. gave 0.7192 gr. WO3 -f V^O^ = 86.03% 0.9786 gr. " 0.8411 gr. " ' =85.95% 1.0846 gr. « 0.0718 gr. Yfi^ — 6.62% The analyses corresi^ond with the formula 10 WO3 . VA . 6 H,0 + 16 aq, which requires : — Calc'd. Found. IOWO3 2320 80.53] 80.30 U. .. VA 183 6.35;^^-^^ 6.62 r^-^^ 22 H.,0 378 13.12 13.08 2899 100.00 I did not succeed in obtaining salts corresponding to the 10: 1 acid above described by saturating the acid with alkaline bases, as mixtures of the acid with alkaline vanadates and tungstates were formed until the point of complete saturation was reached. 18:1 Vanadio-tungstic Acid. — The orange-yellow mother liquor from which the 12:1 acid separated gave on evaporation beautiful crystalline needles of a second acid, the formula of which is 18 WO3 . VA . 6 HoO + 30 aq. OF ARTS AND SCIENCES. 253 Of this acid, — { 1.0343 gr. lost on ignition 0.1342 gr. = 12.97% water. 1.0343 gr. gave 0.0363 gr. V.O^ = 3.51 9^ 1.2540 gr. lost on ignition 0.1617 gr. = 12.90% The formula requires : — Calc'd. Found. 18 WO3 4176 183 ^^•4?| 87.05 3.65) 83.55 )g. 3.51 j 36 up 648 12.95 12.90 12.97 5007 The sum of the two oxides is determined by difference, which is the most accurate method whenever applicable. In this, as in all the other vanadio-tungstic compounds analyzed, the vanadic pentoxide was deter- mined by boiling with chlorhydric acid in the manner already described. The crystals of the 18 : 1 acid are readily soluble iu water, and may be recrystallized without decomposition. The compounds which I have described appear to establish a com- plete analogy between the vanadio-tungstates and phosplio-tungstates already described. Rammelsberg * has described a salt which crystal- lizes in beautiful brown-black cubo-octahedrons, and which he obtained by saturating a commercial sodic vanadate with acetic acid and evapo- rating spontaneously. According to his analyses, the salt has the formula (NH,),0 . WO3 . 3 VPg + 6 aq. I suspect that it contains VO., as well as V^O^ . I did not succe'^d in preparing it by synthesis, employing pure VOgNII^ and WO^(NH^).,. It may prove to be the type of an entirely new class of complex acids, and well deserves further investigation. PHOSPHO-VANADIO-MOLYBDATES. Triple acids of this class are formed when solutions of phospho- vanadates are digested with molybdic teroxide; whenvanadio-molybdates and alkaline phosphates are heated together in solution, especially in the presence of an acid ; and when vanadic pentoxide is heated with a solution of an alkaline phospho-molybdate. The salts of this class are as a whole less stable than the vanadio- * Berichte der Deutschen Chem. Gesellschaft, i. 161. 25J: PROCEEDINGS OP THE AMERICAN ACADEMY raolybdates. They are, however, very well defined, and usually highly crystalline. In color they vary from an orange to a deep garnet, or ruby red. In general character they closely resemble the salts of the double compounds already described, and are often very beautiful. Analytical Methods. — These are for the most part similar to those which I have already described. The three oxides may be precipitated together by raercurous nitrate and mercuric oxide, and then ignited with sodic tuugstate in the manner described for the analysis of phospho-molybdates and arsenio-molybdates. The phosphoric oxide cannot be determined with accuracy by direct precipitation with mag- nesia-mixture. It is necessary first to remove the vanadic oxide. This may be done by dissolving the salt, adding ammonia in small but distinct excess, and afterward ammonic nitrate in large quantity. The" solution is to be boiled for a short time, care being taken that after boiling free ammonia shall still be present. After standing in the cold for twenty-four hours the precipitated ammonic meta-vanadate may be filtered off, washed with a cold concentrated solution of ammo- nic nitrate, and titrated in the manner which I have described in speaking of the vanadio-molybdates. In the filtrate from the meta- vanadate phosphoric oxide may be determined by double precipitation with magnesia-mixture and final treatment with ammonic sulphide. Molybdic oxide is best determined by difference, the sura of the weights of the three oxides being known. Water, ammonia, and basic oxides may be found by the methods which I have already described in the cases of the binary compounds. 48 : 2 : 1 Series. — When 10 : 2 acid phospho-molybdate of am- monium, 10 M0O3.2 P2O5.5 (NH4).,0-f-G ^1"> ^^^^ ammonic meta- vanadate are dissolved together, there appears to be no reaction ; but if a small excess of chlorhydric acid is added, and the solution is boiled, a beautiful deep orange-red crystalline precipitate is formed at once. This may be drained on a filter and washed with cold water, in which it is but slightly soluble. Hot water dissolves it rather more freely, but the salt cannot be purified by recrystallization, as it is more or less completely decomposed by solution. Ammonia water dissolves it, forming a colorless liquid, in which baric acetate produces a nearly colorless precipitate. Of this salt, — 1.3011 gr. lost on ignition with WO^Nao 0.1399 gr. = 10.75% ^'Hg + H„0 1.0425 gr. lost on ignition with WO^Na^ 0.1124 gr. = 10.78% NH3 + H,0 { OF ARTS AND SCIENCES. 255 1.5611 gr. gave 0.1361 gr. NH.Cl = 4.24% (NH,)„0 1.0113 gr. « 0.0900 gr. " =4.32% "' 1.3997 gr. " with MuO.K 0.0304 gr. V.Og = 2.17% 1.9173 gr. " " " 0.0463 gr. " =2.41% 1.9173 gr. " 0.1112 gr. P.,0-M£r, =3.71c^P.,0. o O J J OJ JO J a In the last two analyses the vanadic pentoxide was first separated by ammonic nitrate as VOoNIT^ ; the phosphoric oxide was then de- termined in the filtrate. The analyses correspond fairly well with the formula 48 M0O3 . 2 pp. . V,0, . 7 (NHJ.O + 30 aq. Calc'd. Mean. Found. 48 M0O3 6912 83.45 83.23 83.23 (diff.) 2 PA 284 3.43 3.71 3.71 VA 183 2.21 2.29 2.17 2.41 7 (NH,),0 364 4.39 4.28 4.32 4.24 30 H^O 540 6.52 6.50 6.50 6.51 8283 100.00 The compound may be regarded as a double salt, with the formula 2 {16 M0O3 . PA . 2 (NHJ.O . H.,0} + 1 6 Moa . Vi)^ . 3 (Nil,),© + 28 aq, though, of course, other arrangements of the constituents are, in the present state of our knowledge, equally probable. Thus, we may also represent the results of the analyses by the expression, 2(12 M0O3 . PA • 2 (NHJ2 • H,0} + 24 M0O3 • ^^P, • 3 (NHJP + 28 aq. 14: 1 : 8 Series. — The beautiful yellow crystalline phospho-raolyb- dates of ammonium, containing respectively twenty-four and twenty- two molecules of M0O3 to one molecule of i^hosphoric oxide, slowly dissolve when boiled with a solution of ammonic meta-vanadate, giv- ing a very fine deep orange-red liquid. After standing a few hours, the solution gives splendid deep ruby-red crystals in large quantity. These crystals appear to be octahedra ; they dissolve readily in hot water to a de"ep orange-red liquid, without undergoing any apparent decomposition, and the salt crystallizes from the solution unchanged. The solution gives no precipitate at first with baric chloride, but after a time very fine garnet-red crystals are formed in small quantity, mixed 256 PEOCEEDINGS OF THE AMERICAN ACADEMY with a pale orange flocky or indistinctly crystalline substance, with an orange-red supernatant liquid. Potassic bromide in large excess gives an orange crystalline, and argentic nitrate a cinnamon-colored not distinctly crystalline precipitate. Mercurous nitrate and plumbic acetate give orange precipitates. A solution of chloride of trimethyl- ammouium, ^(CPygHCl, gives an orange precipitate in the concen- trated solution, soluble in boiling water, and crystallizing in beautiful small granular crystals, which are orange with an aurora-red tint. The crystals of the ruby-red salt became duller upon the surfaces when dried on woollen paper, but did not distinctly effloresce. Of this salt, — 1.0686 gr. lost on ignition with WO^Na^ 0.2833 gr. = 26.51^ NHg and H^O 1.3051 gr. gave 0.2245 gr. NII^Cl t= 8.36% (NH,),0 1.1020 gr. " 0.3253 gr. VoO^ =29.51% 1.1113 gr. " 0.0598 gr. F.jO^Mgo = 3.44% P2O5 The analyses lead to the formula, 14 M0O3 . PA . 8 V2O5 . 8 (NHJP + 50 aq. Calc'd. Found. 14 M0O3 2016 40.83 \ 40.54 ^ 8VA 1464 29.64 [-73.36 29.51 [-73 PA 142 2.89) 3.44) 8 (NHJ.O 416 8.42 8.36 50 HP 900 18.22 18.14 4938 100.00 If we assume that in this salt vanadic pentoxide stands in a relation to phosphoric oxide exactly analogous to that of molybdic teroxide, the compound will be of the same type as the phospho-molybdate already described, 22 MoO, . P,0, . X R,0, since we may write y.J^o ^^ '^^ '^^^ rational formula were V^O., . O.3. In some preparations of this salt I observed the formation of two other salts in relatively small quantity. One of these formed pale orange-colored needles ; the other, glimmering scales but slightly solu- ble in hot water. OF ARTS AND SCIENCES. 257 PHOSrHO-VANADIO-TUNGSTATES. These compounds bear a general resemblance to the phospho-vanadio- molybdates already described, and may be prepared by similar processes. They have usually a more or less deep orange or orange-red color, and very often exhibit a peculiar and highly characteristic aurora-red tint. They are crystalline and well defined, and many salts of the different series are very beautiful. Analytical Methods. — In all these salts it will, as in similar cases, be found most advantasfeous to determine the three acid-formiun: oxides by means of mercurous nitrate and mercuric oxide in the manner already pointed out. The estimation of phosphoric oxide may usually be made with a fair approximation to precision by direct precipitation with magnesia-mixture in the ammoniacal solution, redissolving the ammonio-magnesic j^hosphate, and precipitating a second lime. In some cases I have found it better first to reduce the vanadic pentoxide to vanadic dioxide by boiling with strong chlorhydric acid, evaporating to dryness, and redissolving with the addition of a little tartaric and chlorhydric acids. A perfectly satisfactory method of estimating phos- phoric oxide in these compounds remains to be discovered. Vanadic pentoxide may be estimated with accuracy by the methods already pointed out for the analysis of the vanadio-tungstates ; that is, by boil- ing with strong chlorhydric acid, collecting the chlorine evolved in a solution of potassic iodide, and determining the free iodine by titrition with sodic hyposulphite. A solution of potassic hypermanganate does not always oxidize vanadic dioxide in presence of tungstic, phosphoric, and free sulphuric acid, or only with great diflaculty, so that tlie method is not generally applicable for the analysis of this class of compounds. Nitric acid, however, readily oxidizes the dioxide under the same circumstances. 60 : 3 : 1 Series. — When the white insoluble phospho-tungstates of ammonium containing twenty-two or twenty-four molecules of tungstic to one of phosphoric oxide are dissolved in ammonia water, and a solu- tion of ammonic meta- vanadate is added, no precipitate is formed ; but if a small excess of chlorhydric acid is present in the boiling liquid, a fine lemon-yellow crystalline precipitate soon forms, which is to be well washed with a cold dilute solution of ammonic nitrate, as otherwise the salt passes readily through the filter, giving a milky liquid. The final washing may be made with a very dilute solution of the nitrate. After drying on woollen paper, the salt closely resembles tungstic oxide in color. It is almost insoluble in cold, and but slightly soluble in hot VOL. XVIII. (n. s. X.) 17 258 PROCEEDINGS OF THE AMERICAN ACADEMY water, but with a large excess of ammonic phospliate it dissolves to a yellow solution ; with ammonia water it gives a colorless solution. In a solution of ammonic carbonate it dissolves with strong effervescence, indicating its distinctly acid character. The salt is not readily reduced by boiling with sulphuric and sulphurous acids, or by citric acid in the presence of chlorhydric acid, but easily by boiling with a strong solu- tion of potassic cyanide, and, as is usual with this class of compounds, by fusion with the same salt. Of this compound, — 2.0684 gr. lost on ignition with WO.Naj 0.2068 gr. = 10.00% NHg and HoO 1.0971 gr. gave 0.0747 gr. NH.Cl = 3.31% (NH,)20 1.3424 gr. " 0.0568 gr. PjO^Mg = 2.71% }\0. 2.5488 gr. " 0.1 102 gr. " =2.77% " 1.0555gr. " 0.0]23gr. V2O5 =1.10% The analyses correspond very closely to the formula, 60 WO3 . 3 P^Og . Yfi, . 10 (NIIJP + 60 aq, which requires : — 90.00 Calc'd. Found. 60 WO3 13920 86.29 \ 2.64 [- 90.00 1.15 ) 86.10 (diff.) 3 PA 426 2.71 2.77 yp. 183 1.16 10 (NHJ.O 60 H^O 520 1080 ^•^^1 9.92 6.69 i ^••'''U 10.00 6.69 i 16129 100.00 The compound is very probably a double salt, and may have the formula, 3 {16 WO3 . P,0, . 3 (NH,),0} -f- 12 WO3 . VA . (NH,),0 . 2 HP + 58 aq. The arrangement of the constituents is here, of course, purely arbi- trary, and must be regarded as only provisional. In the analyses above given the phosphoric oxide was determined directly and by double precipitation. The vanadic oxide was determined by boiling with chlorhydric acid and titrition, in the manner already described. 16 : 1 : 3 Series. — A boiling solution of ammonic meta-vanadate dissolves the white insoluble phospho-tungstates of ammonium quite readily to a very deep orange-red solution. After standing some OF ARTS AND SCIENCES. 259 days, large deep orange or garnet-red crystals separate in quantity. They appear to be octahedra, and when first separated from the mother liquor are very beautiful ; but on standing in the air they lose their lustre, perhaps from a superficial eflfervescence, and become dull red. The salt is readily soluble in water, giving a deep orange-red solution, and crystallizes from the solution unchanged. The constitu- tion of this salt is represented by the formula, 16 WO3 . 3 V2O5 . PPg . 5 (NHJ^O -I- 37 aq, as the following analyses show : — 1.0379 gr. lost on ignition with W0,Na2 0.1826 gr. = 17.59% NH, and ILO 1.2811 gr. gave 0.1264 gr. NH.Cl = 4.80% (NHJ2O 1.0652gr. " 0.1074 gr. V2O5 =10.08% 1.0130 gr. " 0.0419 gr. P20.Mg2= 2.64% PgOj. The formula given requires : — Calc'd. Found. 16 WO3 3712 69.67 ^ 69.69 ^ 3V2O5 548 10.28^82.62 10.08 >- 82.41 PPj 142 2.67) 2.64) 5 (NH,),0 260 4.88 4.80 37 H2O ' 666 12.50 12.79 5328 100.00 100.00 Adopting the provisional hypothesis which I have proposed above, that V2O5 as V2O2 . O3 may partially replace M0O3 or WO3 in these combinations, and that, on the other hand, V2O5 also replaces P^Oj, we may write the formula given above, 8 WO3 . 2 V2O2.O3.P2O, . 3 (NH,)20 -f 8 WO3 . V2O5 . 2 (NHJ^O . H2O + 36 aq, in which formula the first term is reduced to the type of 10 WO3 . P2O, . 3 (NHJ2O. The presence of five molecules of ammonic oxide shows that the salt belongs to the acid type so often met with in this class of compounds, and upon the view which I consider probable,* that the formulas of * Proceedings, Vol. XVII. p. 89. 260 PROCEEDINGS OF THE AMERICAN ACADEMY all the phospho-tungstates and phospho-molybdates as now received should be doubled, we should write the above formula 16 WO3 . 2 V2O2.O3.V2O5. PA • 5 (NH,)20 . H2O + 36 aq; corresponding to 16 WO3 . 2 P,A • 5 (NHJ2O . H2O. I consider this view of the subject as most probable in the present state of our knowledije. 60 : 3 : 2 Scries. — When the 20 : 1 : 6 baric phospho-tungstate already described is boiled with vanadic hydrate, V0(0Ii)3, the acid dissolves readily, and a beautiful orange-red solution is formed. On cooling, a salt sejaarates in octahedral crystals, which have a very fine aurora-red color. The crystals dissolve rather easily in hot water, but are at the same time decomposed. A brownish orange salt then sepa- rates in distinct crystals, together with a white powder. The two can be separated mechanically. The mother liquor of the aurora-red salt yields on evaporation large dark-red crystals. Of the aurora-red salt, — 0.41 65 gr. lost on ignition with WO^Na^ 0.0540 gr. = 12.96% 1.1550 gr. " " " " 0.1500 gr. = 12.98% 0.8819 gr. gave of mixed oxides 0.6474 gr. = 73.41% 1.4699 gr. " " " 1.0784 gr. = 73.37% 1.5188 gr. « " « 1.1145 gr. = 73.38% 1.5188 gr. " of P^O-Mg, 0.0508 gr. = 2.14% P2O5 1.0522 gr. " of mixed oxides 0.7709 gr. = 73.26% 1.0522 gr. " ofP.A-Mg2 0.0380 gr. = 2.31% P2O5 1.3324 gr. " of V^ by titrition 0.0258 gr. = 1.93% 0.2693 gr. " " " 0.0051 gr. = 1.87% The analyses correspond to the formula 60 WO3 . 3 P._,0, . 2 V2O5 . 18 BaO + 144 aq, which requires : — Calc'd. Mean. 69.14 Calc'd. Mean. 60 WO3 13920 69 39 J 69.23 ^ 69.29 69.25 69.26 3P2O5 426 2.14 [ 73 .35 2.22 f 73.35 2.14 2.31 2 V.,05 366 1.82) 1.90) 1.93 1.87 18 BaO 2754 13.73 13.68 13.68 144 H2O 2592 12.92 12.97 12.96 12.98 20058 100.00 100.00 The baric oxide was determined by difference. In all determina- tions of the three acid oxides it was found necessary to ignite finally OP ARTS AND SCIENCES. 261 with a weighed quantity of normal sodic tungstate, in order to expel the mercuric oxide completely, and obtain a constant weight. The aurora-red suit may be regarded as a double compound, with the possible formula 3 {12 WO3 . P2O5 . 4 BaO . 2 11,0^ + " 2 {12 WO3 . VPs . 3 BaO . 3 Hp} -f- 132 aq. It has, I believe, the highest molecular weight, 20058, yet observed, though I shall describe a little farther on a phospho-vauadio-vanadico- tungstate with the formula 60 WO3 . 3 P2O5 . V2O5 . VO2 . 18 BaO + 150 aq, with the molecular weight 200GG. It will be interesting to determine the specific heats of bodies of this class, as well as the heat of forma- tion. The formation of the aurora-red salt is very simply expressed by the equation, 3 {20 WO3 . P2O5 . G BaO} + 2 Vp. = GO WO3' . 3 P2O5 . 2 V2O5 . 18 BaO, the process being one of simple addition. I have mentioned above the fact that a dark red salt crystallizes from the mother liquor of the aurora-red salt. The following ana- lytical results were obtained with the small quantity of this salt at my disposal : — 0.7GG0 gr. gave 0.5570 gr. mixed oxides = 72.71% 1.0405 gr. " 0.2133 gr. SO.Ba r= 13.45% BaO 1.0405 gr. lost on ignition 0.1451 gr. = 13.94% In the orange-brown salt formed by the decomposition of the aurora- red salt, 1.1919 gr. lost on ignition with WO.Na^ O.lGll gr. = 13.51% 1.0476 gr. gave 0.7G53 gr. mixed oxides = 73.05% 1.4122 gr. « 0.3078 gr. SO.Ba =14.31% 1.2372 gr. " 0.0087 gr. V^ = 0.70% No formulas can be deduced from these analyses, but they may serve to identify the salts analyzed in future investigations. 18 : 3 : 4 Series. — The 24 : 1 phospho-tungstate of sodium already described, 24 WO3 . Vp^ . 2 Na.O . 4 H,0 -f 23 aq, is readily dis- solved by boiling with a solution of ammonic meta-vanadate, and gives a deep orange-red liquid. This solution does not yield crys- 262 PROCEEDINGS OP THE AMEIilCAN ACADEMY tals on evaporation, or after standing for some time. Wlien, however, a solution of potassic bromide is added in large excess, a deep orauge- red crystalline precipitate is quickly formed in large quantity. The salt exhibits the peculiar aurora-red tint which is often observed when phosphoric acid or a soluble phosphate is mixed with a solution con- taining both tungstic and vanadic oxides. The compound dissolves in a rather large proportion of hot water, but at the same time undergoes decomposition, and the solution after a time deposits a bright orange- brown crystalline salt without the peculiar aurora-red tint. The first- mentioned potassic salt, as precipitated from a cold solution, allowed to stand twenty-four hours, then washed with cold water and dried ou woollen paper, gave on analysis the formula 18 WO3 . 4 V2O5 . 3 PjOj . 8 K^O + 32 aq, which may perhaps be written 2 {6 WO3 . 2 V2O5 . P.p. . 3 K,0} + 6 WO3 . P^Og . 2 K^O . H^, the type of the first compound being 8 WO3 . P2O5 . 3 K.p. 1.1017 gr. lost on ignition with WO^Na^ 0.0973 gr. = 8.83% 1.0803 gr. gave 0.8646 S^- mixed oxides — 80.03% 1.1159 gr. " 0.1218 gr- v,o, — 10.91% 1.2104 gr. " 0.1227 gJ*- P,0,Mg, — 6.48% The formula given requires : ■ — Calc'd. Found. 18 WO3 4176 62.68 \ 62.64 \ 4 Vp, 732 10.99 [-80.06 10.91 [-80.03 3 P2O5 426 6.39) 6.48) 8 K,0 752 11.29 11.14 32 HJO 576 8.65 8.83 6662 100.00 7:1:1 Series. — The bright orange-brown salt formed by the decomposition of the 18:4:3 salt was in small distinct granular crystals. Of this salt, — 0.9773 gr. lost on ignition with WO^Na, 0.0780 gr. = 7.98% 1.0160 gr. gave 0.8205 gr. mixed oxides = 80.76% 1.3077 gr. " 0.1037 gr. Yfi^ = 7.93% 1.0113 gr. " 0.0958 gr. Pp,Mg3 = 6.06% P^O^ OF ARTS AND SCIENCES. 263 The analyses correspond, though not very closely, to the formula 7W03.VA.PA-3K,0+llaq, which requires : — Calc'd. Found. 7W03 1624 GG.86 \ 6G.77 \ v.o, 183 7.53 [-80.23 7.93 [-80.76 PA 142 5.84) 6.0G) 3 K,0 282 ll.Gl 11.26 11 lip • 198 8.16 7.98 2429 100.00 According to the view which I have taken as to the function of V^Og in this class of compounds, the 7:1:1 potassic salt helongs to the type 8 WO3 . P,0, . 3 K,0, VgOj . O3 taking the place of one molecule of WO3. A much more extended study will be necessary to test this hypothesis. The vanadio- phospho-tungstates are probably numerous, and from their great beauty, as well as from their theoretic interest, form an attractive subject for investigation. The following notes may serve to furnish fresh points of departure. When the solution of vanadio-tungstate of sodium (ob- tained by boiling 12:5 acid sodic tungstate with the mixed oxides of vanadium and oxidizing completely with bromine) is mixed with a so- lution of hydro-disodic phosphate, no apparent action takes place ; but on boiling, the orange solution takes a deep red color, and soon deposits splendid ruby-red crystals in quantity. These crystals are decomposed in part even by cold water, which appears to separate phosphoric acid or sodic phosphate. An orange-colored sodium salt then separates. Almost exactly the same results are obtained when a solution of vanadio-tungstate of ammonium is boiled with a solution of ammonic phosphate. The liquid takes a beautiful deep red tint, and soon de- posits splendid ruby-red crystals. The solution of the sodium salt, after a day or two, gives with one of trimethjl-ammonium chloride, N(CH3)3HC1, very fine granular ruby-red crystals. Of these crystals, 0.9752 gr. gave 0.8549 gr. mixed oxides = 87.66^ 1.1543 gr. " 0.0631 gr. VA = 5A6% 1.0061 gr. " 0.0552 gr. p"p^Mg2 = 3.51% The loss corresponding to water and trimethyl-ammonium oxide is 12.34%. The ratio of the three oxides, WO3, V^O^, and T./)^, is 264 PROCEEDINGS OF THE AMEllICAN ACADEMY 34 WO3 . 3 V2O5 . 2 P2O5 ; but a determination of the trimethyl- animonium oxide will be necessary in order to settle the formula completely. I am indebted to the kindness of Prof. Arthur Michael for a supply of the trimethylamin salt, which has proved of great service to me. The disposition of the corresponding oxide to form well-crystallized salts makes it a valuable test, and it should become an article of commerce for chemists' use. VANADIO-VANADICO-MOLYBDATES. The salt about to be described constitutes the type of a new and extensive series of complex acids, which contain two different linking oxides, embraced respectively under the formulas R^Oj and R'Oo, in which, however, R and R' may be identical. The general formula for this class of molybdenum compounds may be written m M0O3 . n Rfi^ . p R'O, . x W'.f>, which, in the case of the identity of R and R', becomes m M0O3 • '^ ^2^s . JO RO2 . a: R^'^O. I shall show that these are corresponding salts, containing tungsten in place of molybdenum. Vanadio-vanadico-molybdates are very readily formed by boiling a mixture of the two oxides of vanadium with an acid molybdate ; by the partial reduction of vanadio-molybdates ; or by digesting solutions of acid molybdates with solutions which contain vanadic dioxide and pentoxide. 28 : 4 : 1 Vanadio-imnadico-molyhdate of Ammonium. — When pure ammonic divanadate is ignited in an ojaen platinum vessel, and the remaining mass is boiled with an excess of a solution of 14:6 acid ammonic molybdate, a greenish solution is formed, which after fil- tration and evaporation yields on cooling a pale greenish-yellow crystalline salt. After draining on the filter-pump, the salt may be redissolved and recrystallized, when it presents very distinct gran- ular greenish-yellow crystals. The solution is bright yellow. Of this salt, — 1.4613 gr. lost on ignition with WO.Nag 0.2527 gr. = 17.29% 1.3326 gr. gave by titrition 0.1423 gr. (NHJP = 10.68% 1.2031 gr. " " 0.1288 gr. " =10.71% 2.1968 gr. " 0.2184 gr. Yjd, = 9.95% VO., + V^O^ 0.9980 gr. " 0.0607 gr. VO2 = 6.08% VO2 OF ARTS AND SCIENCES. 265 The analyses lead to the formula 28 MoO.. , . 4 V,0, . VO, . 11 (NI IJP + 20 aq, which requires : — Calc'd. Found. 28 M0O3 4032 73.56 73.34 4V0, 334 6.09 6.08 VA 183 3.34 3.29 11 (NHJP 572 10.44 10.08 10.71 20 H^O 360 6.57 6.00 5481 100.00 The compound is doubtless to be regarded as a double salt, but there are at present no data upon which to base even a conjectural arrangement. The salt is slightly soluble in cold water, the solution being strongly acid to litmus paper. It is soluble in hot water, and separates from the solution without sensible decomposition. The solu- tion is reduced with great diihculty, either by sulphurous oxide or by sulphydric acid gas. For analysis I found it best, after oxidation with nitric acid, to boil with excess of ammonia, evaporate with ammonic chloride, and separate the ammonic meta-vanadate upon an asbestos filter. The vanadium was then determined by titrition with liyper- mauganate. The vanadic dioxide was determined by hypermangauate in the solution of the salt, after adding phosphoric and sulphuric acids. It was found necessary to use very dilute solutions, and the close agreement of the determination of vanadic dioxide with the formula cannot be regarded as other than accidental. The reactions of this salt are as follows: the cold dilute solution gives no precipitate with salts of zinc, copper, manganese, and cadmium ; a pale yellow flocky precipitate. with baric chloride, which soon becomes granular- crystalline ; with potassic bromide, after some days, very fine, large prismatic crystals; with argentic nitrate, the solution gives a flocky precipitate, which is yellow with a tinge of buff; with mercurous nitrate, a bright, and with thallous nitrate, a pale yellow, flocky precipitate. 15 : 1 : 2 Vanadio-vanadico-mohjhdate of Barium. — Baric chlo- ride added to the mother liquor from which the preceding salt was prepared gave a pale yellow crystalline, and, so far as could be seen, homogeneous precipitate, in very small grains. This was filtered off, well washed with cold water, and dried on woollen paper for analysis. The filtrate was greenish, and gave no other salt on evapo- 266 PROCEEDINGS OF THE AMERICAN ACADEMY ration. Tlie barium salt is very slightly soluble in cold water, and is decomposed by boiling water, with separation of baric molybdate, and formation of a pale greenish-yellow solution, which possibly contains a new salt of the same class. The salt is decomposed by boiling with mercurous nitrate, giving a bright yellow crystalline body. Boiled with argentic nitrate it gives an orange-colored precipitate, which is also crystalline. Of this salt, — 1.1 GOO gr. gave 0.72G0 gr. WO3 -f V^O^ + VO., = 62.09% and 0.4772 gr. SO.Ba = 20.80% BaO 1.5526 gr. gave 0.6332 gr. " = 26.70% " 1.0341 gr. lost on ignition 0.1127 gr. = 10.90% Hfi 2.1990 gr. gave by titrition 0.1748 gr. = 7.95% Yfi^ The titrition was effected by SOJI, + SO^(NH4)2 -f- 6 aq, in a solu- tion to which HCl had been added, after oxidation with nitric acid and addition of an excess of sodic carbonate. All the vanadium present was therefore estimated as VgO^. The analyses correspond closely to the formula 30 M0O3 . 2 V2O5 . 3 VO2 . 14 BaO + 48 aq, which requires : — Calc'd. Found. 30 M0O3 4320 54.40 54.40 (diff.) 2VA 366 4.62 4.73 3 VO2 249 3.13 3.22 14 BaO 2142 26.97 26.70 26.80 48 up 864 10.88 10.90 7941 100.00 The compound is doubtless a double salt, and its formula may perhaps be 2 {6 M0O3 . Y,0, . 4 BaO . 2 H,0} -j- 3 (6 M0O3 . VO,, . 2 BaO . 4 H^O} -f- 32 aq ; only it must be remarked that the empirical formula given above must be doubled in order to obtain a symmetrical structural formula, as the number of molecules of vanadic dioxide is uneven in the simpler ex- pression given. OP ARTS AND SCIENCES. 267 VANADIO-VANADICO-TUNGSTATES. The class of salts to which I have given this name come also under the general formula m RO3 . n W.p, . p R"0, . X ^'\0, and constitute, like the corresponding compounds containing molybde- num, a nevjr ternary series. They are formed under the same condi- tions as these last, and like these have an orange or orange-red color, with a more or less distinct tinge of green. 12:2:3 (?) Vauadio-vanadico-tungstate of Sodium. — This salt, whicli was the first which I obtained containing vanadium, was formed by boiling with 12:5 acid sodic tungstate, a commercial vanadic pent- oxide, which I owed to the kindness of Dr. J. Lawrence Smith, and which was probably prepared by igniting ammonic meta-vanadate, and therefore contained a certain proportion of vanadic dioxide. I did not succeed in preparing it a second time with a new preparation of the mixed oxides, and therefore trust that the incomplete analyses and meagre description of this and the corresponding ammonium and silver salts will be excused. The solution of the mixed oxides in the acid tungstate gave a deep orange-red solution, which, on evaporation to the consistency of a syrup, yielded after a time large orange-red apparently triclinic crystals, extremely soluble in water, and crystalliz- ing only from syrupy solutions. In this salt, twice recrystallized, — 0.5968 gr. lost on ignition to fusion of the residue 0.1019 gr. =^ 17.07^ 0.6852 gr. " " " " 0.1 1 64 gr. = 16.99% 0.331 1 gr. gave 0.2481 gr. WO3 + Yfi, + VO^ = 74.96% These analyses, taken in connection with those of the ammonium and silver salts, may, with at least a certain degree of probability, be considered as leading to the formula 12 WO, . 2 VA . 3 VO, . 6 Na.p -f 43 aq, ich requires 12 WO3 2 V.,(), 3 VO, 6 Na.,b 43 H,6 Calc'd. Found. 2784 ^ 366 \ 74.79 \ 74.96 249) ( 372 8.18 8.05 774 17.03 16.99 17.07 4545 100.00 268 PROCEEDINGS OF THE AMERICAN ACADEMY The solution of this salt had a deep orange-red color with distinct greenish reflections. Bromine water instantly gave a very fine deep orange solution, having nearly the color of jaotassic dichromate, and without the greenish tint : the liquid then contained only a sodic vana- dio-tungstate. The solution gave flocky precipitates with various salts of heavy metallic oxides, and a bright red crystalline precipitate with argentic nitrate. A solution of acid potassic tungstate dissolved the mixture of oxides of vanadium, forming a greenish-orange solution, which also became bright orange-red with bromine. The potassic salt crystallized from this solution after evaporation to the consistency of a syrup, and gave crystals of a peculiar greenish-orange tint. The solu- tion of this salt gave a bright orange indistinctly crystalline precipitate with mercurous nitrate. This precipitate was decomposed by dilute chlorhydric acid, yielding a yellow solution from which no crystals were obtained by evaporation. This is perhaps the acid of the series. 12 : 2 : 3 (?) Ammonium Salt. — 12:5 acid ammonic tungstate was boiled with a portion of the same commercial vanadic oxides in excess. The oxides dissolved readily, leaving, as in the cases of the sodium and potassium salts, a quantity of a black insoluble powder. The deep orange-yellow solution deposited on cooling beautiful orange- colored crystals of an ammonium salt ; but on evaporating the main solution in vacuo, two kinds of crystals were obtained, one in relatively large dark-red octahedrons, the other much lighter-colored and resem- bling potassic dichromate. The darker salt gave in two analyses 17.98 and 18.05 f)^ of water and ammonic oxide. Of the lighter-colored salt separated mechanically from the first-named, — 0.8429 gr. lost on ignition 0.1149 gr. = 13.63% H^OandNHg 0.81G4gr. " " 0.1107 gr. =13.56% " " 0.9047 gr. gave 0.1502 gr. NH.Cl = 8.07% (NH,)20 The analyses agree, so far as they go, very well with the formula, 12 WO3 . 2 Yfi, . 3 VO2 . 6 (NHJ^O + 12 aq, which requires : — 12 WO3 2784 ^ Calc'd. Found. > 86.41 (diff.) 2VA 366 [■ 86.55 3 VO2 249) 6 (NHJ.O 312 7.94 8.07 I2H2O 216 5.51 5.52 3927 100.00 OP ARTS AND SCIENCES. 269 The solution of this salt gives a beautiful scarlet precipitate with argentic nitrate, and a fine yellow precipit;ite with salts of strychnin, which after standing some hours becomes granular crystalline. 12 : 2 : 3 (?) Vanadlo-vanadlco-tungslate of Stiver. — The salt an- alyzed was in beautiful scarlet crystals, and was prepared by precipi- tating the ammonium salt with argentic nitrate, and washing with cold water. The salt is not distinctly crystalline Avhen first thrown down, but becomes so after standing in the liquid. It is very slightly soluble in cold water, but dissolves in much hot water to a yellow liquid. Of this salt, — 2.11 93 gr. lost on ignition 0.0621 gr. = 2.93% 0.7511 gr. gave 0.7420 gr. AgCl = 28.21% Ag.p These analyses agree with the formula, 12 WO3 . 2 V2O5 . 3 VO, . 6 Ag, 0 + 8 aq, which requires : — 12 WO3 2784^ Calc'd. Found. [-68.86 (diff.) 2VA 3VO2 3G6>- 249) 68.87 6 Ag,0 1392 28.21 28.21 8 II^O 108 2.92 2.93 4935 100.00 The analyses which I have given may not be considered as suffi- ciently complete to establish the formulas assigned, but they serve to prove the existence of at least one class of vanadio-vanadico-tungstates. In substances of such high molecular weights the agreement between the formulas of three different salts prepared under precisely the same conditions has a certain value, but it is less conclusive than when the molecular weight is lower, because such a change as is produced by writing, for instance, 2 VO.^ for VgO-? f'o^s not greatly affect the percentage results. If we admit the correctness of the formulas given, it will still be necessary to double them in order to construct a structu- ral formula which shall be symmetrical, since the number of molecules of VOg, either free or contained in V2O-, is uneven. For the complete analysis of compounds of this class it will be most advantageous to de- termine the vanadic pentoxide by heating with strong chlorhydric acid in the manner already indicated, and then to determine the dioxide in another portion by means of hypermanganate, if possible, or by first 270 PROCEEDINGS OF THE AMERICAN ACADEMY oxidizing with bromine, and th^n determining the whole of the vanadium as pentoxide by boiling with chlorhydric acid and titrating as before. rnOSPHO-VANADIO-VANADICO-TUNGSTATES. I have given this rather ponderous appellation to a class of com- pounds in which vanadium exists partly as pentoxide and partly as dioxide. They may be regarded simply as double salts, but in the present state of our knowledge it will be found most convenient to consider them as a special class. Salts of this type are formed whenever phospho-tungstates are mixed with vanadates in presence of vanadic dioxide, when vanadio-vanadico- tungstates are heated with solutions of alkaline phosphates or with phosphoric acid, and when phospho-vanadates and alkaline tungstates are brought together in presence of a reducing agent and of an acid. The salts are sometimes green and sometimes orange-red. In the last case they have frequently the peculiar aurora-red tint noticed among the colors of the phospho-vanadio-tungstates. They pass readily by ox- idation with bromine or nitric acid into salts of the last-mentioned type, and they may be also derived from these by a partial reduction of the vanadic pentoxide. Analytical Methods. — These are essentially the same as those which have been described. All the non-basic oxides may be determined together by means of mercurous nitrate and mercuric oxide, after com- plete oxidation with nitric acid. Phosphoric oxide may usually be determined directly, or after separation of a non-alkaline base, by double precipitation with magnesia-mixture. The vanadic pentoxide can be estimated by boiling with chlorhydric acid and titrition in the manner already pointed out. To determine the vanadic dioxide the solution must first be oxidized completely, so as to convert the dioxide into pentoxide, any excess of the oxidizing agent employed being carefully removed. I prefer to use bromine water for this purpose. The whole of the vanadium may then be determined by titrition as above. The difference between the amount of vanadic pentoxide found before and after complete oxidation then gives, by a simple proportion, the corre- sponding amount of vanadic dioxide. It must be remembered that the sum of the non-basic oxides found by the mercury process requires to be corrected by adding the amount of oxygen required to convert the vanadic dioxide present into the equivalent of pentoxide. When the whole quantity of vanadium present is small, this correction may be neglected, as falling within the limits of the errors of analysis unavoid- OF ARTS AND SCIENCES. 271 « able with our present methods. Baric oxide in these salts is best esti- mated by difference, as the direct estinaation almost always gives too high a percentage. 60 : 3 : 1 : 1 Barium Salt. — When ammonic vanadate is heated in a porcelain crucible until all the ammonia is expelled, the greenish residue consists, as already stated, chiefly of a mixture of vanadic dioxide and pentoxide. If this mixture be added in small portions at a time to a boiling solution of the baric phospho-tungstate, 20 WO3 . P2O5 . 6 BaO, already described, the liquid takes at once a rather dull green color. The filtrate from the excess of mixed oxides, after evaporation in a water-bath and standing for some hours, yields a mass of deep green crystals, mechanically mixed with a rela- tively small proportion of a fine white powder, which may easily be removed by washing with cold water and pouring off the powder in suspension. The dark green crystals are regular octahedrons, fre- quently in long aggregates and beautifully defined. The salt is rather insoluble in cold but readily soluble in hot water, with a dark and rather dull green color. The cold solution, after adding dilute sul- phuric acid, is not sensibly oxidized by potassic hypermanganate or in alkaline solution by iodine. The hot solution is oxidized by bromine and by nitric acid, and becomes deep orange-red. At a boiling heat potassic hj'permanganate also oxidizes it, the quantity required for oxidation being very small, so that it can with difficulty be estimated. Of this salt, — 1.2596 gr. gave 0.9178 gr. mixed oxides = 72.86% 1.0160 gr. lost on ignition 0.1362 gr. = 13.40% 1.4649 gr. " " 0.1969 gr. =13.44% 1.8580 gr. gave 0.0624 gr. P^O.Mg^ = 2.15% Pp^ 1.3846 gr. " 0.0105 gr. V265 = 0.76% 1.1972 gr. « 0.0131 gr. " = 1.09% Tn these analyses the vanadic pentoxide was determined directly in the salt, by boiling with chlorhydric acid and titrating. In two other analyses, the vanadic dioxide was first completely oxidized by means of bromine ; the whole quantity of vanadium was then determined as before. The percentage of vanadic dioxide was then calculated from the excess of V^O^ over that found by direct analysis. In this process, — 1.1379 gr. gave 0.0161 gr. V^O^ = 1-44% 1.1714 gr. « 0.0200 gr. " =1.71% Calc'd. Found. 60 WOg 13020 69.37 69.32 3 PA 426 2.12 2.15 v,o, 183 0.92 1.09 vo. 83 0.42 0.46 18 BaO 2754 13.72 13.72 150 H,0 2700 13.45 13.40 ] 272 PROCEEDINGS OP THE AMERICAN ACADEMY The analyses correspond very closely to the formula, 60 WO3 . 3 P2O5 . Y.fl, . VO2 . 18 BaO + 150 aq, which requires : — 0.76 13.44 20066 100.00 The baric oxide is estimated by difference. The relation of this salt to the aurora-red octahedral phospho-vanadio-tungstate of barium already described is interesting. We have respectively the formulas, 60 WO3 . 3 P.O^ . VA . V 0, .18 BaO +150 aq, 60 WO3 . 3 pp. . V2O5 . VA . 18 BaO + 144 aq, and it is easy to see how, at least theoretically, one salt could be pre- pared from the other. With respect to the rational constitution of the green salt, it is possible at present only to form a provisional hypoth- esis. I am disposed to regard it as a triple compound, and to assign to it the formula, 3(12 WO3 . F,0, . 3 BaO . 3 H.O} + 1 2 WO3 . Vp, . 5 BaO . H,0 + 12 WO3 . V02.4BaO In this formula all the terms correspond to known compounds, the last to the dodeka-silico-tungstate type established by Marignac, VOg replacing SiO^. Of course, as in similar cases, various other formulas may be proposed. I lay no particular stress upon the view I have taken, which a wider and deeper study of these compounds may prove to be untenable. The formation of the salt may be expressed by the equation, 3 {20 WO3 . PoO, . 6 BaO} + V.O^ + V0,= 60 WO3 . 3 P.O^ . V.O^ . TO, . 18 BaO. The formula must be doubled to permit of a representation by means of a symmetrical structural formula. If we omit all the molecules of tungstic oxide except two, in order to save space, the OP ARTS AND SCIENCES. 273 linking portion of the structural formula of the corresponding acid may be written as follows: — HO - WO., I o W02-OH o vo„ vo,. 2 (HO 2 (HO 2 (HO 2 (HO 2 (HO 2 (HO 2 (HO = VO - 0 - OV = (0H)2 I = VO - O - OV = (0H)2 I = PO - O - OP = (OH), I = PO - 0 - OP = (OH), I I = PO - 0 - OP = (OH), I I = PO - O - OP = (OH), 1 I = PO - 0 - OP = (OH), 3 (HO) E PO - O - OP E (0H)3 This formula, which, like most of those which I have given, is purely conjectural, will at least serve to show how the two different states of oxidation of vanadium may be represented in the combination, and how the basicity of PO and VO may be affected by their position. Such formulas are not without value, as suggesting the possibility of forming new combinations, even if, as I prefer in this case to do, we consider the salt represented as double or triple. Structural formulas for double and still more for triple inorganic salts would probably be still more complex, and what I have aimed at is to show how all the valences may be satisfied in an arbitrarily selected compound contain- ing four oxides of three different types. The general results deducible from the formulas which I have given in the present instalment of my work are as follows : — 1. Hypophospliorous and phosphorous acids may enter into combi- nation with tungstic and molybdic oxides as links, so as to form com- plex inorganic acids. The structure of these four classes of acids indicates the possibility of forming new series of acids, in which methyl and other organic radicals or residues may take the place of the constitutional hydrogen of the hypophospliorous and phosphorous VOL. xviii. Is. s. X.) 18 274 PROCEEDINGS OF THE AMERICAN ACADEMY linking terms, and again of others in which, besides the replacement of hydrogen, phosphorus may be replaced by arsenic, and possibly b}^ antimony and other elements. 2. Vanadium may replace phosphorus and arsenic so as to form well-defined series of vanadio-molybdates and vanadio-tungstates em- braced under the general formula m RO3 . n V2O5 . p RI2O. 3. Vanadic and phosphoric pentoxides may enter simultaneously into combination with tungstic or molybdic oxide, so as to form classes of triple acids embraced under the general formula m RO3 . n P.O. . p V2O5 . V II2O. 4. A class of quadruple acids exists into which, in addition to phos- phoric and vanadic pentoxides, vanadic dioxide may enter, the general formula being m RO3 . n P2O5 . p V2O5 . r VO2 . v ll.Jd. 5. In another class of ternary or triple acids molybdic or tungstic oxide may be combined with both vanadic pentoxide and vanadic dioxide, the general formula being m RO3 . n V2O5 . p VO2 . V H2O. I shall show hereafter that all of these results are capable of further generalization ; that, for example, other oxides of the types RO2 cor- responding to hydrates of the form R(OH)^ may replace VO2 or V(OH)^; that other pentoxides may replace F.20^, AS2O5, and V2O5, either in the presence or in the absence of oxides of the type RO2 ; in short, that the complex inorganic acids form a new department of inor- ganic chemistry, and not a series of isolated compounds. (2b be co7itinued.) OF ARTS AND SCIENCES. 275 XVIII. CONTRIBUTIONS FROIVI THE CPIEMICAL LABORATORY OF HARVARD COLLEGE. THE VOLUMETRIC DETERMINATION OF COMBINED NITROUS ACID. By Leonard P. Kinnicutt and John U. Nkf. Presented May 9th, 1883. The amount of nitrous acid contained in commercial samples of potassic and sodic nitrites has been commonly determined in the fol- lowing manner. The nitrites are dissolved in slightly acidulated water ; a solution of potassic permanganate is added till the oxidation of the nitrous acid is nearly completed; the solution is then made strongly acid, and potassic permanganate added until the solution has a faint red color. This method is far from satisfactory, closely agreeing results being rather the exception than the rule. The cause is most probably due to the escape of a small amount of nitrous acid, and also to the slow oxidation of the last traces of the nitrous acid by the potassic per- manganate. A further study of the analyses of nitrites volumetrically seemed desirable, and after numerous experiments the following process, or modification of the old process, as it might more properly be called, was devised. The sample of nitrite is dissolved in cold water, one part of the salt to at least three hundred parts of water. To this solution a deci- normal solution of potassic permanganate is added, drop by drop, till the liquid has a decided and permanent red color, then two or three drops of dilute sulphuric acid, and immediately afterwards an excess of the potassic permanganate solution. The liquid, which should now be of a dark red color, is made strongly acid with sulphuric acid, heated to boiling, and the excess of potassic permanganate determined by means of a deci-normal solution of oxalic acid. 0.1472 t' 84.51 % 0.2024 u 84.49 % 0.2210 a 84.53 % 276 PEOCEEDINGS OP THE AMERICAN ACADEMY Analyses of samples of both potassic and sodic nitrites, made in accordance with the above modification, show that results agreeing very closely with one another can easily be obtained. Potassic Nitrite Solution. [One litre contained 4.3550 grammes.] Taken. KNO, found. 25 C.C. = 0.1089 gramme 0.09194 gramme = 84.44 % 35 c.c. = 0.1525 " 0.1289 " 84.48 % 40 c.c. = 0.1742 55 c.c. = 0.2395 '^ 60 C.C. = 0.2613 " Sodic Nitrite Solution. [One litre contained 3.090 grammes.] Taken. 25 C.C. = 0.0919 gramme 0.07713 gramme = 83.95 % 35 c.c. = 0.1287 " 0.1082 " 84.07% 45 C.c. = 0.1654 " 0.1390 " 84.05% 53 c.c. = 0.1949 " 0.1639 " 84.03% 60 c.c. = 0.2206 " 0.1854 " 84.05 % The volumetric method for the determination of sulphites is also most unsatisfactory. The study of this subject was therefore given to Mr. R. Penrose, a student in this laboratory. He experimented both with potassic permanganate and oxalic acid as above, and also with iron alum and the permanganate ; but, although many variations of these processes were tried, and tlie work carefully conducted, the results were unsatisfactory. OF ARTS AND SCIENCES. 277 XIX. CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF HARVARD COLLEGE. THE (3 PHENYLTRIBROMPROPIONIC ACID. By Leonard P. Kinnicutt and George M. Palmer. Presented May 9th, 1883. The a phenyltribroinpropionic acid and the products formed when this acid is decomposed by boiling water were briefly described by one of us last year.* During the past winter the study of the /3 acid was undertaken, and it has been considered best to give at this time the results so far obtained, as the further investigation must be carried on in different relations. The f3 phenyltribrompropionic acid was obtained by the notion of dry bromine on /3 monobromcinnamic acid, this last having been pre- pared in the way previously described. t By the action of bromine on j3 monobromcinnamic acid, GlaserJ obtained an acid, which he describes as melting during the absorption of the bromine and only solidifying again after several days. The melting point he found to be 45-48° C. The results obtained by us are very different. Perfectly pure /3 monobromcinnamic acid melting at 120° C. was placed under a bell glass with the theoretical amount of bromine. Not the slightest indication of melting was observed, and after twenty-four hours the bromine was all absorbed. The acid so obtained was purified by crystallization from chloroform and melted at 151° C. It is soluble in alcohol, ether, carbonic disulphide, chloro- form, and benzol. The analyses gave the following results: — 1. 0.2711 gr. substance gave 0.2788 gr. CO, and 0.0454 gr. H.p. 2. 0.3845 gr, substance gave 0.3912 gr. CO2 and 0.0702 gr. Rfl. 3. 0.1894 gr. substance gave 9.2769 gr. AgBr. 4. 0.1839 gr. substance gave 0.2696 gr. AgBr. * Kinnicutt, Amer. Chem. Jour., iii. 4. t Ibid. } Annalen der Chemie, cxliii. 339. 278 PROCEEDINGS OF THE AMERICAN ACADEMY Calculated for CoUjEraOj. j 2 ^°^°^- 3 ^ 28.04 27.73 1.86 2.00 c 27.9 H 1.8 Br G2.17 62.24 62.40 Decomposition of the j3 Phenyltrihrompropionic Acid hy Water heated to 100° C. Twenty grammes of the acid were placed in a flask with two hundred cubic centimeters of boiling water. Decomposition began immediately, a volatile oil separating out, which at the end of eight hours had for the greater part been carried over with the steam, leaving a clear liquid that on cooling deposited a white crystalline substance. On examination, the oil was found to be a dibromstyrol, the white crys- talline substance the a monobromcinnamic acid, and a third substance, which remained in solution in the liquid, gave on analysis results cor- responding very closely to those required for a phenyldibromlactic acid. Dibromstyrol, CgHgBr, . The oil that was carried over by the steam was separated from the water by ether, and, after thorough washing to remove all traces of hydrobromic acid, the ether was distilled off. The oil thus obtained wa^ of a light amber color, growing gradually darker, and giving off on long standing traces of hydrobromic acid. It boils at 253-254° C. with slight decomposition, hydrobromic acid being formed. The analyses of the oil, dried over sulphuric acid, gave the follow- ing results: — 1. 0.2518 gr. substance gave 0.3328 gr. CO2 and 0.0518 gr. H.p. 2. 0.3592 gr. substance gave 0.4810 gr. CO^ and 0.0744 gr. H^O. 3. 0.2518 gr. substance gave 0.3615 gr. AgBr. 4. 0.3032 gr. substance gave 0.4379 gr. AgBr. Calculated for CJL.Br,. , „ Found. lur — S) -f- Refraction. (c.) A comparison of the observed with the tabular polar distances of fundamental stars symmetrically distributed in declination from the pole to a point as far south as the refraction can be securely deter- mined, will give the index error under the form of a polar-point cor- rection. The index error determined in this way, however, involves the systematic errors in declination of the fundamental system through which the observations are reduced. On the other hand, if the funda- mental system is really free from this class of errors, this method fur- nishes the data for an approximate determination of the periodic errors of the circle. OP ARTS AND SCIENCES. 285 At "Washington, and at most other first-class observatories, the first method is employed. At Greenwich, both the first and the second methods are in use, the value adopted for any day being the mean result given by the two methods. At Harvard College Observatory, the third method is employed in all differential observations. Each method has its advantages, and also its disadvantages. In the use of the first method, either the latitude must be considered as known, or else it must enter as an unknown quantity into the equations of con- dition formed from the observations. Easy reference to a fixed point would seem to be about the only advantage that can be claimed for this metliod. Except for this tliere would seem to be no good reason why we should measure a quantity which is not the quantity sought. Polar distance is the co-oi'dinate to be directly measured, and the polar- point correction is tlie correction needed. This can be obtained by observing the polar distance of the Pole-star at both the upper and lower culminations. This method has been exclusively followed for the past five years in the series of observations undertaken by the writer, for the determination of the absolute co-ordinates of about one hundred stars between the first and fourth magnitudes. The defect of this method consists in the requirement that the index error of the circle must remain constant between two adjacent culminations. It is proposed to verify the constancy of this quantity in the fol- lowing way. It has been found that the reversible level invented by Mr. John Clark of the United States Coast Survey serves in the most admirable way to define a fixed reference plane. The reading of the microscopes of the Harvard College Meridian Circle for the indicated zero of the level, which is attached to the cube of the telescope, has now been continued without interruption for nearly two years. A provisional discussion of the results shows that the reference plane thus indicated remains nearly invariable, — certainly it is more steady than the position of the mean of the microscopes upon the circular frame upon which they are mounted with respect to the position of the circle itself. It is proposed to mount a level of this form upon a horizontal table attached to an arm having an angle with the axis of the earth nearly equal to the polar distance of Polaris when the telescope is set at this polar distance. If the lower end of this arm is mounted upon centres, and if there is attached to the upper end a micrometer screw which is tangent to the arc of revolution, it is obvious that, when the reading of the screw for either culmination of Polaris is known, we can measure 286 PROCEEDINGS OP THE AMERICAN ACADEMY the deviation of the optical axis of the telescope from this plane by reading the circle, the level, aud the index of the micrometer screw. In this way a constant watch may be kept ujjou the position of the microscopes with respect to the circle. The whole apparatus may be conveniently attached to the cube of the telescope. The steadiness of both the level and the microscopes may be inferred from the following readings of the circle for the zero line of the level. They involve the accidental errors of reading both of the microscopes and of the level, as well as actual changes in the position of the mean of the four microscopes. That part of the change which is due to the latter cause will be determined when the observations of Polaris are reduced. Only the seconds of arc are given. Date. Circle Reading. Date. Circle Reading. Date. Circle Readiug. 1883. 1883. 1883. Feb. 7 57.3 March 7 57.6 March 28 57.3 11 58.8 8 55.7 28 57.5 13 59.8 11 57.4 29 58.5 18 58.7 12 56.5 29 59.8 19 58.3 13 57.5 30 59.3 28 54.9 15 57.6 April 1 60.3 2.3 56.4 15 59.4 2 56.6 25 ■ 55.9 21 57.9 3 57.0 27 58.6 22 57.4 6 57.4 March 2 66.8 24 59.2 2 57.4 26 60.1 OF ARTS AND SCIENCES. 287 XXII. STUDIES IN METROLOGY. FIRST PAPER. By William A. Rogers. Presented May 9th, 1883. It will be the aim of the present paper to present a critical study of certain standards of length, which have been compared either directly or indirectly with the original standards, which are now recognized throughout the civilized world as the ultimate and supreme authority in all matters relating to units of length ; viz. with the " Imperial Yard" at London, and with the "Metre des Archives" at the Inter- national Bureau of Weights and Measures, situated at Breteuil, near Paris. The second paper will contain a discussion of all the standards of length which have been constructed by the writer from the prototypes investigated in this paper. These prototypes are designated and de- fined as follows : — I. The Tresca Meter, having the designation T. The bar upon which the defining lines of this meter are traced is composed of pure copper, and has narrow strips of platinum inserted at each end. The bar has the X shape proposed by Professor Tresca, which allows the graduations to be placed nearly in the plane of the neutral axis without interfering materially with their examination under a microscope having considerable magnifying power. The platinum surfaces are in the same plane with the surface of the copper, not only at each end, but throughout the entire length. These surfaces are fairly well adapted to receive sharply defined graduations ; but this material is far inferior to platinum-iridium in this respect. This bar was placed upon the tracing comparator of the Conserva- toire des Arts et Metiers, on the morning of February 4, 1880. After remaining at a constant temperature for about forty hours, M. Gustave 288 PROCEEDINGS OF THE AMERICAN ACADEMY Tresca, at two o'clock on the morning of February 6, transferred to it the Conservatory line meter No. 19, whose relation to the Metre des Archives had been previously determined with great exactness by Professor Tresca. There are three defining lines at each end, with an interval of 17.4 /a. The width of each line is about 5 /a. It appears from a large number of subsequent comparisons of the three meters defined by these lines, that they do not differ inter se by a measurable quantity. Immediately after the transfer was completed, a direct comparison with meter No. 19 was made. Comparisons were continued during the next day and the next night. The certificate which accompanied this meter states that it is 1.00 ix longer than the corrected value of meter No. 19 at 13°.70 C. Employing in the reduction the coefficient of expansion for No. 19, .000008G0860, we find, therefore, that Tis 118.94 /A m O 3) W H > Z o > 03 O H O M 0 Q m W 0 o 0 g 0 THE BOGERS-BC o FIG. 4. PLArO i ) COMPARATOR. OOMPARATOR. THE ROQERS-BOND COMPARATOR. tS FIG. 5. END OF CARRIAGE G IN FIG. 1. FIG. 7. THE MICROSCOPE CARRIAGE. OF ARTS AND SCIENCES. 317 (1.) AflJHstment of the standards T, C. S., R^, and R,, upon sup- ports at their neutral points, upon the table S^ The defining lines at one end were placed nearly over the fulcrum at the left end of the carriage. T, having the least mass, is placed in front. (2.) Permanent adjustment of the microscope plate I at a con- venient distance from the end of the frame L. (3.) Rapid movement of the carriage S by the handle D, until the right defining line of the meter T is, brought nearly under the micro- scope M^ (4.) Movement of the plate K by the hand-wheel R, until the de- fining lines at the opposite end of T'are brought into the field of the microscope M. (5.) Adjustment of the left-hand defining line under the micrometer of the microscope M, by the horizontal movement of the slide S^ and by the vertical movement S^, and finally by the movement of transla- tion through the lever S^. The first two of these movements are made with sufficient exactness by the coarse adjustment. The defining line of the standard liavinw been brought into coincidence with the fixed line of the micrometer of M by the fine adjustment S^ no fur- ther change is made in the positions of K and I. (6.) The adjustment of the right defining line by the motion of the micrometer of M\ by the lever S^ and by the vertical screw S^. These adjustments will disturb the adjustment xinder M only in a slight degree. Usually, however, a second series of adjustments is necessary. (7). The length of T' having thus been transferred to the micro- scopes M, M\ the standard C. S. is then brought into position by the slides S^ and the adjustments described above are repeated. The left defining line being coincident with the fixed wire of M, the difference in the length of the two standards is measured by means of the micrometer of M^ An increasing reading of the micrometer- head corresponds to an increase of length. (8.) Comparison of the meters R^ and R., in a similar manner. (9.) Adjustment of the defining line of the yard of C. S. under M^ by a rapid movement of the carriage S through the hand-lever D. (10.) Movement of the plate K till the left defining line of the yard falls under the microscope M. (11.) Repetition of the various adjustments and measures described above. The average time required to make these adjustments, and to take four readings of M^ for the defining lines T^', T''\ for each edge of 318 PROCEEDINGS OF THE AMERICAN ACADEMY C. S., for Hy^^ R^ ^ and R^"^ of the m£ter, and the corresponding defining lines of the yard, is nineteen minutes. The average time of a single comparison of two units is therefore somewhat less than two minutes. {!).) Comparison by means of two Microscopes attached to the same Movable Carriage. The steps are as follows : — (1.) The standards are placed in position upon the table S, one near the middle, and the other at a given distance in front of it. (2.) The microscope K occupying a position near the middle of the comparator, the defining line at the left end of the bar is brought into focus of the microscope M by the screw M^ Fig. 7. The carriage is then moved by the handle D till the defining line at the right end of either one of the standards is in the field of the same micro- scope. The adjustment for parallelism with the cylindrical ways is now made with the lever S*"' and for focus with the screw S''. (3.) Both microscopes are now placed upon the plate K. By means of the adjustments shown in Fig. 7, microscope M is adjusted upon the left-hand defining line of one bar, and M^ is adjusted upon the corresponding defining line of the bar in front of it. (4.) By a motion in translation through D, the right defining line of the first bar is brought into the field of M, and adjusted for coinci- dence with the fixed micrometer wire by the lever S''. (5.) The difi'erence in the length of the bars is then measured with the micrometer of Mj. (G.) The bar in front is now placed at an equal distance back of the first bar, and the operation described above is repeated. (7.) The mean of the two results will be the diflTerence in the length of the standards, free from the effect of the curvature of the ways along which the carriage moves. The same result will be obtained if the microscope carriage is moved along the cylindrical ways, the bars remaining stationary during each independent opera- tion ; but the curvature eliminated will in this case be that which belongs to the cylindrical ways. (c.) Comparison by means of Stops and one Microscope. The stops H H^ move freely upon the cylinders X X, but they are capable of being clamped to them with great firmness by the levers shown near L. At one end they terminate in an oval projection of tempered steel, which is hidden behind the cylinder X, in Fig. 1. OF ARTS AND SCIENCES. 119 It is nearly in line with the centre of gravity of K, which has a corresponding flat surface of tempered steel at each end. These stops receive a slow motion by means of a screw, which is shown near the pillow blocks in Fig. 3. (1.) The stops H H^ are set approximately, e. g. 1 meter apart plus the length of K, and are securely clamped. (2.) The plate K is brought into contact with the left-hand stop. (3.) The standard to be compared is placed upon S, and the car- riage is moved by the arm D till the left-hand defining line is adjusted under M. (4.) The plate K is then brought into contact with the right-hand stop, and the other defining line is brought into position and into focus under M by the adjustments already described. (5.) These adjustments having been completed, K is brought into contact, first with H, and then with H^, and the micrometer is read for each contact. (G.) These operations are rei^eated for each standard comi^ared. Since each one has been compared with the invariable distance be- tween the stops, the data are thereby furnished for the comparison with each other. In practice, the standard with which other stan- dards are to be compared is always compared first with the distance between the stops, the record being written at the left of the page. The following example will illustrate the form of record. R signi- fies contact with the right sto}), and L with the left stop. Bar T. Bar C. S. (R'-L')-(R-L) L R R — L L' R' R'-L' rev. 4 div. 16.2 div. 14.6 div. —1.6 rev. 4 div. 19.7 div. 19.9 div. +0.2 div. + 1.8 Under these definitions, the second standard is longer than the first, when {R' — U) — (i? — L) is positive. In this case, therefore, C. S. is 1.8 div. longer than T. With the microscope of Comparator No. 1, however, this order is reversed. In that case, the second standard is shorter than the first, when {R' — L') — (R — L) is positive. (d.) Comparison hy means of Stops, and with two Microscopes. (1.) The standards to be compared are placed side by side upon the table S, and the carriage is placed at a convenient point upon E. 320 PROCEEDINGS OF THE AMERICAN ACADEMY (2.) The plates K and I are adjusted so that the defining lines of the first standard to be compared shall fall under the microscopes M and M^. (3.) The stops H and H\ having been brought into contact with the plates K and I, are securely clamped. (4.) After the adjustments for position and for focus have been made, successive contacts of the j^lates K and I are made with the stops H and H^, and the microscopes M and M^ are read for each con- tact. These operations having been repeated for each standard to be compared, the values of (M^ — M) when reduced to a common unit and compared inter se, will give the relations required. It is the experience of the writer that the microscope carriage can be brought into actual contact with the stops, by means of the rack and pinion movement, with greater certainty than it is possible to make a coincidence of the micrometer thread with the defining lines of the standard. The following test has been frequently tried, and always with the most conclusive results. With a quarter-inch ob- jective, in which the value of one division of the micrometer screw is only 0.11 /x, a series of one hundred successive contacts with the stops were made without disturbing the position of the micrometer thread. The number of cases in which the deviation from the mean of the first two or three readings of the micrometer was perceptible to the eye were noted, and the amount of the deviation was estimated in terms of the apparent width of the micrometer thread. One hundred readings of the micrometer thread were then taken for coincidence with the defining line of the standard, the plate K remaining station- ary. A comjjarison of the results obtained in this way has always been found to be in favor of the stop contacts. "With a little experi- ence on the part of the observer, the stop method admits of the high- est degree of precision. It is the experience of the writer, that one hundred successive contacts may be made, in which another observer at the microscope will be unable to detect the slightest deviation from cons;^ancy. The stop method, also, has the great advantage over all other methods, that it allows perfect freedom in the adjustment of the micro- scope for focus, at any time during the comparisons. It is only required that the stops shall remain fixed during the two or more comjiarisons. But in order to meet the objection which is sometimes urged against the certainty of actual contact, an electro-magnetic attachment has been added to the stops H and H^ by which the plates K and I are OF ARTS AND SCIENCES. 321 securely locked after the contact has been made by the rack and pin- ion movement. By means of a screw, shown at the left of H, the core of the magnet is adjusted at the proper distance with respect to the armature shown at the left of K, after contact has been made be- tween the stops. A battery is employed of sufficient force to move the carriage K, when the magnet is one eighth inch distant from the armature. (e.) Comparison by means of tico Microscopes placed in a Horizontal Position. (1.) By means of two angle-plates, microscopes M and M^ are made to occupy a position at right angles to the position shown in Fig. 1. (2.) The standards to be compared are placed upon the table S, supported at their neutral points, and with their graduated surfaces in a vertical plane. (3.) The comparisons are then made in the manner described under (a). By this arrangement, the apparatus becomes a vertical comparator. The intersection of the transverse line with the defining lines being in the plane of the neutral axis, the deflection will be inappreciable, even if the bar is not supported at its neutral points. The first sug- gestion of this form of apparatus is generally credited to Neuman, and the first construction to Wilde, who has given a full description of the vertical comparator, constructed under his supervision, in the Repertorium fiir Experimental-Physik, Vol. XIII. p. 567. But a comparator of this form, invented by Lane, had been in use for several years previous to this time in the office of the U. S. Coast Survey at Washington. Under the fifth requirement the following methods are employed. The frame of the stop V, Fig. 4, is securely fastened to the bed-plate of the comparator. It has a vertical adjustment by means of gibbed ways. The stop U is firmly attached to the plate K. This stop has a vertical adjustment also ; but the line V U was made parallel with the cylindrical ways by the makers. For observations of this class, the plate N, Fig. 4, which carries the microscope M i, occupies a position the reverse of that shown in the cut. The line bar to be compared is first placed upon the table at a known distance outside of the line U V. The adjustments are then made as follows : — VOL. XVIII. (X. 8. X.) 21 322 PROCEEDINGS OF THE AMERICAN ACADEMY (1.) The stops U V are set at the same height above the table. (2.) The Hue bar is then adjusted so that the horizontal Hue is par- allel with the cylindrical ways, and is at the same time in the focal plane of the objective. The means of adjustment in three planes are not shown in the figure, but they are the same as those already de- scribed. The frame which carries the lever movements is fitted to the bed-plate by the dowel pins 0 0. (3.) The jilate K is moved upon the cylindrical ways till a contact between U and V takes place. While the plate remaias in this posi- tion, micrometer M' is read for coincidence with the defining line at this end of the bar. (4.) The carriage having been moved to the other end, the end- measure standard is placed in position between the stops U and V. (5.) After firm contacts have been made between the stops and the defining surfaces of the eud-measure standard, through the hand-wheel R of the rack and pinion, microscope M^ is read for coincidence with the defining line at that end of the bar. The difference in the two readings will be the difference in the length of the two standards, pro- vided the cylinders have no horizontal curvature. (6.) In order to eliminate the effect of horizontal cnrvatnre, the comparison is again made with the line bar, placed at the same dis- tance inside of the line U V. Good results have been obtained by this method, bnt it is of course open to two objections ; first, that since the bar must be moved in order to secure contact at V, the pressure at the two ends is unequal ; and second, that the force required to make the contacts secure, may pi'oduce indentations in the defining surfaces of the standard bar. It will be seen from the series of observations with the end-measure standard in melting ice, detailed on pp. 345-359, that the second ob- jection will not hold if the steel is properly tempered. The diffi- culty, if it exists, is easily remedied by the use of protecting pieces having parallel surfaces. The first objection is a more serious one. It is certainly open to criticism in a theoretical view, but the results shown on page 350 seem to indicate that this objection is not a serious one in actual practice. A second method of comj^aring line with end measures will need to be described without the aid of a drawing. The apparatas is attached to table S, Fig. 1. Three requirements most be met in the successful comparison of line-measure with end-measure standards : — (1.) The position of the end-measure standard must not be disturbed during the comparison. OP ARTS AND SCIENCES. 323 (2.) If only one microscope is used, either the movement of the microscope along the horizontal defining line must be in the line of the stops, or there must be a convenient way of placing the line stan- dard at an equal and constant distance on either side of tlie line of the stops, without the necessity of adjustment for i^arallelism and for focus. If two microscopes are used, means of adjustment in three planes become necessary. (3.) The pressure of the stops at each end must be equal and constant. These three conditions are met in the following arrangement. Upon a table attached to S, Fig. 1, two slides move freely upon cylin- drical ways of rather small diameter, but they can be firmly secured to the cylinder at any point by clamps. A second slide is mounted upon each of these plates, which has a movement of about four inches upon a cylinder and a flat way. The parallelism of these upper plates with the plane described by the carriage K, is secured by an adjustable ver- tical piece which passes through the jjlate near one edge and rests upon the plane way, which has also a vertical adjustment. There are two of these plane ways, placed equidistant from the cylindrical way on either side. The carriage can therefore be reversed by simply lifting it from its semicircular bearings. These upper slides terminate with tempered steel stojjs, which were set by the maker in a line with each other, and in the vertical plane which passes through the axis of the cylinder. The forward motion is given by means of an adjustable spiral spring, while a lever and stop control the backward motion. An adjustable graduated bar is firmly attached to each of these plates, which has its upper surface nearly in a line with the stops. With this arrangement of stops it is possible to compare line with end measures by the aid of either one, two, or three microscopes. The method by two microscopes has decided advantages over any other tried by the writer. The explanation, therefore, will be limited to this method. (1.) The two double-slide plates are placed in such a position upon the main cylindrical ways that the distance between the spring-stops is e. g. about one meter. (2.) The end meter, supported at its neutral points, is placed be- tween the stops, and an equal pressure upon each end is given by means of the adjustable springs. (3.) Plate K is then placed nearly opposite one end of the meter, and plate I nearly opposite the other end. The micrometer line of M-*^ must now be i>laced exactly in the verti- 324 PROCEEDINGS OP THE AMERICAN ACADEMY cal plane with the contacts of the stops at one end, and the micrometer line of M must be placed in the same vertical plane with the contacts of the stops at the other end. This is accomplished in the following manner. The stop-plate is thrown back by means of the controlling lever, and a rectangular block of metal is placed between the stop and the defining surface of the bar. This block has two of its faces exactly parallel and one inch apart. The upper surface is supposed to be in the same plane as the upper surface of the short graduated reference- bar attached to the stop-plates. The ujDper surface has a slight pro- jection at each end, which allows defining lines one inch apart. This surface is bisected approximately by a horizontal and a perpendicular defining line, and a perpendicular line is drawn at each end exactly half an inch from the line at the middle point. The first step is to set the micrometer M^ for coincidence at the in- tersection of the cross lines upon the plate. The block is then turned 180° and a second reading of M-^ is taken. One half of the difference between the two readings will measure the distance of the defining line on the block from the middle point between two stops when contacts are made with the end surfaces. If the plate K is moved forward a distance equal to the micrometer line of the microscope will be in the perpendicular plane which passes through the point of contact formed when the two stops are brought together by the removal of the block. In the same manner the reference line of micrometer M is brought into coincidence with the plane passing through the point of contact of the stops at the other end. The distance between the micrometer lines of the two microscopes is now equal to the length of the end-measure standard. (4.) The line-measure standard to be compared is now placed upon the table S, and the distance between the defining lines of the meter is compared with the distance indicated by a constant plus the read- ings of the microscope micrometers. The adjustments required are the same as those described under division («), page 302. The comparison of short-end measure gauges can be expeditiously made by means of the graduated reference-bar attached to the stop- plate. For this purpose the two lower slides are brought near enough together to allow the stops of the upper plates to be brought into con- tact. Both slides are then securely fastened to the cylindi-ical ways upon which they rest, and one of the stop-slides is securely clamped OF ARTS AND SCIENCES. 325 also. After contact has been made between the free and the fixed stops, the micrometer line of the microscope is brought into coinci- dence with the defining line at one end of the bar attached to the free stop-plate. The end gauge is then placed between the stops, the free slide being moved back the required distance in order to allow the in- sertion. During this operation the microscope remains undisturbed, and the graduated bar passes under it without disturbance of the focal plane. The difference in the readings, therefore, for the two positions of the free stop-plate, i. e. before and after the insertion of the end gauge, measures its deviation in length from the line standard. If three microscopes are mounted upon plate K, and one of the stop- plates is attached to the front face of the carriage in such a manner that the two stops are parallel with the cylindrical ways, the method of compari.'^on already described is applicable, and conditions (1) and (2) are both fulfilled. The sixth condition is met in two ways. (1.) By the use of the two stops, H, H^ Fig. 4. The stops are first set approximately at the distance apart indicated by the subdivisions to be compared. The method of comparing each space with the constant distance between the stops is tlie same in every respect as that described already. The following example is given in illustration. COMPARISON OF INCH SUBDIVISIONS OF (?/=. {R — i) m»i!ts Constant. 2 — 2.7cliv. =— 1.4;n —lAfj. -(-2.2 div. = +11 II —0.3 iJL — l.Odiv. = — 0.5;u —0.8/1 -i-0.5 div. = +0.3 IX —0.5 ^ -f-2.6div. = +1.3;u +0.8 /t —1.7 div. = —0.8 IX +0.0 IX In this comparison the distance between the stops was 6.1 div. less than the average value for one inch. When this constant is subtracted from the separate values of ^ — Z, the residuals represent the relative values of the separate subdivisions. With the microscope of Com- parator No. 1 a positive residual indicates that the measured space is too short. In this case the first space is 1.4 /x relatively too long, and the second 1.1 /a relatively too short. In order to obtain the error of any line reckoned from the first line, we must sum the residuals alge- braically. Here the first five inches are 0.8 ya too short. Space. L R R-L 1 5 rev. 0.4 div. 3.8 div. +3.4 div. 2 0.0 div. 8.3 div. +8.3 div. 3 0.6 div. 5.7 div. +5.1 div. 4 1.3 div. 7.9 div. +6.Gdiv. 5 1.0 div. 9.7 div. +8.7 div. 6 1.1 div. 5.5 div. Mea +4.4 div. n +6.1 div. 326 PROCEEDINGS OF THE AMERICAN ACADEMY (2.) By the use of two microscopes. It will be seen in Fig. 1 that there are two carriages, S and S^ which traverse independent ways. S^ is supposed to be in front of S. Two arms are attached to the upper surface of table S-^ (not shown in the figure), which project about half-way over the surface of S, allow- ing a sliirht clearance between the two surfaces. The standard whose subdivisions are to be compared is placed upon the table S, and a bar having upon its surHice a graduated space, X, approximately equal to one of the subdivisions of the first bar, is placed upon the projecting arms attached to S^. Both microscopes are now secured to the car- riage K. M^ is adjusted for coincidence with the initial line of the standard, which is placed upon S, and M is adjusted for coincidence with the corresponding line upon the other bar. The carriage K is moved toward the left, and a second coincidence of M is made with the other defining line. A comparison of the two readings of M^ for the two positions of M will give the relation between the two spaces compared. M^ is then adjusted for coincidence with the second line, and the carriage S^ is carried back by the rack and pinion D till the first line is again under M. The second subdivision can now be com- pared with the same constant space, X, as before. It is obvious that, by the proper disposition of the two bars with respect to M and M\ subdivisions of any magnitude whatever can be compared. It is to be noted, however, that the results obtained in this way are subject to errors due to the horizontal curvature of the cylindrical ways. (3.) For long distances, and for any distance exceeding one decime- ter, more i-eliable results can be obtained by the use of two micro- scopes in a fixed position. The various adjustments required in order to bring tlie defining lines of any subdivision into coincidence with M and M^ have already been described. Description of Comparixg-Rooms. The comparator first described is mounted upon isolated brick piers in the cellar of the Observatory. Through the liberality of the Di- rector of the Observatory a small room in the shape of a trapezium was partitioned off for this purpose. This comparator was at first mounted upon stone piers mounted upon the clock pier in the prime- vertical room of the Observatory. But notwithstanding the great size and stability of this pier, it was found impossible to make comparisons except very early in the morning before the disturbance from passing teams began. This pier rests upon a layer of blue clay having a large OF ARTS AND SCIENCES. 327 inclination to the horizon. Beneath there is a layer of sand. The tremors communicated to the clock pier through this combination were found to be surprisingly great. The tremors produced by ice-carts at the distance of 1,000 feet rendered it impossible to make exact com- parisons. The heavy steps of an assistant could be counted to the distance of 100 feet, by noticing the effect of the concussion upon the pier, which was in turn communicated to the surface of the bar ex- amined under the microscope. Heat is communicated to this comparing-room from the furnace in the cellar by a pipe which enters the room near the ceiling and nearly over the comparator. Under certain circumstances the temperature in this room may be kept under very good control, but great care has been found necessary in this regard. The comparator is directly in the line of the windows. By opening both windows during the night, the temperature within the room is found to be reduced nearly to the temperature of the outside air. By making the observations with this comparator on cloudy days and early in the morning, much better re- sults have been obtained than were expected. By the liberality of the President of Harvard College, comparing- room No. 2 was fitted for the reception of the Universal Comparator. It is situated in the basement of Harvard Hall. The dimensions of the room are 12 feet in length, 9 feet in width, and 8 feet in height. The brick walls which surround the room are twelve inches in thick- ness. The brick piers upon which the comparator rests extend to a depth of eight feet. The walls, the ceiling, and the floor are all double- planked, with two intervening air spaces. Between the inner and the outer partition there is a layer of rosin-soaked paper. The room has double windows and double doors. The steadiness of the tempera- ture within the room may be inferred from the record on pp. 366-371. Durino; the summer of 1882 the extreme change of the Fahrenheit thermometer for eicjht weeks was 1°.3. During the same time the daily variation in the temperature of the outside air often amounted to 25°. Between April 14 and June 1, 1883, the extreme range was 0°.75 C. On June 3 the temperature of the room was raised by artificial means. By June 5 the temperature had reached the stationary point, viz. 17°. 07 C, and between this date and June 28 the rise was only 0°.96. On July 6, the reading of 1^61 was only 18°. 48, notwithstanding the average temperature of 31° for the two preceding days. On July 7, the room was exposed to the open air. An attempt has been made to produce desired variations of temper- 328 PROCEEDINGS OF THE AMERICAN ACADEMY ature by the following arrangement, which has been found to be mod- erately successful. Sheets of galvanized iron three feet in width, after having been fastened at the edges by soldering, and riveted together at intervals of twelve inches, were fastened to the inner walls of the room in such a manner that there is a gradual decline in their height above the floor. They are connected together by rubber tubing. In the opposite room a tank is arranged for either hot or cold water, which is connected with the reservoir at the highest point. At the lowest point there is an outlet through the walls of the room. Either hot or cold water entering this reservoir of narrow section slowly percolates through the enclosed space, and flows off through the outlet, maintaining a nearly constant supply of either hot or cold air within the room. The reser- voir holds about five gallons, and the amount of surface exposed on one side is about 100 square feet. This comparing-room has one fault in construction which has given considerable trouble, and which it has been found impossible to remedy entirely. In order to be able to raise the comparator as high as the window, it was found necessary to give the piers a height of four feet. The head of the observer is therefore very near the ceiling. This dif- ficulty has been partly remedied by a large trap-door in the ceiling, which allows the heat developed by the presence of the observer to enter the space between the partitions. Description of the Thermometers employed in the Comparisons. Throughout the entire series of observations the Yale College stan- dard has been adopted. In the earlier part of the work a Fahrenheit thermometer graduated to fifths of deiirees was used. It is desiirnated 0. It was purchased of a dealer in New York at a low price, but it was found to be an exceptionally fine instrument. Its error was de- termined by Dr. Waldo, by comparison with the Yale standard. It was afterwards carefully compared with Cassella No. 3235, which had been rigorously compared with the air thermometer of Professor Row- land by Mr. S. W. Holraan of the Massachusetts Institute of Tech- nology. The independent comparisons of Dr. Waldo and of Mr. Hol- man agree in giving the same tenth of a degree for every point compared. The corrections adopted are given below. OF ARTS AND SCIENCES. 329 T O 32 u 0 —0.74 o!80 35 —0.70 0.81 40 0.70 —0.84 45 0.71 0.86 50 —0.75 —0.89 55 —0.79 —0.91 T u Ka;io O 60 — 0°90 o!94 65 —0.98 0.95 70 0.98 0.97 75 0.92 —0.97 80 0.93 0.98 As a check upon the observations with 0, a Centigrade thermometer, marked No. 1, was read in connection with it. The corrections to No. 1 were found from a comparison with 0 to be as follows : — T No. 1 T No. 1 T No. 1 o o o o o o 0 —0.50 12 —0.94 21 —0.72 3 —0.67 15 —0.97 24 —0.50 6 —0.78 18 —0.90 • 27 —0.63 9 —0.90 The standard designated T 61 was received from Dr. Waldo in October, 1882. Since this date all comparisons have been made with reference to this standard. The following Report accompanied the standard : — "The Obsekvatort of Yale College. — Thermometkic Bcreau. "Examination of the Y. 0. S. Thermometer, No. 61, made by Tonnelot. "1st. This thermometer has been examined in a vertical position with the metallic scale and tube immersed in water having the tem- perature of the bulb. " 2d. When the correction is + it must be added to the thermometer reading, and when — it must be subtracted. For example, suppose the thermometer to register 81°.0 and the respective tabular correc- tions at 72° and 92° to be — 0°.5 and — 0°.7, then the corrected read- ing of the thermometer would be 81°.0 — 0°.6 = 80°.4. " The theoretical mercurial standard thermometer to which this in- strument has been referred, is graduated by equal volumes upon a glass stem of the same dimensions and chemical constitution as the Ivew standards 578 and 584. The permanent freezing point is determined by an exposure of not less than forty-eight hours to melting ice, suji- 330 PROCEEDINGS OF THE AMERICAN ACADEMY posing the temperature of the standard has not been greater than 25° C. = 77° F. during the preceding six months. The boiling point is determined from the temperature of the steam of pure water at a barometric pressure of 760 mm. = 29.922 in. (reduced to 0° C.) at the level of the sea and in the latitude of 45°, This standard coincides with the perfect gas thermometer within 0°.l F. for temperatures be- tween zero and 212° F. 'LEONARD WALDO, Astronomer in Charge. " New Haven, Conn., March-October, 1882. ■Yale Observatory Standard No. 61. — O. T. S., Observer. Reading of Correction to be Dcpres?ion at 0° for Reading of the 0° point wlien hori- zontal. Correction depend- Y. 0. S. 61. applied. 100° Elevatioa. ing on Calibration. o o o o o 0.0 c. 0.00 -0.20 +0.04 0.00 5.0 —0.06 10.0 0.00 12.5 +0.17 15.0 4-0.02 20.0 +0.07 25.0 +0.12 +0..33 30.0 +0.16 85.0 +0.18 37.5 +0.86 400 +0.18 45.0 +0.20 60.0 +0.12 +0.41 55.0 +0.14 60.0 +0.20 62.5 +0.54 65.0 +0.16 70.0 +0.28 75.0 +0.21 +0.45 80.0 +0.20 85.0 +0.13 87.5 +0.29 90.0 +0.02 05.0 —0.02 100.0 +0.07 0.00 " 1. The first column gives the scale readings on the thermometer. " 2. The second column gives the sum of all the corrections to be applied at the points of the scale indicated in 1, to reduce the readings to the standard of this Observatory. '• 3. The third column gives the depression of the zero point caused by heating the standard to 100° C. OF ARTS AND SCIENCES. 331 " 4. The fourth column gives the reading of the zero point when the standard is inclined 90°. " 5. The fifth column gives the correction depending on the interior figure of the standard column." It will be noticed that the report of Dr. "Waldo gives only the cor- rections of F61 between the limits 0° and 100°. In the reduction of the observations at temperatures below 0° for the determination of the absolute coefficients of expansion of the bars under consideration, I found a constant tendency to a positive correction, on the supposition that the coefficient was constant. For example, instead of finding the constant difference between bars 7^ and S in meltiuij ice to be 75.1 div., as determined from the equations of condition on the following pages, I found continually diminishing values, until for T= — 11° the value was 52.6 div. In the case of bar C. S. a similar result was found. The coefficients were now assumed to be a constant, and the corrections to the thermometer required to make all the values of S — T and S — C. S. below 0° agree with the values derived from observations above 0° were computed, with the following results. Corrections to YGl. T61 From T I'61 From T 10°8 -f0.°35 o —4.5 —0.02 10.4 +0.18 —3.6 0.01 — 9.9 +0.20 2.1 +0.06 7.9 +0.13 —1.2 —0.04 — 7.0 --0.03 0.7 —0.07 6.1 +0.10 —0.5 --0.05 ■4.6 +0.03 —0.4 —0.01 A similar series of corrections was derived from bar C. S. Smootli curves were now drawn through the points determined by these resid- uals, and the following corrections were obtained. Afterwards Mr. S. W. Holman. of the Institute of Technology, compared Z61 with an alcohol standard thermometer by Baudin. His results are given be- low. It should be noted that Mr. Holraan's values were derived before he had any knowledge of the results obtained by the writer. 332 PROCEEDINGS OF THE AMERICAN ACADEMY rei From T From C. S. Mean. Holman. Adopted Corrections, o 0 o o 0 o — 1 —.02 +.09 +.03 +.03 +.03 — 2 —.02 +.14 +.06 +.06 +.06 — 3 —.01 +.18 +.09 +.09 +.09 — 4 +.01 +.22 +.12 +.13 +.13 — 5 +.04 +.22 +.13 +.13 +.13 — 6 +.06 +.22 +.14 +.14 +.14 — 7 +.14 +.22 +.18 +.15 +.16 — 8 +.20 +.23 +.22 +.18 + .20 — 9 +.30 +.24 +.27 +.24 +.25 —10 . +.40 +.26 +.33 +.31 +.32 —11 +.48 +.32 +.37 +.39 +.38 The writer is using at the present time in connection with T'Gl a spirit thermometer made by Mr. J. S. Iluddleston of Boston. The lenirth of each desfree Centigrade is about 2.5 centimeters, and the length of the column of (colored) alcohol is about thirty-nine inches. The complete determination of the errors of this thermometer will need to be deferred till the coming winter ; but according to the present indications it is an instrument of extraordinary precision. The greatest deviation thus far observed from the corrected readings of rCl is about 0°.06. Description of Microscopes. Values of One Revolution of Micrometer Screws. The measuring microscope used in connection with Comparator No. 1 has a tube fourteen inches in length. The micrometer was made by Powell and Leland. Nearly all of the observations have been made with a Tolles four- system inch. The illumination is hivariably obtained by the use of a prism inserted between the two front lenses, a device known as Tolles's opaque illuminator. The principle of this illuminntor is so often stated incorrectly, that it is well to restate it here. The focus of the rays of light which pass through the prism is a little outside of the focus of the objective itself. The image under the objective, therefore, is witliui a cone of diffused light, the axis of the cone being in the line of collimation of the objective. This condition, however, requires a some- what careful adjustment of the prism when it is set by the maker. The illumination of polished metal surfaces is simply perfect. Sky illumination gives better results than artificial illumination. The dis- tance of the objective from the opening through which the light passes OF ARTS AND SCIENCES. 3S may be as great as 100 feet. It is only necessary that the plane face of the prism shall be directed towards the source of light. In order to get the best results, the power of the objective should be as great as the equivalent of au inch lens. But if an objective of great working distance is required, a large prism may be mounted in front of the lens. The writer has made use of this method of illumination for the micro- scopes of the Harvard College Meridian Circle with good success. The focal length of these objectives is four inches. The following are the results of the various determinations of the values of the micrometer screws. Comparator No. 1, Microscope A, UniTersal Comparator, Microscope A, 1 inch objective. 1 inch objective. 0.441 0.441 0.442 0.440 1880, Apr. 25 1 div. : = 0.505fjt. 1882, Oct. 15 1880, Apr. 26 a 0.504 1883, Mar. 23 1882, June 8 u 0.503 1883, Mar. 29 1882, Oct. 15 a 0.504 1883, Apr. 5 1883, Feb. 26 a 0.505 1883, Apr. 6 1883, Feb. 28 (I 0.504 Mean, Mean, 1 0.504 0.440 It will not escape attention that no mention has thus far been made of any arrangement for protecting the standard bars to be compared from the effect of the increase of temperature due to the presence of the observer in the comparing-room. The omission has not been accidental. The common impression, that the effect of such increase of temper- ature will be immediately apparent, is erroneous. If the meter is traced upon a thin ribbon of steel, any i^jcrease of temperature amount- ing to 10° will produce the change in length which its coefficient of expansion demands, within 15 or 20 seconds ; but if its mass be in- creased two hundred fold, a change in temperature of the same amount will require from one to two hours for its normal action. The preparatory work which needs to be done with evei-y bar which is to receive standard graduations is the determination of the time required for a given change of temperature to produce its full effect. This time is a function of the shape and the mass of the bar. It is proposed during the approaching winter to make an exhaustive study of this element for the bars under consideration. The few observa- tions which have already been made seem to show that, if these bars are quickly removed from a temperature of 32° to a constant temper- 334 PKOCEEDINGS OP THE AMERICAN ACADEMY ature of C2°, the times required for them to reach theu' normal length will be about as follows : — T requires from 15 to 20 minutes. C S. requires from 30 to 40 minutes. i?j requires about 2 hours. i?2 and G require about 4 hours. Conversely, the times within which an increase of temperature amount- iug to one degree, a& indicated by the thermometer, will be inappreciable in the com^Darisons, are about as follows : — T ^ra as. 10™ R, 12°> R, 18"> G 22m The Tresca bar, T, seems to possess decided advantages over every other form for the usual conditions under which observations are made. However sudden the change of temperature, and however great the amount of the change, the thermometer will indicate the true length of the bar, if an observed temperature can remain constant for about eleven minutes after the mercury reaches the stationary point. On the other hand, standards having a large cross-section are to be preferred, if a constant temperature can be maintained for several hours, since the effect of any change can be neglected for a consider- able time. Instead, therefore, of arranging protecting screens for the compar- ator, I have endeavored to arrange the adjustments in such a manner that a complete set of comparisons can be made before the heat devel- oped by the presence of the observer could produce any effect. In the comparisons described in this paper, the bar T, having the least mass, is placed in front, and the microscopes are left in adjustment upon the defining lines from the jji'ovious observation. The time re- quired to complete the observations upon this bar is not, therefore, over one or two minutes. Bar C. S., being the next in order of mass, is observed next in order of time, and bar R.^, having the greatest mass, is observed last. Bat after the observations are completed, the compar- ing-room rernains closed for at least four hours. During this time, the inci-ease of temperature due to the presence of the observer, which is OF ARTS AND SCIENCES. 335 usually about 0°.4 C, will have become absorbed in the general tem- perature of the room, and the several bars will have reached a state of rest as far as this special increase is concerned. We are now prepared to enter upon an examination of the standard prototypes described in this paper. The various comparidons will be given nearly in the order in which they were made. Comparison of Yard R^"" with "Bronze 11" at Washington. Professor Hilgard having kindly consented to undertake the com- parison of the bronze yard R^^ with "Bronze 11," Assistant Edwin Smith was assigned to this work. The observations by Mr. Smith were made with the Lane vertical comparator. At his request, the writer made independent micrometer readings, after all the adjustments had been made, but there was a complete avoidance of any knowledge of the results obtained. The fidl text of Professor Hilgard's report will be found in the report by the writer to the Pratt and Whitney Company, relative to the standards constructed for them ; but the portion relating to R.^ is given here. Date. Temperature. F. "Bronze 11 " — 7?,. Smith. Rogers. 1831 h m .Jan. 26 9 49 a m. 11 21 " 1 28 P.M. 3 11 " Jan. 27 9 39 a.m. 11 24 " 1 23 P.M. 3 10 " Jan. 28 9 36 a.m. " 11 22 " 12 36 P.M. 2 16 " 56°.20 56.15 56 20 56.35 55.90 55.55 55.10 56.40 52.00 51.75 51.30 51.30 in. —.000116 —.000114 +.000004 —.000060 +.000063 — .000002 —.000140 —.000133 —.000064 —.000041 —.000018 +.000015 in. —.000100 -.000089 +.000022 —.000084 +.000052 —.000014 —.000125 —.000098 —.000072 —.000041 Smith 54.37 54.98 —.000050 —.000055 Rogers At 54°.70 F. " Bronze 11 " — i?^ = —0.000052 inch. T— « Bronze 11" = +0.000088 " R„ ~ +0.000036 336 PROCEEDINGS OP THE AMERICAN ACADEMY I am indebted to the courtesy of Professor Hilgard for the oppor- tunity of comparing R.^ with "Bronze 11" upon Comparator No. 1, which was sent to Wasliington for this jDurpose. Since subsequent comparisons were to be made with this comj^arator, it seemed impor- tant that the relations between these standards should be determined under the same conditions as those under which future investigations would be made. For this work I was assigned to a room in the basement of the building, in which a pretty steady high temperature could be main- tained. Afterwards the comparator was removed to a small observa- tory building in the rear, which was admirably adapted for the [tur- pose. Here a nearly constant low temperature was maintained for three days. The comparator was then mounted again in its former location, and further observations were made at a nearly constant temperature, which had now become reduced to about 62°. The following are the results of the comparisons. Date. 1881 Feb. 1 A.M. Observer. K. Thermometer. 35-2 " Bronze 11 " minus li^*^. in —.000039 " 1 " R. 35.2 +.000028 " 1 P.M. R. 35.6 —.000002 " 1 " R. 85.6 —.000083 " 2 A.M. R. 30.9 —.000014 " 2 " S. 30.9 —.000030 " 4 P.M. R. 60.9 —.000015 " 7 " R. 62.2 —.000059 Mean....— .000027 We have, therefore, " Bronze 11 " — R.^- — —0.000027 inch. " Bronze 11 " — F = —0.000088 '' Finally, R.^' — Y = — O.OOOOGl " „ a . 0.000036 in. + 0.000061 in. ^ ^2 ' H o = ^• Or, R.^'- -f 0.000048 in. = Y. Since the metal in each bar has the same composition, it is assumed that they have the same coefficient of expansion. Comparisons were also made between the Tresca meter and tlie Coast Survey meter "No. 49," which bears a known relation to tl.e Berlin meter, and thence with the Metre des Arcl'.ives. OP ARTS AND SCIENCES. 337 The following equations of condition were obtained. Date. "49" — r»» 1881 <'49"_ 7-«a (T-32') at 32° Aa Jan. 24 +139.4 M = a 40.2 b +90.0^ —1.7 m " 24 + 140.1 /i = a —40.3 b +90.5 Ai — 1.2/i " 24 +138.GAt == a —40.3 b +89.0/* — 2.7|u " 24 +140.3ai = a —40.5 6 +90.5 /x — 1.2 fi " 25 + 130.6^ = a —37.8 b +93.1/1 +1.4 /x " 26 +140.9/1 = a —38.3 b +93.8/1 +2.1 /t " 30 + 0C>.2fi = a — 4.2 6 +91.0 /i —0.7/1 " 31 + m.Ofi = a — 3.3 6 +91.9 /t +0.2/1 Feb. 1 + QoAfx = a — 4.16 +90.4/1 —1.3/1 " 2 + 120.1^ = a 30.4 6 +91.8 /* +0.1 /t " 6 +i;3i.o^ = a —29.46 +94.8/1 +3.1/1 Normal Equations. +1380.0 = +11 a — 308.8 b 6 = +1.23/* — -42076.8 = —308.8 a + 1123 ;4.16 a = +91.7 fi It will hereafter be shown that at 32° 7^=4- 102.8 /i = J. But »49»_7^«^ =91.7 IX. Hence "49" + ll.l/x = A Forster gives for " 49 " the following relations : — From the direct comparison of the Berlin meter with the Metre des Archives, "49" + 21.4^ = ^. From a comparison of the Berlin meter with the meter of the Con- servatory, «49"-|_ 5.2/x — J. It will be seen that the value found in terms of the Tresca meter falls between these values. Since the absolute coefScient of expansion of " 49 " has been deter- mined both by Forster and by Pierce, the relation here obtained be- tween T and " 49 " will yield a value for T. We have for " 49," for each degree Centigrade, Forster, 18.69 /x. Pierce, direct, 18.83 /x. Pierce, indirect, 18.81 fx. VOL. xviii. (n. s. X.) 22 338 PEOCEEDINGS OF THE AMERICAN ACADEMY Reducing the value h = 1.23 /a to its equivalent for one degree Centigrade, we have the following values for the absolute coefficient of 7^: — From comparison with Fbrster, 16.48 |m. « « Pierce, 16.60//. « « Pierce, 16.62 /i. It will be seen that these values are somewhat larger than the value derived from the observations which follow ; but it can hardly be ex- pected that the correct relation between T and " 49 " could be obtained from the limited number of observations here given. Comparison of the Froment End-Meter F^ with T^^ WITH Comparator No. 1. Date. 1880. r(Fahr.) T'^i — Fe *6=r3.40n r=2_ireat32='Fahr. Mean values, Nov. 19 o 47.6 + 53.3 m +106.3 M " 22 47.1 + 54.6 ju + 105.9 M " 24 19.1 +158.0 M +114.1 M " 25 33.9 +109.2 M +115.7 M " 28 76.1 — 44.8 /x +105.1 M " 29 45.3 + 66.0 /t +111.6 M 109.8 M Dec. 1 57.3 + 19.1 M +105.1 M " 17 37.4 + 90.0 M +108.4 M " 19 35.4 + 10.2 yu +113.8 M " 21 38.9 + 84.4 m + 107.9 M " 22 46.1 + 58.8 m +106.7 M " 24 34.6 +105.6 M +114.4 M 109.4 m " 26 49.6 + 51.9 m +111.7M " 27 51.5 + 40.8 m +107.1 M " 28 39.8 + 8G.9m +113.4 M " 29 19.2 +157.4 M +113.9M " 31 5.0 +204.4 M +112.6 M 1881. Jan. 4 52.9 -1- 34.9 m +106.0 M 110.8 m We have, therefore, for 0° C, y«=_i?;=:+110.0/x. F, — A =+ 8.4,.. T^'^' — A =:+102.8,x. Diff. = 1.2 |M. But Whence According to Tresca * This value of 6 is the final value derived from the investigation on the following pages. OP ARTS AND SCIENCES. 339 Comparison of the Tresca Meter T^'^ with the Line-Meter 1881. F, with Comparator No. 1. TH—Fe Apr. 25 26 27 27 28 28 29 29 May 2 « 2 + 3.2 yU +25.6 M +23.2 /. + 6.8 m +32.4 ju +18.3 M +36.0 ju —12.0 IX +.39.4 /I +34.4^1 = 102.3 |M = 102.8^ ^A. 6 = 3.40 /u. atO°G. T^z — Fe +104.2/* +101.1/* + 103.4/* + 102.9/* +102.8/* +101.5/* +102.0 /* +102.4 /* +101.4/* +100.9/* (t — 0°)C. +16.5 +12.3 +13.1 +15.7 +11.5 +13.6 +10.8 +18.7 +10.2 +12.5 "We have, therefore, for 0" C, T'^ — F, But T'''- — A Hence F^ — 0.5 /x This relation has an importance far beyond any ordinary comparison of standards, since the centimeter derived from the Froment line-meter is the unit upon which Angstrom's wave lengths depend. It is be- sides the basis of nearly all the later physical investigations under- taken in France. If, therefore, the transfer of this meter to the surface of bar F is assumed to be without error, the correspondence of the whole unit with the Metre des Archives is nearly perfect. Comparison between Meters T and R^. After my return from Washington, two series of comparisons be- tween these standards were instituted, one series with Comparator No. 1, and the other with the Universal Comparator. In the first series two microscopes were used, being attached to the carriage. The bars wei'e placed at a distance 2 x centimeters apart, and observations were made for the positions -\-x and — x. For X ■=. -(-3.0 cm. Date. At62°.0F. 1881. (t — 62. °0) F. T^. — R^i y"2 _ n^ Feb. 14 +24.1 +177.7/* +164.0/* " 15 +23.5 +177.2/* +163.8/* " 16 —12.2 +152.2/* +159 2/1 " 17 —13.2 +151.0 /i +158.5/* " 20 +32.5 +185.4/* +166.9/* " 21 +22.2 +172.2 M +159.6 At 340 PROCEEDINGS OF THE AMERICAN ACADEMY Date. 1881. (t — 62. °0) F. T'^i — n^'i T''2 - lij-i Feb. 22 —13.7 +145.5 M +153.3M " 23 —13.7 + 142.8 M +150.6 /t Mar. 16 — 8.9 + 147.5 M +152.5 /t " 23 —13.6 4-144.6 M +152.3 /t " 24 — 9.7 +154.0 M + 165.2 /t " 25 +26.8 +178.9 /i +163.7 fi " 29 —11.8 +155.0 M +lG1.7/t " 30 —13.2 +151.3 iu +158.8/1 " 31 —15.4 +151.0 /x +159.7 /i Apr. 3 +29.3 +187. 2/x +160.5 /t " 8 + 6.9 +165.0 M +161.1 /i " 10 + 8.9 For X +167.6/* —3.0 cm. +162.6/1 Feb. 24 —16.3 +165.5 ;u +174.7/4 « 25 +35.9 +197.8 M +177.4/* Mar. 11 + 4.8 +174.7/4 +172.0/1 " 13 +23.1 +183.G/i +170.5/* " 14 +19.6 +186.1/* +175.3/1 " 15 +22.4 +189.3 /i +176.6/* " 16 — 9.0 +163.2 fi +163.7/* lave, therefore, T'^i. — R'i For X — -j-3 1.0 cm. -{-1 59.7 fi. X— 3 ;.o cm. -\-l 72.9 fi. Mean — -j"! GG.3 ^• ?F^VA 9 5 " +16.04 1 —454,2 tl 8 33 " + 18.10 515.1 OF ARTS AND SCIENCES. 349 Series II. — Continued. Date. Time. yei S—T^i Date. Time. y6i S—T^^ 18S3. h. in. o div. 1883. h. in. o div. May 4 8 4!) P.M. +18.18 —521.0 May 7 5 34 a.m. + 8.00 — 1'.»3.3 t( 8 43 " + 18.18 — 519.7 t( 6 50 " +29.25 —884.4 ft 2 55 P.M. +20 05 —582.8 It 6 53 " +29.25 —879.7 (( 2 59 " +20.05 —580.8 CC 7 0" +29.14 —879.3 it 7 3" +29.14 —876.3 May 6 9 0 A M. +16.44 4G5.6 (( 9 3 " +16.44 —466.1 May 8 5 25 a.m. +12.82 —359.3 May 7 5 20 am. + 7.90 —197.3 (( 5 30 " +12.82 —347.8 ti 5 24 " + 7.95 —197.8 ({ 5 85 " +12.82 349.2 ti 5 30 " + 7.98 —192.4 (1 5 40 " +12.82 —348.7 EQUATIONS OF CONDITION BETWEEN T AND 5. Seiiies I. S- r*i = a-h (t 1883. S— T"! (t - 0°) Feb. 7 + 17.6 div. = a + 1.76 i " 7 — 52.3 div. = a + 3.83 6 " 7 —172.4 div. = a + 7.60 6 " 8 +218.0 div. = a — 4.30 b " 8 + 20.4 div. := a + 1.46 6 " 9 +221.4 div. = a — 4.54 6 " 11 —360.1 div. = a +13.47 6 " 12 + 20.4 div. = a + 1.78 6 " 12 +169.0 div. = a — 2.96 6 " 12 + 98.3 div. = a — 0.79 6 " 13 + 21.4 div. a + 1.69 6 " 13 + 70.7 div. = a + 0.12 6 " 13 — 2G.4 div. = a + 3.26 6 " 14 +280.6 div. = a — 6.50 6 " 15 —116.9 div. = a + 5.82 6 " 16 + 49.0 div. = a + 0.78 6 " 18 —849.2 div. = a +28.40 6 " 19 —719.5 div. = a +24.53 6 " 20 +132.9 div. = a — 1.92 6 " 25 — 18.9 div. =: a + 2.96 6 " 25 -107.1 div. a + 7.58 6 " 25 —186.8 div. r= a + 8.31 6 " 26 —645.2 div. = a +22.37 6 " 27 +380 6 div. = a — 9.59 6 " 27 +293.9 div. a — 6.71 6 — 00)6 a +74.5 +71.6 +73.4 +78.9 +67.6 + 75.1 +75.4 +77.9 +73.3 +72.8 +76.0 +74.6 +79.0 +70.4 +71.3 +74.8 +69.1 +73.8 +70.8 +76.8 +78.0 +81.9 +78.0 +70.5 +76.9 —0.5 div. —3.4 div. —1.6 div. +3.9 div. —7.4 div. +0.1 div. +0.4 div. +2.9 div. — 1.7 div. —2.2 div. —1.0 div. -0.4 div. +4.0 div. —4.6 div. —3.7 div. —0.2 div. — 5.9 div. —1.2 div. —4.2 div. +1.8 div. +3.0 div. +6.9 div. +3.0 div. — 4 5 div. +1.9 div. Aa — 0.2iu -1.7m —0.8 m + 1.9m —3.7 m +0.0m +0.2 M +1.4m —0.8 m -1.1m —0.5 m —0.2 m +2.0 M —2.3 m —1.8 m —0.1m —2.9 m — 0.6m -2 1m +0.9 M +1.5m +3,4 u + 1.5 m -2.3 m +0.9 M 350 PROCEEDINGS OF THE AMERICAN ACADEMY 1883. S—Ti>i Feb. 27 — 18.8 div. " 28 +189.8 div. " 28 + 83.9 div. (t - 0°) a Aa Aa a + 2.01 b +75.3 +0.3 div. +0.1 M a — 3.47 b +77.6 +2.0 div. +1.3m a — 0.22 b +76.8 +1.8 div. — 0.9ju Normal Equations. —1065.1= 28 a + 97.636 6 = —32.-34 —76975.0 = +97.63 a + 260.67 b a = +75.0 EQUATIONS OF CONDITION BETWEEN T AND S. Series II. 1883 S— Tbl (T-0=) a Aa Aa Feb. 28 + 86.3 div. = a — 0.71 b +63.5 +2.2 div. +1.1 M Mar. 1 — 54.8 div. := a + 3.64 6 +62.1 +0.8 div. +0.4 ;U (£ 3 —562.4 div. = a + 19.33 6 +58.5 —2.5 div. — 1.3/i (t 4 +385.0 div. = a —10.05 6 +62.2 +0.9 div. + 0.4 ;U (t 4 + 70.4 div. = a — 0.35 6 +59.2 —2.1 div. — 1.0/i <( 5 +207.4 div. = a — 4.38 6 +06.7 +5.4 div. +2.7 Hi <( 5 + 103.5 div. = a — 1.18 6 +65.6 +4.3 div. +2.2 M it 6 +308.2 div. = a — 7.72 6 +60.3 —1.0 div. —0.5 m Apri 115 —560.8 div. = a +19.41 6 +02.7 +1.4 div. +0.7 M (( 17 —332.7 div. = a +12.25 6 +60.8 —0.5 div. —0.3 m (( 18 —230.6 div. a + 9.14 6 +63.0 +1.7 div. +0.8 M (( 19 —210.2 div. =z a + 8.64 6 +61.3 +0.0 div. +0.0 M ft 20 —516.8 div. = a +17.96 6 +60.1 —1.2 div. — 0.6m it 22 — 86.9 div. = a + 4.57 6 +59.9 —1.4 div. — 0.7m << 23 —130 8 div. z= a + 5.97 6 +60.9 0.4 div. — 0.2/i <( 24 —133.9 div. — a + 6.02 6 +59.5 —1.8 div. —0.9 m it 24 —122 0 div. = a + 5.67 b +00.1 —1.2 div. —0.6 m « 24 —752.0 div. =^ a +25.40 6 +04.0 +2.7 div. +1.3 M a 24 —593.9 div. z= a +20.47 6 +63.6 +2.3 div. + 1.2m i( 25 — 20.6 div. = a + 2.47 6 +58.7 —2.6 div. —1.3 m « 25 — 60.9 div. — a + 3.75 6 +59.5 —1.8 div. —0.9 m <( 25 —586.8 div. — a +20.04 6 +57.0 4.3 div. —2.1m .9 a 8 20 " +27.00 —458.6 tt 8 30 " +17.88 — 137.4 ii 8 50 " +27.16 —462.0 ii 8 33 " + 17.88 —137.4 tl 8 40 " +17.86 — 137.0 Apr 30 5 26a.m. + 1.72 +413.9 tt 8 43 " +17.86 —137.5 " 5 20 " + l.:2 +406.8 it 1 0 p.m + 1816 —143 3 ■ t 5 44 " + 1.82 +403.6 it 1 3 " +18.10 —143.8 " 5 48 " + 1.82 +400.0 it 1 15 " + 18.16 — 139.6 " 5 55 " + 2.02 +396.2 It 1 18 " + 18.16 —141.8 " 0 0" + 210 +402.9 <• 6 10 " + 2.15 +398.8 May 4 5 40 AM +18.40 -104.8 It 0 20 " + 2.24 +392.5 (( 5 43 " +18.4C^ -1588 it 5 50 " +18.35 —158.2 May 1 5 15 a.m. + 5.13 +291.0 tt 5 53 " + 18.35 —159.0 <( 5 18 " + 5.13 +286.7 it 6 0" +18.25 —1 53 5 If 5 25 " + 5.13 +21)0.9 tt 6 8" + 18.25 —152.0 (( 5 27 " + 5 13 +287.1 tt 6 10 " +18.16 —140.3 (( 5 30 " + 5.20 +296.7 tt 6 13 " + 18.16 —146.3 tt 5 33 " + 5.20 +290.5 « 5 40 " + 5.2fi +291.0 May 6 7 Oa.m. +17.42 -124.1 it 5 43 " + 5 26 +289.2 (( 7 3" + 17.42 —123.0 it 7 38 p.m. +16.(i7 — 88.0 « 9 12 " +16.47 — 77.1 tt 7 41 " +16.07 — 89.5 « 9 15 " +16.47 — 78.2 (t 7 50 " +16.63 — 90.3 tt 9 45 " +l(j.47 — 80.8 OP ARTS AND SCIENCES. 355 Series II. — Continued. Date. Time. YGl S—C.S. Date. Time. TGI S—C.S. 1883. May 6 a It it a h. 111. 9 48 a.m. 12 10 P.M. 12 13 " 12 20 " 12 23 " +16°47 +16.(J7 +16.67 +16.67 +16.67 div. —84.6 —93 6 —94.9 —91.1 —91.2 1883. May 7 h. in. 6 45 a.m. 5 48 " G 10 " 6 12 " 6 35 p.m. 6 37 " + 7.°80 + 7.80 + 8 08 + 8.08 +29.64 +29.64 div. +210.1 +2i;}.7 +200.0 + 198.8 —540.0 —544.1 EQUATIONS OF CONDITION BETWEEN METERS C.S. AND S. 1883. S— C.S eb. 11 + 53 3 div. « 12 +502.2 <]iv. it 12 +542 9 div. it 13 +340 8 div. U 13 +772.6 div. « 14 +G73.9 div. it 15 +281.6 div. it 16 + 539.2 div. it 18 —407.6 div. it 18 -408.6 div. it 19 456.1 div. it 20 +593.3 div. ii 25 +443.6 div. « 25 +217.9 div. it 26 —298.2 div. it 26 — 2G8.9 div. n 27 +460.2 div. it 27 +887.6 div. it 28 +.592.6 div. a 28 +538.8 div. it 28 +505.0 div. Series I. (T - 0°) a Aa Aa a +13.02 6 +500.1 + 0.9 div. +0.5 M a — 0.14 6 +497.3 — 1.9 div. —1.0m a — 1 156 +502.9 + 3.7 div. +1.8m a + 4.09 6 +504.1 + 4.9 div. +2.4 M a — 7.76 6 +502.4 + 3.2 div. + 16m a — 4.87 6 +504.3 + 5.1 div. +2.6 M a + 6.14 6 +495.4 — 3.8 div. —1.9 m a — 1.44 6 +487.8 —11.4 div. —5.7 m a +27.56 6 +492.0 — 7.2 div. —3.6 m a +27.84 6 +500.8 + 1.6 div. +0.8 M a +27.36 6 +496.6 — 2.6 div. —1.3 m a — 2 96 6 +490.2 — 9.0 div. —4.5 m a + 1.75 6 +504.5 + 5.3 div. +2.6 M a + 8.28 6 +506.1 + 6 9 div. +3.5 M a +23.11 6 +506.5 + 7.3 div. +3.6m a +21.96 6 +495.7 — 3.5 div. -1.7 m a + 0.07 6 +489.5 — 9.7 div. —4.8 m a — 9.79 6 +490.7 — 2.5 div. —1.3 m a — 2.58 6 +502.8 + 3.6 div. +1.8 M a — 1.07 b +501.5 + 2.3 div. +1.1 M a — 0.11 6 +501.2 + 2.0 div. +1.0 M Normal Equations. +5942.1 = 21 a + 130.51 6 b = —34.82 —67160.4 = +130.51 a + 3800.56 6 a = +499.2 356 PROCEEDINGS OP THE AMERICAN ACADEMY EQUATIONS OF CONDITION BETWEEN METERS S AND C.S. Series II. 1883. s-c.s (t - 0°) a Ao Aa Feb. •28 + 514..3div. r= a — 0.80 b +486.5 + 1.4 div. +0.7 M ii 28 +5(J6.0 div. = a — 2..33 b +485.0 — 0.1 div. — 0.1^ it 28 +614.7 div. r=: a — 3.76 h +484.0 — 1.1 div. —0.5 m . ■ ■ .... +416.1 Apr. 1 + 0.10 —13.1 +469.6 +155,8 • > • > +408.7 " 1 + 0.06 —15.7 +474.7 + 162.0 +415.1 « 1 + 0.04 —19.9 +462 6 +155.1 +407.9 " 1 -1- 0.26 —13 7 +473.0 • • • • ■ • • • " 2 — 0.33 —13.4 +470.7 • • > • ■ ■ ■ • • • • • " 2 — 0 26 —10.8 +477.1 . . • • ■ • • • • • • • " 2 — 0.23 —15.8 +474.1 > > • • • • • • > * • ■ " 2 — 0.14 —14.8 +473.9 " 2 — 0 14 —13.7 +478 2 +150 3 +409.2 " 3 + 3.98 —15 6 +473.8 +214.6 +409.5 " 3 + 4.39 —13.4 +404,0 +218.4 +4123 " 3 + 4.63 —15.6 +408.1 +225.2 +400 8 " 3 + 5.02 —14.4 +482.8 +228,9 ■ • • • +404.8 " 8 + 1324 —12.1 +424.6 +328.2 +379.8 " 8 +12.86 —16.8 +430.1 +3324 +382.2 " 8 + 12 23 —13,4 +441.1 +326,5 • • • ■ + 887.4 " 8 + 11.99 — 13.1 +4393 + 324.0 • • • • +391.6 " 9 +10.54 — 14.6 +447.7 +310,9 ■ ■ • ■ +395.6 " 9 + 10.26 —14.8 +441.9 +299.8 +393.6 " 9 +10.23 —13.0 +414.5 +302.3 • • • • +393.7 " 10 + 6.98 — 12.6 +445.1 +249.5 +392.2 May 14 +14 68 —13.6 +435,9 +849.4 +356.4 +390.1 " 14 +14.68 —13.6 +436.3 +359.0 +346.4 +385.7 OF ARTS AND SCIENCES. 361 COMPARISON OF METERS. — Continued. Date. roi T'-. — nx Ti—C.S. T^ — R^i T"'- — /.'i"- 7'°2 —R.f2 13S3. o div. div. diT. diy. div. M.iy 1.5 +11.08 -20.4 +427.1 +3.50.4 +349.4 +380.1 " 15 + 14.(;8 — 12 9 +431.4 + 369.2 +301.7 +3820 " ItJ + 15.02 — 143 +433.0 +36i).0 +303.8 +389.4 " 17 + 11.43 —10.4 + 420.8 +350.5 +340.9 +383.3 " 17 + 1'..0J —18.2 +423.4 + 309.1 +371.8 +377.9 " 18 + 14.40 —15.9 +421.4 +304.3 +357.0 +377.0 " 19 + U54 —15.0 +424.2 + 353.8 +345 8 + 381.7 " 20 + U.33 — 18 0 +423.2 +352.7 +344.3 +383.2 " 20 + 14.1(5 — 1:!.3 +427.4 +3.52.4 + 340.0 +384.5 " 20 + U.4;) -17.0 +423.4 +363.4 +354.9 +384.9 " 21 + H.Oi —10.5 +422.5 +357.4 +347.3 +381.0 " 21 + 14.0ti —16.3 +425.9 +.357.9 +318.0 +380.5 " 22 + 14 84 — 16 6 +4206 +.363 4 +354.5 +384.7 " 23 + 14.58 —17.3 +420.3 +354.2 +314(1 +332.8 " 23 + 14.53 —10.4 +424.2 +355 3 +317 4 +33.5.6 " 24 + 11.40 —18.4 +421.6 +313.5 + 330.6 +374.5 " 21 + 14. .54 —10.8 +424.4 +318.0 +340.0 +376.8 " 24 + 14.48 —10.0 +425.4 +353 3 +344.8 +381.1 " 25 +1420 —14.6 +4.30 2 +362.2 +3.32.5 +389.3 " 25 + 14.28 —159 +427.7 +34J.O +3^2 9 +382.0 " 27 + 14 23 —18.2 +424.4 +351 >.0 +342.8 +382.4 " 27 + 14..54 —18.6 +425.0 +3547 +317.0 +3835 " 28 +n.Gi —17.7 +420.9 +3.36.2 +347.8 +3310 " 2i} + 14.70 —18.0 +424.9 +356.4 +349.1 +330.6 " 30 + 14.74 —18.3 » +428.9 +360 9 +3-37.6 +388.5 " 30 + 1484 —15.1 + 420.4 +3-34.8 +310.3 +378.7 " 31 + 14.71 — 10 8 +423 5 +854.7 +315.9 +380.2 " 31 + 14.80 —10.0 +418.0 +352.1 +343.4 + 376.0 June 1 + U.'.)2 -12.1 +427 7 +370.2 +3(;(».6 +335.6 " 1 + 15.03 —10.9 +426.0 +362.0 +3-32.2 +334.4 " 3 +10 70 —16.5 +404.8 +415.7 +409.1 +3622 + 10.15 —10 6 +400.2 +417.7 +411.1 +369.2 " 3 +13.00 —15.0 +404.8 +419.3 +412 3 +304.0 " 4 +17.70 —17.9 +411.2 +392.3 +385.4 +375.5 « 4 + 17.03 —15 6 +411.9 +397.7 +3899 +375.8 " 4 + 17.48 —14.9 +413.9 +394.9 +387.3 +374.9 " 4 + 17.49 —16 5 +410.2 +392-2 +384.0 +376.1 " 5 + 17.01 —13.5 +420.4 +393.5 +;;80.7 +332.0 " 5 + 17.13 —10.5 +4190 -1-400.2 +314.3 +382.1 " 6 + 17.09 —10.1 +420.4 +400.2 +3915 +377.7 " 7 + 17.23 —17.5 +417.4 + 400 5 +394.5 +378.5 " 7 + 17.23 —17.1 +421.7 +400.4 +393.3 +379.1 " 25 + 17.86 —17.0 +413.3 +.397.5 +389.8 +368.3 " 2fi + 17.87 —10.5 +414.4 +402.2 +394.9 +370 1 " 2ij +1804 —1.5.1 +417.6 +406.6 +399.5 +374.0 " 27 + 17.87 —13.9 +414.2 +402.9 +3P0 2 +371.7 " 27 + 17.97 —14.0 +416.4 +408.4 +400 0 +371.6 " 27 + 18.16 —16 6 +419.0 +414.1 +404.2 +377.4 " 28 +18.03 —ISO +416.0 +40.3.5 +397.0 +373.2 362 PROCEEDINGS OP THE AMERICAN ACADEMY COMPARISON OF YARDS C.S., 7?i\ R^\ AND ZZ/a WITH UNI- VERSAL COMPARATOR. (Objective = 1 inch.) (1 div. = O.UOfi = .0001732 in.) Date. yei (7.5. — TJjN c.s. — n^"^- C.5. — 7?/' 1j^83 o div. dir. div. Mar. 22 — 1.65 —331.2 • ■ ■ • — 62.7 " 23 — 2.06 —346.8 —58.4 " 23 — 0.62 —321.7 —63.6 " 23 — 0.62 —316.0 —58.1 " 25 — 0.64 —31.5.0 —61.3 " 25 -1- 1.74 -270.9 —54.7 " 26 -+- 0.03 —303.4 —62.8 " 26 + 0.85 —300.1 .... —62.0 " 26 + 1.27 —301.1 • • > • -60 0 " 28 -+■ 6.40 —208.3 —53 7 " 29 + 0.63 —303.4 • ■ • • —62.6 " 29 + 0.42 —301.5 —63.2 " 29 + 1.21 —283.8 —53.8 " 29 -1- 1.92 —278.1 -57.7 " 30 — 0.48 —315.5 —55.8 " 30 — 0.29 —315.2 —56.6 " 30 + 1.25 —284.1 —54.7 Apr. 1 + 0.10 —303.3 • • • • -52.7 1 + 0.06 —.309.6 • • • • • —62.0 1 -1- 0.04 —309.2 —59.9 " 2 — 0.14 —310.4 • • • • —60 3 3 + 3.98 —252.3 • • • • —58.0 3 + 4.39 —237.4 —57.9 " 8 + 4.03 —240.3 —52.2 " 3 + 5.02 —2.33.7 —55 2 " 8 +13.24 —105 9 .... —47.9 8 -4-12.86 —115.0 .... —51.9 8 + 12.23 —118.5 -52.1 " 8 + 11.99 —122.1 —51.2 9 + 10.54 —153.1 .... —54 8 9 + 10.26 —144.7 —46.9 9 + 10.23 —150.6 .... —47.0 " 10 + G.98 —202.4 —52.2 Mny 14 + 14.68 — 89.3 —52 4 " 15 + 14.48 — 82.7 -83.1 —52.8 " 15 + 14.68 — 81.7 —81.1 —50.8 " ]6 +15.02 — 80.0 —82.0 —478 .< 17 +14.48 — 84.6 —84.9 —50.6 " 17 +15.02 — 76.0 —77.9 —50 2 " 18 + 14.46 — 78.6 —79.7 —50 5 OP ARTS AND SCIENCES. 363 COMPAKISON OF YARDS. —Continued. Date. Y61 c.s.—n{-- C.S. — Ri'^ C.5. — ZiV» 1833. o div. div. div. May 10 14.54 —84.9 —84.3 -50.3 " 20 1 4.-33 —83.8 —85.8 — .;oi *• 20 14 46 —85.3 —87.1 — 4i).7 " 20 14.49 —86 2 —88.7 —47.5 " 21 14 6G —82.3 —83.4 —48.6 " 21 14.6G —77.4 —79.5 —48.8 " 22 14.84 —85.4 -86.6 —40.2 " 23 14.53 —78.2 —80.8 —53.8 " 23 14 53 —87.5 —89.4 — 51.7 " 24 14.46 —80.2 —87.7 —50.7 " 24 1454 —91.0 —92.4 —45.1 " 24 14.48 —88.4 —88.5 —51.2 " 25 14.26 —95.8 —97.9 —55.6 " 25 14.28 —91.1 —91.9 —52.7 " 27 14.28 —94.0 —95.0 —55 0 " 27 14.54 —84.1 —85.5 —47.2 " 28 14.64 —91.4 —93.6 —50 8 " 23 14.70 —79.7 —82.4 —49 6 " 30 14.74 —86.3 —88.0 —51.7 " 30 14.84 —83.6 -86.6 —51.8 " 31 14.74 —84.9 —85.5 —52.0 " 31 14.80 -84.1 —84.8 —51.2 June 1 14.02 —80.1 —84.5 —50.9 1 15.08 —77.2 —78.7 —46.0 3 19.70 — 4.4 — 9.4 —48 5 3 19.15 — 3.3 — 6.5 —43.7 " 3 18 63 —20.8 —23.0 —47.6 4 17.70 —36.8 —39.1 —47.8 " 4 17.69 —41.1 —42.8 —48 0 4 17.48 —41.4 —43.2 —49 9 " 4 17.49 —39.5 —40.7 —44.8 " 5 17.01 —43.5 —46.0 —48.4 5 17.13 —44.8 —45.3 —47.6 6 17.07 —48.5 —40.6 —48.3 7 17.23 —46.2 —42.5 —49.1 7 17.23 —41.3 —45.5 —48.1 " 25 17.86 —32.0 —32.0 49.1 " 26 17.87 —34.6 —35.6 —48.6 " 26 18 04 —35.0 —37.0 —48 5 " 27 17.87 —32.2 —34.0 —48.3 " 27 17.97 —29.6 —32.7 —48.7 " 27 13.16 —31.7 —30.7 —48.5 " 28 18.03 —32.1 —30.0 —49.2 364 PROCEEDINGS OP THE AMERICAN ACADEMY EQUATIONS OF CONDITION BETWEEN METRES T'- AND C.S. 6 = —3. 05 div. T'i—C.S. 188: !. T\ — C.S. (0^ - t) AtO° Act Aa Mar. 22 -4-476.5 div. = a — 1.93 b +470.6 div. —2.6 div. -1.1 /i K 23 -4-408.5 div. ~— a — 1.30 6 +476.5 div. +3.3 div. -4-1.5 ju It 25 -i-477.4 div. = a — 0.25 6 +476.6 div. +3.4 div. + 1.5 /x H 25 +400.6 div. = a + 2.27 6 +473.5 div. +0.3 div. +0.1 /X it 26 -f471.1 div. = a + 0.92 6 +473.9 div. +0.7 div. +0.3 M (( 28 -1-4G3.0 div. a + 6.40 6 +472.5 div. —0.7 div. — 0.3m II 29 -t-408.4 div. = a + 1.05 6 +471.6 div. —1.6 div. —O.lfi (, = — 3. 05 div. which is the value which has been used in obtaining the reduced values of r^ — as. 366 PROCEEDINGS OP THE AMERICAN ACADEMY EQUATIONS OF CONDITION BETWEEN METERS T'^ AND Rj'i. 6 r= +13.80 div. T^a — n^i 1883. T^" — i?,''2 (T-0°) At 0° C. Aa Aa Mar. 22 + 12G.1 div. = a — 1.93 6 + 152.7 div. -3 0 div. —1.3 m <( 23 + 143 3 div. =^ a — 1.30 6 +161.2 div. +5.5 div. +2.4 m it 25 + 154.0 div. ■= a — 0 25 6 + 157.5 div. +1.8 div. +0.8 M << 25 + 178.Gdiv. = a + 2.27 6 +147.3 div. —8.4 div. —3.7 m a 2G + 1G3.1 div. = a + 0.92 6 +150.4 div. —5.3 div. —2.3 m (C 28 +248.3 div. = a + 6.40 6 +160.0 div. +4.3 div. H-1.9m it 29 +lG6.2div. = a + 1.05 6 + 151.7 div. —4.0 div. —1.8m it 30 + 149.2 div. = a — 0.38 6 + 154.4 div. —1.3 div. —0.6 M t( 30 + 179.7 div. := a + 1.25 6 + lC2.4div. +6.7 div. +■2.9 M April 1 +157.0 div. = a + 0.07 6 +156.Gdiv. +0.9 div. +0.4 M 2 +150.3 div. = a — 0.14 6 +152 2 div. —3.5 div. —1.5 m O +221.8 div. = a + 4.51 6 +159.Gdiv. +3.9 div. +1.7 M 8 +327.7 div. = a +12.58 6 +154.1 div. —1.6 div. —0.7 m 9 +304.3 div. = a +10.34 6 +161.6 div. +5 9 div. +2.6 M 10 +249.5 div. = a + 6.98 6 +153.2 div. —2.5 div. -1.1m At 1G°.C7 May 14 +354.2 div. — a + 14.68 6 +381.6 div. —5 3 div. -2.3 m a 15 +362.8 div. = a +14.58 6 +391.6 div. +4.7 div. +•2.1 M it 16 +369.6 div. = a +15.02 6 +.392.4 div. +5.5 div. +2.4 M it 17 +362.8 div. z= a + 14.75 6 +,389.3 div. +2 4 div. +1.1 M u 18 +364.3 div. = a +14.46 6 +394.8 div. +7.9 div. +3.5 M (( 19 +353.8 div. — a +14.54 6 +383 2 div. —3.7 div. — 1.6m ti 20 +350.2 div. r= a +14.43 6 +387.1 div. +0.2 div. +0.5 M It 21 +357.6 div. = a +14.66 6 +38-5.4 div. —1.5 div. —0.7 m (C 22 +363.4 div. = a +14 84 6 +388.6 div. +1.7 div. +0.7 M a 23 +354.8 div. =r a +14.58 6 +383.6 div. —3.3 div. —1.5 m tt 24 +348.5 div. a +14.49 6 +.378.6 div. —8.3 div. -3.7 m (S 25 +355.9 div. a +14.27 6 +389.0 div. +2.1 div. +0.9 M a 27 +352.7 div. =T a + 14.416 +383.9 div. —3.0 div. —1.3m tt 28 +356.2 div. = a +14.64 6 +384.2 div. —2.7 div. -1.2 M « 29 +356.4 div. = a +14.76 6 +382.8 div. —4.1 div. —1.8m May 30 +360.8 div. a +14.79 6 +.386.7 div. —0.2 div. —0.1m t( 31 +.353.4 div. ^= a +14.80 6 +379.2 div. — 7.7 div. —3.4 m June 1 +.360.1 div. = a +14.99 6 +389.3 div. +2 4 div. +1.1 M It 3 +417.6 div. = a +19.18 6 +383.0 div. —3.9 div. -1.7 m tt 4 +394.3 div. a +17.59 6 +381.6 div. — 5 3 div. —2.3 m OF A.RTS AND SCIENCES. 367 rs — i?i»» 18S3. r»3 - 7?,"^ (T-0°) At 16°. 67 A(z Aa June 5 -f39G.8 div. = a +17.07 6 +801.3 div. +4.4 div. +1.9 M « G +400.2 div. = a +17.07 6 +394.7 div. + 7.8 div. +3.4 /x it 7 +400.4 div. = a +17.23 6 +392.7 div. +5.8 div. +2.Gm t< 25 +307.5 div. = a +17.86 6 +381.1 div. —5.8 div. —2.6 IX €t 26 +404.2 div. = a +17.87 6 +387.6 div. +0.7 div. +0.3 yu « 26 +406.6 div. = a +18.04 6 +387.6 div. +0.7 div. +0.3 /x i< 27 +402.9 div. = a +17.87 6 +386.3 div. — O.G div. — 0.3/x it 27 +408.4 div. = a +17.97 6 +390.4 div. +3.5 div. +1.5^ <( 27 +414.1 div. = a +18.16 6 +394.0 div. +7.1 div. +3.1 M (( 28 +405.5 div. = a +18.03 6 +386.7 div. —0.2 div. —0.1/M Normal Equations. +11378.5 = + 38 a + 394.2 6 6 = +13.80 +141584.9 = +394.2 a + 5810.56 a = +156.2 EQUATIONS OF CONDITION BETWEEN METERS T'^ AND R/^. -2.29 div. T'2—Ii,^^ 1883. TH — i?2»2 (r - 0°) AtO°cf Aa Aa Mar. 22 +419.6 div. = a — 1.93 6 +415.2 div. —0.4 div. —0.2 m ft 23 +425.6 div. =: a — 1.30 6 +422.6 div. +7.0 div. +3.1 M (( 25 +423.1 div. = a — 0.25 6 +422.4 div. +6.8 div. +3.0 /i ti 25 +408.1 div. = a + 2.27 6 +413.3 div. —2.3 div. — 1.0/i « 26 +412.4 div. = a + 0.92 6 +414.5 div. —1.1 div. —0.5 fi (1 28 +404.7 div. a + 6.40 6 +419.4 div. +3.8 div. +1.7m u 29 +410.7 div. = a + 1.05 6 +413.1 div. —2.5 div. -1.1m « 30 +417.2 div. = a — 0.38 6 +416.3 div. +0.7 div. +0.3 M (( 30 +416.1 div. = a + 1.25 6 +419.0 div. +3.4 div. +1.5m Apr . 1 +410.6 div. = a + 0.07 6 +410.7 div. —4.9 div. —2.2 m <( 2 +409.2 div. a — 0.14 6 +408.9 div. —6.7 div. —2.9 m « 8 +408.4 div. = a + 4.51 6 +418.8 div. +3.2 div. +1.4m it 8 +385.2 div. = a +12.58 6 +414.0 div. —1.6 div. —0.7 m ti 9 +394.3 div. = a +10.34 6 +418.0 div. +2.4 div. +1.1 M « 10 +392.2 div. a + 6.98 6 +408.3 div. At 16°.67 — 7.3 div. -;3.2m May 14 +387.9 div. = a +14.68 6 +383.3 div. +6.9 div. +3.0m « 15 +384.1 div. = a +14.58 6 +379.3 div. +2.9 div. +1.3 M « 16 +389.4 div. = a +15.02 6 +385.6 div. +9.2 div. +4.0 m « 17 +380.6 div. = a +14.75 6 +376.2 div. —0.2 div. —0.1m (1 18 +377.0 div. = a +14.46 6 +371.9 div. —4.5 div. —2.0 m 368 PROCEEDINGS OP THE AMERICAN ACADEMY yag /?.,*2 188? !. T^i — i?2»S (T-0°) At 16°. 67 Aa Aa May 19 +381.7 div. = a +14.54 b +376.8 div. +0.4 div. +0.2/* (< 20 +384.2 div. = a +14.43 b +379.0 div. +2.6 div. +1.1 M (( 21 + 380.7 div. — a +14.66 6 +376.1 div. —0.3 div. — 0.1/t cc 22 +384.7 div. = a +14.84 b +380.5 div. +4.1 div. +1.8 M It 23 +384.2 div. ^= a +14.58 6 +379.4 div. +3.0 div. +1.3 M « 24 +377.5 div. — a +14.49 b +372.5 div. —3.9 div. -1.7 m (( 25 +385.7 div. :^ a +14.27 b +380.2 div. +3.8 div. +1.7 M (( 27 +382.9 div. = a +14.41 b +377.7 div. +1.3 div. +0.6 M <( 28 +881.6 div. = a +14.64 6 +376.9 div. +0.5 div. +0.2 M (C 29 +380.6 div. = a +14.76 6 +376.2 div. —0.2 div. —0.1(1 <( 30 +383.1 div. a +14.79 6 +378.8 div. +2.4 div. +1.1 M (C 31 +378.4 div. = a +14.80 6 +374.1 div. —2.3 div. —1.0 m June 1 +385.0 div. =: a +14.99 6 +381.1 div. +4.7 div. +2.1 M « 3 +365.1 div. = a +19.18 6 +870.9 div. — 5. 5 div. —2.4 m a 4 +375.6 div. = a +17.59 6 +377.7 div. +1.3 div. +0.6 M June : 5 +382.0 div. a +17.07 6 +382.9 div. +6.5 div. +2.9 M « 6 +377.7 div. = a +17.07 6 +378.0 div. +2 2 div. +1.0 M <( 7 +378.0 div. =: a +17.23 6 +379.3 div. +2.9 div. + 1.3m (f 25 +368.3 div. = a +17.86 6 +371.1 div. —5.3 div. -2.3 m <( 26 +370.1 div. = a +17.87 6 +373.9 div. —2.5 div. -1.1m <( 26 +374.0 div. a +18.04 6 +370.9 div. — 5.5 div. —2.4 m (£ 27 +371.7 div. = a +17.87 6 +369.0 div. —7.4 div. —3.3 M C( 27 +371.7 div. == a +17.97 6 +368.7 div. — 7. 7 div. —3.4 m « 27 +377.4 div. a +18.16 6 +374.0 div. —2.4 div. -1.1m « 28 +373.2 div. = a +18.03 6 +370.1 div. —6.3 div. —2.8 m Normal Equations. +14905.1= +38a+ 394.26 6 = —2.29 = -1,01m +150711.1 = +394.2a + 5810.5 6 a = +433.6 = +190.8 m EQUATIONS OF CONDITION BETWEEN YARDS C. S. AND K^V b = +15.57 div. C.-S. -/?i^2 1883. as. — i?i»* (t-O^) AtO°C. Aa Aa Mar. 22 —331.2 div. = a — 1.93 6 —301.7 div. —6.8 div. —3.0 m " 23 828.4 div. = a — 1.30 6 308.2 div. —0.3 div. —0.1m " 25 —315 0 div. T=Z a — 0 64 6 —305.0 div. —3.5 div. — 7.5 M " 25 —279.9 div. a + 1.716 —307.0 div. —1.5 div. —0.7 m " 26 —301.5 div. = a + 0.92 6 —315.8 div. +7.3 div. +3.2 M OF ' ARTS AND SCIENCES. 369 r..s. — i?i"2 18S3. C.S. - lii^ (T-0°) At 0== C. Ao Aa Mar. ,28 —208.3 div. = 0 + 6.40 ^* —307.9 div. —0.6 div. —0.3 n it 29 —291.7 div. == a + 1.05 6 — 3US.0 div. — 0.5 div. —0.2fji t( 80 —315.2 div. = a — 0.38 b —309.4 div. +0.9 div. +0.4 M it 30 —284.1 div. z= a + 1.25 6 —303.6 div. —4.9 div. -2.2 m Apr. 1 —307.4 div. = a + 0.07 6 —308.5 div. 0.0 div. 0.0 M <( 2 —310.4 div. — a — 0.14 6 —308.2 div. —0.3 div. — 0.1/x (( 3 —241.1 div. = a + 4.51 6 —311.3 div. +2.8 div. +1.2m it 8 —115.4 div. = a +12.58 6 —311.3 div. +2.8 div. +1.2m it 9 —149.5 div. = a +10.34 6 —310.5 div. +2.0div. +0.9 M n 10 —202.4 div. a + 6.98 6 —311.1 div. At 160.67 +2.6 div. +1.1 M May 14 — 80.3 div. = a +14.68 6 — 58.3 div. —5.6 div. -2.5 m <{ 15 — 82.2 div. = a +14.58 6 — 49.7 div. +3.0 div. + 1.3m tt 16 — 80.0 div. = a +15.026 — 54.3 div. —1.6 div. — 0.7m t( 17 — 80.4 div. = a + 14.75 6 — 50.5 div. +2.2 div. +1.0 M tt 18 — 78.6 div. = a +14.46 6 — 44.2 div. +8.5 div. +3.7 M tt 19 — 84.9 div. — a +14.54 6 — 51.7 div. +1.0 div. +0.4 M tt 20 — 85.1 div. = a +14.43 6 — 50.2 div. +2.5 div. +1.1 M tt 21 — 79.9 div. = a +14.66 6 — 48.6 div. +4.1 div. + 1.8 M tt 22 — 85.4 div. = a +14 84 6 — 56.9 div. —4.2 div. —1.8 m tt 23 — 82.8 div. = a +14.58 6 — 50.3 div. +2.4 div. +1.1 M tt 24 — 88.3 div. = a +14.49 6 — 54.4 div. —1.7 div. —0.7 m tt 25 — 93.4 div. = a +14.27 6 — 56.0 div. —3.3 div. — 1.5m tt 27 — 89.0 div. = a +14.416 — 53.8 div. —1.1 div. —0.5 M tt 28 — 91.4 div. = a +14.64 6 — 59.8 div. —7.1 div. —3.4 m tt 29 — 79.7 div. = a +14.76 6 — 50.0 div. +2.7 div. +1.2 M tt 30 — 85.0 div. — a +14.79 6 — 55.7 div. —3.0 div. -1.3 m tt 31 — 84 5 div. = a +14.S0 6 — 55.4 div. —2.7 div. -1.2 m June 1 — 78.7 div. = a +14.99 6 - 52 5 div. +0.2 div. +0.1 M tt 3 — 9.5 div. = a +19.18 6 — 48.6 div. +4.1 div. +1.8m it 4 — 39.7div. = a +17.59 6 — 54.0 div. —1.3 div. —0.6 m June 5 — 44.1 div. — ■ a +17.07 6 — 50.4 div. +2.3 div. +10m «< 6 — 48.5 div. =: a +17.07 b — 54.8 div. —2.1 div. —0.9 m tt 7 — 43.7 div. = a + 17.23 6 — 52.4 div. +0.3 div. +0.1 M tt 25 —^32.0 div. z=z a +17.86 6 — 50.5 div. +2.2 div. +1.0 M tt 26 —'34 6 div. = a +17.87 6 — 53.3 div. —0.6 div. —0.3 M tt 26 — 35.0 div. — a +18.04 6 — 56.3 div. —3.6 div. — 1.6m tt 27 — .32.2 div. = a +17.87 6 — 50.9 div. +1.8 div. +0 8m tt 27 — 29.6 div. = a +17.97 6 — 49.8 div. +2.9 div. +1.3 M tt 27 — 31.7 div. =r a +18.16 6 — 54.9 div. —2.2 div. —1.0 m tt 28 VOL. — 32.1 div. XVIII. (\. s. X.) a +18.03 6 24 — 53.3 div. -0.6div. —0.3 m 370 PROCEEDINGS OF THE AMERICAN ACADEMY Normal Equations. —5685.7= +38(3+ S94.2i i = +15.53 = +6.83;* —32302.0 = +394.2 a + 5807.1 6 a = —310.7 = —136.7 /t This value of h reduced to the equivalent for one meter becomes 7.48 /x. But from T—C.S. & = — 3.29div. r— i?i fe = -f-13.80div. Whence from C.S. — R^. * = +1 7.09 = +7.52 /* We have, therefore, for 1 meter, h = +^-^"'' + ^-^-'' = +7.50 ^ = +17.04 div. For 1 yard, h = +6-8-V + 6.87^ ^ +6.85;x =+15.57 div. EQUATIONS OF CONDITION BETWEEN YARDS C. S. AND 7?/s. 6 = +€.69 div. C.S. - 7?2='s 188S C.S. — li^H (t-0^) At 0° C. Aa ACI Mar. 22 —62.7 div. t=: a — 1.93 6 — Ol.Sdiv. +8.0 div. +1.3 /i " 23 — 60.0div. = a — 1.306 —59.1 div. +0.8 div. +0.4 yU « 25 —61.3 div. = a — 0.64 b —60.9 div. +2.6 div. + 1.1 iU " 25 —54.7 div. = a + 1.746 —55.9 div. —2.4 div. -1.1 /x « 26 —61.6 div. = a + 0.92 6 —62.2 div. +3.9 div. +1.7m " 28 —53.7 div. a + 6.406 —58.1 div. —0.2 div. — O.lju " 29 —59.3 div. = a + 1.056 —54.6 div. —3.7 div. —1.6m •' 30 —56.2 div. := a — 0.386 —55.9 div. —2.4 div. -1.1m " 30 —54.7 div. = a + 1.256 —55.6 div. —2.7 div. -1.2m Apr. 1 —58.2 div. = a + 0.07 6 —58.2 div. —0.1 div. —0.0 m " 2 —60.3 div. a — 0.146 —60.2 div. +1.9 div. +0.8 M •' 3 55.8 div. =: a + 4.51 6 —59.0 div. +0.7 div. +0.3 M " 8 —50.8 div. = a +12.586 —59.5 div. +1.2 div. +0.5m " 9 —49.6 div. = a +10.346 —56.7 div. —1.6 div. —0.7 m " 10 —52.2 div. ■"■^ a + 6.986 —57.0 div. At 16°.67 —1.3 div. —0.6 m May 14 —52.4 div. = a +14.686 —51.0 div. —1.9 div. — 0.8/i " 15 —51.8 div. = a +14.58 6 —50.4 div. —1.3 div. —0.6 m « 16 —47.8 div. = a +1.5.026 —46.7 div. +2.4 div. +1.1 M " 17 50.4 div. = a +14.756 —49.1 div. 0.0 div. 0.0 m '•• 18 —50.5 div. a +14.466 —49.0 div. +0.1 div. 0.0 M OP ARTS AND SCIENCES. 371 C.S. - /?,»* 1883. C.S. — 2?2°s (t - 0°) At 16.°67 Aa Aa May 19 —50.3 div. — a 4-14.54 & —48.8 div. +0.3 div. +0.1/4 i( 20 —49.1 div. = a +14.43 6 — 47.5 div. + 1.6 div. +0.7 /i « 21 —48.7 div. == a +14 666 —47.3 div. + 1.8 div. +0.8 iu (( 22 —49.2 div. = a +14.846 —47.9 div. +12 div. +0.5 /t (t 23 —52.8 div. = a +14.586 —51.3 div. —2.2 div. — l.Oju « 24 —49.0 div. —^ a +14.496 —47.5 div. +1.6 div. +0.7 M cc 25 —54.1 div. = a +14.27 6 —52.4 div. -3.3 div. — 1.5/t (( 27 —51.1 div. = a +14.416 —49.5 div. —0.4 div. — 0.2/t (( 28 —50.8 div. z= a + 14646 —49.4 div. —0.3 div. —O.l/j. (( 29 —49.6 div. = a +14.76 6 —48.3 div. +0.8 div. +0.4 /* <( 30 —51.7 div. — a +14.796 —50.5 div. —1.4 div. —0.6/1 (( 31 —51.6 div. = a + 14.806 —50.4 div. —1.3 div. — 0.6/t June 1 1 48.4 div. = a +14.99 6 47.3 div. +1.8 div. +0.8 /t t( 3 —46.6 div. = a +19.186 —48.3 div. +0.8 div. +0.4/1 (( 4 —47.8 div. z=: a +17.596 —48.4 div. +0.7 div. +0.3 /t (t 6 —48.0 div. a +17.07 6 —48.3 div. +0.8 div. +0.4 /i « 6 48.3 div. a +17.07 6 —48.6 div. +0.5 div. +0.2/* FROM THE NORMAL VALUES FOR 0° AND 1G°.G7. For the temperatures (t — 0°) the reductions to 0° have been made with the values of b derived from the normal equations. The value assumed for (16°.67 — r) is written at the head of the column. Bar T. b = : +32.18 div. Date. (t-0°) 5— T"! Means by Groups. Date. (16°.67— t) S—T^i IVIeaus by Groups. 1883. o div. div. 1883. 0 div. div. Feb. 7 +1.7(5 +60.7 Feb. 11 +3.20 —476.9 " 7 +3.83 +57.8 " 19 -7.86 —480.4 " 7 +7.60 +59.6 " 25 +9.09 —473,2 " 8 —4.30 +65.1 " 25 +8.36 —469.6 " 8 +1.46 +53.8 +59.4 " 26 —5.70 —475.6 —475.1 " 9 -4.54 +61.3 Mar. 3 —2.66 —476.8 " 12 +1.78 +61.4 Apr. 15 —2.74 —472.6 " 12 —2.96 +59.5 " 17 +4.42 474.9 " 12 —0.79 +59.0 " 18 +7.53 —472.9 " 13 +1.69 +62.2 +60.7 " 19 +8.03 —474.6 —474.4 " 13 +0.12 +60 8 " 20 —1.29 —475.3 " 13 +3.26 +05.2 " 24 —3.80 —471.6 " 14 —6.50 + 56 5 " 25 —3.37 -478.4 " 1.5 +5.82 +57.5 " 26 —4.59 —474 7 " 16 +0.78 +61.0 +00.2 " 27 +7.65 —475.8 —475.2 378 PROCEEDINGS OF THE AMERICAN ACADEMY Bar T. — Continued. Date. 1883. Feb 20 " 25 " 27 " 27 " 28 " 28 " 28 Mar. 1 " 4 " 5 " 5 Apr. 22 " 23 " 24 " 25 (r-0°) o —1.92 +2.96 — G.71 +2.01 —3.47 —0.22 —0.71 +3.64 —0.35 —4.38 —1.18 +4.57 +5.97 +0.02 + 5.67 S— T" div. +57.0 +63.0 +63.1 +61.5 +63.1 +63.0 +63.5 +02.1 +59.2 +60.7 +65.6 +59.9 +60.9 +50.5 +60.1 Means by Groups. div. +61.5 +62.9 +61.2 Date. 1883. Apr. 27 " 28 " 29 " 29 " 30 " 30 May 1 " 1 " 2 " 4 « 4 " 4 " 6 " 7 " 8 16°67- +0.30 —1.87 +1.32 +0.66 +0.79 —1.09 —1.01 +0.11 +7.05 —1.40 —1.40 —3.45 +0.20 +8.75 +3.80 S—T" Means by Groups. div. —475 3 —473.9 —473.1 —475.1 —474.4 —475.0 —472.5 —476.4 —4751 —467.4 —469.9 —470.8 —472.2 —476.8 —473.6 div. —474.4 —472.7 Bar as. b = +34.63 div. 1883. Feb 12 —6.14 (i 12 —1.15 t( 13 +4.69 ti 13 —7.76 (i 14 —4.87 ic 15 +6.14 (( 16 —1.44 (C 20 —2.96 a 25 +1.75 tc 27 +0.67 (( 28 —2.58 i( 28 —1.07 ti 28 —0.11 t( 28 —0.80 a 28 —2.33 (( 28 —3.70 if 28 +3.13 Mar . 1 +5 65 (( 4 —8.00 i( 4 —4.40 (( 4 —0.89 (f 19 +0.70 Apr 22 +4.07 it 23 + 5.79 it 23 +5.88 it 24 +5.77 it 25 +2.23 j. S—R, T— as. T—R, C. S. — xs„ b b b b b b +16.18/i +17.59/. +17.04/* +1.41/X +0.86/X — 0.55 /* Combining these values with the relative values found from the observations with the universal comparator, we have finally the fol- lowing values for the absolute coefficients : — 380 PROCEEDINGS OF THE AMERICAN ACADEMY standards. Coefif. for 1 Meter. Coefif. for 1 Yuri. T —16.18^ — 14.80 M as. 17.59+17.61 ^^_g^^ 16.09//, R, 10.08+lO.U ^^_^^^ 9.24 /x R, 17, .21 + 17.27+17.01 17.17, 15.70 /A "We are now prepared to place side by side the relations obtained from the comparison of T, C. S., and R.^ with the standard S in melt- ing ice, and the values found by direct comparisons upon the universal comparator. The constant reduction from T^'i to T^^ = 6.9 fi is first applied to the observed values S — T, S — C. S., and S — R.^. 3Ieters. From Comparisons upon the Universal From Comparisons with Bars in Melt- Comparator, iug Ice. At 0° C. Wt. At 160.67 C. Wt. At 0° C. Wt. At 160.67 Wt. 2^a, - c.s. +208.2 /A 4 + 184.4 M 4 +208.7, 1 +185.3, 1 7-2. -R,^^ + 68.4 M 4 +170.2, 4 • • • • • • ■ • • , 2^12 . — R2"- -4-182.9 M 4 +165.G , 4 +179.0, 1 +164.9, 1 as. — R{^ — 139.7 /i 4 — 14.1, 4 • ■ > ■ • • ■ • • , as. — R2' — 25.3 /t 4 — 18.7, 4 — 22.8, 1 — 13.5, 1 Z?!"!- -Rp +lUAju 4 — 4.6, 4 • • • • Adopted Relations for the Meter. At 0° C. At 16^67 C. T^i _ c. S. = +208 .3, = +181.G, y "2 7^ !'2 + C8.4, +170.2, T'a — /?2"2 +182 .1, + 165.5, c. s. — Rj!^ —139 .7, — 14.1, C. S. — Rp — 24 8, — 17.7, Hl"^ — li-I' +114.4, — 4.6, Adopted Relations for the Yard. At 0° C. At 16°.67 C. C. S. — 2?i% = —135.7 , = —23.2 , c. S. — /?/2 = — 25.6 , = —21.6 , i?l'2 — i?/2 ^+110.1, = + 1.6, We have now the data for the direct comparison of the independent prototypes T and C. S. of the Metre des Archives, both at 0° and at 16°. 67. Representing the Metre des Archives by A, we have: According to Trcsca. According to Pernet. T\ — 118.9, = ^ at 13°.70 C. C.S. -\- 310.0, = J at 0° C. OP ARTS AND SCIENCES. 381 With the determined coefficients 16.18/x and 17.00/:* for T and C. S. respectively, we have AtO°C. r"2-|- 102.8/x = ^ But at 0° C. 5. + 310.0^ = ^ Hence T«= — CS=. -f 207.2 /x From observation T''^ — C.S.= +208.3 /* DiflP. = 1.1 /x Atl6°.67, ^"2— 167.0 ;x = ^ as. -\- 16.6 fi = A Hence T^2 — C S. = +183.6 ;* From observation T^*^- — C. S. = +184.6 /x Diff. = l.Ofi We have therefore an agreement which is quite as close as one ought to expect. For the yard we have, from observations at Washington, At 16°.67, i?2 + 1.22 iM = Y= Imperial Yard. From the Eeport of Mr. Chaney, a s. + 20.68 /i = r Hence C. S. — i?2«2 = — 19.5 ^ From observation C S. — i?^"^ = — 21.6 /x Diff. = 2.1 /x Here again the agreement is extraordinarily close. It may be assumed, therefore, that the meters T and C. S. represent the Metre des Archives within the limits of the ordinary errors of observation. The agreement, also, of the yard C. S. by direct comparison with the Imperial Yard with the relation established through " Bronze 11," in- dicates that both of these standards represent the Imperial Yard when the determined corrections are applied. In the determination of the length of the meters and yards i?j"i and R,"^ it will be assumed that T and C. S., with the determined corrections, represent the original standards with equal weight. 382 PROCEEDINGS OF TUE AMERICAN ACADEMY We have, therefore, At 0° 0. Th — A = —102.8 ^ But T", _ 7?^"= = _L 68.4 /x T"2 — i?/2 = -f 182.1 /* Whence i?^°2 — ^ = —171.2 /x Rf2 — A = —284.9 /i Also a S. — A = —310.0 ,1 But a S. — R,"^ = —1S9. 7 iJL C. S. — E,"2 = — 24.8 /i Whence i?^«2 — ^ = —170.3 fi i?2«2 — ^ = —285.2 /x At 16°.6- C. T"> — A = -\-lG7.0iJi But T^, — i?^«. :z= -{-170.2 fi Whence ^^«2 — ^ =z —3.2 ^ Also C.S. — A = —16.6 But C. ^S. — Rj"2 = —14.1 /i a S. — R.^2 = —17.7 IX Whence E,\_ — A = —2.5 fx i?/2 — ^ = -j-l.l fX We have therefore, finally, by combination, At 0° C. i2i«2 + 170.7 [A = A i?2«2 + 285.1 11 = A At 160.67 C. i2i«2 + 2.8 |x =- A i22«2 — 1.3 1* = A It will be observed that the relation for ^^,"2 for 16°. 67 is nearly identical with that determined in 1880 and 1881. For the yard we have the following final results. According to Rogers -|- Smith 2 Chaney From observations Whence i?,/2 — Y =z— 1.2ix as. — Y = —20.7 IX a^. — i2,^ = — 21.6 B.^^. — T =4-0.9 OF ARTS AND SCIENCES. 383 And finally, At 160.67 C. or. R,^'- + 0.2 ii i?2"= 4- .000008 in. For R^'^ we have, since or. R^'- _ .000056 in. Y T :+1.6/* Y Y COMPARISON OF METERS R^'-, G^'^, AND (7/2, WITH UNIVERSAL COMPARATOR. Date. 1883. (Objective = 1 inch. 1 div. = .440 yti.) Equations of Condition. Jan. 9 " 9 " 10 " 11 " 12 " 12 " 12 " 12 7?,>2 — Gi'3 — 15. 7 div. —14.6 div. —48.9 div. —35.2 div. —66.0 div. —51.6 div. —53.0 div. —49.9 div. " 14 +20.4 div. " 19 +32.7 div. " 21 +18.1 div. Jan. 14 +33.4 div. " 15 +31.4 div. " 17 +48.7 div. " 17 +57.6 div. " 17 +56 .3 div. " 18 +38.3 div. " 18 +51.0 div. July 6 +51.0 div. " 8 +66.1 div. " 8 +02.6 div. " 9 +56.5 div. " 9 +56.5 div. At 0° C. b = +4.5 div. jr?i»2 — G/2 (t — 0)° i?i*2 ■ — 4.6 div. = a +8.506 (—53.9) div. (—42.8) div. —15.1 div. = a +6.046 (—41.9) div. (—42.4) div. —46.9 div. = a —4.046 —30.7 div. —28.7 div. —29.0 div. = a —1.386 —29.0 div. —22.8 div. —62.9 div. = a —7.666 —31.5 div. —28.4 div. —51.2 div. = a —7.706 (—16.0) div. (—15.6) div. —58.4 div. = a —7.566 (—19.0) div. —24.4 div. —48.2 div. = a —4.536 —29.5 div. —27.8 div. +17.6 div. = a +11.786 —32.6 div. —35.4 div. +33.2 div. = a +13.826 —29.5 div. —29.0 div. +21.4 div. = a +11.856 —35.2 div. —31.9 div. At 16°.67 C. +35.5 div. +26.5 div. +58.9 div. +65.7 div. +66.4 div. +43.9 div. +52.3 div. +54.0 div. +72.9 div. +70.5 div. +66.1 div. +63.9 div. a +15.776 a +14.446 a +21.116 a +20.926 a +20.586 a +14.86 a +18.92 a +18.48 a +21.72 a +20.78 a +20.25 a +19.95 +37.4 div. +41.4 div. (+28.7) div. +38.5 div. +38.9 div. +46.4 div. +40.9 div. +42.9 div. +43.4 div. +44.1 div. +40.4 div. +41.7 div. +39.5 div. +36.5 div. +38.9 div. +46.6 div. +48.8 div. +52,0 div. +42.2 div. +45.9 div. +50.2 div. +52.0 div. +50.0 div. +49.1 div. 384 PEOCEEDINGS OF THE AMERICAN ACADEMY Date. 1883. i?i'2 — G^^ July 10 +53.6 div. " 10 +55.1 div. " 11 +58.3 div. " 11 +54.6 div. " 12 +54.0 div. " 12 +59.5 div. " 13 +53.7 div. " 13 +53.4 div. 7?1»2 — G2»2 +55.9 div. = +69.4 div. = +63.1 div. = +56.1 div. = +61.2 div. = +62.8 div. = +63.5 div. = +61.8 div. = At 16^.67 C. (t — 0)° i?i='2 — G^H HiH — Gj^ a +19.53 a +19.49 a +19.11 a +19.13 a +19.20 a +19.07 a +19.08 a +19.08 +40.7 div. +42.4 div. +47.3 div. +43.5 div. +42.6 div. +48.7 div. +42.9 div. +42.6 div. +43.0 div. +56.7 div. +52.1 div. +45.0 div. +49.8 div. +52.0 div. +52.7 div. +51.0 div. Normal Equations. For i?i»2 — Gj'i For J?i»2 — G^^i +788.1 = 31 a + 400.6 b +926.3 = 31 a + 400.6 6 +22821.6 = 400.6 a + 8141,3 b +25256.0 = 400.6 a + 8141.3 b b = —4.27 b = —4.48 a = —29.8 a = —28.0 COMPARISON OF YARDS 7?i^ G,'^, AND G/^ WITH UNIVERSAL COMPARATOR. Date. 1883. i?l«2 — Gi»2 Equatiom i?l'2 - (?2»2 > of Condition. (T - or At 0° C. b = +4.1 /?,»2 — Gi'a ^"2 — GjH Jan. , 9 —13.2 div. —10.0 = a + 8.50 h ( 48.0) div. (—44.8) div. <( 9 —19.9 div. — 8.7 — a + 6.04 6 (—44.7) div. —33.5 div. (( 10 —42.8 div. 318 = a — 4.04 h —26.2 div. (—15.2) div. « 11 —26.2 div. —30.8 =z a — 1.38 h —20.5 div. —25.1 div. « 12 —64.9 div. —66.7 = a — 7.66 b —33.8 div. —35.3 div. (( 12 —59.7 div. -61.5 = a — 7.70 6 —28.1 div. —29.9 div. (( 12 —61.4 div. —65.3 = a — 7.56 6 —30.4 div. —34.3 div. « 12 —43.9 div. —37.3 — a — 4.53 6 —25.3 div. —18.7 div. (( 14 +1.3.2 div. + 8.0 = a +11.78 6 —35.1 div. —40.3 iliv. ti 19 +27.2 div. +29.3 =: a +13.82 6 —29.5 div. —27.4 div. <( 21 +20.0 div. +23.6 = a +11.85 6 —28.6 div. —25.0 div. At 16°.67 C. « 14 +29.6 div. +28.8 = a +15.77 6 +.33.3 div. +32.5 div. t( 15 +34.1 div. +.32.5 = a +14.44 6 +43.2 div. +41.6 div. t( 17 +46.4 div. +50.6 = a +21.116 (+28.2) div. +41.4 div. t( 17 +56.2 div. +57.4 = a +20.92 6 +38.8 div. +40.0 div. (C 17 +53.0 div. +55.3 = a +20..586 +37.0 div. +39.3 div. C( 18 +38.0 div. +32.9 = a +14.86 6 +45.4 div. +40.3 div. « 18 +47.2 div. +52.4 = a +18.926 +38.0 div. +43.2 div. July 6 +48.0 div. +49.0 = a +18.48 6 +40.6 div. +41.6 div. it 8 +65.4 div. +64.1 z= a +21.72 6 +44.7 div. +43.4 div. ft 8 +56.0 div. +60.9 =: a +20.78 6 +39.1 div. +44.0 div. OF AETS AND SCIENCES. S85 Date. At 16°.6T C. 1883. i?!^ - G,^i i?l«2 — f?2'2 (T-0)° J?,»2 — GjOj 7?,»2 — fi^2«2 July 9 +50.3 div. +56.2 = a +20.25 6 +41.6 div. +41.5 d'iv. " 9 +55.7 div. +53.4 = a +19.95 6 +42.3 div. +39.9 div. " 10 +61.0 div. +60.8 = a +19.53 6 +49.3 div. +49-1 div. " 10 +51.3 div. +51.3 = a +10.41 b +39.7 div. +39.7 div. " 11 +54.7 div. +56.1 = a +19.116 +44.7 div. +46.1 div. " 11 +58.7 div. +52.0 = a +19.13 6 +48.6 div. +41.9 div. " 12 +50.2 div. +51.8 = a +19.20 6 +.39.8 div. +41.4 div. " 12 +53.5 div. +54.3 = a +19.07 h +43.7 div. +44.5 div. " 13 +51.5 div. +52.2 = a -f 19.08 6 +41.6 div. +42.3 div. " 13 +54.1 div. +50.8 = a +19.08 6 +44.2 div. +40.9 div. Nermal Equations. For J?,"! — G 1^2 For i?j»2 — Gj»2 +739.3 = 31 a + 400.6 6 +780.6 = 31 a + 400.6 6 +22148.0 = 400.6 a + 8141.3 6 +22476.3 =. 400.6 a + 8141.35 b = +4.25 6 = +4.18 a = —31.1 a = —28.8 The two values of h for the yard when reduced to the equivalent for one meter become 4.66 div. and 4.57 div. respectively. The meau value of J, therefore, derived from these equations, is 4.49 div. for one meter, or 4.10 div. for one yard. Substituting these values in the equations, we find a few values of a which differ from the mean value more than four times the probable error of a single value. In the formation of the mean values for 0° and for 16°. 67 these quantities have been rejected. For the meter, we have AtOO R^-— G'l'*'^— Sl.ldiv. R,^' G.f = —28.6 div. For the yard, we have Rf _ C,"' = _28.6 div. Bf _ Gf = —29.9 div. At 16°. 67 +42.3 div. +47.7 div. Mean +41.9 div. +41.7 div. Mean h = +4.40 div. b = +4.58 div. . +4.49 div. h = +4.23 div. b= +4.30 div. . +4.26 div. We have, therefore, finally, _ , ^ 7 4.49 div. + 4.65 div. , a "rr j- o ni For 1 meter, b = ^^ = +4.o7 div. =: 2.01 /x,. „ , , . 4.11 div. + 4.26 div. ' ,iio;i' i q^ For 1 yard, 6 = ^ = 4.18 div. = 1.84 /i. Since the absolute coefficient for B^ \s 10.11 fi, and 9.24 /x for the meter and yard, the absolute coefficient for the glass bars becomes 8.10^ and 7.40^ respectively for the meter and the yard. VOL. XVIII. (S. S. X.) 25 386 PROCEEDINGS OF THE AMERICAN ACADEMY Since for 16°. 67, For the Meter, i?,«'-+ 2.8^ = A H^ — 18.6 fjL = Gj a? Mf — 2\.Q^= Gf we have, finally, G,""" -{-2lAii = A G.f -\- 2Z.% ii = A For the Yard, and Rf — 1.4 ;t Rf'— 18.4 ;t R^ — 18.3 y. Gf + 17.0 ft = T = G, T dt a> G^-^l%.^t>.=: T The Tallies which were acttrally nsecT in the subsequent transfers, derived from a few of the earlier observations, were 21 ^ for the meter and 15 /A for the yard. It will be seen from the following observations that the second transfer was not quite successful, although the magnitude of the residuals is very much reduced. This part of my labor will not be considered as completed until a third transfer has been made, and until advantage can be taken of a lower temperature during the coming winter in order to obtain a more accurate value of the coefficient of expansion of the glass bar. In the following tables, the values of R^' — G, have been reduced to Rf" — G^'^^ and R^' — .^2 — 0.9 div. and — 1,7 div. for the meter, and — 0.8 div. and -f-O.S div. for the yard, respectively. COMPARISON OF METERS B.^\ G-^\ G.^^--^ AND C/i^s WITH ONE- INCH OBJECTIVE. 2 and of i?j G^f^ ^ by applying C/^ (1 div. = ^ .440 >i ) * = +4.57 dJT. 1 ^ ■C PI ■%. %. At 16°. 67 1 1 M ety +19.5 +27.6 —13.1 -4.5 + 2.8 " 8 20.78 + 3.5 .... +15.9 .... .... +23.6 —15.3 -38 - 3.1 " 9 20.25 -- 0.8 .... +11.0 .... .... +22.0 -15.6 —63 + 3.9 " 9 19.95 4- 1.2 .... + 9.6 .... +16.4 —13 8 -6.3 - 0.3 " 10 19.53 — 1.3 + 8.8 .... +10.5 —14.4 -5.2 - 4.4 " 10 19.4!) — 0.5 +18.6 -13.1 +12.9 +18.5 +22.3 +20.4 -13.4 +1.0 + 7.5 " 11 19.11 - 2.7 - 8.1 -11.6 - 9.4 -11.3 -~13.3 +10 3 -13.9 -14 + 0.5 " 11 19.13 - 4.9 - 9 3 —10.8 +11.2 +18.3 -19.2 +12 7 -16.1 -11 + 4.9 " 12 19.20 - 39 - 82 -10.2 + 7.9 —14.3 -16.0 +12.5 -15.5 -2.8 + 2.7 " 12 19.07 — 0.3 - 68 - 8.4 -42 -12.2 -11.0 -11.9 -114 -4.6 + 0.3 " 13 19.08 — 7.4 -13.2 -13.7 -14.2 4-18.6 —21.3 -18.5 -18.4 +2.7 + 8.5 " 13 19.08 — 6.8 +14.7 +15.4 +15.8 +19.9 -231 +19.9 -17.8 -4 3 +10.0 Means -14.9 —2.4 + 3.3 — l.ln + 1.5m -6.6^1 OF AETS AND SCIENCES. 387 Since R^' -f 2.8;^ = A, we have G^b^ —3.8/4 = ^ G^H^-\-AAyi = A COMPARISON OF YARDS R^X G^\ 6V'«, AND G^^^, WITH ONE- INCH OBJECTIVE- ( 1 div. = .440 ^.) 6 = 4.18 diF. ^ ^ « -s -5" ^ At 16° .67 1 n O !i ^: C^^ !i c." Cs .S T MO Date. rei 1 1 1 1 1 1 1 O to s- e3 k »" »? 1 1 1 1883. o div. diT. div. div. div. div. 1 July 8 21.72 +8.1 -32.9 • ■ « • +40 2 .... -13.0 +10.9 +19.6 " 8 20-78 +0.0 -37.2 .... .... +37.9 • • • • -17.2 +19.1 +21.2 " 9 20.25 -1.6 -36 1 ■ ■ > « +35.5 .... — 16.S +20.2 +21.0 " 9 19.95 +0.1 +23.5 . . .« +23.0 -13.8 +10.7 + 9.7 " 10 19.53 —0.3 +15.5 • • • • +23.2 -12 5 + 5.0 -m.o " 10 19.49 +1.0 — 29.i +27.0 --2.5.9 +28.5 +27,2 +31.9 -10.8 +15.5 -j-16.1 " 11 19 11 +0.2 --29.4 +30.3 --26.2 -33.1 +30.3 +32.2 -10.0 +18.4 +22.0 " 11 19.13 +0.5 —31.4 +11-^ +28.4 +35.6 +36 8 +34.1 - 9.8 +20.9 +25.2 " 12 19.20 —5.4 --26.1 +29.1 +22.4 ; +2-5.6 +31.3 -35.3 -16.0 +15.5 +19.0 " 12 19.07 —03 --24 8 +25.2 +23.7 : +24.8 +28.3 —29.5 -10.3 +14.8 +18.6 " 13 19.08 —4.2 --27 0 +26.5 +26.4 1 +31 7 +28.3 +33.7 -14.2 +16.7 +18.2 " 13 19.08 —2.9 +26.5 +29.9 +28.1 +34.0 -HJ0.9 +35.5 -12.9 +21.2 +23.5 Means -131 +15.7 +1S.8 — 5.8n + 6.9^1 + 8,3« Since ^i"=— 1.4^ = T, we have, G,h -7.2^- r GJ'^p '-{-5.5,4 — T 0./^f '4-6.9^ = T 888 PROCEEDINGS OF THE AMERICAN ACADEMY COMPARISON OF THE WHITWORTH YARD W WITH Ri\ WITH COMPARATOR NO. 1. (ldiv. = . 0000197 in.) Date. Time. ra,hr. W-R^^i 188L h. m. o April 27 5 15 A.M. 57.9 + 51.7 div. « 27 6 10 " 58.0 + 52.1 div. « 28 5 15 " 61.7 + 20.8 div. « 28 3 40 P.M. 67.4 — 25.9 div. u 28^ 6 50 " 66.5 — 17.1 div. u 29 5 30 A.M. 63.9 + 7.5 div. u 29 5 35 " 63.9 -+- 8.2 div. u 2.9 5 44 " 64.7 + 11.6 div. « 29 6 0" 64.0 + 8.9 div. M 29 6 10 " 63.9 + 7.3 div. (( 29 6 22 " 63.9 + 15.4 div. « 29 6 45 " 68.7 + 5.9 div. « 29 8 10 " 63.4 + 7.9 div. (( 29 8 15 " 6S.4 + 10.1 div. u 29 8 30 " 63.4 + 10.1 div. n 29 8 50 " 63.8 + 10.2 div. May 1 5 30 a.m. 81.4 —127.4 div. «( 8 30 " 81.6 —131.7 div. C( 8 40 " 81.7 —132.3 div. il 9 15 " 81.8 —130.8 div. u 10 20 " 81.7 —128.7 div. <( 11 0 " 81.7 —128.0 div. w 11 45 " 81.7 —129.8 div. i( 11 55 " 81.7 —130.0 div. « 12 45 p.m. 81.7 —128.0 div. u 1 2 0" 81.6 —128.4 div. « 2 5 40 a.m. 56.1 + 65.9 div. « 2 6 0" 56.1 + 66.4 div. <4 2 6 10 " 56.1 + 63.7 div. M 2 9 45 « 54.8 + 75.4 div. U 3 5 50 " 61.0 + 25.6 div. OF ARTS AND SCIENCES. 389 EQUATIONS OF CONDITION BETWEEN W AND 7?/^ At 62° jr-i?2'2 (T-62°) n- -/.'/* + 1G.3 div. = a — 0.3 6 +18.6 div, + 9.-4div. = a —1.8 6 +23.1 div. —129.5 div. = a —19.7 6 +20.0 div. + 59.4 div. = a + 5.2 6 +19-9 div. Mean +20.4 div. Normal Equations. —44.4= 4 a —10.06 6 = +7.59 +2838.2 = —16.6 a + 418.4 6 a = +20.4 We have, therefore, for 62° Fahr., W— Rf = +.000402 in. But Rf—T= —.000008 m. Hence, W — .000394 in. = T Another investigation, the details of which are not given here, gave the equation JF — .000364 in. = F. Probable Errors of Observation. The errors of observation to which the comparisons are subject may be classified as follows : — (a.) Accidental errors of observations for coincidence of micrometer line with defining lines of standard. (b.) Errors due to an imperfect focus of the defining lines under the objective, and which are not included under (a) . (c.) Errors due to the failure of the thermometer to indicate the real temperature of the standards compared. The comparisons of T"' with T\ R^' with R^\ and R^' with Rf\ furnish the data for the computation of probable errors of the first and second classes. Using the formula of Peters we have for the probable error of a single comparison, — .8453 '^n (n — 1) Whence, From r"= — T^' r— ± 0.45 fi R^^- R^^ (meter) r—.± 0.34 n i?^«. _ R^. (yard) r— ±0.35 /« 390 PROCEEDINGS OF THE AxMERICAN ACADEMY The following include errors of the class (c) : — From T""- — C. S. (meter) r= ±OMfi rpa,_p^a, « r=±1.44|t4 a S. — R^^' (yard) r=± 0.99 /* r—± 0.49 II Its we have, — e=±0.07/* e= ±0.06(M e= ±0.06/* e= ±0.09(M e= ±0.22 |t< 6= ±0.20jt« e= ±0.15|M e = ± 0.07 jM The only conclusion which can be safely drawn from these results is, that the errors due to temperature are between three and four times as large as the accidental errors of observation. The errors due to imperfect focus may be considered as eliminated in a long sei'ies of observations. The writer regards the values given for the probable errors of the final results as entirely illusory. The fact that the formula for proba- ble errors takes no account of constant errors, needs to be strongly emphasized in this connection. Errors of classes (h) and (c) are probably of this sort. Sdbdiyision op Standards. The subdivisions of the various standards were made with some- what unequal precision. In the transfers from one standard to another, the errors of subdivision are in a general way reduced ; but I have thus far found it impossible to reduce them to zero when the system of corrections applied, includes a change in the entire length. . as.- -K' a probable error of the final r( From r"^ - _ T^i i?,«^- -i?/= (meter) R^^'- -i?/^ (yard) rpa^ - as. (meter) rpdi _ -i?,«= t( rpa^ _ -K' (( as.- -< - (yard) as.- -Ro"^ 11 OF ARTS AND SCIENCES. 391 It hardly needs to be said, that one can measure the subdivisions with much greater accuracy than it is possible to obtain in making the transfers. The following results have been obtained for the errors of sub- division of the various prototypes discussed in this paper. In bar H^ the initial defining line is considered to be at the inch end of the bar. In all the other bars the initial line is the middle defining line of the meter and the yard. In the case of the meter the distances are reckoned as follows : — I = distances reckoned from the middle line towards the cm. end. II = distances reckoned from the middle line away from the cm. end. For the yard, I = distances reckoned towards the inch end. II = distances reckoned away from the inch end. The columns under the heading 2 contain the corrections reckoned from the initial line. It is to be remembered that a plus sign indi- cates that the measured space is too short. Subdivisions of R^\ (Idiv. = .504;u.) Feet. Mean of all previous July 17. July 18. Mean. Observations. Adopted Corrections. 2 1 — l.Odiv. — 1.3div. — l.Gdiv. — O.Odiv. — 1.2diT. —0.6^ — 0.6/* 2 +6.8 " +6.4 " +6.6 " +4.2 " +5.4 " +2.8 /t +2.2 /t 3 _4.8 « —5.4 " -5.1 " —3.3 " —4.2 « —2.2/* +0.0 /x Three-Inch Spaces of the First Foot. July 15. July 15. July 17. July 18. July 19. July 20. July 21. Means. 2 1 — 6.6div. — 5.4div. — 3.2div. — 2.8div. — 3.6dlv. — 4.3div. — 4.1div. — 4.3div =— 2.2iu. — 2.2/x 2 +2.9 « +1.0 " -1.3 " +0.3 " -1.0 " +0.9 " +0.9 " +0.2 » = +0.1ft -2.1/u, 3 _3.o " -2.3 " -1.5 " -3.6 " -2.1 " -3.4 " —2.2 " -2.6 " =: -1.3^i -3.4;ol 4 +6.8 " +8.6 " +6.0 " +6.4 " +6.7 " +5.7 " +5.5 " +6.8 " =+3.5^t+0.U Inches of the First Three-Inch Space. July 17. July 18. July 19. Mean. 2 1 —0.9 div. —0.5 div. +0.0 div. —0.5 div. := — 0.2/t —0.2/1 2 +1.6 " +0.8 " +0.8 " +1.1 " +0.5/1 +0.3 /t 3 —0.7 " -0.3 " —0.8 " —0.6 " = — 0.3/t +0.0 /t 392 PROCEEDIXGS OF THE AMERICAN ACADEMY For the subdivisions, near the edge of B^ we have : — Meter. • Yakd. Halves. Halves. I = — 0.7m I=+1.0m 11 = +0.7 M II = — 1.0 m Dm. Spaces • Six- Inch Sf. }aces. I = — 4.4 m 2 —4.4 m I = +4.0m +4^0 M II = — 0.4 m —4.8 m II = — 3.7 m +0.3 M 111 = +1.2 M —3.6 m III = — 0.3 m +0.0 M IV = +3.4m —0.2 m V=+0.2m +0.0 M Cm. Spaces 2 — 3.4 m Inch Spac es. +0.1 M I = — 3.4 m I = +0.1m 11= +1.9m —1.5 m 11= +0.2 M +0.3 M III = +0.Gm — 0.9m 111 = +0.3 M +0.6 M IV = — 1.1m —2.0 m IV = -0.4 m +0.2 M V = — 0.4 m —2.4 m V=+2.0m +2.2m VI=+0.1m -2.3 m VI = -2.2 m +0.0 M VII = — 0.6 m —2.0m VIII = +0.0 M —2.9 m • IX = +0.4m —2.5 m X = +2.0m +0.1 M Subdivisions OF E,\ Meter. Yard. Halves. Halves. I = +4.3 M I = +8.8 M- II = 4.3 /* n = —3.8 /* Ihn. Spaces. Six-Inch Spaces. 2 2 I=+3.4m +3.4 M I = —2.1 M -2.1m 11 = +0.5 M +3.9 M 11 = +0.0 M -2.1m III = — 0.3 m +3.6 M 111= +2.1 M +0.0 M IV = — 2.6 m +1.0 M V = — 1.0 m +0.0 M Five Cm. Spaces. Inch Spaces. I = — 0.1m I = +0.6m +0.6 M II = +0.1 M II = — 0.9 m —0.3 m 111 = +0.0 M —0.3 m IV = +0.1m —0.2m V = +1.2m +1.0m VI = — 1.0 m +0.0 M OP ARTS AND SCIENCES. 393 Cm. Spaces. 2 I = -2.2/i — 2.2/i n = +i.8M — 0.-4^ III=— 1.3/x -1.7 ;a IV = +l.l/i — 0.6jii V = 4-0.6 a +0.0/* Subdivisions OF G^^. Meter. Yard. Halves. Halves. G^2 Gibl Gi='2 G^l"! rl.5;a +1.2,. 1 = —1.7^1 — l.Sfi II = —1.5^0 —1.2^1 Z)m. Spaces. 2 2 I=+l.ll^ +1.1 /a +0.4^ +0.4^1 II = — 2.3fx — 1.2f* —0.9 m. — 0.5i^ III = — 0.2^t. — 1.4^^ +0.3 i>x — 0.2i^ IV=:=.— 0.7^^ —2.1m +1.4 —1.2^ V = +2.1m +0.0 m +1.2 m +0.0 m- Cm. Spaces, 2 2 I = +0.2iJ^ +0.2 M — 1.7n +1.7 fi 11 = +0.4 M +0.6 M —3.1m —1.4 m. III = _0.6m +0.0m +1.4m +0.0/* IV = +1.0m +1.0m +0.3m +0.3M V = — l.Ofc +0.0m — 0.3m +0.0k Five Cm. Spaces. I = — l.lK —3.7 m. 11 = +1.1 M +3.7 M. 11 = +1.7 M + 1.8 M I II: III Six-Inch Spaces. 2 2 :_0.2m — 0.2/x +1.4 i^ +1.4 m :_0.4m —0.0m —1.9m — 0.5|oi :+0.6m +0.0 m +0.4 m +0.1 m Inch Spaces. 2 2 I = — 1.8m —1.3m —1.0m —1.0m 11 = +1.1 M —0.2m —0.7 m —1.7 m III = — 0.5 m —0.7 m —0.1m —1.8 m IV = +0.2 M —0.5 m. —2.2m —4.0 m V = +0.5m +0.0 m +3.1 m —0.9 m . VI = +0.0/^ +0.0 ^. +1.0 M +0.1 M Subdivisions of G.. Meter. Yard. Halves. Halves. G,«2 G^^2 G^i2 Go^2 GM G.i2 I = +3.2M. +i7i^ -I'V I = +4.0/U. +1.7M. +1.4M n - -3.2^1 -1.7m Dm. Spaces. +1.V n = — i.O/i Si -1.7m ix-Inch Spaces. — I.4m I = +2.2^- 2 2 ^2.2^ +1.3^ +1.3^1 -3.3^ - -3~3,a 2 2 I = — 0.4fi —0.4m +2.6ai +2,6m 2 -1.7m -1.7m II = -2.5m -0.3m — 1.3,a +0.0m +0.1m -3.2m 11 ~ +0.0m -0.4m -1.3m +1.3m +0.2m —1.5m III = —1.2m —1 5m +1.4m +1.4m +2.0m —1.2m HI = +0.4m +0.0m —1.3m +0.0m + 1-5m -[-O.Om rv = +1.2m —0.3m —2.8m —1.4m —0.2m —1.4m V = +0.3m +0.0m +1.5m +0.1m +1.4M +0.0m 394 PROCEEDINGS OP THE AMERICAN ACADEMY Cm. Spaces. Inch Spaces. 2 2 2 2 2 2 I = — O.V -0.1/x +1.7^1 +1.7m +2.0/i +2.0n I = — l.Sja —1.3m -4.5^t — 4.5/i -4.2^i -4.2^i n = +0.2^ +0. V — 2.9/x — 1.2/x — 2.3ja — 0.3^t II = +l.lia —0.2^ — 0.1/x — 4.6n — 0.2;a -4.4^ in = —0.1m +0.0m +0.9m —0.3m +0.4m +0.1m III = —0.5m —0.7m +3.6m —1.0m +4.0m —0.4m IV = +0.4m +0,4m -0.2m —0.5m +0.2m +0.3m IV =: +0.3m —0.4m —1.6m —2.6m —2.1m —2.5m V = -0.4m +0.0m +0.5m +0 Om -0.2m +0.1m V = +1.3m +0.9m +3-3m +0.7m +4.2m +1.7m VI — —0.9m +0.0m -0.7m +0.0m -1.7m +0.0m Five Cm. Spaces. 1=:— 0.8m —3.7m —4.8m n = +0.8m +3.7m +4.8m Equation betvteen the Imperial Yard and the Metre des Archives. The writer presented to the Montreal meeting of the American Association for the Advancement of Science, in 1882, a paper in which the following relation was announced: — Imperial Yai'd -{- 3.37015 inches = Metre des Archives. I stated at that time, however, with reference to this relation, that for very obvious reasons I should not like to be held to a very strict account with teference to the last decimal figure given, or even to the last two decimal figures. The problem consists of two parts : — First, the determination of the relation at 62° F. or 16°. 67 C. be- tween the particular yard and meter defined by H^^ and the original standards from which these units were derived. Second, the measurement of the space 3.370-)- inches. Let M= the true value of the meter ^^"^ expressed in terms of the Metre des Archives. Y' = the true value of the yard R^"'^ expressed in terms of the Imperial Yard. X= R^' (meter) — R.^- (yard). Then Xz=M—Ti. In the investigation of 1882, a space of four inches was laid off upon a short bar designated i?, having the same composition as R^. This space was subdivided to inches. The third inch was subdivided to tenths of an inch, and the seventh tenth was subdivided to hundredths of an inch. The following relations between the subdivisions of R.^'^ and B were then determined. OF ARTS AND SCIENCES. 395 Feet. Subdivisions of R.^''. Six-Inch Spaces of First Foot. 1—0 A 11 —0.4// I = - -2.1// U+l.G/i +1.2// II = +2.1// III— 1.2 fi +0.0// Inch Spaces of the First Six Inches. Four-Inch Spaces of First Foot. l = —0.7fj. —0.7// 1= 0.1// —0.1// 11= +1.6^ +0.9// II = —2.8// —2.9// III =3+0.2^ +1.1/* III =+2.9// +0.0// IV = — 0.5/z +0.6// V = — 0.7^ —0.1// VI = +0.1^ +0.0// • Subdivisions OF ^. Inches. 2 +0.5// 1 = +0.5 ft II = +0.1// +0.6// III = —2.2// —1.6// • IV = +1.6// +0.0// Tenths of 2 +0.3// Hundredths o/'an /?zc/i. I=:+0.3/Z +0.1// +0.1 fZ II = +0.2 II +0.5// +0.0// +0.1// 111 = +0.9 /J. +1.4// +0.0// +0.1// IV = —1.3// +0.1 /« —0.2// —0.1// Y = — 0.2/1 -0.1// —0.1// —0.2// Yl = +0.2fi +0.1// +0.3 /J +0.1// VII = — 0.4/i — 0.3/t +0.1// +0.2// VIII = +0.2// —0.1// —0.1// +0.1// IX = —0.3// —0.4// 0.2// —0.1// X = +0.4// +0.0// +0.1// +0.0// The value of X expressed in the same unit as J" was found to be 3.370319 inches. Up to this point in the investigation, the following relations had been found : — i?/- (meter) — 2.QfjL = A, whence and i?,''= (yard) + 1.6/. = T, 1.000002G A — [35.999934 + 3.370319] inches, A = 39.37015 inches. 396 PROCEEDINGS OF THE AMERICAN ACADEMY Since the investigation of 1882, it has been possible to make the relation between B^''- and the original units more secure through the medium of the yard and meter C. S. In the present discussion it was thought better to vary the method of determining the value of X. Let X = the three-inch space beyond the limits of the yard B^'^. y = the distance between tlie defining line of this space and the defining line at this end of the meter i?./". Then M= r -{-x-^y. The value of x was determined by comparing this space with the four three-inch spaces composing the first foot of B"\ This was very easily and expeditiously done by setting the stops of the comparator at a distance approximately equal to x, and then comparing each space with this constant distance. For the measurement of the distance y, a space of two inches was laid off upon a short bronze bar with subdivisions to half-inches. The third half-inch is subdivided into five equal parts, and the third sub- division is again subdivided into ten equal parts. The following rela- tions were found between these subdivisions. • Half-Inch Spaces. July 15. July 17. July 19. July 19. July 20. July 21. July 22. Mean. 2 I. =: — 4.4div. —2 Idiv. — 2.5diT. -2.8aiv. — 2.8aiv. +0.4aiT — l.Sdiv. — 2.3div. = -1.2(1^ — 1.2|ii II.rr+0.1" +1.8" +3.5" +3.5" +2.9" +0.5" +2.8" +2.1" = +1. V ^O.l^i III. = +2.5" +2.2" —2.1" —1.7" —11" —1.3" —1.6" -0.5" := —0.2ft -0.3/it IV. =+1.8" —1.9" +1.1" +1.0" +1.0" +0.2" +0.7" +0.6" rr +0.3/^ +0.0fi One-Tenth Inch Spaces. July 14. July 15. July 17. July 20. July 21. Means. 2 I.- : +2.9 div. +1.5 div. +2.3 div. +2.1 div. +1.7 div . +2.1 cUv. : = +1.1 AX +1.1 A* n. = : +1.8 " +0.6 " -0.4 " +0.6 +0.1 it +0.5 " = +0.2 ^c +1.3 A* III. = : —0.9 " —1.3 " +0.2 " —1.0 -1.0 iC —0.8 " = —0.4 m +0.9 M IV. = : -1 0 " +0.7 " —0.9 -1.1 +07 (( -0.3 " = — 0.1/i.t +0.8 ^L V. = : -2.8 •' —1.6 « —1,0 —0-5 " —1.5 li —1.5 " = — O.SfA +0.0 M One-Hundredth Inch Spaces. July 14. July 15. July 17. July 21. Means. 2 I. := —1.7 div — 1.3 div. + 0.5 div. +1.2 div. —0.3 div. r= -0.2 M. -0.2 M II. = -3.1 " — 6.4 " —45 " -5-9 " -4.5 " = -23/1* -2.5 a* III. = +3.7 " + 36 " +4.6 " +4.3 " +4.0 " = +2.0^1, -0.5 /It IV. = +09" + 1.1 " +0.9 " —0.7 " +0.5 " = +0.3^1 — 0.2^ V. = -1.4 " — 03 " -0.5 " +0.4 " —0,5 " = —0.2 n -0.4/* VI. = —8.0 " — 8.2 " -9.5 " -7.9 " —8.4 " zrz —i.Six — 4.7 A* VII. = +8.5 " +11.4 " +8.6 " +8.7 » +9.3 " r= +4.8 fx +0.1 AX VIII. = +0.6 " + 2.5 " +1.3 " +1.0 " +1.3 " r= +0.6,* +0.7 A* IX. = +0.3 " + 0.5 " 2.4 " —1.4 " —0.8 " = -0.4 /x +0.3 A* X. = +0.2 " - 3.0 " +1.0 " +0.0 " -0.5 " ^ -0.3 M +0.0 A* OF AETS AND SCIENCES. 397 Coinparison of 2 Inches of Scale B with the first 2 Inches of R-^'^. From observations of July 21, J? + 1.9 div. = first 2 inches of R^\. From observations of July 22, 5+1.8 div. = first 2 inches of i?/^ The following relations for x and y were found, x being expressed in terms of the first foot of R.^- divided by 4, and y in terms of line 37 of the scale B. X July 15 3 inches +13.2 div. " 15 ' +19.1 " " 17 ' +17.4 " " 18 ' +16.9 " " 19 ' +16.3 " " 20 ' +14.3 " " 21 ' +16.2 « " 22 ' +16.3 " y +2.9 div +2.8 n +5.0 11 +4.0 (t +2.2 n +2.6 tl +4.5 IC +2.1 u Means 3 inches +16.3 div. = 3.000321 inches. +3.3 div. = .000065 incli. Expressed in terms of Y, x becomes 3.000327 inches, and X + y expressed in the same unit becomes 3.000392 " This quantity is now to be corrected by the amount of the error of line 37 of the third half-inch of the scale B. We have, 2 inches ol B -\- [1.9 + 0.6 — 0.2] div. = j^ i"- The correction to line 37 of the third inch of scale B is, therefore, 2 inches — [l.7 + [1.8 — 1.0 + 0.2]] div. = ^^ 7". Expressed in terms of 7, we have, finally, x^y=z 3.370339 inches. From the observations of 1882, a; 4-2/ = 3.370319 inches. 398 PEOCEEDINGS OP THE AMERICAN ACADEMY Adopting the meau between these values, we have if _|_ x-^y = [36.999992 + 3;370329] inches. We have therefore, finally, 1.0000013 A = 39.370321 inches, and A = 39.37027 inches. OP ARTS AND SCIENCES. 399' XXIII. ON THE REDUCTION OF DIFFERENT STAR CATA- LOGUES TO A COMMON SYSTEM. By William A. Rogers. Presented May 9th, 1883. The communication of Professor Safford, in the March number of the Monthly Notices of the Royal Astronomical Society, cites in a forcible way some of the causes of discrepancies in stellar co-ordinates to which too little attention has hitherto been paid. Incidental!}' he refers to the class of errors which are introduced in the computation of the systematic corrections necessary to reduce different catalogues to a common system. Without this reduction it is impossible to ob- tain the element proper motion with the degree of precision which modern observations call for. It is unfortunate that this necessity exists, since considerable un- certainty must always remain in the determination of these corrections. One of the serious demands of instrumental astronomy at the present time is the independent determination at a few widely separated observatories of all the elements which define stellar positions, without direct reference to any assumed fundamental system. The Catalogue of A. G. Publication XIV. by Dr. Auwers is probably more nearly free from systematic errors than any hitherto constr^ucted ; but the independent researches of Professor Boss show that the fundamental observations in declination from about 1815 to 1845 differ as a sys- tem from the Auwers-Bradley system by an amount which cannot be neglected. Since it is obviously impracticable to redetermine the instrumental constants with which the different catalogues to be compared have been constructed, by a direct reference to the fundamental system to which they are to be referred, and with these constants to deduce new co-ordinates, we must seek the best method of deriving the systematic 400 PROCEEDINGS OF THE AMERICAN ACADEMY corrections required. The general tendency of modern practice is towards the graphic method, in preference to a rigid analytical de- termination. But the difficulty exists that computers do not agree in the details of the graphical methods employed, and hence with the same data different results are obtained. It is the common practice to draw the curves which represent the residuals in right ascension with this function as the horizontal argument, but there are several catalo of Class I. Charles W. Eliot, ) George L. Goodale, ^ Henry P. Bowditch, l of Class II. Asa Gray, J Francis J. Child, \ Charles G. Loring, > of Class III. Edward Atkinson, ) Rumford Committee. Wolcott Gibbs, John Trowbridge, Edward C. Pickering, Josiah P. Cooke, John M. Ordway, Joseph Lovering, George B. Clark. Member of Committee of Finance. Thomas T. Bouv^. The President appointed the following standing com- mittees : — Committee of Publication. Alexander Agassiz, John Trowbridge, Francis J. Child. Committee on the Library. Edward C. Pickering, Henry P. Bowditch, Nathaniel D. C. Hodges. Auditing Committee. Henry G. Denny, Robert W. Hooper. OF ARTS AND SCIENCES. 411 Seven hundred and fifty-fourtli Meeting. June 14, 1882. — Adjourned Annual Meeting. The President in the chair. The Treasurer presented a report on appropriations ; and it was Voted, To appropriate for the following year, subject to the approval of a future stated meeting : — For publishing $ 2,000 For library 1,250 For general expenses . 2,200 Professor Rogers presented a communication on a method of making a perfect screw. Seven hundred and fifty-fifth Meeting. October 11, 1882. — Stated Meeting. The President in the chair. The appropriations recommended by the Treasurer at the last meeting were confirmed. The President read a letter from the Secretary of the Society of Arts inviting the Academy to be present at a meeting in memory of the late Professor William B. Rogers. The following gentlemen were elected members of the Academy : — Charles Sedgwick Minot, of Boston, to be a Resident Fellow in Class If., Section 3. Francis Amasa Walker, of Boston, to be a Resident Fellow in Class III., Section 3. Bernhard Sluder, of Berne, to be a Foreign Honorary Member in Class II., Section 1. Julius Sachs, of Wiirzburg, to be a Foreign Honorary Member in Class II., Section 2, in place of the late Joseph Decaisne. 412 PROCEEDINGS OF THE AMERICAN ACADEMY Carl Friedrich Wilhelm Ludwig, of Leipsic, to be a Foreign Honorary Member in Class II., Section 3, in place of the late Theodor Schwann. The following papers were presented : — Comparisons of Photometric Observations on the Light of the Stars, made by Sir William Herschel. By Edward C. Pickering. On the Effect of Change of Temperature on Hall's Phe- nomena. By Edwin H. Hall. (By invitation.) Contributions from the Physical Laboratory of Harvard College : On the Thomson Effect. By John Trowbridge and C. B. Penrose. Influence of Magnetism on Thermal Conductivity. By John Trowbridge and C. B. Penrose. Electromotive Force. By John Trowbridge. Change of Pitch by the Telephone. By John Trowbridge. Seven bundred and fifty-sixth Meeting. November 8, 1882. — Monthly Meeting. The President in the chair. Li the absence of the Recording Secretary, Mr. Edmands was ap[)ointed Secretary ^ro tern. The President read a letter from the Directors of the Royal Society of Sciences of Gottingen, announcing the death of their secretary, Friedrich Wohler ; also a letter from Dr. Charles S. Minot, acknowledging his election as Fellow of the Academy. The following paper was presented by title : — The Tortugas and Florida Reef. By Alexander Agassiz. Professor Dolbear made some remarks on the maximum temperature of the sun. He also spoke of an attempt to determine the relative amounts of electricity transmitted by different parts of the cross section of a conductor. Re- marks on this subject were made by Messrs Pickering and Edmands. OF ARTS AND SCIENCES. 413 Seven hundred and fifty-seventh Meeting. December 13, 1882. — Monthly Meeting. The President in the chair. The President announced the death of Professor Bischoff, Foreign Honorary Member, Letters were read from Messrs. Studer and Ludwig, ac- knowledging their election as Foreign Honorary Members. The following papers were presented: — On the Determination of the Diameters of Planets by the Method of Inclined Lines. By William A. Rogers. Preliminary Notice of the Action of Phosphorous Trichlo- ride on Anilin. By C. Loring Jackson and A. E. Menke. Professor Pickering gave an account of the observations of the recent transit of Venus made at the Harvard College Observatory. Mr. Searle made some remarks on the brightness of Venus at the time of transit, and on the zodiacal light. Seven hundred and fifty-eighth Meeting. January 10, 1883. — Stated Meeting. The Vice-President in the chair. On the motion of the Corresponding Secretary, it was Voted, That, when the Academy adjourn, it adjourn to the second Wednesday in February. The following papers were presented by title : — On the Products of the Dry Distillation of Wood at Low Temperatures. By Charles F. Mabery. On certain Substituted Acrylic and Propionic Acids. By Charles F. Mabery and Franklin C. Robinson. On the Decomposition of Chlortribrompropionic Acid. By Charles F. Mabery. 414 PROCEEDINGS OF THE AMERICAN ACADEMY Seven hundred and fifty-ninth Meeting^. February 14, 1883. — Adjourned Stated Meeting. The President in the chair. The following gentlemen were elected members of the Academy : — Samuel Pierpont Langley, of Allegheny, to be an Associate Fellow in Class I., Section 2. Setli Carlo Chandler, Jr., of Cambridge, to be a Resident Fellow in Class I., Section 2. Edwin Herbert Hall, of Cambridge, to be a Resident Fellow in Class I., Section 3. William White Jacques, of Newburyport, to be a Resident Fellow in Class I., Section 3. Louis Pasteur, of Paris, to be a Foreign Honorary Member in Class II., Section 3, in place of the late Charles Robert Darwin. Matthew Arnold, of Gorhara, England, to be a Foreign Honorary Member in Class III., Section 4, in place of the late Artliur Penrhyn Stanley. The following papers were presented : — • Quantitative Researches in Photography. By William H. Pickering. (By invitation.) Photography as a Means of Determining the Light and Color of the Stars. By Edward C. Pickering and William H. Pickering. On the Historical Hydrography of the West Coast of North America. By Justin Winsor. Seven hundred and sixtieth Meeting. March 14, 1883. — Stated Meeting. "■5 The President in the chair. The death of Mr. Nathaniel Thayer was announced. The following gentlemen were elected members of the Academy : — OF ARTS AND SCIENCES. 415 Silas Wliitcomb Holman, of Boston, to be a Resident Fellow in Class I., Section 3. Leonard Parker Kinnicutt, of Cambridge, to be a Resident Fellow in Class I., Section 3. Charles Frederic Mabery, of Cambridge, to be a Resident Fellow iu Class I., Section 3. William Henry Pickering, of Boston, to be a Resident Fellow in Class I., Section 3. Walter Faxon, of Cambridge, to be a Resident Fellow in Class II., Section 3. Johaun Friedrich Julius Schmidt, of Athens, to be a Foreign Honorary Member in Class I., Section 2, in place of the late Emile Plantamour. Thomas Henry Huxley, of London, to be a Foreign Hon- orary Member in Class II., Section 3, in place of the late Theodor Ludwig Wilhelm Bischoff. The following papers were presented : — On a Method of Observing the Occultations of Jupiter's Satellites. By Edward C. Pickering. On an Electrical Method of Communicating Intelligence from a Vessel at Sea to a Station on Shore. By Amos E. Dolbear. The following papers by Professor William A. Rogers were presented by title : — Determination of the Absolute Coefficient of Expansion of Bars of Copper, Bronze, and Brass. A New Method of Determining, from Observations of the Pole Star, the Equator Point Correction of a Meridian Circle at any Instant of Time. A New Method of Determining the Flexure of the Gradu- ated Circle of a Meridian Instrument. Seven hundred and sixty-first Meeting. April 11, 1883. — Monthly Meeting. The Peesident in the chair. The Corresponding Secretary read an invitation to the American Academy from the Royal Society of Canada to attend their second meeting at Ottawa. 416 PROCEEDINGS OP THE AMERICAN ACADEMY An invitation to attend the semi-centennial meeting of the Oberhessische Gesellschaft fiir Natur- und Heilkunde at Giessen was also read. On the motion of the Corresponding Secretary, it was Voted, To accept these invitations. 'Dr. Otto W. Struve, of Pulkowa, read a paper on Aber- ration. Professor Lovering showed the bearing of the refined obser- vations of the Pulkowa Observatory upon the question of the influence of the movement of the ether upon aberration and refraction. The following papers were presented : — Results of the Comparisons of Three Independent Copies of the Imperial Yard and of Four Independent Copies of the Metre of the Archives. By William A. Rogers. On the Earliest Observation of a Variable Star. By Seth C. Chandler, Jr. On the Photographs of Stellar Spectra made by the late Dr. Henry Draper. B}^ Edward C. Pickering. The following papers were presented by title : — On Substituted Pyromucic Acids. By Henry B. HilL On certain Parabrombenzyl Compounds. By C. Loring Jackson and G. T. Hartshorn. Notes on the Crjqotogamic Flora of the White Mountains. By William G. Farlow. Seven hundred and sixty-second Meeting. May 9, 1883. — Monthly Meeting. The President in the chair. Tlie Corresponding Secretary read letters from the Congres International des Americanistes, at Copenhagen ; from Seiior Anguiano, Director of the National Observatory of Mexico, at Tacubaya ; from Messrs. Huxley and Schmidt, acknowl- edging election as Foreign Honorary Members. On the motion of the Corresponding Secretary, it was OF ARTS AND SCIENCES. 417 Voted, To appoint Professor Alplieus Hyatt a delegate to represent the American x'Lcademy at tlie meeting of the Royal Society of Canada. The President aitnoimced informally that, at the annual meeting of the Academy, the Rumford Committee would recommend that the Rumford Medal be awarded Professor Henry A. Rowland for his researches on light and heat. The following papers were presented : — On the Collection of Meteorites at Harvard College. By Josiah P. Cooke. Photographs of the Infra Red Portion of the Spectrum. By William H. Pickering. The following papers were presented by title : — Contributions to American Botany. 1. Characters of and Notes upon North American and INIexican CompositcC. 2. Characters of various other North American Gamopetalse. By Asa Gray. A Simple Method of Correcting the Weight of a Body for the Buoyancy of the Atmosphere when the Volume is un- known. By Josiah Parsons Cooke. On the Vapor Density of the Chloride, the Bromide, and the Iodide of Antimony. By C. P. Worcester. Notes on some Species in the Third and Eleventh Centuries of Ellis's North American Fungi. By William G. Farlow. Contributions to American Botany. By Sereno Watson. On the Heat produced in Iron and Steel by Reversals of Magnetization. By John Trowbridge and Walter N. Plill. On the Heat produced in Iron and Steel by Reversals of Magnetization. By John Trowbridge and Charles Bingham Penrose. Influence of Magnetism upon Thermal Conductivity. By John Trowbridge and Charles Bingham Penrose. Papers on Thermo-Electricity. No. 1. By John Trow- bridge and Charles Bingham Penrose. The Electromotive Force of Alloys. By John Trowbridge and E. K. Stevens. The Potential of a Shell bounded by Confocal Ellipsoidal Surfaces. By Frank Nelson Cole. VOL. xviii. (n. s. X.) 27 418 PROCEEDINGS OP THE AMERICAN ACADEMY. Researches on the Complex Inorganic Acids. By Wolcott Gibbs. The Volumetric Determination of Combined Nitrous Acid. By Leonard P. Kinnicutt aud John U. Nef. The ^ Phenyltribrompropionic Acid. By Leonard P. Kinnicutt. On the Crystalline Form of Chlordibromacrjdic Acid. By Oliver W. Huntington. On the Reduction of Different Star Catalogues to a Com- mon System. By William A. Rogers. On a Method of Determining the Index Error of a Meridian Circle at any Instant impending upon the Observed Polar Distance of Polaris. By William A. Rogers. Studies in Metrology. First Part. By William A. Rogers. On a New Method of Preparing Borneol from Camphor. By C. Loring Jackson and A. E. Menke. EEPOET OF THE COUNCIL. MAY 29, 1883. During the past year the Academy has lost by death twelve members ; — viz. four Resident Fellows : Augustus A. Hayes, William B. Rogers, Chandler Robbins, and Nathaniel Thayer ; four Associate Fellows : Charles Avery, of Clinton, N. y., Henry Draper, of New York City, George P. Marsh, of Rome, and Isaac Ray, of Philadelphia ; and four Foreign Honorary Members : T. L. W. Bischoff, of Munich, Joseph Liouville, of Paris, Emile Plantaraour, of Geneva, and Fried- rich Wohler, of Gottingen. JOHN BACON.* John Bacon was born in Boston, September 8, 1817. His father, John Bacon senior, came from Haverhill, England, during the year 1812, and established himself in the drug business, on the site of the present Court House, on Court Street, Boston. He soon became well known as an active merchant, and during his successful life was highly respected and beloved. He v/as a leader in many political, financial, and charitable movements, and was a member of the Old North Church and for many years one of its wardens. Soon after his arrival in Boston, John Bacon senior married Ana Hart, daughter of Edmund Hart, remembered in Boston as the builder of the frigate Constitution. The children of this marriage were John, the subject of this notice, and Anna, who in after life became the sec- ond wife of RoUin H. Neale, a distinguished Baptist clergyman. The son John in his boyhood was noted for his quiet and gentle- manly deportment, and early manifested a strong taste for mechanics. * This notice should have been included in the Report of last year, but was not ready in time. 420 JOHN BACON. He was educated at the Boston Latin School, and at Harvard Col- lege, where he graduated with the Class of 1837, being at that time not quite twenty years of age. Both at school and at college young Bacon was an excellent scholar, and is remembered with respect and affection by those of his classmates who enjoyed his intimacy. He had a warm and generous heart, a sympathetic smile, with genial manners, and a quiet vein of humor which endeared him to those who could draw him out of himself; but one of his classmates writes, "He was one of the least demonstrative persons I ever knew." After his graduation, Bacon entered the Medical School in Boston connected with Harvard University, and received in regular course the degree of M. D., although he never practised the medical profession. Soon after, he made an extended tour in Europe when such a privilege was more rare than at the present time, and this journey gave him the opportunity to 2:)ursue effectively tlie study of chemistry, for which he had acquired a strong taste, and which he continued with great assi- duity after his return home. The bias of his professional associations naturally gave direction to Dr. Bacon's chemical studies, and he soon became the leading au- thority in this community on all questions of physiological chemistry. He very early applied the microscope to the examination of urinary deposits, and his skill in the preparation of objects for study was re- markably great, and it is to be hoped that the very large and unique collection of these objects which he made has not been lost to science. His private laboratory was a model of order and neatness ; his reagents were preserved in the greatest possible purity, and his instruments kept in the most serviceable condition. In 1847, Dr. Bacon, then at the age of twenty-nine, was elected a Fellow of this Academy ; but, so far as the writer can discover, he made but one communication to the Academy which was published in its Proceedings. Most of his papers, generally very brief, were pub- lished either in the Boston Journal of Natural History, or in medical journals. As complete a list of these papers as the zeal of a friend can now secure is given below. Dr. Bacon's modest and retirinor disposition kept him from being much before the world; but when he was called on for an opinion on matters relating to his peculiar depart- ment of study, he would give it with decision, and show the result of thorough knowledge, careful observation, and large experience. In 1851, Dr. Bacon was appointed Chemist and Microscopist to the Massachusetts General Hospital, a position which gave him great fa- cilities for pursuing his special studies, and which he held until 18G3. JOHN BACON. 421 In 1857, when, in consequence of increasing work in the Undergradu- ate Course, the Erving Trofessor in Harvard College was relieved of all duties at the INIedical School, Dr. Bacon was ajjpointed Professor of Chemistry in that School and remained a member of the Medical Faculty of Harvard University until 1871. As a lecturer, he com- manded the respect and attention of the students, and in the laboratory he won their confidence and esteem. He was a successful experi- menter, and combined great clearness of thought with felicity of illustration. Dr. Bacon was a man of slight build, and seems never to have en- joyed robust health. He resigned first his position in the Hospital and then his professorship, on account of failing strength ; and a fever which he passed through soon afterwards still further impaired his en- ergies. A man of quiet habits and reticent manners, he made few new friends, but was beloved heartily by those who knew his virtues and the warmth of his affections. After the death of his sistei-, Mrs. Neale, and later of her husband, leaving him the last of the household, his ill health, aggravated by depression of spirits, led him to shrink more than ever within himself. He saw only a few old friends, and sought com- panionship chiefly in his books. Plis closing years were clouded also by financial ti'oubles, which conspired to aggravate his morbid condi- tion. His last stronor love was for his Alma Mater. In one of his latest notes, written by him but a few hours before his death, were these words : " Save out of the wreck all you can for my beloved College." It had been the great desire of Dr. Bacon's life to found at the Uni- versity a Professorship of Chemistry, to be known as the Bacon Pro- fessorship, and to this the note referred. The word '• wreck " plainly shows the great weakness of his condition just before his decease. He died, November 28, 1881, at his residence on Somerset Street, Boston, aged sixty-four. There was no wreck. Dr. Bacon left the greater part at least of the considerable estate he had inherited from his father ; but unfortunately he had not so ordered his affairs as to make his last wish effective. Papers by John Bacon, M. D. 1. Polythalamia in Sand from tlie Sahara Desert. Bost. Journ. Nat. Hist., v., p. 402; also Proc. Bost. Nat. Hist. Soc, II., 1846, p. 164. 2. Microscopic Examination of Gun-Cotton. Proc. Bost. Soc. Nat. Hist., II., 1847, p. 195 ; Araer. Journ. Sci., 2 ser.. IV., 1847, p. 44.5. 3. Observations on the Dumb-bell Urinary Deposit. Amer. Journ. Med. Sci., n. s., XXL, 1851, p. 297. 4. Urinary Deposit of Epithelial Nuclei. Amer. Journ. Med. Sci., n. s., XXIV., 1852, p. 378. 422 AUGUSTUS ALLEN HAYES. 5. Crystals of Hcematoidm in the Bloody Fluid from a Tumor. Amer. Journ. Med. Sei., n. s., XXIV., 1852, p. 380. 6. Mercurial Poisoning. Amer. Journ. Med. Sci., n. s., XXVI., 18-53, p. 91. 7. Calculi passed per Urethram. Amer. Journ. Med. Sci., n. s., XXVL, 1853, p. 3G3. 8. Factitious Bezoar. Amer. Journ. Med. Sci., n. s., XXVII., 1854, p. 346. 9. Proportion of Fat in a Fatty Liver. Amer. Journ. Med. Sci., n. s., XXVII., 1854, p. 355. 10. Observations on the Oil contained in the Crustaceans found in the Cochit- uate Water. Proc. Amer. Acad., III., 1855, p. 178; Amer. Journ. Sci., 2 ser., XIX., 1855, p. 261. 11. Witli A. A. Hayes. Researches upon Cochituate "Water, and upon the Oily Matter and Crustacea contained therein. Proc. Bost. Soc. Nat. Hist., v., 1855, p. 144. 12. Fossil Foraminifera from South Carolina, and Polycistina from Barbadoes, Proc. Bost. Soc. Nat. Hist., VL, 1857, p. 246. 13. Microscopic Forms of Oxalate of Lime. Proc. Bost. Soc. Nat. Hist., VI., 1857, p. 263. 14. Frequency of the Crystalline Urinary Deposits at the Massachusetts Gen- eral Hospital. Bost. Med. and Surg. Journ., LVIIL, 1858, p. 11. 15. Introductory Address [delivered November 3d, 18-58, to the Medical Class of Harvard University]. Bost. Med. and Surg. Journ., LIX., 1858, p. 289. 16. Elimination of Lead from the System. Bost. Med. and Surg. Journ., LX., 1859, p. 420. 17. On Cocoa-nut Penrl. Proc. Bost. Soc. Nat. Hist.; VII., 1860, p. 290. 18. Calculus, partly Siliceous, from the Kidney of a Sheep. Bost. Med. and Surg. -Journ., LXIV., 1861, p. 211. 19. Note concerning the Cocoa-nut Pearl. Proc. Bost. Soc. Nat. Hist., VIII., 1861, p. 173. 20. Siliceous Urinary Calculi. Bost. Med. and Surg. Journ., LXIV., 1861, p. 417. 21. Chemical Analysis of Three Calculi from the Kidney of an Ox. Bost. Med. and Surg. Journ., LXIV., 1861, p. 473. 22. Siliceous Urinary Calculi. Proc. Bost. Soc. Nat. Hist., VIII., 1861, p. 206. 23. Siliceous Calculi from tlie Kidney of an Ox. Bost. Med. and Surg. Journ., LXV., 1861, p. 132. 24. Arsenical Paper Hangings. Bost. Med. and Surg. Journ., LXIX., 1864, p. 489. AUGUSTUS ALLEN HAYES. Augustus Allen Hayes was born at "Windsor, Vermont, Feb- ruary 28, 180G. He graduated at the Military Academy at Norwich in 1823, and began the study of chemistry as a profession under Doctor James F. Dana, then Professor of Chemistry and Mineralogy at Dartmouth College. In 1825, a laborious research undertaken by him for the purpose of accurately determining the jiroximate composi- tion of various American medicinal plants was rewarded, among other AUGUSTUS ALLExN HAYES. 423 results, by the discovery of the organic alkaloid sanguinaria, a com- pound remarkable for the brilliant color of its salts, although itself nearly colorless. In 1827 he investigated the compounds of chro- mium, and his paper on this subject was highly praised by Berzelius. Removing to Boston in 1828, he resided in that city or its vicinity until his death. He devoted his time to chemical investigations, and also filled successively the posts of director of an extensive manu- factory of colors and chemical products at Roxbury, of consulting chemist or director of some of the most important manufacturing es- tablishments in New England, and of State Assayer of Massachusetts. In 1837 he conducted an elaborate investigation upon the economical generation of steam and the relative value of fuels, which, in 1838, led to a novel arrangement of steam-boilers, afterwards generally adopted. Some of the results of this investigation are embodied in the " Report to the Navy Department of the United States on American Coals applicable to Steam Navigation, and to other Purposes," by the late Walter R. Johnson. To Doctor Hayes belongs also the credit of the important application of the oxides of iron in refining pig-iron in the puddling-furnace so as to produce without loss a pure malleable iron. Still earlier, the refining of copper was, under his direction, rendered a much shorter and more certain operation by the introduction of the scales of oxide of copper produced in refining. His researches on the difference in the chemical constitution and action of sea waters, on and below the surface, on soundings, and at the entrance of rivers, form part of an investigation undertaken under a commission from the United States Navy Department to examine and report on the subject of copper and copper sheathing as applied in the construction of national vessels, and his report embodies a vast amount of scientific and com- mercial information. In 1859-60, while considering the question of water supply for the city of Charlestown, he found, as his earlier analy- sis indicated, that the deep water of Mystic Pond was far less pure than the surface water. The question of difl^usion under a flowing surface came up for study, with the responsibility of accepting or rejecting the source of supply. He had proved that a copper strip or wire, passing vertically through two masses of water of slightly unlike composition, would become polarized and exhibit electrolytic action. This mode of testing the exact limits of the impure water was applied under his direction, and it was shown that a compound affording sulphur, when decomposed, could be detected by its action on the strip forming a black sulphide, and the limits of the existence of this compound were read on the surface of the strip of copper, or silvered copper. Nu- 424 AUGUSTUS ALLEN HAYES. merous observations on this and other bodies of water have proved the high practical value of the application, and demonstrated the presence of a stream of naturally j^ure water, nearly twenty feet deep, flowing without contamination over impure water. After the outbreak of the civil war, Doctor Hayes called public attention to the uncertainty of the foreign supply of saltpetre, and the necessity of domestic produc- tion. His efforts resulted in the manufacture of the supply for the navy from caustic potash and nitrate of soda by a novel process, the product being of great purity. Doctor Hayes visited Europe in 1867, and after his return, at the close of the following year, was attacked by a serious illness. Recov- ering from the first shock, he lived nearly thirteen years, enduring con- tinuous suffering with great patience and tranquillity. He died at his home in Longwood, June 21, 1882, at the age of seventy-six years. His wife, the daughter of the Rev. Samuel Dana of Marblehead, who bad devoted herself wholly to caring for him during his long sickness, had died previously, in 1879. The honorary degree of M. D. was conferred on Doctor Playes in 1846 by Dartmouth College, to which institution he afterwards pre- sented his scientific library. He was elected Fellow of this Academy, August 8, 1838, and his last scientific communication, that on the wide distribution of vanadium, was made to our body. He had the rare faculty of interesting practical men in scientific subjects, and his familiar talks at the meetings of the Thursday Evening Club were highly esteemed in Boston. His chief occupation was that of a con- sulting chemist, and he was for many years the chief authority in this vicinity on all the great commercial questions involving chemical prin- ciples. His opinions were highly valued, and the many industrial interests wisely fostered under his direction gave him an ample com- petency. He was a warm and generous friend, quick and ardeut in his sympathies, full of kindness and good works. During his long illness, when, after such an active life, he was confined either to his bed or to an invalid's chair, he showed a fortitude, a resignation, and a cheerfulness which made a visit to his home an attractive pilgrimage, and these qualities, which won at the time the admiration of his friends, may be here recorded for a memorial of the nobility of his character. Papers hy Augustus Allen Hayes, M. D. 1. Localities of Minerals in Vermont. Sill Journ., XIII , 1828, pp. 195, 196. 2. On the Combinations of Chromium. Sill. Journ., XIV., 1828, pp. 136-144. 3. On a Portable Hygrometer. Sill. Journ., XVII., 1830, pp. 351, 352. AUGUSTUS ALLEN HAYES. 425 4. On the Dew-Point. Sill. Journ., XVIII., 1830, pp. 63-65 5. Hydrobromic Acid and Potash in the Saratoga Springs. Sill. Journ., XVIII., 1830, pp. 14-J, 143. G. Production of Hydrocyanic (Prussic) Acid under uncommon Circumstances. Roy. Inst. Journ., I., 1831, p. 109. 7. On a Singular Instance of Crystallization. Sill. Journ., XX., 1831, pp. 128- 130. 8. Notice of Cobalt, Nickel, &c., of the Chatham Mine, Connecticut. Sill. Journ., XXL, 1832, pp. 195, 196. 9. On two new Acid Compounds of Chlorine, Carbon, and Hydrogen. Sill. Journ., XXII., 1832, pp. 141-143. 10. Details of a Chemical Analysis of Danaite, a new Ore of Iron and Cobalt. Sill. Journ., XXIV., 1833, pp. 38G-388. 11. On the Action of Metallic Tin on Solutions of Muriate of Tin. Sill. Journ., XXXVIII., 1840, pp. 408-410 ; Sturgeon, Ann. Electr., V., 1840, pp. 302, 303 ; Bibl. Univ., XXX., 1840, pp. 411-413. 12. Notice of Native Nitrate of Soda, containing Sulphate of Soda, Chloride of Sodium, lodate of Soda, and Chloriodide of Sodium. [1838.] Boston Journ. Nat. Hist., III., 1840-41, pp. 279, 280. 13. Re-examination of Microlite and Pyrochlore. Sill. Journ., XLVI., 1844, pp. 159-160. 14. On the A State of Columbic Acid. Sill. Journ., XLVI., 1844, pp. 167-169. 15. Description and Analysis of Pickeringite, a Native Magnesian Alum. Sill. Journ., XLVI., 1844, pp. 360-362. 16. Remarks on the Origin of the Chlorine found in the Alabama Iron, and a Description of new Methods employed in the Analysis of Meteoric Irons. Sill. Journ., XLVIIL, 1845, pp. 147-156. 17. On the Manufacture of Pure Sulphuric Acid. Sill. Journ., VI., 1848, pp. 113, 114. 18. On some Specimens of Native Copper from Lake Superior. Amer. Acad. Proc, IL, 1848-52, p. 195. 19. On the Urinary Deposit called "Red Sand." Amer. Acad. Proc, IL, 1848-52, p. 196. 20. On Stereoptene, or the Camplior derived from Crude Oil of Valerian. Amer. Acad. Proc, IL, 1848-52, pp. 199, 200. 21. On the assumed Existence of Ammonia in the general Atmosphere. Amer. Assoc. Proc, 1850, pp. 207-213. 22. On the Blowpipe Characters of the Mineral from the Azores identified with Pyrrhite by J. E. Teschemacher. Sill. Journ., IX., 1850, pp. 423, 424. 23. On the Red Zinc Ore of New Jersey. Sill. Journ., IX., 1850, p. 424. 24. On the different Chemical Conditions of the Water at the Surface of the Ocean and at the Bottom, on Soundings. Sill. Journ., XL, 1851, pp. 241- 244. 25. On the Corrosion of an Alloy, composed of Copper and Silver, in Sea Water. Sill. Journ., XL, 1851, pp. 324-326. 26. On a Remarkable Change which has taken Place in the Composition and Characters of the Water supplied to the City of Boston from Lake Cochituate. Amer. Acad. Proc, III., 1852-57, pp. 173-178; Sill. Journ., XIX., 1855, pp. 257-263. 426 AUGUSTUS ALLEN HAYES. 27. On a New Species of Wax. Amer. Acad. Proc, III., 1852-57, p. 190. 28. On Hydro-electric Currents. Amer. Acad. Proc, IIL, 1852-57, p. 198. 29. On a Specimen of Native Iron from Liberia. Amer. Acad. Proc, IIL, 1852-57, p. 199. 80. On Aluminium. Amer. Acad. Proc, IIL, 1852-57, p. 221. 31. On the Change of Position among the Particles of Solid Metals induced by the Action of gentle but continued Percussion of the Masses they form. Amer. Acad. Proc, III., 1852-57, pp. 322-325. S2. On some Points of Chemical Interest connected with the Manufacture of Ductile Iron by the new Process of H. Bessemer. Amer. Acad. Proc, IIL, 1852-57, pp. 341-345. 33. Reclamation of Borocalcite, as distinct from a Mixture of Minerals, found near Iquique, South Peru. Sill. Journ., XVIIL, 1854, p. 95. 34. Reix)rt on a Specimen of Fossilized Egg, from the Guano Islands, off the Coast of Peru. Proc. Bost. Nat. Hist. Soc, V., 1854-56, pp. 165-167. 35. On Cochituate Water. Proc Bost. Nat. Hist. Soc, V., 1854-56, pp. 169- 177. 3G. On the Existence of Native Iron in a malleable State in Liberia, Africa. Proc Bost. Nat. Hist. Soc, V., 1854-56, pp. 2-50-252 ; Sill. Journ., XXI., 1850, pp. 15.3-157 ; Edinb. New Phil. .Journ., III., 1856, pp. 204-209. 37. Analysis of a Saline Mineral from South America. Proc. Bost. Nat. Hist. Soc, v., 1854-56, pp. 392-394. 38. On Serpentine Pvock. Sill. Journ., XXL, 18-56, pp. 382-38-5. 39. On the Monks Island Guano. Sill. Journ., XXIL, 1856, pp. 300, 301. 40. On the State in which Phosphate of Lime exists in Sea Water. Proc. Bost. Nat. Hist. Soc, VL, 1856-59, pp. 48-51; Edinb. New Phil. Journ,, VL, 1857, pp. 10-3-107. 41. Analysis of a Specimen of Gum from Africa. Proc. Bo«t. Nat. Hist Soc, VL, 1856-59, pp. 129-131. 42. On the Kind of Sugar developed in the Sorghum Saccharatnm, or Cliinese Sugar-cane. Proc Bost. Nat. Hist. Soc, VL, 18-56-59, pp. 200-20-3. 43. On a Chemical Change which takes place in the Glucose of the Sorghum. Proc. Bost. Nat. Hist. Soc, VL, 1 856-50, pp. 297-290. 44. On some Modified Results attending the Decomposition of Bituminous Coals by Heat. Brit. Assoc Rep. 1857, (Pt. 2,) pp. 50, 51 ; Edinb. New Phil. Journ., VII., 1858, pp. 33-35; Sill. Journ., XX VII., 1859, pp. 294, 29-5. 45. On the Composition of the so-called Guano of the Atlantic Islands. Edinb. New Pliil. Journ., VL, 1857, pp. 107-112. 46. On the Corrosion of Yellow-Metal Sheathing in Sea Water. Amer. Acad. Proc, IV., 18-57-60, pp. 28-31. 47. On the Supposed Meteorite from Marblehead. Sill. Journ., XXV., 1858, p. 135. 48. Examination of a Mineral Substance in the Medullary Cavity of Trees growing in the Sandwich Islands. Proc. Bost. Nat. Hist. Soc, VH., 18-59-61, pp. 209, 210. 49. On the Occurrence of Soluble Compounds of Copper, Lead, and Tin in newly distilled Alcoholic Spirits. Chemical News, IV., 1861, p. 117. CHANDLER ROBBINS. 427 50. On the Occurrence of Massive Datholite in the Mines of Lake Superior. Proc. Bost. Nat. Hist. ISac., VIU., 1861-62, pp. 62-04. 51. Description and Analysis of a new Kind of Bitumen. Proc. Bost. Nat. Hist. Soc, X., 18GG, pp. 306, 307. 52. On the Cause of tlie Color of the Water of Lake Leman, Geneva. Amer. Journ. Sci., XLIX., 1870, pp. 186-189; Cosmos, VII., 1870, pp. 125-128. 53. On the Lignites of Middle and Southern Italy. Chemical News, XXL, 1870, p. 157. 5L On the Red Oxide of Zinc of New Jersey. Amer. Journ. Sci., IV., 1872, pp. 191-198. 55. On a Practical Test of the Condition and Composition of Natural Waters. Amer. Acad. Proc, IX., 1874, pp. 78-81. 50. On tlie Wide Diffusion of Vanadium and its Association with Phosphorus in many Rocks. Amer. Acad. Proc, X., 1875, pp. 294-299. CHANDLER ROBBINS. Chandler Robbins was born at Lynn, Massachusetts, Feb- ruary 14, 1810. He graduated at Harvard University in 1829, having maintained a high rank in a class of unusual ability and promise. He spent a year as a teacher in the Boston Latin School, and then entered the Cambridge Divinity School. In 1833 he became pastor of the Second Church in Boston, succeeding in that office Ralph "Waldo Emerson. He resigned his pastorate in 1874, and died at Weston, Massachusetts, September 11, 1882. In his profession he was success- ful as a preacher; eminently assiduous, faithful, and beloved, as a pastor. His style was chaste and pure, his delivery graceful. He possessed in full measure the endowments that belong to the Christian gentleman, scholar, and minister. He had a by no means shallow vein of poetical sentiment, and contributed to the hymnology of the Church several favorite Christian lyrics. His principal extra-profes- sional labors were in the department of history, in which he published many discourses, lectures, and articles, besides serving for many years in various offices in the Massachusetts Historical Society, and aiding in the preparation and editorship of several volumes of its collections. In 1855 he received the degree of Doctor of Divinity from Harvard University. For the latter years of his life a gradual failure of eye- sight, terminating in total blindness, disabled him for active duty, and at the same time brought into conspicuous exercise those, passive virtues which grow only fi'om profound religious faith, trust, and experience. 428 WILLIAM BARTON ROGERS. WILLIAM BARTON ROGERS. William Barton Rogers was born at Philadelphia, on the 7th of December, 1804. His father, Patrick Kerr Rogers, was a native of Newton Stewart, in the north of Ireland ; but while a student at Trinity College, Dublin, becoming an object of suspicion on account of his sympathy with the unfortunate Robert Emmet, he emigrated to this country, and finished his education in the University of Pennsyl- vania, at Philadelphia, where he received the degree of Doctor of Medicine. Here he married Hannah Blythe, a Scotch lady, — who was at the time living with her aunt, Mrs. Ramsay, — and settled himself in his profession in a house on Ninth Street, ojjposite to the University ; and in this house William B. Rogers was born. He was the second of four sons, — James, William, Henry, and Robert, — all of whom became distiniruished as men of science. Patrick Kerr Rogers, finding that his prospects of medical practice in Philadelphia had been lessened in consequence of a protracted ab- sence in Ireland, made necessary by the death of his father, removed to Baltimore ; but soon afterwards accepted the Professorship of Chem- istry and Physics in William and Mary College, Virginia, made vacant by the resignation of the late Robert Hare ; and it is a fact worthy of notice, that, while he succeeded Dr. Hare at William and Mary Col- lege, his oldest son, James, succeeded Dr. Hare at the University of Pennsylvania. At William and Mary College the four brothers Rogers were educated ; and on the death of the father, at Ellicott Mills, in 1828, William B. Rogers succeeded to the professorship thus made vacant. He had already earned a reputation as a teacher by a course of lec- tures before the Maryland Institute in Baltimore during the previous year, and after his appointment at once entered on his career as a scientific investigator. At this period he published a paper on Dew, and, in connection with his brother Henry, another paper on the Vol- taic Battery, — both subjects directly connected with his professorship. But his attention was early directed to questions of chemical geology ; and he wrote, while at William and Mary College, a series of articles for the Farmer's Register on the Green Lands and Marls of Eastern Virginia, and their value as fertilizers. Next we find the young Pro- fessor going before the legislature of Virginia, and, while modestly presenting his own discoveries, making them the occasion for urging upon that body the importance of a systematic geological survey for WILLIAM BARTON ROGERS. 429 developing the resources of the State. So great was the scientific reputation that Professor Rogers early acquired by such services, that in 1835 he was called to fill the important Professorship of Natural Philosophy and Geology in tlie University of Virginia ; and during the same year he was appointed State Geologist of Virginia, and began those important investigations which will always associate his name with American geology. Professor Rogers remained at the head of the Geological Survey of Virginia until it was discontinued, in 1842, and published a series of very valuable annual reports. As was anticipated, the survey led to a large accumulation of material, and to numerous discoveries of great local importance. As this was one of the earliest geological surveys undertaken in the United States, its directors had in great measure to devise the methods and lay out the plans of investigation which have since become general. This is not the place, however, for such de- tails ; but there are four or five general results of Professor Rogers's geological work at this period which have exerted a permanent influ- ence on geological science, and which should therefore be briefly noticed. Some of these results were first published in the American Journal of Science ; others were originally presented to the Associa- tion of American Geologists and Naturalists, and published in its " Transactions." Professor Rogers took a great interest in the organi- zation of this association in 1840, presided over its meeting in 1845, and again, two years later, when it was expanded into the American Association for the Advancement of vScience. In connection with his brother Robert, Professor "William B. Rogers was the first to investigate the solvent action of water — especially when charged with carl)onic acid — on various minerals and rocks ; and by showing the extent of this action in nature, and its influence in the formation of mineral deposits of various kinds, he was one of the first to observe and interpret the important class of facts which are the basis of chemical geology. Another important result of Professor Rogers's geological work was to show that the condition of any coal-bed stands in a close genetic relation to the amount of disturbance to which the enclosing strata have been submitted, the coal becoming harder and containing less volatile matter as the evidence of disturbance increases. This gen- eralization, which seems to us now almost self-evident, — under- standing, as we do, more of the history of the formation of coal, — was with Professor Ro"ers an induction from a great mass of observed facts. 430 WILLIAM BARTON ROGERS. By far, however, the most memorable contribution of Professor Rogers to geology was that made iu connection with Henry D. Rogers, in a paper entitled " The Laws of Structure of the more Disturbed Zones of the Earth's Crust," presented by the two brothers at the meeting of the Association of American Geologists and Naturalists, held at Boston in 1842. This paper was the first presentation of what may be called in brief the Wave Theory of Mountain Chains, This theory was deduced by the brothers Rogers from an extended study of the Appalachian chain in Pennsylvania and Virginia, and was sup- ported by numerous geological sections and by a great mass of facts. The hypothesis which they offered as an explanation of the origin of the great mountain waves may not be generally received ; but the general fact that the structure of mountain chains is alike in all the essential features which the brothers Rogers first pointed out, has been con- firmed by the observations of Murchison in the Ural, of Darwin in the Andes, and of the Swiss geologists in the Alps. " In the Appa- lachians the wave structure is very simple, and the same is true in all corrugated districts where the crust movements have been simple, and have acted in one direction only. But where the elevating forces have acted in different directions at different times, causing interference of waves like a chopped sea, as in the Swiss Alps and the mountains of Wales or Cumberland, the undulations are disguised, and are with extreme difficulty made out." The wave theory of mountain chains was the first important contribution to dynamical and structural geology vrhich had been brought forward in this counti-y. It excited at the time great interest, as well from the noveltv of the views as from the eloquence with which they were set forth ; and to-day it is still re- garded as one of the most important advances in orographic geology. A marked feature of mountain regions is that rupturing of the strata called faults ; and another of the striking geological generalizations of the brothers Rogers is what may be called the law of the distribution of faults. They showed that fiiults do not occur on gentle waves, but in the most compressed flexures of the mountain chains, which in the act of moving have snapped or given way at the summit where the bend is sharpest, the less inclined side being shoved up on the plane of the fault, this plane being generally parallel to, if it does not coincide with, the axis plane ; and, further, that " the direction of these faults generally follows the run of the line of elevation of the mountains, the length and vertical displacement depending on the strength of the dis- turbing force." The last of the general geological results to which we referred WILLIAM BARTON ROGERS. 431 above was published under the name of "William B. Rogers only. It was based on the observed positions of more than fifty thermal springs in the Appalachian belt, occurring in an area of about fifteen thousand square miles, which were shown to issue from anticlinal axes and faults, or fi'om poiiUs veiy near such lines ; and in connection with these springs it was further shown that there was a great preponderance of nitroiren in the gases which the waters held in solution. It must be remembered that, during the time when this ofeolosical work was accomplished. Professor Rogers was an active teacher in the University of Virginia, giving through a large i)art of the year almost daily lectures either on physics or geology. Those who met him in his after life in various relations in Boston, and were often charmed by his wonderful power of scientific exposition, can readily understand the effect he must have produced, when in the prime of manhood, upon the enthusiastic youths who were brought under his influence. His lec- ture-room was always thronged. As one of his former students writes, " All the aisles would be filled, and even the windows crowded from the outside. In one instance I remember the ci'owd had assembled long before the hour named for the lecture, and so filled the hall that the Professor could only gain admittance through a side entrance lead- ing from the rear of the hall through the apparatus-room. These facts show how he was regarded by the students of the University of Virginia. His manner of presenting the commonest subject in science — clothing his thoughts, as he always did, with a marvellous fluency and clearness of expression and beauty of diction — caused the warmest admiration, and often aroused the excitable nature of South- ern youths to tiie exhibition of enthusiastic demonstrations of appro- bation. Throughout Virginia, and indeed the entire South, his former students are scattered, who even now remird it as one of the highest privileges of their lives to have attended his lectures." Such was the impression which Professor Rogers left at the Univer- sity of Virginia, that, when he returned thirty-five years later to aid in the celebration of the semi-centennial, he was met with a perfect ovation. Although the memories of the civil war, which had inter- vened, and Professor Rogers's known sympathies with the Northern cause, might well have damped enthusiasm, yet the {presence of the highly honored teacher was sufficient to rekindle the former admira- tion ; and, in the language of a contemporary Virginia newspaper, " the old students beheld before them the same William B. Rogers who thirty-five years before had held them spellbound in his class of natural philosophy ; and as the great orator warmed up, these men 432 WILLIAM BARTON ROGERS. forgot tlieir age; they were again young, and showed their enthusi- asm as wihlly as when, in days of yore, enraptured by his eloquence, they made the lecture-room of the Uuiversity ring with their ap- plause." Besides his geological papers. Professor Rogers published, while at the University of Virginia, a number of important chemical contribu- tions, relating chiefly to new and improved methods in chemical analy- sis and research. These papers were published in connection with his youngest brother, Robert E. Rogers, now become his colleague as Pro- fessor of Chemistry and Materia Medica in the University ; and such were the singularly intimate relations between the brothers that it is often impossible to dissociate their scientific work. Among these were papers " On a New Process for obtaining Pure Chlorine " ; "A New Process for obtaining Formic Acid, Aldehyde, etc."; "On the Oxidation of the Diamond in the Liquid Way " ; " On New In- struments and Processes for the Analysis of the Carbonates"; "On the Absorption of Carbonic Acid by Liquids " ; besides the extended investio-ation " On the Decomposition of Minerals and Rocks by Car- bonated and Meteoric Waters," to which we have referred above. There was also at this time a large amount of chemical work con- stantly on hand in connection with the Geological Survey, such as analyses of mineral waters, ores, and the like. Moreover, while at the University of Virginia, Professor Rogers published a short treatise on " The Strength of Materials," and a volume on " The Elements of Mechanics," — books which, though long out of print, were very use- ful text-books in their day, and are marked by the clearness of style and felicity of explanation for which the author was so distinguished. The year 1853 formed a turning-point in Professor Rogers's life. Four years previously he had married Miss Emma Savage, daughter of Hon. James Savage of Boston, the well-known author of the New England Genealogical Dictionary, and President of the Massachusetts Historical Society. This connection proved to be the crowning bless- ing of his life. Mrs. Rogers, by her energy, her intelligence, her cheerful equanimity, her unfailing sympathy, became the promoter of his labors, the ornament and solace of his middle life, and the devoted companion and support of his declining years. Immediately after his marriage, June 20, 1849, he visited Europe with his wife, and was present at the meeting of the British Association for tlie Advancement of Science, held that year at Birmingham, where he was received with great warmth, and made a most marked impression. Returning home in the autumn, Professor Rogers resumed his work at the University WILLIAM BARTON ROGERS, 433 of Virginia ; but the new fomily relations which had been established led in 1853 to the transfer of his residence to Boston, where a quite different, but even a more important, sphere of usefulness surrounded him. His wide scientific reputation, as well as his family counectiou, assured him a warm welcome in the most cultivated cii'cles of Boston societ}', where his strength of character, his power of imparting knowl- edge, and his genial manners, soon commanded universal respect and admiration. He at once took an active part in the various scientific hiterests of the city. From 1845 he had been a Fellow of this Academy ; and after taking up his residence among us he was a fre- quent attendant on our meetings, often took part in our proceedings, became a member of our Council, and from 1863 to 18G9 acted as our Corresponding Secretary. He took a similar interest in the Boston Society of Natural History. He was a member, and for many years the President, of the Thursday Evening Scientific Club, to which he imparted new life and vigor, and which was rendered by him an im- portant field of infiuence. The members who were associated with him in that club will never forget those masterly expositions of recent advances in physical science ; and will remember that, while he made clear their technical importance to the wealthy business men around him, he never failed to impress his auditors with the worth and dignity of scientific culture. During the earlier years of his residence in Boston, Pi-ofessor Rogers occupied himself with a number of scientific problems, chiefly physical. He studied the variations of ozone (or of what was then regarded as ozone) in the atmosphere at the time when this subject was exciting great attention. He was greatly interested in the improvements of the Ruhmkorff Coil made by Mr. E. S. Ritchie ; and in this connec- tion published a paper on the " Actinism of the Electric Discharge in Vacuum Tubes." A study of the phenomena of binocular vision led to a paper entitled " Experiments disproving by the Binocular Com- bination of Visual Spectra Brewster's Theory of Successive Combina- tions of Corresponding Points." A paper discussing the phenomena of smoke rings and rotating rings in li(iuids appeared in the American Journal of Science for 1858, with the description of a very simple but effective apparatus by which the phenomena would be readily re- produced. In this paper Professor Rogers anticipated some of the later results of Ilelraboltz and Sir William Thomson. In the same year an ingenious illustration of the properties of sonorous flames was exhibited to the Thursday Evening Club above mentioned, in which Professor Rogers anticipated Count Schafgottsch in the invention of a VOL. XVIII. (n. s. X.) 28 434 WILLIAM BARTON ROGERS. beautiful optical proof of the discontinuity of the singing hydrogen flame. lu 1861 Professor Kogers accepted from Governor Andrew the office of Inspector of Gas and Gas-Meters for the State of Massachu- setts, and organized a system of inspection in which he aimed to apply the latest scientific knowiedo;e to this work ; and in a visit he again made to Europe in 18G4 he presented, at the meeting of the British Association at Bath, a paper entitled " An Account of Apparatus and Processes for Chemical and Photometrical Testing of Illuminating Gas." During this period he gave several courses of lectures before the Lowell Institute of Boston, which were listened to with the greatest enthusiasm, and served very greatly to extend Professor Rogers's repu- tation ill this community. Night after night, ci'owded audiences, con- sisting chiefly of teachers and working-people, were spellbound by his wonderful power of exposition and illustration. There was a great deal more in Professor Rogers's presentation of a subject than felicity of expression, beauty of language, choice of epithets, or significance of gesture. He had a power of marshalling facts, and bringing them all to bear on the point he desired to illustrate, which rendered the rela- tions of his subject as clear as day. In listening to this powerful ora- tory one only felt that it might have had, if not a more useful, still a more ambitious aim ; for less power has moved senates and determined the destinies of empires. The interest in Professor Rogers's lectures was not excited solely, however, by the charm of his eloquence ; for, although such was the felicity of his presentations, and such the vividness of his descriptions, that he could often dispense with the material aids so essential to most teachers, yet when the means of illustration were at his command he showed his power quite as much in the adaptation of experiments as in the choice of language. He well knew that experiments, to be effect- ive, must be simple and to the point; and he also knew how to im- press his audience with the beauty of the phenomena and with the grandeur of the powers of nature. He always seemed to enjoy any elegant or striking illustration of a physical principle even more than his auditors, and it was delightful to see the enthusiasm which he felt over the simplest phenomena of science when presented in a novel way. We come now to the crowning and greatest work of Professor Rogers's life, the founding of the Massachusetts Institute of Tech- nology, — an achievement so important in its results, so far-reaching WILLIAM BARTON ROGERS. 435 in its prospects, and so complete in its details, that it overshadows all else. A great preacher has said that " every man's life is a plan of God's." The faithful workman can only make the best use of the opportunities which every day offers ; but he may be confident that work faithfully done will not be for naught, and must trustingly leave the issue to a higher jxtwer. Liltle did young Rogers think, when he began to teach in Virginia, that he was to be the founder of a great institution in the State of Massachusetts ; and yet we can now see that the whole work of his life was a preparation for this noble destiny. The very eloquence he so early acquired was to be his great tool ; his work on the Geological Survey gave him a national reputation which was an essential condition of success ; his life at the University of Viiginia, where he was untrammelled by the traditions of the older universities, enabled him to mature the practical methods of scientific teachiuii which were to commend the future institution to a workings community ; and, most of all, the force of character and large human- ity developed by his varied experience with the world were to give him the power, even in the conservative State of his late adoption, W mould legislators and men of affairs to his wise designs. It would be out of place, as it would be unnecessary, to dwell in this connection on the various stages in the development of the Insti- tute of Teclinorogy. Tlie facts are very generally known in this com- munity, and the story has been already well told. The conception was by no means a sudden inspiration, but was slowly matured out of a far more general and less specific plan, originating in a com- mittee of large-minded citizens of Boston, who in 1859, and again in 1860, petitioned the legislature of Massach\xsetts to set apart a small portion of the land reclaimed from the Back Bay " for the use of such scientific, industrial, and fine arX institutions as may associate together for the public good." The large scheme failed ; but from the failure arose two institutions' which are the honor and pride of Bos- ton,— the Museum of Fine Arts and the Institute of Technology. In the further development of the Museum of Fine Arts Professor Rogers had only a secondary influence ; but one of his memorials to the legis- lature contains a most eloquent statement, often quoted, of the value of the fine arts in education, which attests at once the breadth of his culture and the largeness of his sympathies. Although the committee of gentlemen above referred to had failed to carry out their general plan, yet the discussions to which it gave rise had developed such an interest in the establishment of an institu- tion to be devoted to industrial science and education that they deter- 436 WILLIAM BARTON ROGERS. mined upon taking the preliminary steps towards the organization of such an institution. A sub-committee was charged with preparing a plan ; and the result was a document, written by Professor Rogers, entitled " Objects and Plan of an Institute of Technology." That document gave birth to the Massachusetts Institute of Technology, for it enlisted sufficient interest to authorize the committee to go forward. A charter with a conditional grant of land was obtained fi'om the legisl'iture in 18G1, and the institution was definitely organized, and Professor Rogers appointed President, April 8, 1862. Still, the final plans were not matured and it was not until May 30, 1864, that the government of the new institution adopted the report prepared by its President, entitled " Scope and Plan of the School of Industrial Sci- ence of the Massachusetts Institute of Technology," which Dr. Runkle has called the "intellectual charter" of the institution, and which he states " has been followed in all essential points to this very day." In striking confirmation of what we have written above, Dr. Runkle fur- ther says : — " In this document we see more clearly the breadth, depth, and variety of Professor Rogers's scientific knowledge, and his large ex- perience in college teachuig and discipline. It needed just this com- bination of acquirements and experience to put his conceptions into working shape, to group together those studies and exercises which naturally and properly belong to each professional course, and thus enable others to see the guiding lines which must direct and limit their work in its relations to the demands of other departments " The experimental element in our school — a feature which has been widely recognized as characteristic — is undoubtedly due to the stress and distinctness given to it in the ' Scope and Plan.' In our discipline we must also give credit to the tact and large-hearted ness of Professor Rogers in the fact that we are entirely free from all petty rules and regulations relating to conduct, free from all antagonism between teachers and students." The associates of Professor Rogers in this Academy — many of them his associates also in the Institute of Technology, or in the Society of Arts, which was so important a feature of the organization — will remember with what admiration they watched the indefixtigable care with which its ever active President fostered the young life of the insti- tution he had created. They know how, during the earlier years, he bore the whole weight of the responsibility of the trust he had volun- tarily and unselfishly assumed for the public good ; how, while by his personal influence obtaining means for the daily support of the school, WILLIAM BARTON ROGEES. 437 he gave a great part of the instruction, and extended a personal regard to every individual student committed to his charge. They recall with what wisdom, skill, tact, and patience he directed the increasing means and expanding scope of the now vigorous institution, overcoming obstacles, reconciling differences, and ingratiating public favor. They will never forget how, when the great depression succeeded the un- healthy business activity caused by the civil war, during which the institution had its rise, the powerful influence of its great leader was able to conduct it safely through the financial storm. They greatly grieved when, in the autumn of 18G8, the great man who had accom- plished so much, but on whom so much depended, his nerves fatigued by care and overwork, was obliged to transfer the leadership to a younger man ; and ten years later were correspondingly rejoiced to see the honored chief come again to the front, with his mental power un- impaired, and with adequate strength to use his well-earned influence to secure those endowments which the increased life of the institution required ; and they rejoiced with him when he was able to transfer to a worthy successor the completed edifice, well established and equipped, — an enduring monument to the nobility of character and the consecra- tion of talents. They have been present also on that last occasion, and have united in the acclamation which bestowed on him the title " Founder and father perpetual, by a patent indefeasible." They have heard his feeling but modest response, and have been rejoicing though tearful witnesses when, after the final seal of commendation was set, he fell back, and the great work was done. We honor the successful teacher, we honor the investigator of nature's laws, we honor the upright director of affairs, — and our late associate had all these claims to our regard ; but we honor most of all the noble manhood, — and of such make are the founders of great institutions. In comparison, how empty are the ordinary titles of dis- tinction of which most men are proud ! It seems now almost trivial to add that our associate was decorated with a Doctor's degree, both by his own University and also by the University at Cambridge ; that he was sought as a member by many learned societies ; that he was twice called to preside over the annual meetings of the American Association for the Advancement of Science ; and that, at the death of Professor Henry, he was the one man of the country to whom all pointed as the President of the National Academy of Science. This last honor, how- ever, was one on which it is a satisfaction to dwell for a moment, because it gave satisfaction to Professor Rogers, and the ofiice was one which he greatly adorned, and for which his unu&ual oratorical abilities 438 NATHANIEL THAYER. were so well suited. He was a most admirable presiding oflScer of a learned society. His breadth of soul and urbanity of manner insensibly resolved tlie discords which often disturb the harmonies of scientific truth. He had the delicate tact so to inti'oduce a speaker as to win in advance the attention of the audience, without intruding his own per- sonality; and when a paper was read, and the discussion closed, he would sum up the argument with such clearness, and throw around the subject such a glow of light, that abstruse results of scientific investi- gation were made clear to the general comprehension, and a recognition gained for the author which the shrinking investigator could never have secured for himself. To Professor Rogers the truth was always beautiful, and he could make it radiant. It is also a pleasure to record, in conclusion, that Professor Rogers's declining years were passed in great comfort and tranquillity, amidst all the amenities of life ; that to the last he had the companionship of her whom he so greatly loved ; and that increasing infirmities were tended and the accidents of age warded off with a watchfulness that only the tenderest love can keep. We delight to remember him in that pleasant summer home at Newport, which he made so fully in reality as in name the " Morning-side," that we never thought of him as old, and to believe that the morning glow which he so often watched spreading above the eastern ocean was the promise of the fuller day on which he has entered. NATHANIEL THAYER. Nathaniel Thayer died at his residence in Boston, March 7, 1883, in the seventy-fifth year of his age, and his well-rounded life, ripe in experience as well as years, can be looked back upon as suc- cessful in all that gives that word its best significance. He was born in Lancaster, September 11, 1808, and was educated iu the same place. His father, Rev. Dr. Nathaniel Thayer, was minister in that town for nearly fifty years. The very high character of his parents, and all the influences surrounding the years of his youth, tended to implant in the young man the genius that found so rich fruition as he grew to man- hood. It is too true, that in the richest soil weeds are most apt to abound ; and a parallel is often found in the waste of opportunities which should furnish the way to the best and highest development. In Mr. Thayer's case we see an instance where, from early youth, his tastes and inclinations led his sympathies into association only with the best, so that at all times it was a pleasure and a compliment to be NATHANIEL THAYER. 439 his friend. He was very clear and strong in his estimate of men, wliich miide him a warm, sincere, and devoted friend to those whom he received into his confidence ; and his relations with many whom the community has most esteemed were especially pleasant and inti- mate. The writer recalls the almost brotherly relations he held with many who have been of most service to their day and generation. To make others happy was Mr. Thayer's highest enjoyment ; and could the many he has assisted be gathered together, those who knew him most would be surprised at the multitude. What has been done by Mr. Thayer for Harvard College, for Lancaster (his native town and the place of his summer residence), is well known in this com- muuity ; but what he has done to assist young men to their education, to aid tlie widows and families of needy friends and acquaintances, and indeed in a hundred ways, will never be known. For many years Mr. Thayer, in partnership with his deceased brother, constituted the firm of John E. Thayer and Brother, in Boston, a firm chiefly concerned in the development of the railroad enterprises which have opened the West to intercourse and traffic. Mr. Thayer had the highest sense of business honor, and no name stood higher, the world over, than that of his firm. The springs of action with him were from a deep, conscientious appreciation of the duties attending success, — which comes not of " luck," as so many think, but through careful, well-matured, systematic conduct of business af!iiirs. It is common for many to judge harshly the men who have been successful in business, and one often hears that it is not possible to be an honest man of business ; but they little understand that honor and honesty go quite as far as capital in giving business men their standing. Those who knew the subject of this article best need not to be told that he never wilfully wronged any one. All are fallible, and may be in error as to what will prove to be the best permanent investment of money ; but he made fewer mistakes in this direction than most men who have managed so large a business. In his family relations Mr. Thayer was all that was tender and lovely, — thoroughly unselfish. His sympathies were always quick to appreciate what would be for the permanent good of the community and individuals, and he was always ready to assist what commended itself to his judgment. He was strong, manly, self-reliant, pure- hearted, — eager to do his part, and more than his part, to raise the community to a higher level, by aiding institutions of learning, charity, art, or science, and promoting with generous gifts all that the best citi- zens most esteem. 440 NATHANIEL THAYER. Nathaniel Thayer was one among the more munificent benefactors of Harvard College who chose to bestow their valued gifts during their own lifetime, having the privilege of witnessing the good uses which they serve. While Mr. Thayer's generosity has its evidences on the subscription papers and donation books of all our multiplied institutions and agencies of science, art, culture, mercy, and charity, his direct benefactions to Harvard University, represented by buildings, endowments, and permanent deposits, exceed a quarter of a million dollars, and include his expenditures on " Thayer Hall," " Thayer Commons Hall," " Gray Herbarium," the " Thayer Expedition," etc. This gross sum is in addition to a considerable amount which for a lou<>- series of years, through channels of his own choosing, he has dis- tributed as pecuniary aid to students in the College, and to scholars in preparation for it. Thayer Hall, erected in 1870, and whose full cost exceeded a hun- dred thousand dollars, was designed by him as a memorial gift com- memorative of his father, Rev. Nathaniel Thayer, D. D., and of his brother, John Eliot Thayer. His father, Rev. Dr. Thayer, was the honored and revered minister of tlie beautiful town of Lancaster, in the fair valley of the Nashua, for nearly half a century. Whatever changes necessity or expediency in time to come may introduce in modifying the obligations and relations of Harvard College to the supply of ministers for the churches, it may be claimed that it has, for at least two centuries, answered fully to the intent and pledge of its first planting by a twofold recognition of its responsibility in this direction, and of a large return of gratitude for its services. It has furnished the churches of New Eno;land with a succession of faithful Christian ministers ; and it has received from the sons of such ministers many of its most devoted and esteemed officers and instructors, and many of its most liberal endowments. Quite a consideralile list might be made of the sons of country minis- ters— some of them, like their fathers, alumni of Harvard, and others wlio had not enjoyed that privilege — who have spent their lives in the service of the institution, or who have left there generous deposits of the wealth accpiired in professional or mercantile life. Di-. Thayer of Lancaster — himself the son of a country minister who had graduated at Harvard in 17.33, and a lineal descendant on the maternal side of the famous John Cotton of the old and the new Boston — was a class- mate and life-long friend of President Kirkland, of the class of 1789. In dignity, and in the graces and virtues of character, he was one of the best examples of that class of ministers to whom all our old vil- NATHANIEL THAYER. 441 lages and towns since their first settlement looked up for the best instruction and the most faithful guidance in all the uobler interests of life. His gravity and serenity of look and mien gave him a sort of Washingtonian dignity. He belonged to a fellowship of divines very remarkable in their period for weight of professional character, en- larged liberality of views, thorough scholarly culture, and a high tone of life, — including such men as Kirkland, Freeman, Buckminster, Thacher, Bancroft, Channing, and Ware. He was for many years the sole minister of a town of about two thousand inhabitants, and was held in true esteem and love by all his people. Probably no higher or purer gratification could have been afforded him, could he have had the fore- knowledge or assurance of it, than that among the venerable halls of the College where he had sjient years of happy and faithful pupilage the filial devotion of a son would rear one that should bear his name. At a time when the high price of board at Cambridge pressed very heavily on the poorer students, Nathaniel Thayer performed for the College another service most needful and helj^ful, in jDroviduig a place and means for such students as wished to avail themselves of a com- mons hall for boarding at low cost. He enlarged considerably, and in large part furnished, the former station of a branch of the Fitch- burg Railroad in Cambridge, as the Thayer Commons Hall. This was in 1865, and it was successfully occupied for ten years, till Memo- rial Hall gave to the students a splendid new room for that purpose. It was understood that Mr. Thayer expended more than $8,000 in securing and fitting his Commons Hall. Its affairs were managed by the students who there took their meals, the expense to them being simply the cost of the materials for their food, and its preparation. Many of the students who sat at those tables were doubtless the guests of the host. It was substantially in the service of the University that Mr. Thayer so generously assumed the whole cost of Professor Agassiz's vigorous and most fruitful visit of exploration and research to South America, known as the " Thayer Expedition." This was in the interests of high science, and it has proved the basis of and incitement to advanced stages already reached, and of infinite progress still inviting its pupils. It is believed that the only hesitancy in facing the known and possible obligations to which Mr. Thayer committed himself in this enterprise was in his humorous lament to Professor Agassiz as to the enox'mous amount of alcohol needed to prepare the fishes of which he appeared to empty the ocean. The relations between Mr. Thayer and Professor Agassiz were those 442 CHARLES AVERY." of the warmest regard and the fullest gratitude. While Agassiz would receive no personal emolument for his laborious work, he had the most generous sense of the claims of high science on men of wealth, and he deli"-hted to give them the most favorable opportunities for advan- cing it. Another of the admirable provisions made by Mr. Thayer, through his friend Professor Gray, in meeting the ever-multiplying needs of the University, was in erecting and furnishing, in 1874, at a cost of over $ 15,000, the fire-proof Herbarium ou the grounds of the Botanic Garden. ASSOCIATE FELLOWS. CHARLES AVERY. Charles Avert was born in Munson, Mass., July 29, 1795. He died at his home in Clinton, N. Y., May 20, 1883. He was the son of Gardner Avery and Amy Newell, who in 1810 removed with their large family to Sauquoit, Oneida Co., N. Y. He belonged to a gen- eration which is now fast passing away, when the advantages for education were comparatively rare, and were prized in proportion to their rarity. His early education was the result of his own energy and thirst for knowledge. He early evinced a marked taste for stud- ies in mathematics and science. In a sketch of his own life he said, " At the awe of seventeen I found myself at evening solving questions in arithmetic which had been proposed by young pedagogues as chal- lenges." This was the awakening of that love for mathematical in- vestigation which characterized his entire life, — a love to which he gave expression in his old age when he spoke of " the delightful science of figures." Id 1816 he entered Hamilton College, was graduated in 1820, and on October 1, 1822, was married to Delia Strong, daughter of Rev. Joseph Strong of Heath, and sister of Professor Theodore Strong, the distinguished mathematician. After completing his college studies he was engaged for fourteen years in teaching in various academies in the State "of New York, — viz. at Horner, Fairfield, and Belleville. His work as an instructor was successful in a high degree. His success at Horner was such as to give him considerable reputation, and to secure him a call to Fairfield, — a call, the wisdom of which CHARLES AVERY. 443 was justified by the immediate additions to the fame and prosperity of the school. At Fairfiehl he became favorably known as a mathematician, and students came in some instances from HamiltoD College to Ftwtfield to profit by bis instructions. His object in removing from Belleville to Clinton was, in part at least, to open a school for the study of the exact sciences. " Mere," said he, " I could indulge in the bigher analy- sis to my heart's content. This I did to my own satisfaction, and much to tlie delight of my pupils." In 1834, he was appointed "Professor of Chemistry and Natural Philosophy in Hamilton College, the only appointment which has ever been made in that institution to that double chair. The winter of 1834-35 he spent in New Haven in order to attend the lectures of Professor Silliman. He entered upon his work with great enthusiasm, and in a short time brought the department of chemistry, which had suffered from neglect, into a respectable prominence. His success, particularly in detecting poisons, gave him a reputation as an analyst of decided ability, and numerous cases in which questions of medicine and law were involved were brought to him for solution. He intro- duced into his department, for the first time, the study of chemical analysis and agricultural chemistry, and made the chemical equipment of the College, which had been very meagre, so good as to compare favorably with the best endowed colleges in the land. On November 14, 1838, he was elected a Fellow of the American Academy of Arts and Sciences. Keenly alive to all matters of experiment or investigation, he en- tered with great zeal into the studies of Daguerre. He took the first daguerrotype ever taken in this country west of Albany, and it might be said ^vest of Neiv York, since he taught the artists in Albany how the work could be successfully done. It was owing to his exper- iments in this art that his health was for a time seriously impaii'ed. In 1844 he was taking daguerrotypes in Rome, N.Y. The oper- ating-room was also used as a lodging-room. The vapors of bromine had so impregnated the air as to make it poisonous, and the sleep of one night resulted in serious and protracted illness. He early saw the value and prominence which astronomical studies were to assume in this country, and largely through his own efforts secured for Ham- ilton College an Astronomical Observatory. By personal effort Pro- fessor Avery added largely to the funds of the College, securing in three different financial campaigns more than one hundred and thirty thousand dollars. During the year which intervened, between the 444 HENRY DRAPER. resiirnation of Dr. Fisher and the inauguration of Dr. Braun, by request of the Trustees he acted as President of the College. In 1869, having reached the age of seventy-four, he resigned his chair of instruction. The closing years of his life were passed quietly in Clinton. A green and cheerful old age, free from complaint and full of genial sympathy, was his enviable portion. He kept up his studies to the end. His mind was characterized by strength and clearness in all lofical processes. He was a close observer, and much given to reflec- tion. He was deliberate and cautious in forming his conclusions, and believed nothing so important as accuracy and truth. In all his inter- course with men he was conspicuous for candor and simplicity. He uniformly looked upon the bright side of life. A fund of native humor was always at his command, and he loved the pleasures of social life, which he could well enliven with anecdote and repartee. He was singularly charitable in all his judgments. At peace with God and man, he fell asleep in a good old age, leaving the i-ecord of a good and useful life, and beloved and lamented by all who knew him. HENRY DRAPER. Henry Draper was born, March 7, 1837, in Prince Edward County, Virginia. He died in November, 1882. His father, Professor John W. Draper, early directed his sou's thoughts toward science, and the researches of the son seem to have been the outcome of the father's work. By the death of Henry Draper, the world has lost the accumu- lated scientific experience of two lives. John W. Draper began his scientific career as Professor of Chemistry at Boydton, Virginia. It was here that Dr. Henry Draper was born. In 1839 the father was appointed Professor of Chemistry in the Uni- versity of New York, and the son, at the age of fifteen, entered the Freshman Class of the institution over which the father presided. During the Junior year he left college, entered the Medical School, and graduated with the degree of Doctor in Medicine in 1858. His graduating thesis was a valuable investigation upon the functions of the spleen, by means of microphotography. During the process of this work he discovered the use of palladium protochloride in darkening collodion negatives. His work in college, and especially in the Medi- cal School, gave promise of his future distinction. Those who knew him at that time speak of his scientific tastes and of his bright and active mind. • He spent the year aftei" his graduation in Europe, and HENRY DRAPER. 445 was especially interested in instruments and appliances for Sfientific research. It is said that a visit to Lord Rosse's great reflecting telescope turned his attention especially to solar physics. On his return, he entered Bellevue Hospital as an assistant, and retained the position sixteen months. It was his intention to become a prac- tising physician, but in 1860 he accepted the position of Professor of Physiology in the academic department of the University of New- York. The civil war, which had just begun, called for the services of all trained young men, and he was appointed, in 1862, surgeon of the Twelfth Regiment of New York Volunteers. In 186G he was appointed to the chair of Physiology in the Med- ical School, and continued in this position until 1873. The present flourishing condition of the School is said to be largely due to his enthusiasm, to his personal contributions, and to his executive ability. While occupying the chair of Physiology he was engaged in many researches. With a fifteen and a half inch reflecting telescope, con- structed under his supervision, he took photographs of the moon fifty inches in diameter. In 1872 he built with his own hands a reflecting telescope of twenty-eight inches' aperture, and, in August, 1872, first succeeded in jjhotographing a star spectrum, — that of Vega. During the same year he made a photograph of the diffraction spectrum of the sun, extending from the neighborhood of G to O. There seem to have been two epochs in his scientific career which are marked by his contributions to science. In the first epoch, from 1864 to 1870, he published the following works : — "A Text-Book of Chemistry." " Philosophical Use of Silvered Glass Reflecting Tel- escopes " (Phil. Mag.). " Silvered Glass Telescopes and Celes- tial Photography." " Petroleum, its Importance and its History." "American Contributions to Spectrum Analysis." " Construction of a Silvered Glass Telescope of fifteen and a half inches' Aperture, and its Use in Celestial Photography" (Smithsonian Institution Contribu- tions, Vol. XIV., 1864). From 1872, and onward till his death, photography played an im- portant part in all his researches, the second epoch having been prepared for during the first. The following are the principal papers which have been published : — "On the Diffraction Spectrum Photog- raphy" (American Journal of Science, 1872). "Astronomical Ob- servations on the Atmosphere of the Rocky Mountains " (American Journal of Science, 1877). "Spectra of Venus and a Lyra3 in 1877" (American Journal of Science). " Discovery of Oxygen in the Sun by Photography, and a new Theory of the Solar Spectrum." " On 446 HENRY DRAPER. the Coincidence of the Bright Lines of the Oxygen Spectrum witli Bright Lines in the Solar Spectrum," 1877. " Eclipse of the Sun in July, 1878" (published in 1878). "Photographing the Spectra of the Stars and Planets," 1879. " Photography of Jupiter's Spectrum, and Photographs of the Nebula in Orion," 1880. "Photographs of the Spectrum of the Comet of June, 1881." His Avork upon the photography of stellar spectra continued from 1872 until his death, and he has left a large number of valuable pho- tographs, which promise to exercise great influence upon the direction of modern astronomical investigation. Although he began with the use of reflectors, most of his subsequent astronomical work was done with an eleven and a half inch refractor. With this instrument he made his well-known photographs of the Nebula of Orion. In 1874 he superintended the photographic work of the Transit of Venus Commission, and the United States government in honor of his able work caused a special gold medal to be struck, which bears upon the face the words, " Decori decus addit avito," and upon the reverse, " Famam extendere factis, hoc virtutis opus." Perhaps his most famous investigation is that upon the presence of oxygen in the sun. The results of this investigation are, if fully substantiated by subsequent observers, extremely important. The method of procedure was to photograph the solar spectrum side by side with that of oxygen. The entire investigation is well worthy of study, not from its results alone, but from its refined and delicate methods. In the photograplis the bright lines of the oxygen spectrum coincide with certain bright spaces between the dark lines of the solar spectrum. In regard to the conclusions of Dr. Draper, Prof. C. A. Young of Princeton remarks : " Naturally there has been some scep- ticism and discussion as to the correctness and soundness of his con- clusions ; but no one with an unprejudiced mind can, we think, resist the evidence after careful examination of the plates, especially those obtained during his second and still more elaborate investigation of the subject in 1878-79." This investigation illustrates the scientific position of Dr. Draper better, perhaps, than any we can choose. His early training as a chemist, his active years spent in the mysteries of photography, and his ample fortune, fitted him to undertake such an investigation. It is by reflecting upon the methods of this work, and upon its results, tlaat we can appreciate liow much the scientific world has lost. At present, photography seems the most potent means for studying the light of the stars, for unravelling the mysteries of the sun, and for estimating the energy of molecular movements in general. GEORGE PERKINS MARSH. 4-i7 The practical photographer speaks to-day of loading the molecules by putting various gums into emulsions in order to make the molecules vibrate slower. This metaphorical expression is extremely suggestive, and opens to the imagination the immense field iu which Dr. Draper was a master. Photography has already shown us the solar spectrum far beyond the limits of the visible red, and it is said that, had Dr. Draper lived even thi'ough the brief space of a twelvemonth longer, he would have succeeded in photographing stars which could not be detected, through the telescope he was using, by the eye- GEORGE PERKINS MARSH. George Perkins Marsh was born at Woodstock, in the State of Vermont, on the loth of March, 1801. He was elected an Associate Fellow in Class III., Section 2, of the Academy, on the 29th of Jan- uary, 1851. He died at Vallombrosa, in Italy, on the 24th of July, 1882, closing peacefully a long career of great and unceasing useiul- ness in the service of the republic and of learning. AVe cannot wonder that the death of a man so pure, so kindly, so noble and earnest in purpose, and so strong in deed, should call forth, as it does, the reverent and loving sorrow of two nations that he loved perhaps equally, and which he had successfully striven to bring into relations of serviceable friendship during the years in which he repre- sented the one at the court of the other. This republic has lost a loyal, watchful, wise, and able servant, who has caused its name to be honored and loved, not only by reason of his eminent diplomatic ser- vices during twenty-five years, but also by the power of his personal worth. United Italy grieves as for a foster-father, who brought to the help of its trembling infancy the strong sympathy of a stuixly re- public in the vigor of its early prime. Perhaps it will never be fully known how jrreatly this noble man strengthened the hands of both the kings of new Italy, as they struggled to break away from the chains of priestcraft and the relics of feudalism into the freedom of self- government. How high a rank our late Associate held as a student and expounder of truth in the fields of natural science, of philosophy, of political economy, of archaeology, of philology, and of literature, is attested by the many learned societies, both in this and in other countries, that deemed it an increase of honor to themselves to write his name in their lists of members. What Mr. Marsh was as a friend and counsellor is happily known 448 GEORGE PERKINS MARSH. to many whom his generous heart embraced in those intimate relations. How dear he must have been to those who stood within the circle of his family, they alone can know. We feel that their loss is unspeaka- ble, and we can only draw near to their sacred sorrow with our best offerings of earnest sympathy for them, and of profound reverence and admiration for him. Such is the mnn whose name death has struck from our roll. We look with desire for a full account of his life from some hand compe- tent to the grateful task. In such a memoir we shall hope to find a just estimate of Mr. Marsh's public services to his native State and to the Republic, both at home and abroad, and also of his scientific and literary work. In the mean while a short outline of his life may fitly be put on record here, together with a brief account of his published writings. George Perkins Marsh was graduated a Bachelor of Arts by Dart- mouth College in the class of 1820. He also received from his College the Master's degree in course. Harvard College and Delaware Col- lege honored him with the degree of Doctor of Laws in 1859, and Dartmouth College did the same in 1860. He was, at the time of his death, a member of this Academy, of the Massachusetts Historical Society, and of the American Philosophical Society, not to speak of others in this country, and of many foreign societies. Having taken his first college degree, Mr. Marsh established him- self at Burlington, Vermont, where he read and practised law. In 1835 he served in the legislature of Vermont, and he represented that State in Congress from 1842 to 1849. In the latter year he was com- missioned by President Taylor as Minister Resident of the United States at Constantinople. He remained at that post until 1853. In 1852 the United States intrusted him with a special mission of pecu- liar delicacy to the King of Greece, " to adjust the difficulties that had sprung up between the Greek government and the Rev. Jonas King, acting Vice-Consul of the United St ;tes." The profound knowledge of the principles of international law, as well as of the Greek constitu- tional law, which Mr. Marsh displayed in his masterly conduct of these negotiations, appears to have made a strong impression of his learning and skill among European statesmen. At the close of his residence at Constantinople, Mr. Marsh returned to America, where his executive ability and scientific acquirements were at once enlisted in various public services by his native State. The years between 1853 and 1801 were spent by Mr. Marsh in these services, and in preparing and publishing several philological and scientific works, and in delivering GEORGE PERKINS MARSH. 449 lectures in "Washington, New York, and Boston. In 1861 President Lincoln accredited Mr. Marsh as Envoy Estraordiiiary and Minister Plenipotentiary of the United States at the Court of Italy. He con- tinued to hold this honorable office until he died. Besides numerous minor writings, including his contributions to peri- odical publications, and besides any writings whicli his literary execu- tors may yet bring to light, Mr. Mai-sh left several larger published works which may conveniently be arranged in two classes. To the first class belong the two works entitled, i-espectively, "The Earth as Modified by Human- Action," and "The Camel, his Organ- ization, Habits, and Uses, considered with Reference to his Introduc- tion into the United States." The former of tliese books is a corrected and enlarged edition of an earlier work of the same author, entitled "Man and Nature, or Physical Geography as modified by Human Action." This book, upon which Mr. Marsh's reputation could well afford to rest, is, like his other works, characterized by thoroughness, earnest- ness and practical good sense. It does not profess to Ije a scientific work, but to address itself to the common sense of men of average intelligence, for purposes merely practical. The work is so complex in its structure, and so full of details as heterogeneous as they are important, that it can only be analyzed in the most general terms. Its general scope is to exhibit the exceptional position of man, as distinguished from all other living organisms, in respect to the power of infiuencing the aspect and the operations of Na- ture ; and to inculcate the wisdom and the duty of directing this power according to the dictates of sound reason and the teachings of experience, so as not only to reach the best results and avoid former errors, but also to remedy, so far as is still iwssible, the evil already caused by inexperience and want of caution. INIan, who in his savage state is a mere consumer of what Nature has provided, soon becomes a producer, using to that end, and modify- ing to a remarkable extent, the powers of Nature of which he has learned the secret more or less completely. That he shall learn it most thoroughly so far as such knowledge is permitted to him, and that he shall use due caution in his interference with Nature's sponta- neous operations, is the author's wise endeavor. Mr. Marsh approached the work in his wonted spirit of earnestness, and with that faithful preparation which he brought to all that he at- tempted. The works which he consulted ai-e more than three hundred in number, and are written in a dozen languages. To give credit in VOL. XVIII. (n. s. X.) 29 450 GEORGE PERKINS MARSH. detail to each author for what he has found useful in his works would have encumbered the book with an intolerable bulk of references. The author has wisely avoided doing so whenever the matter did not seem to require, by its novelty or strangeness, the suppoi-t of some recognized authority. In these cases the statement is generally given in the woi-ds and with the name of the writer who is responsible for it. The book has three principal divisions. First, an introductory chapter exhibits the character, extent, and vai-iety of man's action on Nature. Next, four chapters treat in detail of man's influence upon animal and vegetable life, the forest, the waters, and the sands. Finally, a most suggestive and useful chapter deals with the great projects which this century has brought forth for the modification of the physical character of our globe. Under the first of these heads we are shown how some of the most flourishing provinces of the Roman Empire have been brought to a condition of hopeless decay by neglect of those terms which Nature imposes upon those to whom she permits such wonderful control over her own operations. Man, who could not exist in a civilized state without in a measure unbalancing Nature's stable equilibrium, has per- sistently exceeded that measure. His action has, on the whole, been destructive, although in some places and in recent times there is a reverse to this melancholy picture. There are regions first peopled by Europeans not more than two hundred years ago which already show signs of dilapidation. The author then enters upon a detailed description of man's inter- ference with Nature in respect to animal and vegetable life, showing how he promotes the growth of certain species of plants and animals often changing their nature in a wonderful degree by his care and cul- tivation,— how he greatly reduces the numbers of other animals and plants, often altogether expelling certain animals from particular re- gions, and sometimes, though rarely, effecting, or at any rate greatly hastening, the annihilation of certain species. Mr. Marsh illustrates the matter by copious examples culled from his prodigious and ency- clopedic reading. It would be hopeless to attempt to give any ad- equate idea of their variety and interest. Few men indeed are so minutely acquainted with historical botany and zoology, and with the practical side of natural history, as not to find in these pages a rich harvest of the most interesting and instructive details. No less remarkable is the author's chapter on forests, their position in the economv of Nature, their influence on climate, on torrents and inundations, on health, and the importance of man's operations involv- ing their destruction or conservation. GEORGE PERKINS MARSH. 451 Waters and their management are treated with the same mastery of details. It is shown how, by mau's various devices for obstructing, directing, and in geueral governing water, the action of tides and the fauna and flora of regions may be altogether changed, whether bene- ficially or injuriously. Even dry sands are invested with an interest not their own. The value of dunes, and the details of their wise management, are made the subject of one of the most interesting chapters of this most inter- estinof book. But the part of the work which will pei'haps most engage the atten- tion of the general reader is the concluding chapter, in which Mr. Marsh has examined by the light of wisdom and experience all the great projects proposed within the last quarter of a century for the extensive modification of the face of Nature. In this chapter he discusses such vast su])jects as the cutting of isthmuses like Suez and Darien, the proposed canal to open the Dead Sea, the Caspian and Azof Canal, the flooding of the Lybian Desert, and the diversion of the Colorado River for the reclaiming of the great Colorado Desert, and incidentally dis- cusses such living questions as the damage caused by hydraulic mining, and even the extent to which volcanic action may be subject to man'3 control. And lest the consideration of such immense results of man's action should blind the reader to the equal imjjortance of little agencies repeatedly brought into action, the author concludes his work with this eminently philosophical remark. " In the vocabulary of Nature," says he, " little and great are terms of comparison only ; she knows no trifles, and her laws are as inflexible in dealing with an atom as with a continent or a planet." This last remark is but one of many keen and clever bits of philoso- phy with which the woi'k abounds. Mr. Marsh keeps ever in view the peculiar needs and dangers of the two nations that shared his best affections, America and Italy, and he is abundant in practical sugges- tions for both countries. His views of history are large and clear, especially in regard to the influence of education and of civil and re- ligious liberty. The man's generous nature appears in this, as well as in the frank tribute which he willingly pays to Elisee Reclus, his only rival in this branch of literature. Mr. Marsh's style is always clear and direct. In his choice of words he is not rigidly a purist. "When such words as "degradation," mean- ing the wearing away of the surface of a hill-side, or the like, or "flotation," come handy, lie uses them without apology. Even the American words " lumber " and " lumberman " he does not disdain. 452 GEORGE PERKINS MARSH. In a work of this nature mere diction is, of course, a secondary matter ; yet the reader occasionally meets with some concise sentence which reveals remarkable epigrammatic force, and a passage here and there full of poetic beauty. And if the reader would know liow a man occupied in the varied labors of a life like Mr. Marsh's could find the time or the v/ill to pro- duce a work like this, he will find his answer in the author's admirable disquisition, on pages 11-14 of this book, upon the duty and profit of learning to see. " Sight," says he, "is a faculty; seeing, an art. To the natural philosopher, the descriptive poet, the painter, the sculptor, and indeed every earnest observer, the power most important to culti- vate, and at tlie same time hardest to acquire, is that of seeing what is before him." This power Mr. Marsh had acquired to a high degree, and had so well used it to fill his memory with an infinite variety of useful facts that their expression, when digested in the alembic of his judicious mind, must have been to him as much a delight and a neces- sity as to another it would have been a labor and a weariness ; for from the abundance of the heart the mouth speaketh. The monograph on the Camel belongs to the period in which Mr. Marsh was Minister of the United States at Constantinople. "The practicabiUty and expediency of introducing the camel into the United States " had engaged his attention " as a problem of much economical interest," even before he went to Turkey. In that country he was able to investigate the subject yet more fully. He also turned to good account several months of travel in Egypt, Nubia, Arabia Petrtea, and Syria, and he likewise saw the camel at work in Constantinople and at different points in Asia Minor. Besides these personal observations, he gathered such information as he could by inquiry and correspondence, and by consulting the books of travel and natural history to which he had access. " By these means," he says in his Preface, " I arrived at a strong persuasion of the probable success of a judiciously conducted attempt to naturalize in the New World this oldest of domestic quad- rupeds, and at the same time I collected most of the materials which compose the following pages." After his return to America he added to his previous sources of information the valuable treatises of Hitter, Carbuccia, and others. Before Mr. Marsh's treatise was printed, he had delivered a lecture covering some of the same ground before the Smithsonian Institution, which incorporated it in one of its Reports. The occasion for publish- ing the book appears to have been given by the discussions in Congress on the question of '' importing camels for army transportation and for GEORGE PERKINS MARSH. 453 Other military purposes," wLich culminated in an appropriation of money to this end. Mr. Marsh's handling of this subject shows the spirit in which he studied all subjects. His work never was that of a dilettante. By ori- o-inai investiiiatious he would form clear and strong convictions, which he would then carefully compare with the opinions of other observers, never failing to reach substantial practical conclusions. Of this trea- tise on the Camel he says, " I claim no merit but that of fidelity in presenting the conclusions at which I have arrived." " I have in- tended," he adds, " to take a purely practical view of my subject, and I have, therefore, sought to condense into the limits I have prescribed to myself the greatest possible amount of information, and to fortify my statements by the most reliable authorities." A rapid survey of this book will show how well the author carried out his purpose. In a brief introductory chapter he reminds us that the Creator com- manded man to subdue the earth, and invested him with dominion over all terrestrial creatures. Man has, as yet, fulfilled but a part of this proud destiny. Of all the vegetable and animal products of the globe at least, comparatively few have been subdued to human use, still fewer permanently domesticated in our fields and our households. The proper savage only asks of inorganic Nature the gifts which she spontaneously offers him. But even in the very dawn of social life, man demands of the organic world, uot merely the usufruct of its spon- taneous productions, but the complete appropriation and domestication of many species of both plants and animals. "We accordingly owe to our primeval, untutored ancestors the discovery, the domestication, and the acclimatization of our cereal grains, our edible roots, and our im- proved fruits, as well as the subjugation of our domestic animals, while civilized man has directed his efforts under the Creator's commission almost exclusively to the conquest of the inorganic creation, and has scarcely reclaimed a plant of spontaneous growth, or added a newly tamed animal to the flocks and herds of the pastoral ages. Many of the domesticated families of the organic world are pecu- liarly suited to the uses of man as a migratory animal, and are appar- ently almost exempted from subjection to climatic laws, and accordingly follow him in all his wanderings. Others seem to be inexorably con- fined within prescribed geographical bounds. Others, again, though comparatively independent of climate and of soil, are nevertheless specially fitted to certain conditions of surface, and to certain modes of human life, to the maintenance of which they are themselves indispensable. 454 GEORGE PERKINS MARSH. In the second chapter Mr. Marsh goes on to show that the camel belongs to the last-mentioned class of domesticated animals. Nature has adapted this quadruped chiefly to the desert, where he acquires his true significance and value, his remarkable j^owers being the ne- cessary condition and sole means by wliich man has in any degree extended his dominion over the Libyan and the Arabian wildernesses, for example. But as society advances in refinement, the camel gives place to animals better suited to the wants and caprices of hio-her civilization. Even the enclosing of land for agricultural uses, and the superseding of the coarse herbage of spontaneous growth by artificial vegetation, are unfavorable to his full development and physical per- fection. Hence the attempts to introduce the camel into Spain, Italy, and other European countries have met with at best a very indifferent success. Mr. Marsh next examines the several species and breeds of the camel, in a series of learned chapters on the general and special anat- omy of this animal, treating in detail of the hump, the head, the foot (adapted as well to the yielding sands as to the rugged rocks), and of the complicated structure of the stomach. Then follows a chapter on the size, color, diseases, temper, and longevity of the animal ; after which the useful products of the camel, and his diet and powers of abstinence, are examined. His training and treatment form the next division of the subject. The author here gives us, upon the best authorities, an astonishing estimate of the great carrying power of the camel, and shows us the proper mode of saddling him for this service. Precise statements follow of the camel's speed and gait. Then, after having relieved the severity of his discussion by quoting from another writer an interesting and instructive passage on the char- acteristic pleasures and pains of travel by camel caravan, and after an allusion to the almost incredibly great number of camels employed in Egypt and other Mussulman countries, Mr. Marsii goes on to discuss tlie "geograpliical range" of the several species. One species is found in perfection in some of the hottest countries on the globe. Another bears with impunity the severities of Northern winters. The geographical range of the camel has been greatly extended even in comparatively recent times, and Mr. Marsh confidently expected that this animal would be naturalized in yet other regions, including New Mexico and California. Having thus fully established the great value of the camel as a helper in man's work, the author answers affirmatively the ultimate question whether any large tracts of our territory possess the climate GEORGE PERKINS MARSH. 455 and soil best fitted to the animal's usefulness. lie shows that our Trans-Mississippian regions, and our Southwestern territories, in- cluding the southern passes of the Rocky Mountains, possess all the requisite conditions. In the closing chapter he traces the use of the camel for military purposes from the earliest historical times to the present, and sets forth the expediency of emjiloying the animal in these services iu the United States, especially against our hostile Indian tribes. Mr. Marsh had the satisfaction of seeing the introduction of the camel tried by our goverimient with so much wisdom and skill as to elicit his warmest praise of all those who had a share in the experi- ment. He forgets, however, to claim any praise for his own distin- guished services in the matter. The book has an index, which places its valuable contents readily at the reader's command. While the books that have just been analyzed may l)e called scien- tific, those of the second group belong to the provinces of philol- ogy, literary history, and archaeology. The largest of Mr. Marsh's works in these departments are the courses of lectures delivered by him, in New York and Boston respectively, upon the English Lan- guage. The first of these was given at Columbia College in the years 1858-59, and published under the name of " Lectures on the English Language " ; the second was delivered at the Lowell Institute in 1860-Gl, and issued with the title of "Origin and History of the Eng- lish Language, and of the early Literature it embodies." Another of his philological woi-ks is the admirable enlarged edition of Wedgwood's Dictionary of English Etymology. Mr. Marsh's attainments in the Scandinavian languages and lore were early recognized and honored by the learned societies of North- ern Europe. One fruit of liis studies in that direction was a Grammar of the Icelandic Language, compiled from the several works of Rask, the Danish philologist. The antiquarian researches of IMr. Marsh are represented by the careful study that he made of the position and influence of the Goths in history, even tracing the Gothic element in the Puritans of New England. The two groups into which we have ventured to divide Mr. Marsh's writings combine their forces to prove how vast and exact was his learning, and how thorough and judicious were his methods of intellect- ual work. But it is the first group that specially exliibits his individual chai'acteristics. There we see him pursuing a wholly new inquiry, 456 GEORGE PEEKINS MARSH. and again conducting triumpliantlj the investigation of a subject so abstruse, so vast, and so complex, that it is fair to say he had no rival in the work. These two books of his must long remain the classics in their respective provinces. It is for these reasons that an analysis of them has been attempted iiere. In the second class of subjects, on the other hand, Mr. Marsh was one of many laborers. The study of language, in its several divisions, has been many years enHsting a larger and larger number of able scholars. Moreover, in the rapid progress of modern philology, any man's labors, be they never so eminent, may soon be superseded, wholly or in part. We are very far, however, from intimating that any such destiny has overtaken Mr. Marsh's philological or literary works. They will ever be store- houses of precious materials ; and they are now, in their latest re- visions, so fully abreast of the most recent discoveries, that no earnest student of English philology can afford to neglect them, or is in danger of doing so. All these considerations render it inexpedient to essay here the analysis of any book of Mr. Marsh's in this department ; nor, indeed, could any fair analysis be made that should not transgress the reasonable limits of a notice like this. An account of Mr. Marsh and his work would fall far short of completeness, even in form, without some allusion to his remarkable library. No monument can be reared to the memory of a man of letters more fitting than the one he has reared for himself in the collection of books that he gathered about him as the instruments and helpers of his daily tasks. The scholar's loves and purposes are em- bodied in his library as truly as in his published work ; often, perhaps, even more fully. This library is described as containing twelve thousand volumes, some miscellaneous and modern, " many rare, valuable, ancient, and curious." The languages of Northern and Central Europe are, of course, largely represented; those of Southern Europe probably no less so. For Mr. Marsh's attention had been fixed, for several years before his death, on the revival, which is even now in progress, of the noble Catalan dialect and of the Provencal, and his intimate study of the Italian language had led him, long before, into the less frequented paths of its literature. One of his cherished plans had been that of a complete English-Italian Dictionary which should ade- quately register the " grammatical relations " of the words in each lan- guage, and should be worthy of both. As he felt his own strength declining, he often tried to persuade younger students to engage in this work. ISAAC RAY. 457 By the liberality of an aliiinnus of the University of Vermont, of which Mr. IMarsh was for a time one of the Trustees, this precious collection of books has been secured for that institution. It is to be regretted tliat these literary treasures were not deposited whei-e the largest numbers congregate of those who would turn them to good account. Yet, while we deplore the limitation of its usefulness, we cannot but be glad that Mr. Marsh's library, unlike that of tiie late Mr. Benfey and other valuable collections, has found a large-minded and large-hearted man who would not allow its collective force to be destroyed. ISAAC RAY. Isaac Rat, M. D., LL. D., was born at Beverly, Mass., January 16, 1807, and died in Philadelphia, March 31, 1881. Dr. Ray graduated from Phillips Academy and Bowdoin College, teaching school during vacations in order to help defray his expenses. He took his decree of Doctor of Medicine at the Harvard Medical .School in 1827, and at once began practice in Portland, Maine, where he was married in 1831. Soon after, removing to Eastport in the same State, he published (in 1838) his " Medical Jurisprudence of In- sanity," a book of which the sixth edition has recently appeared, and which has remained for more than forty years the leading work in the English language upon that subject. Dr. Ray was Medical Superintendent of the State Hospital for the Insane at Augusta, Maine, from 1841 to 1846. He was then ap- pointed to take charge of the building of the Butler Hospital for the Insane at Providence, R. I., of which he was the head for twenty years after its completion. He was also for a few months in charge of the McLean Asylum at Somerville, Mass., but failing health com- pelled him to seek a milder climate, and the last fourteen years of his life were spent in Philadelphia, very much saddened toward the end by the death of his only surviving child, a son, practising medicine, and hav- ing hie office in his father's house. Dr. Ray was one of the organizers of the Association of Medical Superintendents of American Institutions for the Insane, in 1844, and was its President from 1855 to 1859. He was a most careful student, having visited Europe to examine the hospitals there, and a most assiduous writer upon the various subjects of interest in his branch of the medical profession. His " Mental Hy- giene," a series of lectures delivered before the Lowell Institute in Boston, published in 1863, and his "Contributions to Mental Pathol- 458 THEODORE LUDWIG WILHELM VON BISCHOFF. ogy," collected for publication in 1873, illustrate the thoroughness of his work, his earnestness of purpose, and liis clear, vigorous style. Dr. Ray was not only for more than a quarter of a century the acknowledged head of the alienists in this country, but, deeply inter- ested in all that pertains to the welfare of the human race, he was also one of the leading sanitarians and social scientists of his day, contrib- uting freely from his abundant resources to the proceedings of the American Public Health Association and the Social Science Associa- tion, As one of the directors of the Blockley Almshouse and Hospi- tal in Philadelphia, he was a practical reformer of institution abuses. During his whole professional career, he was one of the foremost in adopting the more progressive views of recent years in treating the in- sane with increasing freedom, and in endeavoring to make their lives as little unlike the lives of the sane as possible. The monument of his life's work is the Butler Hospital, built under his own eyes, beau- tified and improved from year to year as larger experience suggested, from the chapel of which he chose to be buried, and to which he be- queathed the greater portion of his property, subject to his widow's life interest in it. Dr. Ray's wisdom, purity of character, and faithfulness to every duty, won the regard of his fellow-men. His unremitting care of his patients gained their affectionate esteem, as his genial manner, wide information, and wonderful powers of conversation captivated their attention and drew them away from their morbid thoughts. During a long and painful illness his courage never failed. During an active life of more than threescore years and ten, in which he often saw the worst side of human nature, his faith in mankind never faltered. FOREIGN HONORARY MEMBERS. THEODORE LUDWIG WILIIELM VON BISCHOFF. Theodore Ludwig Wilhelm von Bischoff, who died at Mu- nich on December 5, 1882, was born at Hannover, October 28, 1807. His father was Christian Heinrich Ernst Bischoff, a physician who held professorships at Berlin and Bonn, and was the author of several works on medicine and chemistry. The younger Bischoff began his studies with his father, and pursued them at Diisseldorf, Bonn, and THEODORE LUDWIG WILHELM VON BISCHOFF. 459 Heidelberg, receiving the degree of Doctor of Philosophy in 1829, and that of Doctor of Medicine in 1832. He obtained an appointment as assistant in midwifery at Berlin. Here he met with Johannes Miiller and Ehrenberg, under whom he continued his studies in anatomy and physiology. From 1835 to 18i3 he delivered lectures on comparative patliological anatomy at Heidelberg, and from IS-IS to 1855 was Pro- fessor of Physiology and Anatomy at Giessen, where he established a Museum of Anatomy and a Physiological Institute. In 1854, having declined offers from several German universities, he accepted the chair of Human Anatomy and Physiology at Munich, succeeding the anato- mist Foerg. In 1850, he appeared with Liebig at the famous trial of Count Giirlitz, who was accused of wife-murder, and demonstrated the im- possibility of spontaneous combustion. His views on this subject may be found in his paper, " Ueber die Selbstverbrennung," in the Annales de la Medecine Legale, 1850. Bischoff belonged to the older school of German embryologists, who under the lead of Von Baer laid the foundations of modern mor- phology. He [)aid considerable attention to the anatomy of the Quad- rumana, and his last papers were devoted to the comparative study of the brain of monkeys. His more important memoirs, however, are his investigations on the development of Mammalia, published between 1842 and 1852. The monographs he published on the Dog, the Guinea-Pig, the Rabbit, and the Deer have remained the basis of all the more recent studies on the development of the higher mammals. BischofF was elected Foreign Honorary Member of this Academy, November 13, 1849, and his letter acknowledging his election, dated at Giessen, May 20, 1850, is worthy of being preserved, as showing his large and liberal spirit : — " This unexpected honor, paid me from a land so distant from my native country, possesses for me a high worth, as an evidence of the acknowledgment of my scientific labors and exertions. It encourages me to hope that these labors possess a generally useful character, and that they have acquired the approbation of the patrons of science in your society. This marked honor is flattering to me also, inasmuch as it furnishes fresh evidence that the United States, so long the asylum of my poor and oppressed countrymen, forced to leave their native Germany, will also kindly receive German science, fostering and ad- vancing it upon a more fruitful ground than can be found in the much overcrowded fatherland." 460 JOSEPH LIOUVILLE. JOSEPH LIOUVILLE. Joseph Liouvillb came into the world of science from a liig'ily esteemed family of Lorraine. lie was born on Friday, March 24, 1809. In 1827 he was graduated, with marked distinction, at the Ecole Polytechnique, behng classed in the service of the Pants et Chaussees. But he renou.iced the career thus opened to him, and determined to devote his life to the advance of science and to the work of education. In 1831 he became instructor (repetitenr), and in 1838 professor, at the Ecole Polytechnique. He was called later to professorships at the College de France and at the Sorbonne ; and in the active discharge of his duties at the College de France he remained up to his death. He became a member of the Academy of Sciences in 1839, and of the Bureau of Longitudes in 1841. In the revolutionary year 1848 he was elected to the Constituent Assembly as a representative of Moselle, and was distinguished there, accord- ing to M. Laboulaye, for his clearness and fluency of speech ; but, on the expiration of his official term, he gladly withdrew from a life which only unusual emergencies had induced him to enter. In 1836 M. Liouville founded the Joarmd de Mathhnatiques Pares et Appli- quees, which he edited, with distinguished ability, for a period of thirty- nine years, down to 1875. This |)ublication, which is still everywhere known by his name, is a lasting monument of his industry and scien- tific power, and has contributed greatly to the influence and reputa- tion of French geometers. The later years of Liouville's life were saddened by severe domestic griefs and by failing health. But his mind remained unclouded and active. He undertook, but was unable to finish, his course at the College de France in the last year of his life. He was present at a meeting of the Bureau of Longitudes two days before his death ; which took place, suddenly at the last, on Friday, September 8, 1882. M, Liouville has been an eminent figure among the mathematicians of his day, an able, vigorous, and original worker in the field of science, an example of simple self-devotion, and the centre of an important influence. The titles of his memoirs occupy very nearly twelve pages in the Royal Society Catalogue of Scientific Papers to 1873 inclusive. These writings, treating chiefly of subjects in pure analysis, contain many valuable contributions to mathematical science, and are marked by a beauty of form which is itself a mathematical excellence. They have helped to give a shape to the scientific thought of our time. As an editor and a professor also M. Liouville has EMILB PLANTAMOUR. 461 exerted a strong regulating and stimulating influence. He was a brilliant and inspiring lecturer ; and it was into his 2:5rofessoriaI work that he threw the fulness of his strength, discerning, training, encour- aging, and bringing forward the mathematical genius of a generation, and impregnating it, in his admirable courses, with fertile germs of new discovery. He was no less happy in addressing the Academy. M. Faye, in his speech at the grave of Liouville, tells us that he was in his prime a powerful scientific orator, and that he was equalled only by Arago in ability to give to a general scientific audience a sense of real insight into the abstruse conceptions of the higher analysis. i\l. Liouville was chosen a Foreign Honorary Member of this Academy in 1859, as successor to Cauchy. We have lost in him one who has played an important part in the development of mathematical knowledge during the past half-century. EMILE PLANTAMOUR* Emile Plantamour, Professor of Astronomy and Director of the Observatory at the University of Geneva, died at Geneva, September 7, 1882. He was born at Geneva, May 14, 181.5, and received his eai'Iy education in the old college founded by Calvin, after which he spent eight years in the then celebrated school of Hofrozl. In 1833 he entered the Geneva Academy, where he became one of the astronomer Gautier's most promising pupils. After graduating in philosophy, he resolved to make the study of astronomy the work of his life, a design in which he was encouraged by Gautier, who, on account of an affection of his sight, promised to vacate his chair in Plantamour's favor when the latter had completed his university education. From Geneva Plantamour proceeded to Paris, where he studied for two years under Arago. He was also a pupil of Bessel at Konigsberg, where, in 1839, he took the degree of Doctor, the subject of his thesis being the methods of calculating the orbits of comet:^. From Konisrsberg he went to Berlin, and worked for some time with Encke, who recognized in his quickness of observation and aptitude for complex calculations his special fitness for the career to which he intended to devote him- self. On his return to Geneva Plantamour received the double appointment of the Professorship of Astronomy in the Academy * This notice is taken chiefly from the Montlily Notices of the Eoyal Astro- nomical Society of London, February, 18S3. 462 EMILE PLANTAMOUR. (which has since been transformed into a University) and Director of the Observatory. In 1848 he accepted also the chair of Physical Geography, and he retained all three positions until his health began to fail him, a few months before his death. His publications chiefly related to atmospheric electricity, observations of comets, and meteoro- lo'j-ical observations made on the Great St. Bernard. Special refer- ence should be made to the important investigations of the diurnal oscillations of the soil undertaken by him by means of spirit-levels, and of which accounts are given in the Comptes Rendiis for 1878 and 1879. Much of his time was devoted to meteorology, and his papers in the Bibliotheque Universelle on the subject were numerous; he was also one of the most active members of the Helvetic Scientific Society for the observation of atmospheric phenomena. He devoted attention to geodesy, and in 1861 became the representative of Geneva on the Paris Geodetic Commission. He was also a useful member of the International Geodetic Association, which met a few years ao'o at Geneva. In connection with the Genevan Society of Arts he oro^anized a watch and chronometer competition, which has proved of great value to the staple industry of Geneva. Watches and chronometers are sent to the Observatory and tested there, the results being published, and prizes awarded to tlie best time-keepers. Four years ago he added to the Observatory at his own expense a refractor of ten inches' aperture, and he erected the building for its reception. He was a man of fortune, and might have devoted his life to social enjoyment and ease ; but he was deeply attached to science, and preferred to retain his posts at the University, altiiough the modest salary he received scarcely covered his exjjenses. Plantamour's early work on cometary astronomy must not be passed over unnoticed. One of his most elaborate investigations was his determination of definite elements of Mauvais's comet of 1844, wliich was observed from July 7 in that year to the middle of March, 1845, and therefore offered a favorable opportunity for the calculation of the true form of orbit. Plantamour's lesult was a somewliat notable one : after taking into account the effect of the attraction of the planets during the comet's visibility, he concluded that at the passage through perihelion in October, 1844, the comet was moving in an elliptical orbit with a period of revolution of 102,050 ± 3,090 years. In 1846 he made extensive calculations bearing upon the motion of the two heads of Biela's comet, the I'esults of which will be found in No. 584 of the Astronomische Nachrichten. He further discussed the elements of what was called at the time " Galle's second comet," 1840, FRIEDRICH WOHLER. 463 11. (Asfro7i. Nach., No. 475, 476). In this paper he pointed out some anomalies in the intensity of the comet's light similar to what have been observed from time to time in other comets. Plantamour was a Corresponding Member of the Academy of Sciences of the Institute of France, having been elected as successor to the elder Struve. He was also a Corresponding Member of the Royal Academy of Sciences of Turin, and an Associate of the Royal Astronomical Society of London. He was elected a Foreign Hon- orary Member of this Academy on March 13, 1878. FRIEDRICH WOHLER. Friedrich Wohler, after a long manhood full of the fruits of well-directed intellectual labor, after a tranquil, honored, happy old age, died on the 23d of Sejitember last, surrounded by a loving family, and in the full possession of his faculties. He was born on the 31st of July, 1800, in the village of Eschenheim, near Frankfort-on-the-Main. He entered the Gymnasium in Frankfort in his fourteenth year, and there his boyish fondness for experiment quickly ripened into a strongly marked taste for chemistry and mineralogy, for the study of both of which sciences he had accidental facilities which influenced his whole after life. At the age of twenty he entered the University of Marburg, where he passed a year, and where, in a small extemporized private laboratory, he began the study of the compounds of cyanogen, his first paper on that subject appearing in Gilbert's Annalen, in 1821. From Marburg he went to Heidelberg, and there worked in the laboratory of Leopold Gmelin, whose influence upon him was very marked, and who quickly perceived in him the promise of future emi- nence. Here he published two papers on cyanic acid. He had at this time the prospect of becoming a physician, and took his degree as Doctor of Medicine in September, 1823. The urgency of Gmelin decided him to devote himself exclusively to chemistry, and, after a brief correspondence and warm recommendation from Gmelin, Ber- zelius agreed to receive him into his laboratory. The charming account which he wrote in his old ase of Berzelius himself, of his own residence and travels in Sweden and Norway, and of various distinguished men whom he met, is familiar to all chemists. Wohler spent nearly a year in Sweden, forming a friendship with Berzelius which was never inter- rupted, and which ended only with the life of the latter. He at first settled in Heidelberg as Privatdocent, but by the advice of Berzelius, Gmelin, and Von Buch, in 1825 went to Berlin, and there became 464 FRIEDRICH WOHLER. teacher of chemistry and mineralogy in an industrial school founded by Von Barensj^rung. While in Berlin he succeeded in isolating aluminum by the action of sodium upon aluminic chloride, and pub- lished papers upon various other subjects. In 1828, while still in Berlin, he made his memorable discovery of the synthesis of urea. We who are familiar with the artificial preparation of alizarin, of indigo-blue, and of citric and uric acids, and who can see the shadow of the coming syntheses of chinim and morphine, find it perhaps difficult to understand the influence of Wohler's discovery in the year 1828. But, as the first synthesis of an organic body from the elements, it marks the beginning of an era in the history of chemistry. In 1831 Wohler removed from Berlin to Cassel, where his wife's family resided, and where he obtained a professor's chair in the Gewerbschule. Before this, however, his lifelong fi-iendship with Liebig had been formed, and when, in 1832, his young wife died, Wohler sought for a time a congenial home with Liebig in Giessen. There the two produced their noble study of the oil of bitter almonds, — an investigation re- ceived with a general burst of admiration, and which roused even the calm nature of Berzelius to enthusiasm. In 1836 Wohler succeeded Stromeyer at Gcittingen, and was succeeded at Cassel by Bunsen. Then came the grand work with Liebig on uric acid. To this suc- ceeded a long series of papers, partly in conjunction with Liebig, partly his own exclusively. The complete list of Wohler's writings includes two hundred and seventy-five titles. There is no department of chem- istry not enriched by his labors. Many of his papers are very short, but every one is at least suggestive. Every method in analytical chemistry which he gave admitted of generalization. Nearly all the rarer elements passed through his hands, and perhaps no chemist ever had so wide an experience. Wohler had a mind fertile in methods, and a judgment seldom at fault. His character was singularly well balanced, and an inborn, keen sense of humor kept his whole nature sweet and wholesome. His pupils were warmly attached to him. They celebrated his sixtieth and seventieth birthdays, and the fiftieth anniversary of the discovery of the synthesis of urea. But on his eightieth birthday chemists of all lands united to honor the grand old man. Contributions poured in from all quarters, and not last or least from our own country. A beauti- ful marble medallion in a frame of bronze was the form which the memorial assumed, and which, worthily bestowed, was accepted with a few dignified and touching words. In 1880 the old chemist published his last paper, — a brief notice of a galvanic element containing alumi- FRIEDRICH WOHLER. 465 num. The decline of his long life had all that makes old age endura- ble, — the society of family friends and pupils, freedom from sickness or serious infirmity, a reasonable competence, and an honest, well- earned consciousness of a life full of usefulness and without stain. Since the last Report, the Academy has received an acces- sion of eighteen new members ; viz. nine Resident Fellows, one Associate Fellow, and eight Foreign Honorary Members. One member has resigned, and another has abandoned his fellowship. The list of the Academy corrected to the date of this Report is hereto added. It includes one hundred and ninety-four Resident Fellows, ninety Associate Fellows, and seventy-two Foreign Honorary Members. VOL. XVIII. (n. S. X.) 30 LIST OF THE FELLOWS AND FOREIGN HONORARY MEMBERS. KESIDENT FELLOWS. — 194. (Number limited to two liimdred.) Class L — Mathematical and Physical Sciences. — 72. Section I. — 6. Mathematics. William E. Byerly, Cambridge, Benjamin A. Gould, Cambridge. Gustavus Hay, Boston. James M. Peirce, Cambridge. John D. Rmikle, Brookliue. Edwin P. Seaver, Newton. Section II. — 13. Practical Astronomy and Geodesy. J. Ingersoll Bowditch, Boston. Seth C. Chandler, Jr., Cambridge. Alvan Clark, Cambridgeport Alvan G. Clark, Cambridgeport George B. Clark, Cambridgeport, John R. Edmands, Cambridge. Henry Mitchell, Boston. Robert Treat Paine, Brookline. Edward C. Pickering, Cambridge. William A. Rogers, Cambridge. Arthur Searle, Cambridge. Leopold Trouvelot, Cambridge. Henry L. Whiting, Tisbury. Section III. — 38. Physics and Chemistry. A. Graham Bell, Cambridge. Clarence J. Blake, Boston. Francis Blake, Auburndale. John H. Blake, Boston. Thos. Edwards Clark, Williamstown. W. S. Clark, Amherst. Josiah P. Cooke, Cambridge. James M. Crafts, Boston. Charles R. Cross, Boston. William P. Dexter, Amos E. Dolbear, Charles W. Eliot, Moses G. Farmer, Thomas Gaffield, Wolcott Gibbs, Frank A. Gooch, Edwin H. Hall, Henry B. Hill, N. D. C. Hodges, Silas W. Holman, Eben N. Horsford, T. Sterry Hunt, Roxbury. Medford. Cambridge. Newport. Boston. Cambridge. Cambridge. Cambridge. Cambridge. Salem. Boston. Cambridge. Montreal. Charles L. Jackson, Cambridge. William W. Jacques, Newburyport. Leonard P. Kinnicutt, Cambridge. Joseph Lovering, Cambridge. Charles F. Mabery, Cambridge. William R. Nichols, Boston. John M. Ordway, Boston. William H. Pickering, Boston. Robert H. Richards, Boston. Edward S. Ritchie, Brookline. Stephen P. Sharpies, Cambridge. Francis H. Storer, Jamaica Plain. John Trowbridge, Cambridge. Cyrus M. Warren, Brookline. Charles H. Wing, Boston. Edward S. Wood, Cambridge. Section IV. — 15. Technology and Engineering. George R. Baldwin, Woburn. John M. Batchelder, Cambridge. CharlesO.Boutelle, Washington, DC. Henry L. Eustis, Cambridge. James B. Francis, Lowell. 468 FELLOWS. John B. Henck, Boston. E. D. Leavitt, Jr., Cambridgeport William R. Lee, Roxbury. Frederic W. Lincoln, Boston. Hiram F. ]\Iills, Lawrence. Alfred P. Rockwell, Charles S. Storrow, William R. Ware, William Watson, Morrill Wyman, Boston. Boston. New York. Boston. Cambridge. Class IL — Natural and Physiological Sciences. — 60. Section I. — 8. Geology, Mineralogy, and Physicft of the Globe. Thomas T. Bouve, William T. Brigham, Algernon Coolidge, William O. Crosby, Jules Marcou, William H. Niles, Nathaniel S. Shaler, Charles U. Shepard, Boston. Boston. Boston. Boston. Cambridge. Cambridge. Cambridge. Amherst. Section IL — 8. Botany. William G. Farlow, George L. Goodale, Asa Gray, H. H. Hunnewell, Charles S. Sargent, Charles J. Sprague, Edward Tuckerman, Sereno Watson, Cambridge. Cambridge. Cambridge. Wellesley. Brookline. Boston. Amherst. Cambridcfe. Section IIL — 22. Zoology and Physiology. Alex. E. R. Agassiz, Joel A. Allen, Robert Amory, Nath. E. Atwood, James M. Barnard, Henry P. Bowditch, Edward Burgess, Samuel Cabot, John Dean, Walter Faxon, Cambridge. Cambridge. Brookline. Provincetown. Boston. Boston. Boston. Boston. Waltham. Cambridge. Hermann A. Hagen, Charles E. Hamlin, Alpheus Hyatt, Samuel Kneeland, Theodore Lyman, Charles S. Minot, Edward S. Morse, James J. Putnam, Samuel H. Scudder, D. Humphreys Storer, Henry Wheatland, James C. White, Section IV, Medicine and Samuel L. Abbot, Henry J. Bigelow, Henry I. Bowditch, Benjamin E. Cotting Frank W. Draper, Thomas D wight, Robert T. Edes, Calvin Ellis, Charles F. Folsom, Richard M. Hodges, Oliver W. Holmes, Robert W. Hooper, Alfred Hosmer, Edward Jar vis, Francis Minot, John P. Reynolds, Wm. L. Richardson, George C. Shattuck, J. Baxter Upham, Charles E. Ware, John C. Warren, Henry W. Williams, Cambridge. Cambridge. Boston. Boston. Brookline. Boston. Salem. Boston. Cambridge. Boston. Salem. Boston. oo Surgery. Boston. Boston. Boston. , Roxbury. Boston. Boston. Boston. Boston. Boston. Boston. Boston. Boston. Watertowu. Dorchester. Boston. Boston. Boston. Boston. Boston. Boston. Boston. Boston. FELLOWS. 469 Class HI. — Moral and Political Sciences. — 62. Section I. — 14. Philosopluj and Jurisprudence. James B. Ames, Cambridge. Charles S. Bradley, Providence. Phillips Brooks, Boston. James F. Clarke, Jamaica PL Charles C. Everett, Cambridge. Horace Gray, Boston. John C. Gray, Boston. Lam-ens P. Hickock, Northampton. Oliver W. Holmes, Jr., Boston. Mark Hopkins, C. C. Langdell, John Lowell, Henry W. Paine, James B. Thayer, Williamstovim. Cambridge. Newton. Cambridge. Cambridge. Section H. — 18. Philology and Archceology. Ezra Abbot, William S. Appleton, William P. Atkinson, Lucien Carr, Henry G. Denny, Epes S. Dixwell, William Everett, William W. Goodwin, Ephraim W. Gui-ney, Henry W. Haynes, Charles R. Lanman, Bennett H. Nash, Frederick W. Putnam John L. Sibley, E. A. Sophocles, John W. White, Justin Winsor, Edward J. Young, Cambridge. Boston. Boston. Cambridge. Boston. Cambrid'jfe. Quincy. Cambridge. Cambridge. Boston. Cambridge. Boston. , Cambridge. Cambridge. Cambridge. Cambridge. Cambridge. Cambridge. Section HL — 19. Political Economy and History. Chos. F. Adams, Jr., Henry Adams, Edward Atkinson, John Cummings, Charles Deane, Charles F. Dunbar, Samuel Eliot, George E. Ellis, Edwin L. Godkiu, William Gray, Edward Everett Hale, Henry P. Kidder, Henry C. Lodge, Francis Parkman, Andrew P. Peabody, Joseph S. Ropes, Henry W. Torrey, Francis A. Walker, Robert C. Wiuthrop, Quincy. Boston. Boston. Woburn. Cambridge. Cambridge. Boston. Boston. New York. Boston. Boston. Boston. Boston. Boston. Cambridge. Boston. Cambridge. Boston. Boston. Section IV. — 11. Literature and the Fine Arts. Charles F. Adams, George S. Boutwell, J. Elliot Cabot, Francis J. Child, Charles G. Loring, James Russell Lowell, Charles Eliot Norton, Thomas W. Parsons, Charles C. Perkins, H. H. Richardson, John G. Whittier, Boston. Groton. Brookline. Cambridge. Boston. Cambridge- Cambridge. Way land. Boston. Brookline. Amesbury. 470 ASSOCIATE FELLOWS. ASSOCIATE FELLOWS. — 90. (Number limited to one hundred.) Class I. — Mathematical and Physical Sciences. — 36. Section I. — 7. Mathematics. E. B. Elliott, Washington,D.C. William Ferrel, Washington, D.C. Thomas Hill, Portland, Me. Simon Newcomb, Washington, D. C. H. A. Newton, New Haven, Conn. James E. Oliver, Ithaca, N.Y. T. H. Saiford, Williamstown, Mass. Section H. — 13. Practical Astronomy and Geodesy. S. Alexander, Princeton, N.J. W.H.C.Bartlett, Yonkers, N.Y. J. H. C. Coffin, Washington, D.C. Wm. H. Emory, Washington, D.C. Asaph Hall, Washington, D.C. J. E. Hilgard, Washington,D.C. George W. Hill, Nyack, N.Y. Sam. P. Langley, Allegheny, Pa. Eli as Looniis, New Haven, Conn. Maria Mitchell, Poughkeepsie, N. Y. C. H. F. Peters, Clinton, N.Y. George M. Searle, New York. Chas. A. Yomig, Princeton, N.J. Section HI. — 11. Physics and Chemistry. F. A. P. Barnard, J. Willard Gibbs, S. W. Johnson, John Le Conte, A. M. Mayer, W. A. Norton, Ogden N. Rood, H. A. Rowland, L.M. Rutherfurd, Benj. Silliman, J. L. Smith, New York. New Haven, Conn. New Haven, Conn. Berkeley, Cal. Hoboken, N.J. New Haven, Conn. New York. Baltimore. New York. New Haven , Conn. Louisville, Ky. Section IV. — 5. Technology and Engineering. s Henry L. Abbot, New York. A.A.Humphreys, Washington, D.C. William Sellers, Philadelphia. George Talcott, Albany, N.Y. ' W.P.Trowbridge, New Haven, Conn. Class II. — Natural and Physiological Sciences. — 28. Section I. — 13. Geology, Mineralogy, and Physics of the Globe. George J. Brush, New Haven, Conn. James D. Dana, New Haven, Conn. J. W. Dawson, Montreal, Canada. J. C. Fremont, New York. F. A. Genth, Philadelphia. Arnold Guyot, James Hall, F. S. Holmes, Clarence King, Princeton, N.J. Albany, N.Y. Charleston, S.C. Washington, D. C. Joseph Le Conte, Berkeley, Cal. J. Peter Lesley, Philadelphia. R. Pumpelly, Newport, R.I. Geo. C. Swallow, Columbia, Mo. ASSOCIATE FELLOWS. 471 Section II. — 3. Botany. A. "W. Chapman, Apalachicola, Fla. G. Engelmann, St. Louis, Mo. Leo Lesquereiix, Columbus, Ohio. Section UI. — 7. Zoology and Physiology. S. F. Bah-d, Washington, D.C. J. C. Dalton, New York. J. L. Le Conte, Philadelphia. Joseph Leidy, Philadelphia. O. C. Marsh, New Haven, Conn. S.Weir Mitchell, Philadelphia. A. S. Packard, Jr. , Providence. Section IV. — 5, Medicine and Surgery. Fordyce Barker, New York. John S. Billings, Washington, D.C. Jacob M. Da Costa, Philadelphia. W.A.Hammond, New York. Alfred Stille, Philadelphia. Class III. — Moral and Political Sciences. — 26. Section I. — 7. PJiilosophy and Jurisprudence. D. R. Goodwin, Philadelphia. R. G. Hazard, Peacedale, R.L Nathaniel Holmes, St. Louis, ]Mo. James McCosh, Princeton, N.J. Charles S. Peirce, New York. Noah Porter, New Haven, Conn. Jeremiah Smith, Dover, N.H. Section II. — 8. Philology and Archceology. A. N. Arnold, Pawtuset, R.I. D. C. Gilman, Baltimore. A. C. Kendrick, Rochester, N.Y. A. S. Packard, Brunswick, Me. E. E. Sahsbury, New Haven, Conn. A. D. White, Ithaca, N.Y. W.D.Whitney, New Haven, Conn. T. D. Woolsey, New Haven, Conn. Section IH. — 6. Political Economy and History, George Bancroft, Washington, D.C. S. G. Brown, Hanover, N.H. Henry C. Lea, Philadelphia. J. H. Trumbull, Hartford, Conn. M. F. Force, Cincinnati. W. G. Sumner, New Haven, Conn. Section IV. — 5. lAterature and the Fine Arts. James B. Angell, Ann Arbor, Mich. L. P. di Cesnola, New York. F. E. Church, New York. R. S. Greenough, Florence. William W. Story, Rome. 472 FOREIGN HONORARY MEMBERS. FOREIGN HONORARY MEMBERS. — 72. {Appointed as vacancies occur.) Class I. — Mathematical and Physical Sciences. — 22. Section I. — 5. Section III . — 9. Mathematics. Physics and Chemistry. John C. Adams, Sir George B. Airy, Brioschi, Cambridge. Greenwich. Milan. Berthelot, R. Bunsen, M. E. Chevreul, Paris. Heidelberg. Paris. Arthur Cayley, J. J. Sylvester, Cambridge. Baltimore. J. Dumas, H. Helmholtz, A. W. Hofmann, Paris. Berlin. Berlin. G. Kirchhoff, Berlin. Balfour Stewart, Manchester Section II .—7. G. G. Stokes, Cambridge. Practical Astronomy and Geodesy. Arthur Auwers, Berlin. Section IV — 3. Dollen, Pulkowa. Technology and E ngincering. H. A. E. A. Faye, Paris. R. Clausius, Bonn. J. F. J. Schmidt, Athens. F. M. de Lesseps, Paris. Otto Struve, Pulkowa. Sir Wm. Thomson, Glasgow. Class II. — Natural and Physiological Sciences. — 28. Section I. — 7. Geology, Mineralogy, and Physics of the Globe. Barrande, Prague. Des Cloizeaux, Paris. James Prescott Joule, Manchester. C. F. Rammelsberg, Berlin. A. C. Ramsay, London. Sir Edward Sabine, London. Bernhard Studer, Berne. Section II. — 7. Botany. J. G. Agardh, Lund. George Bentham, London. Alphonse de Candolle, Geneva. Oswald Heer, Zurich. Sir Joseph D. Hooker, London. Carl Niigeli,. Munich. Julius Sachs, Wurzburg. FOREIGN HONORARY MEMBERS. 473 Section III. — 10. Zoology and Physiology. Milne Edwards, Paris. Thomas H. Huxley, London. Albrecht KiiUiker, Wiirzburg. Rudolph Leuckart, Leipsic. C. F. W. Ludwig, Leipsic. Richard Owen, London. Louis Pasteur, Paris. C. Th. von Siebold, J. J. S. Steenstrup, Valentin, Munich. Copenhagen. Berne. Sectiox IV. — 4. Medicine and Surgery. C. E. BrowTi-Sequard, Paris. F. C. Bonders, Utrecht. Sir James Paget, London. Virchow, Berlin. Class IIL — Moral and Political Sciences. — 22. Section I. — 3. Philosophy and Jurisprudence. Sir Henry Sumner Maine, London. James Martineau, London. Sir James F. Stephen, London. Section II. — 7. Philology and Archceology. Georg Curtius, Leipsic. Pascual de Gayangos, Madrid. Benjamin Jowett, Oxford. Lepsius, Berlin. Max Miiller, Oxford. H. A. J. Munro, Cambridge. Sir H. C. Rawlinson, London. Section III. — 8. Political Economy and History. Ernst Curtius, Berlin. W. Ewart Gladstone, London. Charles IMerivale, Ely. F. A. A. Mignet, Paris. Mommsen, Berlin. Mark Pattison, Oxford. Von Ranke, Berlin. ^N'illiam Stubbs, Oxford. Section IV. — 4. Literature and the Fine Arts, jMatthew Arnold, Gerome, John Ruskin, Alfred Tennyson, London. Paris. Coniston. Isle of Wight. INDEX. A. Abies religiosa, Selileclit, 158. Acalypba anemioides, HBK., 154<. Lilidheimeri, Muell., 154. Neo-Mexicana, Muell., 154. phleoides, Cav., 154. radians, Torr., 154. vagaiis, Cav., 154. Acerates viridiflora, Ell., 114. Acetic aldehyde, 49. Acetone, 51. Achyronychia Parryi, Hemsl., 143. Acid, monobroraciunamic, 279. nitrous, volumetric determiuatiou of combined, 275. parabrombeozylsulpho, 86. plienyldibroralactic, 280. phenyltribrompropiouic, 277. Acids, inorganic, researches on the complex, 232. Acleisauthes Berlandieri, Gray, 143. lougiflora, Gray, 143. Acnide tamariscina, Gray, 144. Acrostichum gratum, Fee, 183. venustum. Fee, 183. Acrylic and propionic acids, on cer- tain substituted, 41. Actinella insignis. Gray, 109. linearifolia, Torr. & Gray, 109. odorata. Gray, 109. Palmeri, Gray, 109. scaposa, Nutt., 109. Adiantum teuerum, Swartz, 188. capillus-veneris, Linn., 187. tliabctroides, Willd., 187- ^cidium convallerise, Schra., 74. nitens, 76. thalictri, Grev., 75. jEpogon cenchroides, Humboldt & BonpL, 173. Agave Americana, Linn., 162. asperima, Jacobi, 162. bracteosa, Watson, 162. falcata, Eugelm., 162. Agave guttata, Jac. & Boucbe, 161. maculosa. Hook., 161. Reginse, Moore, 163. revoluta, Klotzsch (?) 162. variegata, Jacobi, 161. Wislizeni, Engelm., 162. Ageratum corymbosum, Zucc, 100. Agrostis scabra, Willd., 176. verticillata, Vill., 176. Alcohol, allyl, 53. methyl, 51. Aldehyde, acetic, 49. Allionia incarnata, Linn., 142. Allium Plummerse, 195. scaposum, Benth., 165. Alloys, electromotive force of, 221. their composition, 222. Allyl alcohol, 53. Alternanthera achyrautha, R. Br., 144. Amarantus albus, Linn., 143. chlorostachys, Willd., 143. Palmeri, Watson, 144. polygonoides, Linn., 143. retrofiexus, Linn., 143. spinosus, Linn., 143. Amblyolepsis setigera, DC., 109. Ambrosia aptera, DC, 104. Artemisisefolia, Linn., 104. psilostachya, DC, 104 Ammonium salt, 269. Anagallis arveusis, Linn., 112. Andropogou hirtillorus, Kunth, 174. laguroides, DC, 173. leucopogon, Nees, 174. myosurus, Presl., ('^) 174. Virginicus, Linn., 174. Aneimia adiantifolia, Swartz, 189. Mexieana, Klotzsch, 189. tomentosa, Swartz, 189. Anemopsis Californica, Hook., 148. Anhydride of Curcumin Dihydride, 2. Anisacanthus pumilus, Nees, 133. virgularis, Nees, 133. Wrightii, Benth. & Hook., 133. 476 INDEX. Antliericum leptopliyllum, Baker, 164. stenocarpum, Baker, 164;. Antigonou leptopus^ Hook. & Arn., 148. Antimony, the bromide of, 62. the ciiloride of, 61, 62. the iodide of, 61, 62. on their vapor density, 61. Antiphytum floribundum, Gray, 121. Parryi, 122. Autirrhiniun maurandioides, Gray, 129. Aphauostephus Arkansanus, Gray, 102. humilis. Gray, 102. ramosissimus, DC, 102. Aphyllon Dugesii, 132. Ludoviciauum, Gray, 132. multifioruin. Gray, 132. Aplopappus divaricatus. Gray, 102. rubiginosus, Torr. & Gray, 102. spinulosus, DC, 102. Apocyuum cannabium, Linn., 113. Arbutus glandulosa, Mart. & Gal., 111. xalapeusis, HBK. (?), 111. Arctostaphylos puugens, HBK., 111. Argythamina humilis, Muell., 153. mercurialina, MueU, 153. Neo-Mexicana, Muell, 153. Aristida bromoides, HBK., 174. divaricata, Humb. & Boupl, 174. pui'purea, Nutt., 174. Aristolochia brevipes, Benth., 148. pardiua, Duchartre, 148. Artemisia Mexicana, Willd., 109. Arundo donax, Linn., 181. Asclepias brachy Stephana, Engelra., 114. linaria, Cav., 114. glaucescens, HBK., 114. longicoi'nu, Benth., 114. perenuis, Walter, 114. setosa, Benth., 114. Asclepiodora circinalis, Eournier, 114. decumbens, Gray, 114. Aspidium aculeatum, Swartz, 188. athyrioides, Mart. & Gal, 188. patens, Swartz, 188. trifoliatum, Swartz, 188. Asplenium furcatuni, Thuub., 188. monanthemum, Linn., 188. parvulum. Mart. & Gal., 188. trichomanes, Linn., 188. Aster divaricatus, Nutt., 103. Drummondii, Lindl., 103. ericsefolius, Rothr., 103. Aster multiflorus. Ait., 103. Pahneri, Gray, 103. phyilolepis, Gray, 103. tanacetitolius, HBK., 103. Astragalus hypoxylus, 192. Matthewsii, 192. Wingatanus, 192. Atriplex acanthocarpa, Watson, 146. canescens, James, 146. oppositifolia, Watson, 146. parvifolia, HBK., 146. Texana, Watson, 146. Avery, Charles, notice of, 442. B. Baccharis angustifolia, Michx., 103. Bigelovii, Gray, 103. glutiuosa, Pers., 103. pteronioides, DC, 103. Texana, Torr. & Gray, 103. Bacon, John, notice of, 419. Bahia absinthiifolia, Benth., 107. Baileya multiradiata, Gray, 109. Barbiila cirrhata, Muell., 189. obtusissima, Muell., 189. Barium salt, 271. Barroettea subuligera, Gray, 101. Bartramia Gardneri, Muell. (?), 190. Basanacantha (?) reticulata, 98. Benzyl compounds, researches on the, 86. Berlandiera tomentosa, Torr. & Gray, 104. Bernardia myricaefolia, Watson, 153. (?) fasciculata, 153. Beschorneria tubiflora, Kunth, 161. Bidens chrysanthemoides, Michx., 107. heterophylla, Ort., 107. Bigelovia coronopifolia. Gray, 102. Drummondii, Gray, 102. veneta. Gray, 102. Bigonia buccinatoria, Mairet, 132. Bischoff, T. L. W. von, notice of, 458. Blechnum occidentalis, Linn., 188. Bletia campanulata, Llave (?), 159. Boehmeria cylindrica, Willd., 155. Boerhaavia erecta, Kinn., 142. erioselena. Gray, 142. linearifolia, Gray, 142. gibbosa, Pavon, 142. viscosa. Lag. & Rodr., 142. Bomaria acutifolia. Herb., 161. INDEX. 477 Boraeol from camphor, a new method of preparing, 93. Borricbia frutescens, DC, 105. Botrycbium ternatum, Swartz, 189. Virgmiauum, Swartz, 189. Boucbetia erecta, DC, 129. Boussingaultia basseloides, HBK., 147. Bouteloua Aristoides, Thumb., 178, 180. bromoides. Lag., 177, 179. Burkei, Scribuer, 179. cbondrosioides, Beutb., 179. cUiata, Griesb., 179. disticba, Bentb., 180. eriopoda, Torr., 179. havardi, Vasey, 179. hirsuta. Lag., 177, 178. litigiosa. Lag., 179. multiseta, Beutb., 180. oHgostacbya, Torr., 177, 179. pilosa, Beutb., 179. polystacbya, Torr., 177, 179. prostrata. Lag., 176. racemosa. Lag., 177, 179. scorpioides. Lag., 176, 178. simplex, Lag., 178. tenuis, Griesb., 176, 178. Texaua, Watson, 180, 196. triatbera, Bentb., 180. trifida, Tburb., 177, 179. Bouvardia augustifolia, HBK (?), 96. hypoleuca, Bentb., 97. tripbylla, SaUsb., 97. Bracbypodium ctepitosum, Roem. & ScbuL, 183. Brass yard and meter, 294. Bravoa gemiuiflora, Llav. &Lex., 161. Brickeliia Coulteri, Gray, 101. cybndracea, Gray, 101. laciuiata. Gray, 101. odontopbylbi. Gray, 101. Palmeri, Gray, 101. Riddellii, Gray, 101. Briza Rotunda, Steud., 182. Bromide of antimony, on the vapor- ' density of the, 61. Bromine, action of, on the Anhydride of Curcumin Dybidride, 4. on Curcumin, 5. on dibromstyrol, 280 Bromus ciliatus, Linn., 183. Bronze yard and meter, 293. Brunella vulgaris, Linn., 140. Bryum argeuteum, Linn., 189. Buchloe dactyloides, Engelm., 178. Bucbnera htijospermifoUa HBK. (?), 130. pilosa, Beutb. (?), 131. Buddleia Humboldtiana, Roem. & Scbult., 116. marrubiifolia, Bentb., 116. perfoUata, HBK., 116. scordioides, HBK., 116. verticillata, HBK., 116. Bumelia spiuosa, DC, 112. Buoyancy of the atmosphere, effect of the, on the weight of a body, 55. Cacabus Mexicanus, 127. Calicarpa Americana, Liuu., 136. CalUandra eriopbylla, Beutb., 191. CaUisia iusiguis, Clarke, 167. Callitricbe Austini, Engelm., 154. heteropbylla, Pursh., 154. verua, Linn., 155. Calochortus ilavus, Scbult., 165. Calophaues decumbeus. Gray, 133. linearis. Gray, 133. Calyptospora Goeppertiana, Kiibn, 79. Campanula rotuudifolia, Linn., 111. Camphor, a uew method of preparing borneol from, 93. Cauabis sativa, Liuu., 155. Capiscum baccatum, Linn., 127. Carex Schaffneri, W. Boott., 172. Carya olivseformis, Nutt., 155. Castilleia canescens, Benth., 132. lauata. Gray, 131. tenuiflora, Beutb., 131. sessiliflora, Pursb., 131. scorzouei'sefolia, HBK., 131. Cedrella Dugesii, 190. Cedronella Mexicana, Bentb., 140. Celosia Palmeri, 143. pauiculata, Linn., 143. Celtis Berlandieri, Klotzsch, 155. pallida, Torr., 155. reticulata, Torr., 133. Cencbrus ecliinatus, Linn., 173. tribuloides, Linn., 173. Centaurea Americana, Nutt., 110. Centunculus minimus, Linn., 112. Cepbalanthus Occidentalis, Linn., 96. Ceratodon purpureus, Brid., 189. Ceratopbyllum demersum, Liuu., 157- Cestrum lauatum. Mart. & Gal., 128. 478 INDEX. Oestrum laxum, Benth., 128. multiuerviuin, Duii., 128. Chaetopappa modesta, Gray, 102. Chamsesaraclia cornopus. Gray, 126. Cliapfalia nutans, HeinsL, 110. Cheilauthes Alabameusis, Hooker, 185. ciunamomea, 186. Clcvelautlii, Eaton, 186. Coopera3, Eaton, 185. farinosa, KauU'., 186. gracillima, Eaton, 186. Liudheinieri, Hooker, 186. meifolia, 185. microphylla, Swartz, 185. myriopliylla, Desv., 186. tomeutosa, Link., 186. viscosa, Link., 186. Wrightii, Hooker, 185. Chenopodium ambrosidoides, Linn., 146. Berlandieri, Moq., 146. fcetidum, Linn., 145. Fremontii, Watson, 146; murale, Linn., 146. stellatum, 146. Chilopsis saligna, Don, 132. Chlordibroniacrvlic acid, crystalline _ form of, "282. Chloride of antimony, on the vapor- density of the, 61. Chloris cucullata, Bisch., 176. elegans, HBK., 176. submutica, HBK., 176. Chlortribrompropionic acid, on the decomposition of a, by alkaline hydrates, 45. Chrysactinia Mexicana, Gray, 108. Chrysopsis pilosa, Nutt., 102. villosa, Nutt., 102. Cladothrix lanuginosus, Nutt., 144. Cnicus altissimus, Pursh., 110. Coefficients of expansion, 341. Coefficients of meters, determination of, 377. Coix ai'undinacea. Lam. (?), 173.. Coldenia canescens, DC, 119. Greggii, Gray, 120. hispidissima, Gray, 119. Mexicana, 119. tomentosa, 120 Colubrina Texaua, Gray, 190. Communications, — Josiah Parsons Cooke, 55. W. G. Earlow, 65. Wolcott Gibbs, 232. ^' [ 275. *'' [ 277. 197. Communications, — Oliver W. Huntington, 282. C. Loriug Jackson, ) o„ G. T. Hartshorn, ; ^'^• C. Loring Jackson, > -. „„ A. E. Menke, \ ^' ^'^• Leonard P. Kinuicutt, John U. NeH; Leonard P. Kinnicutt, George M. Palmer, C. F. Mabery, ) . , F. C. Robinson, | *^- Charles F. Mabery, 47. Frank Nelson Cole, 226. Edward C. Pickering, 15. William A. Rogers, 284, 287, 399. John Trowbridge, ) Walter N. Hill, ^ Sereuo Watson, 96. C. P. Worcester, 61. Comparator, Rogers-Bond Universal, 300. Comparing-rooms, description of, 326. Comparison of meters, 360, 372, 383. of yards, 362, 384. Comparisons of line and end meters, 351, 357. Comparisons of line meters, 345. Complex inorganic acids, researches on the, 232. Commelina dianthifolia, DC, 167. erecta, Linn., 167. graminifolia, HBK., 166. hirtella, Vahl, 167. pallida, Willd., 166. unditlora, Linn., 167. Virginica, Linn., 166. Conditions of Equations, 349, 355, 359, 364. Conobea multiiida, Benth., 130. Conopholis Mexicana, Gray, 131. Conyza subdecurrens, DQ., 103. Convolvulus incanus, Vahl, 123. Cooperia Drummondii, Herb., 161. Cordia Boissieri, DC, 119. Greggii, Torr., 119. podocephala, Torr., 119. Coreopsis cardaminefolia, DC, 106. Corisperum hyssopifoliuni, Linn., 146. Corrigiola Andina, Trian. & Planch., 143. Cotoneaster denticulatn, HBK., 191. Cranichis Scliaffneri, Reichenb., 159. Cressa cretica, Linn., 124. Croton capitatus, Michx., 152. INDEX. 479 Croton corymbulosus, Engolm., 152. t'ruticiilosus, Torr., 152. glaudulosus, Limi., 152. gracilis, MuclL, 122. Liudlieiincrianus, Scheele, 152. inaritinius,AValt., 152. monauthogynus, Miclix., 152. morifolius, \1'illd., 152. Paliiieri, 152. Texensis, Muell., 152. ? 152. Torreyauus, Muell. , 152. Crystalline form of chlordibromacrylic acid, 282. Cunila secunda, 136. Cuphaia cyanea, DC, 191. Cupressus Arizoiiica, Greeue, 157. Bentliami, Eudl., 157. Curcumin, 1. Anhydride of, diliydride, 2. Bromine, action of, on the anhy- dride of, diliydride, 4. Bromine, action of, on the anhy- dride of, dihydride, on, 5. Diliydride of, 1. Hydrogen, action of nascent, on, 1. Tetrabromide of, 5. Cuscuta arvensis, Beyr., 124. decora, Chois., 124. odontolepsis, Engelm., 125. Potosina, Schaffner, 124. squamata, Engelm., 124. tinctoria, Mart., 125. umbellata, HBK., 124. Cylindrothecium compressum, Bruch. & Scliimp. (?) 190. Cyperus aristatus, Rottb., 169. articulatus, Linn., 170. Baldwinii, Torr., 170. divergens. HBK., 169. flavus, Vahl, 170. flavescens, Linn., 169. flavicomus, Michx., 169. incompletus, Link., 170. inelanostacliyus, HBK., 169. Michauxianus, Schultes, 170. phymatodes, Muhl., 170. ovularis, Torr., 170. Schweinitzii, Torr., 169. uniflorus, Torr., 170. virens, Michx., 169. Cypripedium molle, Lindl., 159. Cystopteris fragilis, Bemh., 188. D. Dasylirion acrotrichum, Zucc, 164. glaucophyllum. Hook., 163. Datura meteloides, DC, 128. quercifolia, HBK., 128. Demagnetization, 201. Demagnetization, perfect, 203. Dianthera parvifolia, Benth. & Hook., 133. Dibromacrylic acid, j3, 41. Dibromstyrol, 278. Dibromstyrol, action of bromine on, 280. Dichaetophora campestris. Gray, 102. Dichoudra argentea, Humb. & Bonpl., 124. repens, Eorst., 124. Dicliptera brachiata, Spreng., 133. Dicranocarpus parviflorus,Gray, 104. Dicraurus diffusus. Hook., 145. Dicromena leucocephala, Michx., 171. Dihydride of Curcumin, 1. Dimethylacetal, 51. Diodia prostrata, Swartz, 98. teres, Walt., 98. tetracocca, Hemsl., 98. tricocca, Torr. & Gray, 98. Dioscorea — ? 163. Diospyros Texana, Scheele, 112. Diplachne dubia, Benth., 181. fascicularis, Beauv., 181. Dothidea perisporioides, B. & C, 190. Draper, Henry, notice of, 444. Dryobalanops Camphora, the natural borneol obtained from, 93. Dysodia chrysauthemoides. Lag., 108. pubescens, Lag., 108. E. Echeandia terniflora, Ort., 164. Echites CouUeri, 113. Eclipta alba, Hassk., 105. Ehretia elliptica, DC, 119. Electricity, thermo, 214. Electromotive force, 219. Electromotive force of alloys, 221. Electromotive force of the alloys of copper and zinc, 223, 224. lead and tin, 224. tin and lead, 223. 480 INDEX. Eleocliaris acicularis, R. Brown, 171. areuicola, Torr., 170. cancellata, 170. capitata, 11. Brown, 170. palustris, R. Brown, 170. Ellis's North American Fungi, 65. Pernosporae, 65. Urediuae, 65. Elytraria bromoides. Oersted, 1.33. Eucelia calva. Gray, 106. Mexicana, Mart., 106. microphylla, Gray, 106. subaristata. Gray, 106. Engelmannia pinnatifida, Torr. & Gray, 104. Epherdra antisypliilitica, Meyer, 157. aspera, Eugelm., 1.57. peduuculata, Engelm., 157. Epioampes — ? 175. Equations of conditions, 349, 355, 359, 364, 889. Equisetum robustum, Al. Braun, 189. Eragrostis lugens, Nees, 182. major, Host., 181. Mexicana, Link., 183. minor Host., 181. oxylepis, Torr., 181. Palmeri, 182. pilosa, Boem. & Schutt., 182. reptans, Nees, 181. Erigeron Canadensis, Linn., 103. dryopliyllus. Gray, 103. Palmeri, Gray, 103. pubescens, HBK., 103. Eriogonura Abertianum, Torr., 147. annum, Nutt., 147. atrorubens, Engelm., 147. ciliatum, Torr., 147. Greggii, Torr. & Gray, 147. Jamesii, Bentli., 147. longifolium, Nutt , 147. multiflorum, Benth., 147. tenellum, Tori'., 147. Wrightii, Torr., 147. Eriogonum Havardi, 194. Sheckleyi, 194. Eritrichium fulvocanescens. Gray, 121. hispidum, Buckl., 121. Eryugium discolor, 193. Erythraea calycosa, Buckl., 117. — ?li7. Eupatorium altissimum, Linn., 100. azureum, DC., 100. betouicum, Hemsl., 100. Eupatorium caelestinum, Linn., 100. Coahuilensis, Gray, lUl. dissectum, Gray, 100. incarnatum, Walt., 100. petiolare, M05., 101. Euphorbia adenoptera, Bettol., 149. acuta, Engelm., 150. albomarginata, Torr. & Gray, 149. angusta, Engelm., 150. ammatotricha, Boiss. (?), 151. antisyphilitica, Zuec, 149. bardellata, Engelm., 150. biformis, 151. campestris, Cham. & Schlecht, 150. calyculata, HBK., 151. cumbraj, Boiss., 149. deutata, Michx., 150. exclusa, 150. Fendleri, Torr. & Gray, 149. graminea, Jacq., 149. glyptosperma, Engelm., 149. heteropliylla, Linn., 150. lathy ris, Linn., 150. maculata, Linn., 149. marginata, Pur-sli., 150. Plumnierse, 195. Preslii, Guss., 149. polycarpa, Benth., 149. prostrata, Ait., 148. radians, Benth., 151. serpens, HBK., 149. serpyllilblia, Pers., 151. serrula, Engelm., 149. sphserorrhiza, Benth., 151. tenera, 150. villifera, Scheele, 149. Eurotia lanata, Moq., 146. Eustoma cxaltatuni, Griesb., 117. Evax multicaulis, DC, 103. Evolvulus alsinoides, Linn., 124. discolor, Benth., 123. sericeus, Swartz, 123. Exoascus flavus, Parlow, 83. Expansion, coefficients of, 341. F. Fellows, Associate, deceased,- Charles Avery, 419. Henry Draper, 419. George P. Marsh, 419. Isaac Bay, 419. INDEX. 481 Fellow, Associate, elected, — Samuel Pierpont Laugley, 414. Fellows, Associate, List of, 470. Fellows deceased, — Augustus A. Hayes, 419. Cliandler Robbius, 419. William B. Rogers, 411. Nathaniel Thayer, 414. Fellows elected, — Seth Carlo Chandler, 414. Walter Faxon, 415. Edwin Herbert Hall, 414. Silas Wliitcomb Holmau, 415. William White Jacques, 414. Leonard Parker Kin nicutt, 415. Charles Frederic Mabery, 415. Charles Sedgwick Miuot, 411. William Henry Pickering, 415. Francis Amasa Walker, 411. Fellows, List of, 467. Fimbristylis autumnalis, Roem. & S'chult., 171. capillaris, Gray, 171. Flaveria angustifolia, Pers., 107. chloraefolia, Gray, 107. longifolia, Gray, 107. repanda, Lag., 107. Florestina tripteris, DC, 107. Flourensia cernua, DC, 106. Force of alloys, electromotive, 221. Foreign Honorary Members elected, — Matthew Arnold, 414. Thomas Henry Huxley, 415. Carl Friedrich Wilhelm Ludwig, 412. Julius Sachs, 411. Bernhard Studer, 411, Louis Pasteur, 414. Johann Friedrich Julius Schmidt, 415. Foreign Hon. Members deceased, — T. L. W. von Bischoff, 413. Joseph Liouville, 419. Emile Plantamour, 415. Friedrich Wohler, 419. Foreign Honorary Members, List of, 472. Forestiera angustifolia, Torr., 113. Formiate, methyl, 49. Franseria tenuifolia. Gray, 104. Fraxinus cuspidata, Torr., 113. pistacisefolia, Torr., 113. viridis, Michx., 113. Vroelichia floridiaiia, Moq., 144. gracilis, Moq., 144. interrupta, Moq., 144. 81 Froment meter, the, 28 S. Fuirena squamosa, Michx., 171. Fungi, Ellis's North American, notes on some species in the third and eleventh centuries, 65. Furfurol, in the dry distillation of wood at low temperatures, 47. G. Gaillardia comosa. Gray, 109. lanceolata, Michx., 109. Mexicana, Gray, 109. pinnalifida, Torr., 106. pulchella, Foug., 109. simplex, Scheele, 109. Galinsoga parviflora, Cav., 107. Galium Aschenbornii, Schauer, 99. Mexicanum, HBK., 99. microphyllum. Gray, 99. polyplocum, Henisl., 99. proliferum. Gray, 99. unciuulatum, DC, 99. Gayophytum pumilum, 193. Gentiana lanceolata, Griesb., 117. spathacea, HBK., 117. Gerardia Greggii, 131. peduncularis, Bentli., 131. GiUa aggregata, Spreng., 117. incisa, Benth., 117. rigidula, Benth'., 117. Glyphosperma Palmeri, 164. Gnaphalium decurrens, Ives, 104. oxyphyllum, DC, 104. pannosum. Gray, 104. purpurascens, DC, 104. purpureum, Linn., 104. semiamplexicaule, DC, 104. Sprengelii, Hook. & Arn., 103. Wrightii, Gray, 104. Gochnatia hypoleuca. Gray, 110. Gomphrena decumbens, Jaeq., 144. tuberifera, Torr , 144. Gonolobus erianthus, Decaisne, 116. (?) sp., 116. parviflorus. Gray, 115. pilosiis, Benth., 116. reticulatus, Engelm., 115. Schaffueri, Gray, 116. Gossypianthus, rigidiilorus, Hook., 144. Greggia linearifolia, 191. Grindelia Arizonica, Gray, 101. costata, Gray, 102. 482 INDEX. Grindelia inuloides, Willd., 101. squaiTosa, Duii. (?), 101. Guilleiniua illecebroidcs, HBK., 14 . Gutierrezia microcepliala, Gray, 101. Texana, Torr. & Gray, 101. Gymnogramme calomelanos, Desv., 184. Ebreubergiana, Klotzsch, 184. pedata, Kaulf., 184. tartarea, Desv., 184. Gymuolomia tenuifolia, Bentliam & Hooker, 105. Gymuosperma corymbosum, DC, 101. H. Habenaria volcana (?), 159. (?), 159. Halenia llotlirockii, Gray, 117. Haploesthes Greggii, Gray, 109. Hayes, A. A., notice of, 422. Heat produced in iron and steel by reversals of magnetization, 197, 205. Hebantlie Palmeri, 144. Hechtia glomerata, Zucc., 159. Hedeoma costata, Henisl., 136. Drummondii, Beiith., 136. Palmeri, HemsL, 137. teneila, HemsL, 137. Helenium amphibolum, Gi'ay, 108. elegans, DC, 108. microcepbaluni, DC, 109. oocliuium. Gray, 108. tenuifolium, Nutt., 108. Heliantliella Mexicana, Gray, 106. HeUantlius annus, Linu., 105. ciliaris, DC, 106. debilis, Nutt., 106. laciniatus. Gray, 106. Maximiliani, Sclirad., 106. Heliopsis parvifolia, Gray, 105. Heliotropium angustifolium, Torr., 120. confertifolium, Torr., 120. convolvulaceum, Gray, 121. Curassavicum, Linn., 121. glabriusculuni, Torr., 121. Greggii, Torr., 121. inundatum, Swartz, 120. Palmeri, Gray, 121. parviflorum, Linn., 121. Hemicarpha subsquarrosa, Nees, 171. Hemiphylacus, 165. latil'olius, 164. Herpestis chamfEdrioides, HBK., 130. monniera, HBK., 130. rotundifolia, Pursh., 130. Heteranthera Limosa, Valil, 166. Mexicana, 166. reniformis, Ruiz & Pavon, 166. Heteropogou contortus, Roem. & Sciiult., 173. Heterotheca chrysopsidis, DC. (?), 102. Laniarckii, Nutt., 102. Heterotoma lobelioides, Zucc, 111. Hesalectris aphylla, Baf., 159. Hieraciuni crepidispermum, Pries., 110. Mexicanum, Less., 110. Hoffmanseggia Jamesii, Torr. & Gray, 191. Houstouia acerosa. Gray, 98. angustifolia, Miclix., 97. fasciculata. Gray, 98. longipes, 97. Palmeri, Gray, 97. Hydrochloric acid, action of, on tur- merol, 11. Hydrogen, action of nascent, on cur- cumin, 1. Hjmenatherum acerosnm, Gray, 108. gnaphaliopsis, Gray, 108. pentaclisetum, DC, 108. Wrightii, Gray, 108. Hymeuoclea mouogyra, Gray, 104. Hymenopappus artemisieefolius, DC, 107. flavescens, Gray, 107. Hyoscyamus albus, Linn., 128. Hypnum adnatuni, Hedw. (?), 190. Huffleri, Juratz, 190. Hypopliosplio-molybdate of ammoni- um, 232. tungstates, 235. Hypoxis decumbens, Linn., 161. I. Index error of a meridian circle on a method of determining the, 284. Indigofera leptosepala, Nutt., 190. Inorganic acids, researches on the complex, 232. Iodide of antimony, on the vapor- density of the, 61. Ipomcea cardiophylla, Gray, 122. I coccinea, Linn., 123. INDEX. 483 Ipomcea commutata, Roem. & Sclmlt., 122. costcUata, Torr., 123. hctei-ophylla, Ori. (r), 123. Lindlicimeri, Gray, 122. Llavcana, Mcissu., 123. Mpxicaua, Gray, 122. muricata, Cav., 122. Schaffueri, 123. siuuata, Ort., 122. stans, Cav., 123. trifida, Dow., 122. versicolor, Meissu., 123. Iresine cassinseforniis, 145. celosioidcs, Lion., 115. latifolia, Bentli. & Hook., 145. Iris floreiitiua, Linn., 160. Missouriensis, Niitt., 160. Isanthus cajruleus, Michx., 140. Isobutylether of Turmcrol, 13. Iva angustifolia, Nutt., 104. ambrosisefolia, Gray, 104. dealbata, Gray, 104. J. Jacobiaia incana, Benth. & Hook., 133. Mohintli, Bentb. & Hook., 133. Jatropha Berlaudicri, Torr., 151. spathulata, Muell., 151. Juglaus nigra, Linn., 155. rupcstris, Eiigebn., 155. Juucus acuminatus, Micbx., 169. Balticus, Willd., 167. Bufonius, Linn., 168. marginatus, Rest., 169. nodosus, Liuu., 168. tenuis, Willd., 168. xipbioides, Meyer, 169. Juniperus flaccida, Scblecbt, 158. Mexicaua, Scbiede, 158. Occidentalis, Hook., 158. K. Kuhuia lupatorioides, Linn., 101. rosmarinifolia, Vent., 101. Lamoreuxia rbinantbifolia, HBK., 132, Lantana camara, Linn., 134. canescens, HBK., 134. Lantana macropoda, Torr., 134. vclutiua, Mart. & Gal., 134. Laurauthus calycatus, DC., 148. Leucopliylluui Texauuni, Benth., 129. Lepacbvs columuaris, Torr. & Gray, 105. peduncularis, Torr. & Gray, 105. Leptochloa mucronata, Kuuth, 181. Liatris punctata. Hook., 101. Limosella aquatica, Linn., 130. Liouville, Joseph, notice of, 460. Lippia graveoleus, HBK., 134. lanceolata, Michx., 135. lycioides Steud., 135. niacbrostachya, 134. noditiora, Michx., 135. purpurea, Jacq., 134. Lithospermum angustifoUum, Micbx., 122. disticbum, Ort., 122. Matamorense, DC, 122. Palmeri, 122. spatbulatum, Mart. & Gal., 122. strictum, Lehm., 122. Litsea glaucescens, HBK., 148. Llavea cordilblia, Lagasca, 187. Lobelia Berlandieri, DC, 111. clifortiana, Linu^, 111. fenestralis, Cav., 111. gruina, Cav., 111. laxiHora, HBK., 110. spleudens, Humb. & Bonpl., 110. Loeselia cserulea, Don, 117. coccinea, DC, 117. glandulosa, Don, 117. Greggii, 117. Lonicera albitiora, Torr. & Gray, 96. pilosa, Willd., 96. Lycium barbinoduin, Miers., 128. Berlandieri, Dun., 127. brachyanthum. Gray, 127. Carolinianum, Walt., 128. Schaffueri, Gray, 128. Lycurus phalaroides, HBK., 175. Lygodesmia grandiflora, Torr. & Gray, llO. Lygodium Mexicanum, Presl., 189. Lysanthes gratioloides, Raf., 130. M. Macrosipbonia Berlandieri, Gi"ay, 113. bypoleuea, Muell., 113. 484 INDEX. Madotheca Mexicana, Hainpe, 190. Maguetism, iullueiice of, upon ther- mal conductivity, 210. Magnetite, very pure, 203. Magnetization, lieat produced iu iron and steel by reversals of, 197, 205. Marrubium vulgare, Linn., 140. Marsh, George P., notice of, 447. Marsilia Mexicana, A. Braun, 189. Martynia proboscidea, Glox., 132. fragraus, Lindl., 133. Maurandia Barclayana, Lindl., 129. erecta, Hemsl., 129. Melampodium cinereuni, DC, 104. Menodora Coulteri, Gray, 112. heterophylla, Moric, 112. longiflora, Gray, 112. scabra. Gray, 112. scoparia, Engelin., 112. Mentha arvensis, Linn., 136. rotundifolia, Linn., 136. Meridian circle, on a method of deter- mining the index error of a, 284. Metastelma Californicum, Benth., 115. Palmeri, 115. Meter, — Tresca, 287. Troment, 288. Bronze yard and, 293. Brass yard and, 294. Glass yard and, 295. Meters, comparison of, 360, 383, 386. Methyl, alcohol, 51. acetate, 50. acetone, 51. formiate, 49. Metrology, studies in, 287- Metzgeria pubcscens, Raddi, 190. Microchloa setacea, R. Br., 176. Micromeria Xalapensis, Benth., 136. Microscopes, description of, 332. Microstylis corymbosa, 195. purpurea, 195. Microstylis fastigiata, Reichenb., 159. montana, Rothr., 159. Mikania scandens, Willd., 101. Milla biflora, Cav., 165. Mimnlus glabratus, HBK., 130. Mirabilis jalapa, Linn., 142. longiflora, Linn., 142. Mitracarpium breviflorum, Gray, 98. Mitreola petiolata, Torr. & Gray, 116. Monar.da citriodora, Ccrv., 140. punctata, Lhiu., 140. Monobromcinnamic acid, 279. Montia Howellii, 191. Muhlenbcrgia Berlaudieri, Trin. (?), 174. Calamagrostidca, Kunth, 174. clomena, Trin., 174. scabra, 174. SchafFueri, Fourn., 174. N. Naraa Coulteri, Gray, 118. dichotomum, Choisy, 118. hispidum, Gray, 11*8. Jamaicense, Linn., 119. origanifolium, HBK., 119. Palmeri, Gray, 118. rupicola, Pavon, 119. Schaffneri, Gray, 119. serphylloides. Gray, 119. stenocarpum. Gray, 118. stenophyllum. Gray, 118. subpetiolare. Gray, 119. undulatum, HBK., 118. Neckera Ehreubergii, Muell., 190. Nectouxia formosa, HBK., 127. Nemastylis multiflora, Benth & Hook., 160. nana, 160. tenuis, Benth. & Hook., 160. Nicoletia Edwardsii, Gray, 108. Nicotiaua glauca, Linn., 129. nudicaulis, 128. repanda, Willd., 128. trigonophylla. Dun., 128. Nierembergia angustifolia, HBK., 129. Nitella asagrseana, SchafTner, 190. clavata, A. Braun, 190. Nitrate solution, potassic, 276. Nitrous acid, volumetric determina- tion of combined, 275. NoHna liumilis, Watson, 163. Lindheimeriana, Watson, 163. Notholsena Aschenborniana, Klotzsch, 184. brachypus, J. Smith, 184. Candida, Hooker, 185. ferruginea. Hooker, 184. Grayi, Davenport, 184. Hookeri, Eaton, 184. nivea, Desv., 185. sniuata, Kaulf., 184. Nothoscordum striatum, Kunth, 165. Nyctagmea capitata, Chois., 142. INDEX. 485 0. Oils, high boiling, 53. Oldeulaudia ovata, 97. Omphalodcs alieua, Gray, 121. cardiopliylla. Gray, 121. Oplismeuus setarius, Roem. & Schult., 173. Orthocarpus Mexicanus, Hemsl., 132. Oxidation of Tuniicrol, 13. Oxybaphus aggregatus, Vahl, 112. angustifolius, Sweet., 142. Cervantesii, Sweet., 112. glabrifolius, Vahl, 142. P. Palafoxia Hnearis, Lag., 107. Paiiicum csepitosum, Swartz, 172. colonum, Linn., 172. Crus-Galli, Linn., 172. dichotomum, Linn., 172. divaricatum, Linn., 171. ? 17L leucophfeum, HBK., 172. obtusum, HBK., 172. repeus, Linn., 172. Pappophorura apertum, Munro, 180. Wrightii, 17S. Parabrombenzyl compounds, 86. Parabrombenzylbromide, 86. Parabrombenzyldisulphide, 91, 92. Parabrombenzylmercaptan, 90, 92. mercaptid, 90, 92. Parabrombeuzylsulphide, 89, 92. Parabrombenzylsulphone, 90, 92. Parabrombeuzylsulpho-acid, 86. barium salt, 87. calcium salt, 87. chloride of the sulpho-acid, 88. _ lead salt, 88. Parietaria floridana, Nutt., 155. officinalis, Linn. (?), 155. Paronychia Mexicaua, Hemsl., 143. Parthenium argentatum, Gray, 104. confertum. Gray, 104. incanum, HBK., 104. lyratum. Gray, 104. Paspalum distichum, Linn., 172. Humboldtianiim, Fluegge, 172. Pectis angustifolia, Torr., 108. prostrata, Cav., 108. Pedicularis Canadensis, Linn., 132. Pellsea aspera, Baker, 187. atropurpurea, Link., 187. PelLsa cordata, J. Smith, 187. llexuosa. Link., 187. marginata, Baker, 187. pulciiella, Fee, 187. rigida. Hooker, 187. Secmauni, Hooker, 187. ternifolia, Link., 187. Pentabromcurcumiudibromide, 7. Pentacsena polycuemoides, Bartl., 143. Pentstemon baccharil'ohus. Hook., 129. barbatus, Nutt., 129. campanulatus, AVilld., 129. imberbis, Trautv., 129. steuophyllus, Gray, 130. tenuifolius, Benth., 130. Peperoraia umbilicata, Ruiz & Pavon, 148. Perezia Wrightii, Gray, 110. runcinata. Lag., 110. Pernospora Halstedii, Farlow, 71. obducens, Schrt., 70. viticola, DeBary, 70. Persea gratissima, Gaertn., 148. Petunia parviflora, Juss., 129. Phaceha congesta,.Hook., 118. glandulosa, Nutt., 118. integrifolia, Torr., 118. Phenyldibromlactic acid, 280. Pheuyltribrompropionic acid, 277. Philibertia cynachoides, Benth. & Hook.,^ 113. elegans, Benth. & Hook., 114. linearis, Benth. & Hook., 114. Phlox Drummoudii, Hook., 117. Phosphoroso-molvbdate of ammonium, 237. Phospho-vanadio-molybdates, 253. Phospho-vanadio-tungstates, 257. Phospho-vanadio-vanadico-tungstates, 270. Phyllactis pratensis, Benth. & Hook., 99. Phyllauthus polvgonoides. Spring., 151. Phyostegia Virginiana, Benth., 140. Physalis sequata, Jacq., 126. angulata, Linn., 126. Pendleri, Gray, 126. lobata, Torr.,'l26. mollis, Nutt., 126. Philadelphica. Lam., 126. pubescens, Linn., 126. viscosa, Linn., 126. Phytolacca Mexicaua, Sweet, 147. octandra, Linn., 147. 486 INDEX. Pileolaria brevipes, B. & Uav., 76. Puiaro])a[jpus roseus, Less., 110. Pinguicula candata, SclilecUt, 132. Pinus Ayacahuite, Elirenb., 158. cenibroides, Zucc, 158. latisquaraa, Eiigelm., 158. MontezuniEe, Lamb., 158. Teocote, Cham. & Schleclit (?), 158. Plantago caulescens, 141. Hu-tella, HBK., 141. major, Liuii., 141. Mexicaua, Link., 141. Palagduica, Jacq., 141. Virginica, Linn., 141. Plantamour, Emile, notice of, 461. Platanus Liudeniaua, Mart. & Gal., 155. Mcxicana, Moric, 155. Plucliea campliorata, DC, 103. odorata, Cass., 103. subdecurrens, DC, 103. Plumbago pulcbeHa, Boiss., 112. scandeus, Linn., 112. Plumiera ? 113. Poa annua, Linn., 182. Ruprecbtii, Peyr., 182. Pogonatum cucullatum, Hampe, 190. PoHomintba glabrescens. Gray, 137. Polygonum acre, Linn., 147. aviculare, Linn., 147. Peunsylvanicmn, Linn., 147. persicaria, Linn., 147. Polypodium aureum, Linn., 183. cbeliosticton, Pee, 183. elipsoideum. Pee, 183. furfuraceum, Scblccbt, 183. incanum, Swartz, 183. lanceolatum, Linn., 184. Martensii, Mett., 183. plebeium, Schleclit, 183. plesiosorum, Kunze, 184. subpetiolatum, Hook., 183. tbyssanolepsis, Al. Br., 184. Polyprenuun procumbens, Ijinn., 116. Polyptcris callosa. Gray, 107- Hookeriana, Gray, 107. Texana, Gray, 107. Populus alba, Linn., 156. Fremonti, Watson, 157. Porophvllura amplexicaule, Eugelm., 108. filifolium. Gray, 107. macrocppbalum, DC, 108. scoparium. Gray, 108. Potamogeton hybridus, Michx., 169. Potamogeton natans, Linn., 169. paucitlorus, Pursli., 169. Potassic nitrite solution, 276, Potassic salt, 235. Potential of a shell bounded by con- focal ellipsoidal surfaces, 226. Priva tuberosa, 135. Products of the dry distillation of wood at low temperatures, 47. Propionic and acrylic acids, on certain substituted, 41. PseudotsugaDouglasii, Eugelm., 158. Psilactis breviUngulata, Schultz Bip., 102. Pteris aquilina, Linn., 187. Pterocaulon virgatum, DC, 103. Puccinia curtipes, Howe, 82. emaculata, Schw., 81. epdobii, DC, 80. lantanaj, Farlow, 83. veratri, Duby, 81. vexans, Farlow, 82. Pylaiseea intricata, Bruch. & Schimp., 190. Pyropappus multicaulis, DC, 110. Pyroxauthiu, 47. Q. Quercus castanea, Nee (?), 156. coccinea, Wang., 156. confcrtifolia, Humb. & Bonpl., 156. crassifolia, Humb. & Bonpl., 156. Durandi, Buckley, 156. grisea, Liebm., 156. macrocarpa, Michx., 156. nigi'a, Linn., 156. reticulata, Humb. & Bonpl., 156. stellata, Willd., 156. tomeutosa, Wild. (?), 156. ? 156. virens. Ait., 155. R. Randia xalapensis. Mart. & Gal., 98. Ray, Isaac, notice of, 457. Rb'agadiolus hedypnoides, All, 110. Rhynchospora F 171. Ribes ambiguum, 193. Richardsonia scabra, St. Hil., 99. Ridcllia arachnoidea. Gray, 107. Rivina Isevis, Linn., 147. INDEX. 48T Robbins, Chandler, notice of, 427. Roestelia botryapites, Scliw., 75. comuta, TuL, 75. peuicillata, Fr., 75. B-ogers-Boud uiiiversal comparator, 300. Rogers, Wm. B., notice of, 428. Rouiinia Palmeri, 115. unifaria, Engehn., 115. Ruellia Parryi, Gray, 133. tuberosa, Liuu., 133. Rumes Berlaudieri, Meissu., 148. crispus, Linn., 147. Mexicauus, Meissn., 148. s. Sagina crassicaulis, 191. Salazaria Mexicana, Torr., 140. Salex Bouplandiana, HBK., 156. taxifolia, HBK., 156. Salvia angustifolia, Cav., 138. axilaris, M05. & Seese, 139. azurea, Lam., 137. ballotajflora, Beuth., 137. chamsedryoides, Cav., 137. coccinea, Liim., 137. farinacea, Benth., 137. glechomffifolia, HBK., 137. Graliami, Benth., 138. Greggii, Gray, 136. fulgens, Cav., 138. Hispanica, Linn., 138. lanceohita, Brouss., 138. lasiantha, Benth., 138. leucantlia, Cav., 138. Lindeuii, Benth., 138. microphylla, HBK., 138. Mexicana, Linn., 138. Nana, HBK., 138. patens, Cav., 138. pentstemouoides, Kunth, 137. regla, Cav., 137. Roemeriana, Sheele, 137. tiliajfoHa, Vahl, 137. Salviastrum Texanum, Sheele, 140. Samolus ebracteatus, HBK., 112. Sanvitalia angustifolia, Engeltn., 105. Saracha umbcllata, Don, 127. Sartwellia Mexicana. Gray, 107. Schaffuera gracilis, Benth., 173. Schoenocanlon Drummondii, Gray, 166. Scirpus lieterocarpus, 171. supiuus, Linn., 171. Sclerocarpus uniserialis, Bcntbam & Hooker, 105. Scleropogon Karwiuskyanus, Beuth., 181. Scutellaria Drummondii, Beuth., 140. Wrightii, Gray, 140. Sedum radiatum, 193. Selaginella cuspidata. Spring, 189. lepidophylla, Spring, 189. pilifera, A. Braun, 189. rupcstris. Spring, 189. saccharata, A. Braun, 189. SeKnocarpus angustifolius, Torr., 143. Palmeri, HemsL, 143. Seneco lobatus, Pers., 109. madrensis. Gray, 110. salignus, DC, 109. sanguisorba, DC, 110. toluccanus, DC, 110. Setaria imberbis, Roem. & Schult., 173. glauca, Beauv., 173. uniseta, Pourn., 173. Seyraeria bipiunatisecta, Seem., 131. virgata, Benth., 131. Shell, potential of a, bounded by confo- cal ellipsoidal surfaces, 226. Silphiuni asperrimum, Hook., 104. Siphonoglossa pilosella, ToiT., 133. Sisyriuchium scabrum, Cham. & Schleclit, 160. Schaifneri, 160. tenuifolium, Humb. & Boupl., 160. Smilax Bona-nox, Linn., 163. Solanum Cervantesii, Lag., 125. elseagnifolium, Cav., 125. heterodoxum. Dun., 125. nigrum, Linn., 125 rostratum, Dun., 125. Torreyi, Gray, 125. triquetrum, Cav., 125. tuberosum, Linn., 125. torvnm, Swartz, 126. Solidago Canadensis, Liuu., 102. nemoralis. Ait., 102. velutina, DC, 102. Speiranthes aurantiaca, Bentham & Hooker, 159. cinnabarina, Benth. & Hook. 159. Speimiacoce podncephala, Benth., 99. subulata, Pav., 99. Spirfea occidenlalis, 192. Sporobolus atrovirens, Kunth, 175. cryptandrus, Gray, 175. repens, Presl., 175. ?, 175. 488 INDEX. Stacliys agraria, Cham. & Slcheclit, 140. Bigelovii, Gray, 140. cocciuea, Jacq., 140. Drummoudii, Bentli., 140. Standards, subdivision of, 390. Star catalogues, on their reduction to a common system, 390. Stemodia durantifolia, Swartz, 130. Stenandrium dulce, Nees, 133. Stevia Berlandieri, Gray, 100. eupatoria, Willd., 100. pauiculata, Lag., 100. salicit'olia, Cav., 100. Stilliugia angustifolia, Engehn., 154. sanguiuolenta, Muell., 154. Torreyana, Watson, 154. Stipa avenacea, Liun., 174. Jurava, Beauv., 174. viridula, Trin., 174. Studies in metrology, 287. Sugeda diffusa, Watson, 147. miuutiiiora, 194. Torreyana, Watson (?), 147. Subdivisions of standards, 390. Symblepharis hehcophylla, Montg. (?), 190. Symphoricarpus microphyllus, HBK., 96. Synchytrium fulgens, Schrt., 70. Synedrella vialis, Gray, 106. Tagetes lucida, Cav., 108. Taphrina flava, Parlow, 84. Taraxacum officinale, Vill., 110. Taxodium distichum, Rich., 158. mucrouatura. Ten., 158. Tecoma stans, Juss., 132. Tetraclea Coulteri, Gray, 140. Tetragonotheca Ludoviciaua, Gray, 105. Texana, Engelm. & Gray, 105. Tetramerium hispidum, Nees, 134. Tetrahromide of Curcumin, 5. Tetrabrompropiouate, 42. baric, 42. calcium, 42. potassic, 43 Teucrium Canadense, Linn., 141. cubense, Linn., 141. Thayer, Nathaniel, notice of, 438. Theiesperma filifolium. Gray, 106. gracile, Torr. & Gray, 107. subsimpHcifolium, Gray, 106. Thermal conductivity, influence of magnetism upon, 210. Thermo-electricity, 214. Thermometers employed in the com- parisons, 328. Thevetia Yccotli, DC, 113. Tigridia Van Houttei, Roezl., 160. Tillandsia recui-vata, Linn., 159. Tinautia anomala, Clarke, 168. fugax, Scheidvr., 166. Touruefortia capitana, Mart. & Gal., 120. monclovana, 120. Townsendia Mexicana, Gray, 102. Trachypogon montufari, Nees, 173. Tradescantia crassifolia, Cav., 166. floridiana, Watson, 168. Karwinskyaua, Roem. & Schult., 166. leiandra, Torr., 167, 168. linearis, Benth., 167. micrantha, Torr., 168. rosea. Vent., 168. Virginica, Linn., 168. tuberosa, Greene, 168. Tragia nepette folia, Cav., 154. urticsefolia, Michx., 154. Tragus racemosus, Desf., 173. Transit of Venus, 15. Tresca meter, the, 287. Trichostomum Schlimii, Muell. (?), 189. strictum, Bruch. (?), 189. Tridax procumbens, Liiiu., 107. Triodia avenacea, HBK., 180. mutica, Benth., 180. Schaffneri, 181. Texana, 180. Trixis angustifolia, DC, 110. Turmeric, on certaiu substances ob- tained from, 1. Turmeric oil, 8. Turin erol, 8. action of hydrochloric acid on, 11. isobutylether of, 13. oxidation of, 13. Turmerychloride, 11. Turnera diffusa, Willd, 191. u. Ulmus crassifolia, Nutt., 155. Uromyces liliacearum, linger, 79. INDEX. 489 Uromyces Martiuii, Farlow, 78. Peckiauus Faiiow, 78. SpartiuiE Farlow, 77. Urtica cliamcedn'oides, Pursli., 155. spirealis, Blume, 155. mens, Liuu., 155. Ustilago Maydis, Corda, 190. Utricularia deuticulata, Beuj . (?),132. V. Valeriana sorbifolia, HBK., 99. tolucana, DC, 99. Vanadio-molybdates, 240. Vanadio-tungstates, 219. Vauadio-tungstic acid, 251, 252. Vauadio-tungstate of ammouium, 250. Vauadio-vanadico-molybdates, 261;. Vauadio-vauadico-molybdate of am- monium, 261. of barium, 265. tungstate of sodium, 267. tungstate of silver, 269. Vapor-deusity, on the, of the chloride, the bromide, and the iodide of antimony, 61. VariUa Mexicana, Gray, 105. Texana, Gray, 105. Venus, transit of, December 5 and 6, 1882, at the Harvard College Observatory, 15. Contacts, 17. Observers, — S. C. Chandler, Jr., 23. J. R. Edmands, 22. E. C. Pickering, 19. W. H. Pickering, 24. Arthur Searle, 20. O. C. Wendell, 21. at other stations, 24. diameter of, 30. report of S. C. Chandler, Jr., 35. report of WilUam A. Rogers, 30. photometric observations, 25. spectroscopic observations, 29. Verbascum virgatura. With., 129. Verbena bipinnatilida, Nutt., 136. bracteosa, Michx., 136. canescens, HBK., 135. ciliata, Benth., 136. officinalis, Linn., 135. polystachia, HBK., 135. remota, Benth., 136. Verbena urticsefolia, Linn., 135. xutha, Lehm., 136. Wrightii, Gray, 136. Verbesina Coahuilensis, Gray, 106. encelioides, Benth. & Hook., 106. stricta. Gray, 106. Virginica, Linn., 106. Wrightii, Gray, 106. Veronia artissima, Nutt., 100. angustifolia, Michx., 100. Ervendbergii, Gray, 100. Greggii, Gray, 100. Lindlieimeri, Gray, 100. Schaffneri, Gray, 100. Veronica peregrina, Linn., 130. Viburnum membranaceum, Benth. & Hook., 96. prunifolium, Linn., 96. Viguiera canescens, DC, 105. helianthoides, HBK., 105. linearis, Schultz Bip., 105. Vincetoxicum Mexicauum, 115. w. Weight of a body, a simple method of correcting the, for the buoy- ancy of the atmosphere when the volume is unknown, 55. Weissia longirostris, Schwaegr. (?), 189. TVTiitworth steel yard, 297. Wigandia Kunthii, Choisy, 118. Wohler, Priedrich, notice of, 463. Wood, on the products of the dry distillation of, at low tempera- tures, 47. Woodsia mollis, J. Smith, 188. obtusa, R. Br. (?), 188. Mexicana, Pee, 188. Xauthisma Texanum, DC, 102. Yale observatory standards, 330. Yard, Bronze yard and meter, 293. Brass yard and meter, 294. Glass yard and meter, 295. Whitworth steel, 297. 490 INDEX. Yards, comparison of, 362, 3S4, 3S7. Yucca augustifolia, Pursh., 163. rupicola, Scheele, 163. Zaluzania megacepliala, Scliultz Bip. (?), 105. triloba, 105. Zephyrantlies aurea, 161. cariuata, Herb., 161. Zephyrantlies concolor, Benth. Hook., 161. pallida, R,oem., 161. Texana, Herb., 161. Zexmenia brevifolia, Gray, 105. hispida. Gray, 105. Zinnia acerosa, Gray, 104. auomala. Gray, 105. juniperitblia, Gray, 104. pauciflora, Linn., 104. Zygadenus porrilblius, Greene, 166. volcauicus, Benth., 165. & University Press : John Wilson & Son, Cambridge. Mlil. WHOl UBKAKV H 1A7Z G 1 ^'^7