482 



SCIENCE. 



with special precautions, viz., washing the respired gases, 

 and performing parallel experiments, in which, for the 

 breath I substituted a rapid current of air, and lastly rais- 

 ing the latter to a temperature of 40 C. The result was 

 to prove conclusively my original statement that the de- 

 composition is brought about by a constituent of the 

 respired air, and therefore by its carbonic acid. In per- 

 forming this experiment it is only necessary to secure the 

 neutrality of the solution ; this being done, the develop- 

 ment of a full purple color occupies from two to three 

 minutes. 



It is evident that this demonstration of the presence of 

 some acid body precedes the lime-water test in the logical 

 development of the complete proof of the presence of 

 carbonic acid. — Chemical A r ews. 



THE BEST METHOD OF MOUNTING WHOLE 

 CHICK EMBRYO * 

 By Dr. Charles S. Minot. 

 The blastoderm is removed and cleaned in the usual 

 manner, and then floated out on a glass slide, where it re- 

 mains permanently. It is carefully spread out and allowed 

 to dry until the edges become glued to the slide. It is 

 then treated with a 0.5 per cent osmic acid solution, until 

 a slight browning occurs. Stain with picro-carmine. The 

 next step is particularly important, because it prevents the 

 further darkening by the osmium, which otherwise injures 

 or ruins the specimen. Pour Midler's fluid, or 0.5 per 

 cent chromic acid solution, on the slide, and leave it over 

 night. The next morning the blastoderm is ready for de- 

 hydration by alcohol, and mounting in the usual manner 

 in balsam or dammar lac. Embryos prepared in this 

 manner make particulary beautiful specimens. 



ON THE ALLEGED DECOMPOSITION OF THE 

 ELEMENTS.t 

 By Prof. Dewar, M.A.. F.R.S. 



In his remarks Prof. Dewar dealt chiefly with the spec- 

 troscopic work from which Mr. Norman Lockyer had 

 drawn conclusions very different from those of Professors 

 Liveing and Dewar, especially concerning the value of 

 evidence on the subject. Prof. Dewar argued that Mr. 

 Lockyer's views regarding the existence of carbon vapor 

 in the corona of the sun would not bear scientific investi- 

 gation, and that his views regarding the modification of 

 the spectrum of magnesium were equally illusory, and 

 gave no proof of the decomposition of elementary sub- 

 stances. Finally he discussed Mr. Lockyer's theory of 

 "basic lines," and addressed himself to a refutation of 

 the same. The results recorded, he said, strongly con- 

 firmed Young's observations, and left little doubt that the 

 few as yet unresolved coincidences either would yield to a 

 higher dispersion, or were merely accidental. It would 

 indeed be strange it amongst all the variety of chemical 

 elements and the still greater variety of vibrations which 

 some of them were capable of taking up, there were no 

 two which could take up vibrations of the same period. 

 They certainly should have supposed that substances like 

 iron and titanium, with such a large number of lines, 

 must each consist of more than one kind of molecule, 

 and that not single lines, but several lines of each, would 

 be found repeated with the spectra of some other chemi- 

 cal elements. The fact that hardly a single coincidence 

 could be established was a strong argument that the ma- 

 terials of iron and titanium, even if they be not homo- 

 geneous, were still different from those of other chemical 

 elements. The supposition that the different elements 

 might be resolved into simple constituents and even into 

 a single substance had long been a favorite speculation 



* Read before (he A. A. A. S., Cincinnati, 1881. 

 t British Association, 1881 . 



with chemists ; but however probable that hypothesis 

 might appear & priori, it must be acknowledged, accord- 

 ing to Prof. Dewar, that the facts derived from the most 

 powerful method of analytical investigation yet devised, 

 gave it but scant support. 



ASTRONOMY. 

 Elements and Ephemeris of Comet (d), 1881. — 

 Barnard. 



Mr. S. C. Chandler, Jr., has computed the following 

 elements and ephemeris of Comet (d), 188 J — Barnard — 

 which are published, by permission of Prof. E. C. Pick- 

 ering, of Harvard College Observatory. The observa- 

 tions upon which the computation is based are the fol- 

 lowing : Washington Mean Time being given with the 

 Nashville observation, which was obtained at Vander- 

 bilt University, by Prof. O. H. Landreth, and Cambridge 

 Mean Time with the two others : 



^-R. A.-, , Decl. , 



d. h. m. s. h. m. s. o , . 



1881. Sept. 20 7 46 Nashville 13 28 2 +3 47 



21 7 34 43 Harvard Obs. 13 30 20 4 54 

 2 5 7 *7 5 2 Harvard Obs. 13 36 29.63 9 6 43.7 



The observation of the 20th was received by tele- 

 graph, and that of the 21st depends on only two compar- 

 isons, taken when the comet was but one degree and 

 a half above the horizon. 



ELEMENTS. 



T = 1881, September, 14.785. Washington Mean Time. 



o / 



W - 271 22"! 



Q = 260 43 {-Mean Eq., 1881. o. 

 l = 107 27] 

 log. q = 9.7053 



EPHEMERIS. 



Wash, midnight, ^-R. A.— , ^-Decl.-^ 



1881. m. s. o / Log. r. Log. A. Light 



Sept. 29 13 41 36 +13 4 9.7894 0.1350 1.00 



Oct. 3 13 45 28 16 26 9.8270 0.1467 .80 



7 13 48 40 wg 29 9.8648 0.1569 .65 



11 13 51 32 22 18 9.9014 0.1628 .52 



The light of the comet on September 29 is taken as 

 unity, and in this scale its light at discovery, on Septem- 

 ber 17, was 1.85. The orbit does not resemble that of 

 any known comet. 



The comet is circular, not over one minute of arc in 

 diameter, with a very decided central condensation. Its 

 collective brightness is not more than equivalent to that 

 of an 8j4 mag. star. The comet is rapidly decreasing in 

 light, and the moon is advancing, so that observations of 

 it at once are very desirable. So far as is known, posi- 

 tions have been obtained only at Nashville and Cam- 

 bridge, the early setting of the comet, and ciouds, having 

 greatly interfered. Under the circumstances, the orbit 

 cannot be other than a rough one, and considerable lati- 

 tude for error had better be allowed in searching for it. 



MICROSCOPY. 



The following method of hardening the spinal cord for 

 microscopic sections has been highly recommended by 

 Dr. M. Debove : 



Place the cord in a 4 per cent solution of bichromate 

 of ammonia for three weeks, then in a solution of phenic 

 gum for three days, and for three days more in alcohol. 

 Sections may theu be cut with great facility. They 

 should be placed in water to prevent curling. They are 

 then immersed in a saturated solution of picric acid for 

 twenty-four houis, and colored with carmine for about 

 twenty minutes, the picric acid acting as a mordant. — 

 Archives de Neurologic 



An era of microtomes appears to be approaching, and 

 numerous are such devices which are advertised by the 

 opticians. Mr. Thomas Taylor of the Agricultural de- 



