484 /Scientific Intelligence. 



Between two definite compounds which exist in solutions, it is to 



ds 

 be expected that the differential coefficient -=- will be a rectilinear 



dp 



ds 

 function of p : i. e., — =A + 2B». This conclusion can be veri- 

 dp 



fied by experiment. Moreover, it gives the means of ascertaining 

 what the definite compounds are which exist in the solution. 

 Applying now the method to the solutions of H 2 and C„H O, 

 three definite compounds ai'e found to exist : C„H 6 with (H 2 0) 12 

 and (H 2 0) 3 , and (H 2 0) with (C 2 H e O) s ; containing 17-56, 46-00 

 and S8-46 per cent of alcohol respectively. The rectilinear char- 

 acter of the differential coefficient is shown by plotting the results 

 in a diagram. Calculating the constants of the parabolas, ex- 

 pressions are obtained for the specific gravity in terms of the 

 percentage composition, the values calculated from which agree 

 very closely with those obtained by experiment. The author 

 finds tho above hypothesis respecting the rectilinear character of 

 the differential coefficient to be correct, not only for solutions of 

 a hundred different salts but also for solutions of H 2 S0 4 , of NH 3 , 

 of HC1, and other similar substances. Indeed up to the present 

 time he has not met with a single solution which is an exception. 

 At present he is investigating minutely, solutions at low tempera- 

 tures ; and in connection with Teeshenko he has already obtained 

 the compounds C 2 H 6 0(H 2 0) 12 and C 2 H 6 Q(H 2 0) 3 in the solid form 

 and crystallized; the former at — 17° C., and the latter in a mix- 

 ture of solid C0 2 and ether. — J. Chem. Soc, li, 778-782, October, 

 1887. G. F. B. 



7. On, the Chemical action of Bacterium Aceti. — Brown has 

 continued his experiments on the chemical action of the ferment 

 Bacterium aceti. He had shown that mannitol is completely 

 decomposed by it, levulose being the main product. He now 

 finds that its isomeride dulcitol suffers no change whatever. by the 

 action of the ferment. Glycol is readily oxidized to glycollic 

 acid. Glycerol is converted into carbon dioxide and water. 

 Erythrol undergoes no change whatever. Hence, by transform- 

 ing dextrose into mannitol by sodium amalgam, and mannitol 

 into levulose by the ferment, dextrose may be converted iuto 

 levulose. Moreover, Brown finds that the cellulose formed by 

 the ferment Bacterium xylinum from levulose, yields a dextro- 

 rotatory sugar on treatment with sulphuric acid. — J. Chem. Soc, 

 li, 638, July, 1887. ' « G. F. b. 



8. On the light emitted by glowing solid bodies. — According 

 to Dr. J. Draper, all solid bodies begin to glow at the same tem- 

 perature, which is about 525° C. As soon as a platinum wire, 

 heated by an electrical current, reaches a temperature slightly 

 above 525°, the light emitted shows a spectrum from the line 

 B to b. When the temperature reaches 645°, the spectrum ex- 

 tends from B nearly to F. At the temperature 718°, it extends 

 from B to G. And at the temperature 1165°, the spectrum has 

 nearly the full extent of the solar spectrum. Dr. Draper was led 



