226 Scientific Intelligence. 



dichloricle and free chlorine. Mictiaelis has undertaken a study 

 of tellurium tetrachloride, the vapor density of which has not 

 thus far been determined. On preparing this substance the author 

 found that it was much more volatile than the books stated, and 

 that it boiled constantly at 380°. For its production a flask was 

 employed somewhat similar to that which is used for distilling 

 liquids in indifferent gases, but in which the lateral exit tube for 

 the vapor was widened to avoid obstruction by the solid chloride 

 formed. This lateral tube passed into the vertical tube of a sec- 

 ond similar flask, the chloride distilling directly from one of these 

 flasks to the other. On admitting the chlorine and gently heat- 

 ing, the tellurium passes first into the dichloricle, which is dark 

 brown when fused and gives a dark red vapor, and then with con- 

 siderable increase of volume into the tetrachloride. This when 

 fused is amber yellow and gives a vapor of the same color, but 

 solidifies into a colorless, crystalline and very deliquescent mass. 

 By a second distillation in a current of chlorine, it was entirely 

 freed from the dichloricle. Redistilled in carbon dioxide gas, it 

 boiled constantly at 380°, and its analysis agreed closely with the 

 formula TeCl 4 . The vapor density was determined by Victor 

 Meyer's method, the apparatus being filled with dry nitrogen, and 

 great care being taken to avoid the presence of moisture. In sul- 

 phur vapor at the temperature of 448°, two determinations gave 

 the values 9028 and 9*224 ; the calculated value from the for- 

 mula being 9*32. In the vapor of phosphorus pentasulphide at 

 530° — and therefore 150° above the boiling point of the tetra- 

 chloride — the values 8*859 and 8*468 were obtained. Hence it 

 appears that tellurium tetrachloride does not suffer decomposition 

 even at this temperature, thus resembling the analogous chlorides 

 of tin, of silicon and of titanium; and moreover that its formula 

 in the state of vapor is actually TeCl 4 . The author regards it as 

 proved, therefore, that tellurium has certainly a valence as high 

 as four; and from its analogies with sulphur and selenium that 

 this fact is probably also true of these elements. — Ber. Berl. 

 Chem. Ges., xx, 1780, June, 1887. g. f. b. 



6. On Diamide (Hydrazine). — When diazoacetic ether is 

 treated with hot concentrated solution of potassium hydrate, 

 Curtius has observed the formation of a new diazo-fatty acid. 

 The potassium salt is distinguished from previously described 

 diazo-compouncls by the fact that the diazo-acid set free from it 

 by the addition of a mineral acid is not decomposed with the evo- 

 lution of nitrogen, but separates in gold yellow scales. If an 

 aqueous solution of this diazo-acid be digested a short time with 

 very dilute sulphuric acid, it becomes colorless without evolving 

 gas, and the solution on cooling deposits a colorless and magnifi- 

 cently crystalline body. This substance is the sulphate of %he 

 lono* sought diamide (hydrazine) H 2 N . NH 2 . In consequence of 

 its slight solubility in water it is easily obtained pure. On warm- 

 in g its salts with alkali solution, diamide is set free as a perma- 

 nent gas, possessing a very peculiar odor, scarcely recalling that 



