CHEMISTRY. 433 



Hydrates of gases. — Yillard fiuds that when certain gases mixed witli 

 aqueous vapcn- are condensed in Cailletet's apparatus, crystalline hy- 

 drates are produced, which decompose spontaneously at the following 

 teujperatures: Of CH4, at 2l.o5; of CzHg, at 120; of C2H4 at 18. o5; 

 of C2H2, at 14°; of N2O, at 12°. Nitrogen, hydrogen, carbonic oxide, 

 nitric oxide, cyanogen, ammonia, propylene, butylene, and allylene gave 

 no crystals un<ler similar conditions. (Compt. Rend., cvi, 1602.) 



The formation of alloys. — The claim made by Spring that Wood's alloy 

 could be formed from its component metals hj means of pressure has 

 led Hallock to investigate the subject from another point of view. One 

 part cadmium, one part tin, two parts lead, and four parts bismuth, in 

 fine filings, were mixed in a glass tube of about five millimeters interior 

 diameter, closed at one end. The mixture was packed in the tube by 

 gentle pressure with an iron wire, and the whole was then suspended 

 in a water bath and exposed to a temperature of 98° to 100°. Within 

 two days the entire mass was tluid, the alloy having formed at a tem- 

 perature 130° below the melting point of its most fusible constituent. 



The well-known alloy of sodium and potassium, which is liquid above 

 6° C, can be produced with great ease at ordinary atmospheric tem- 

 peratures. When freshly cut surfaces of the two metals are gently pressed 

 together, liquefaction begins at the points of contact, almost instantly, 

 and spreads rapidly to completion. In short, it seems probable that all 

 alloys may be made from their components at temperatures little, if 

 any, in excess of their own melting Doints. (Zeitschr. Physikal. Chem., 

 II, 379.) 



The same alloy of sodium and potassium has also been investigated 

 thermochemically by Joaunis, who i^repared it by the usual method of 

 melting the two metals together under petroleum. The calorimetric 

 data given by the action of water upon this alloy, led Joannis to con- 

 clude that the only true compound among the sodium-potassium alloys 

 is represented by the formula NaK2. ^Ann. de Chim. Phys. (6), xii, 

 358.) 



The dehydration of metallic hydroxides by heat. — By experiments on 

 the temperature and rate of dehydration of hydrates corresponding to 

 sixteen metals, Caruelley and Walker conclude that Henry's views con- 

 cerning the polymerization of metallic oxides are mainly true. They 

 find that when a precipitated hydrate is heated, it gradually loses water 

 with the successive formation of a large number of definite hydrates, 

 each of which is further decomposed on a small rise in temperature, with 

 the formatiou of a compound containing a smaller proportion of water. 

 As the elimination of water proceeds, the residual molecule becomes 

 larger and more complex, until at last a highly complex molecule of 

 anhydrous oxide is left, of which the formula is some multiple of that 

 generally received. For the oxides of silicon, titanium, and tin the coef- 

 ficient of polymerization must be at least ten, while oxide of zirconium 

 must be at least Zr^^O^g, and autimonious oxide at least Sb2o03o. The 

 H. Mis. 142 28 



