CHEMISTRY. , 501 



suggests fiat pure oxygen may be manufactured from air on this prin- 

 ciple. The silver must not be heated above 800° 0. {Comptes rendus, 

 xcvni, June 9, 1884.) 



On Bismutliic Acid, by Carl Hoffmann. — The highest oxide of bismuth, 

 bismuthic acid, has the formula BijOs. The potassium salt is obtained by 

 passing chlorine into a solution of potassium hydroxide (specific gravity 

 1.539) in which bismuth hydroxide is suspended. The operation is re- 

 peated three times, with the addition of fresh lye. The potassium bis- 

 muthate so obtained is of the composition 2 BiOgK -f iiElil);,. It is of a 

 red-brown or dark violet-brown color, and contains more or less potas- 

 sium according to the strength of the lye. By treating the body re- 

 peatedly with water holding carbon dioxide in solution, a lighter-brown 

 compound is formed, not quite free from potassium. These compounds 

 treated with acetic acid leave an orange-colored bismuthyl-bismuthate, 

 Bi409, and treated with dilute nitric acid, a yellow-brown body, Bi408. 

 {Liehig^s Annalen der Chemie, ccxxiii, 110.) 



The Alkali Industry, by Walter Weldon. — In our review of the prog- 

 ress of chemistry in 1883 we gave an abstract of Mr. Weldon's paper 

 before the London section of the Society of Chemical Industry, Janu- 

 ary 8. This eminent authority on the alkali industry delivered (July 

 9, 1884) an address as retiring president of this society, in which he 

 continues to trace the decline of the Leblanc method and the increasing 

 growth of the ammonia method. The ammonia process being more than 

 70 per cent, cheaper than the Leblanc process per given quantity of soda, 

 the only claim the latter has for continuance is in its production of the 

 necessary article hydrochloric acid. In order to avoid closing Leblanc 

 soda works, the makers have temporarily combined to reduce production 

 and force up prices. 



One of the important problems connected with the ammonia-soda in- 

 dustry is the recovery of the chlorine at present thrown away in the cal- 

 cium chloride. Mond has recently patented the following process : The 

 residual liquor, consisting of a nearly saturated solution of sodium and 

 ammonium chlorides, is evaporated to such a degree that the sodium 

 chloride deposits, leaving the ammonium chloride in solution; this 

 is then evaporated to dryness and the solid salt treated with enough 

 sulphuric acid to convert it into hydroammonium sulphate, the chlorine 

 going off as HCl. The residual sulphate is then treated with free 

 ammonia, and so converted into neutral ammonium sulphate, for sale 

 as such, or it is sold to manufacturers of ammoniacal phosphatic fer- 

 tilizers. This process is, after all, not the recovery of chlorine from the 

 calcium chloride, but from the sodium chloride, and it involves, more- 

 over, a ra<lical change in the process, viz, the abandonment of the plan 

 of regenerating the ammonia employed, and the necessity of finding a 

 sale for the ammonium sulphate produced. Mr. Mond is said to manu- 



