Chemical Science, 207 



insoluble parts separated by the filter, and the solution evaporated 

 under the air-pump, or in close vessels by heat. It then crystallizes 

 with more or less water, according to circumstances, those obtained 

 by heat having the least. 



The hypo-phosphites of baryta and strontia may be prepared in 

 the same way, and have the same general properties : these earthy 

 salts are insoluble in alcohol. 



The alkaline salts of this class may be made either directly or by 

 mixing hypo-phosphite of lime with excess of the alkaline carbonate, 

 filtering, evaporating to dryness, and digesting in alcohol, the alka- 

 line hypo-phosphites are dissolved. The potash salt is the most de^ 

 liquescent salt known to M. Rose, but may be dried under the air- 

 pump by sulphuric acid ; the soda salt is less deliquescent, and cry- 

 stallizes in rectangular prisms. The salt of ammonia differs a little 

 from the others, principally in the action of heat ; for whilst all the 

 other salts when heated first lose water, and are then converted 

 into phosphates with the evolution of phosphuretted hydrogen, 

 this allows ammonia to rise, and there remain hypo-phosphorus 

 acid and water, which ultimately produce phosphuretted hydrogen 

 and phosphoric acid. 



By boiling the oxalate of magnesia for a long time with the 

 hypo-phosphite of lime, filtering and evaporating the Hquid, large 

 regular nacreous octoedral crystals of the magnesia salt were ob- 

 tained, containing 54.92 per cent, of water. The salts of alumine 

 and glucina appeared, when dry, like gum. Crystals of the cobalt 

 salt were most readily obtained, and were exceedingly beautiful ; 

 they were red, octoHdral, efflorescent, and contained 49.35 per cent, 

 of water. 



All the hypo-phosphites are soluble in water. 



The hypo-phosphorus acid was obtained pure and in quantity, by 

 boiling the hydrate of baryta with water and phosphorus, until all 

 garlic odour ceased ; filtering the liquid, and decomposing it by 

 sulphuric acid in excess, separating the precipitate, and digesting 

 the clear fluid for a short time with an excess of oxide of lead ; then 

 filtering the sulphate of lead from the solution of hypo-phosphite, 

 and decomposing the latter by a current of sulphuretted hydrogen. 

 The acid freed from the sulphuret of lead was then concentrated, 

 until strong enough to form the required salts. — Bull. Univ. A. ix, 

 p. 37. 



15. On Pyro'phorus. — M. Gay-Lussac has made certain experi- 

 ments on pyrophorus, with the intention of determining its nature 

 more distinctly than has yet been done, and has arrived at a method 

 of preparing one much more powerful than that ordinarily made from 

 alum, yet producingits effects in the same way. A mixture of alum and 

 lamp-black, heated in an earthenware retort, gave at first a mixture 

 of nearly equal parts of carbonic and sulphurous acids, then pure 

 carbonic acid gas ; at a later period oxide of carbon appeared, and 



