SODIUM OR rOTASSIUM : EDWAED DIVERS. 69 



that is, the quantity equivalent to the hydrochloric acid taken. 

 Next day, the remainder (in very hot weather) showed the 

 presence of .131 gram acid in lOOcc, by the same method of 

 testing. 



In alkaline solution Thum has found alkali hyponitrite to 

 be quantitatively converted into nitrite by permanganate ; I 

 have not examined the point myself. But that nitrite is then 

 formed, and that nitric acid is formed in Thum's acid per- 

 manganate method are points I have easily verified by simple 

 qualitative testing. Kirschner doubts that either is produced. 



Barium, strontium, and calcium hyponitrites. 



Barium hyponitrite is most simply prepared by adding 

 barium chloride to a concentrated solution of sodium hyponitrite 

 and stirring well. It is crystalline and almost insoluble. It 

 has been prepared by Zorn, Maquenne, and Kirschner. It is 

 an unstable and exceedingly efflorescent salt, but Kirschner 

 has succeeded in determining ils water of crystallisation satis- 

 factorily. Its formula is BaN.Oo^HaO. A crystalline acid salt 

 exists (Zorn). 



Strontium hyponitrite, Sr l^.f).,, .5H.0, Maquenne, Kirschner. 



Calcium hyponitrite, CaNoO^„4HoO, Maquenne, Kirschnei". 

 Crystalline, very sparingly soluble, and stable, not losing its 

 water even over sulphuric acid. I find that it can bo easily 

 precipitated from a fairly concentrated solution of sodium 

 hyponitrite, and can thus be prepared more easily than in the 

 ways followed by Maquenne and by Kirschner, using the silver 

 salt. On account of its stability it is a good hyponitrite to 

 keep in stock. It is sufficiently soluble for its solution to serve 



