218 Mr JOHNSTON on the Combination of Chlorine 



Thus, for example, 56 - 4 grs. lost 6*6, as near 6'591 which 3 atoms 

 of water amount to as possible ; and after this loss, being heated 

 to 300, it lost only '08 of a grain. The chlorine, therefore, in 

 combining with the prussiate to form this yellow powder, expels 

 from its previous state of combination the three atoms of water 

 which enter into its constitution. 



7. There only remains, then, to ascertain the relation be- 

 tween this yellow powder and the red crystals, which, as men- 

 tioned above, are the state in which the salt under consideration 

 occurs. If the dry powder be dissolved in a smah 1 portion of 

 distilled water, carefully evaporated, and a gentle heat continued 

 till the whole moisture be driven off, the salt will be obtained 

 in beautiful crystals, and of the same weight as the powder em- 

 ployed. Or if the moist and newly saturated powder be dissolved 

 and crystallized, the loss of weight will amount as before to that 

 of 3 atoms of water. 



Thus, 37'7 grs. gave 33'6 grs. of dry crystals. 

 80 grs. ... 71 

 30 grs. ... 26-7 

 50 grs. ... 44'2 



The 1st lost 4-1 grs., should have lost 4'4 



2d ... 9 ... 9'35 



3d ... 3-3 ... 3-5 



4th ... 5'8 ... 5-836 



in which the approximation is as close as can be looked for in 

 such a process. There is therefore no difference between the 

 yellow powder and the red crystals, except the crystalline ar- 

 rangement of the particles ; the elementary constitution of both 

 is the same. 



