OF POTASH. 2.57 



phate of potash may be obtained in regular crys- 

 tals. The taste of this salt is saline and not 

 strong; its crystals are octahedrons, having, 

 most commonly, a short rectangular prism in- 

 terposed between the two pyramids. It produces 

 no alteration on vegetable blues, and its constitu- 

 ents are 



1 atom phosphoric acid 3-5 

 1 atom potash . 6* 



1 atom water . 1-125 



10-625 



In general, the crystals contain rather more than 

 1 atom of water. Indeed, in a very careful ana- 

 lysis I obtained exactly 1 *68 grain of water from 

 11*18 grains of the crystals; this is precisely li 

 atom water. I am rather inclined to consider 

 the half atom as chemically combined with the 

 salt likewise ; because the crystals may be kept 

 for any length of time in a temperature above 

 500 without losing any weight. When phosphate 

 of potash is fused it assumes a yellow colour, 

 but becomes again white on cooling. 



8. Binarseniate of potash. This salt crystal- Bi 

 lizes in four-sided prisms, with square bases ; m 

 but the primary form, according to Mitcherlich, 

 is an octahedron, with a square base. Its con- 

 stituents are 



VOL. II. R 



