Some Peculiar Double Salts of Lead 



15 



solution, and can not again be dissolved, as the sodium and 

 potassium compounds are, by boiling with the mother liquor. 

 The conditions of preparation may be varied between wider 

 limits in the case of the ammonium salt than with the others, 

 the same product being always obtained. A number of prep- 

 arations were made, a white, highly crystalline product being 

 obtained in each case. The method of washing and purifica- 

 tion was the same as used with the sodium and potassium 

 salts ; the salt is quite unstable, undergoing decomposition 

 very readily on exposure to air and is also acted upon by light. 



a 



In a few cases rather large, i to 2 mm. , 

 crystals were obtained. These upon ex- 

 amination under the microscope were ap- 

 parently orthorhombic prisms; the more 

 common type and the planes upon it are 

 represented in the accompanying figure. 



I a=OP 



r = GO /'oO 



d=y:PH 

 /=Poo 



Figf. 2 



The following analytical results were obtained with three sep- 

 arate preparations, designated as A, B, and C, respectively : 



The lead in these was determined by direct evaporation after 

 treatment with concentrated sulfuric acid. 



321 



