106 COMPOSITION OF SALINE INCRUSTATIONS. 



Ou examiDation iinder the microscopej the same crystals were observed as ia the former case, 

 mixed up with amorphous powder. 



Salts of silver and baryta gave abundant precipitates ; oxalate of ammonia gave no precipi- 

 tate, nor was the solution troubled by carbonate of soda, or ammonia phosphate. 



The sulphuric acid and the chlorine were determined by the usual methods, and the absence of 

 potass proved : a small quantity of nitric acid was detected. 



The portion which was insoluble was made up of fine felspathic clay and rounded grains of 

 silica. These amounted to more than one-fourth of the whole. 



By quantitive analysis the following results were obtained in 100 parts : 



Insoluble clay and quartz 28. 



Moisture and a trace of nitric acid 7. 



Sulphate soda 19.5 



Chloride sodium 38, 



Carbonate of soda 6. 



Sulphate of lime 1.5 



100.0 



In plate 6, fig. 1, the structure of Cajon pass is shown ; in the same plate, fig. 2, the course of 

 the Mojave river is shown, with the character of the ranges it crosses, the whole number of which, 

 however, are not inserted. 



