382 



APPENDIX E. 



The silicic acid was always supplied in the form of silicate of 

 potash; the potash as nitrate. In the series of experiments 

 (3) which were made without nitric acid, sulphate of potash 

 was used instead of the nitrate. 



The phosphoric acid was used in the form of 2jSraO, HO, POg -f 

 24H0 ; in experioaental series 5, in which soda was excluded, a 

 potash salt was used, 2K0, HO, PO5, of which a concentrated 

 solution was prepared, containing a known quantity of potash and 

 phosphoric acid. As the phosphate of soda contained more 

 soda than was requisite in the composition of the ash, there 

 was thus in the fluids in the experimental series 1 to 7 an excess 

 of this base ; at a later period, a' correspondingly smaller 

 quantity of phosphate of soda and more of the potash salts 

 were employed. 



The sulphuric acid was in the form of sulphate of magnesia, 

 with the exception of 7, in which sulphate of ammonia was used, 

 the magnesia required was added in the form of nitrate of 

 magnesia. 



The oxide of iron was supplied in the form of pure sublimed- 

 chloride ; the liTne as nitrate, and in the case of 3 as chloride of 

 calcium ; the ammonia as nitrate, sulphate, or chloride. 



It was scarcely possible to avoid using a larger or smaller 

 excess of one or other of the substances. This was particularly 

 the case with soda and chlorine. These deviations will be best 

 shown in the following tables. 



E.rperimental series. 



