348 EXPERIMENTS ON THE RELATION 



requires no water of composition, that we can ever expect to 

 obtain the combined or latent water of sulphuric acid, or of 

 muriate of ammonia. By this general principle, all my efforts 

 have been directed. 



I shall now endeavour to demonstrate, by particular experi- 

 ments, the accuracy of these views. 



1, Sal ammoniac was put down to the sealed end of a glass- 

 tube ; over it was placed a few inches of river sand, which, af- 

 ter having been digested with muriatic acid, had been well 

 edulcorated with water, and ignited, in a platina crucible. On 

 passing the vapour of the salt, through the ignited sand, liquid 

 of a reddish-brown colour was copiously condensed in the pro- 

 jecting and cool part of the tube. This liquid was acidulous 

 muriate of iron. I naturally ascribed the origin of this to the 

 red oxide of iron, still contained in the sand after the above 

 operations. 



2. To verify this idea, 1 then took pounded flints, and ob- 

 tained from the same quantity of salt, in various repetitions of 

 the process, a very small quantity of blue liquid, which seemed 

 to be an ammoniacal solution of copper, by its colour and 

 smell. 



S. I next had recourse to quartz nearly pure. The quanti- 

 ty of liquid obtained in the same circumstances, was now very 

 inconsiderable indeed ; and I conceived it might be ascribed to 

 some interspersed particles of mica and felspar, whose alu- 

 mina might fix a little of the dry acid, and leave water of am- 

 monia. 



4. When pure rock-crystal was employed, the aqueous pro- 

 duct became almost evanescent. The salt sublimed through 

 the ignited quartz powder, without any apparent decomposi- 

 tion. 



5. When 



