Royal Society, 2 1 7 



eludes, from his experiments on this subject, that there is no proof 

 of the existence of a single supernitrate. 



In the third section he discusses the constitution of the phos- 

 phates. Phosphoric acid, he observes, is quite peculiar in being 

 capable of combining with bases in three different proportions ; 

 forming, besides the usual class of monobasic salts, containing one 

 atom of acid to one atom of protoxide as base, two other anormal 

 classes of salts, in which two or three atoms of base are united to 

 one atom of acid, namely, the pyrophosphates and the common 

 phosphates, as they are usually denominated, but which the author 

 proposes to designate by the terms, bibasic^ and tribasic phosphates. 

 Arsenic acid forms only one class of salts; but that class is anormal; 

 every member of it containing three atoms of base to one atom of 

 acid, like the common, or iribasic, phosphates. These anormal 

 classes of phosphates and arseniates, with, perhaps, the phosphites, 

 are, the author believes, the only known salts tq which the ordinary 

 idea of a subsalt is truly applicable: all other reputed subsalts be- 

 ing probably neutral in composition, as has been shown by the au- 

 thor in the case of the subnitrate of copper 5 for they all bear an 

 analogy to this salt in their small solubility and other properties, 

 while they exhibit little resemblance to those classes of phosphates 

 and arseniates which really possess more than one atom of base. A 

 table is then given, containing the formulae expressing the composi- 

 tion of the most important phosphates, together with a new nomen- 

 clature by which, in accordance with his views, the author proposes 

 to designate these salts. He then enters into the details of experi- 

 ments illustrating the composition of, 1st, tribasic phosphate of soda, 

 ammonia, and water, (or the microcosmic salt of the old chemists): 

 2ndly, tribasic phosphate of zinc and water, (or what is commonly 

 called phosphate of zinc^i: Srdly, tribasic arseniate of magnesia and 

 water, (the common arseniate of magnesia): 4thly, tribasic phosphate 

 of magnesia and watej-, (or ordinary phosphate of magnesia): and 

 5thly, tribasic phosphate of magnesia and ammonia, (or ammoniaco- 

 magnesian phosphate). 



In the fourth section he treats of sulphates, and supports, by fur- 

 ther evidence, the ojjinion he formerly advanced; that as bisulphate 

 of potash is a double sulphate of water and potash, and therefore 

 neutral in its composition, so, with the sole exception of the anor- 

 mal class already noticed, all salts, usually considered as bisalts are, 

 in like manner, really neutral in composition. He shows that this 

 theory is strictly applicable to the red chromate of potash, which 

 appeared to present a difficulty. 



The chlorides are next considered. The law followed by the 

 chlorides of the magnesian class of metals appears to be that they 

 have two atoms of water strongly attached to them, and which may 

 therefore be regarded as constitutional. Thus, chloride of copper 

 crystallizes with two atoms of water, and with no lower proportion; 

 but several chlorides of this class have two or four atoms more; the 

 proportion of water advancing by multiples of two atoms. The 

 chlorides have probably their analogues in the cyanides, although we 

 Third Series. Vol. 10. No. 60. March 1837. 2 F 



