on the Use of Chemical Symbols. 247 



present opportunity of replying also to Mr. Prkleaux's " Re- 

 marks", published in the Magazine for January. 



I remain, clear Sir, yours faithfully, 



R. Phillips. 

 I presume that the following terms used in your paper in 

 the Philosophical Transactions, all refer to the same salt, viz. 

 Page 253, " Phosphate of soda." 



255, " Common rhomboidal phosphate" of soda. 



" Common phosphate of soda." 



256, " A phosphate of neutral composition, such as 



the common phosphate of soda." 

 You also state (p. 255.) " that common phosphate of 

 soda, for instance, is a phosphate of soda and of water, 



and that its symbol is Na 2 HP;" and I cannot here but re- 

 mark, that even while asserting the system of notation which 

 you adopt is that last proposed by Berzelius, you admit that 

 two out of three symbols do not occur in it. His symbol for 



water is H, yours H ; he supposes it to contain two atoms of 

 hydrogen, you admit but one atom ; he represents phosphoric 

 acid by _P, you by P ; he supposes it to contain two atoms of 

 phosphorus ; you but one atom. On these, as well as some 

 other grounds, I cannot agree with you that a system is 

 "convenient" which requires so much patching, from the 

 hand even of a professed admirer, to make it express his opi- 

 nions both as to theory and as to facts. 



But to proceed. In your letter to me you regard crystal- 

 lized phosphate of soda as consisting "of two atoms of soda and 

 one atom of basic water united to the atom of phosphoric acid, 

 together with twenty-four atoms of water of crystallization." 

 Now allow me to inquire in what sense the term neutral is 

 applied to this salt in p. 256. of your paper? The above ac- 

 count of its constitution shows that it is a subphosphate, and 

 consequently it cannot be atomically neutral ; it turns turmeric 

 brown, and therefore is not chemically neutral : on the other 

 hand, you cannot consider it as a subsalt, though it contains 

 two atoms of base to one atom of acid; for (p. 253.) you di- 

 rect the subsesquiphoaphate to be formed by adding to "phos- 

 phate of soda at least half as much soda as already in the 

 salt." These directions would be quite proper for the con- 

 version of a neutral into a sobsesquisalt ; but a salt which con- 

 sists of two atoms of soda united to one atom of acid is a ili- 

 sa/l and consequently already contains one third more soda 



