Mr. Prideaux on Chemical Notation. 41 



t c* cos <t T» 1 I L J 



u = —3-^ 3 5 — - — --.. But these remarks are beyond 



r sin <p- + <r cos $- 



the purpose" of the present occasion. I shall conclude with 

 observing, that the equation u% = a cot <p suggests a much 

 readier process for outlining the second cissoid than that 

 which was indicated by its optical development. 



P.S. I have not thought it requisite to give a more parti- 

 cular description of the instrument, having communicated 

 every needful part of the detail, some weeks ago, to a respect- 

 able optician of Bristol, Mr. King, jun. The publication 

 seems, however, to have met with some impediment, probably 

 in the sketching of the figures. 



XII. Remarks on Mr. Phillips's Observations on the Use of 

 Chemical Symbols. By Mr. John Prideaux, Member of 

 the Plymouth Institution. 



To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, 

 r T , HE observations of Mr. Phillips will, it is to be hoped, 

 -*- have their effect; if not that so much desired by him, yet 

 in inducing chemists to conform as nearly as possible to the 

 symbols already extensively known and employed. Perfection 

 is as unattainable in a system of symbols, as in any other; and 

 although improvement may be desirable here, as in other 

 cases, one should be well convinced, before attempting inno- 

 vations, that their effects and inconveniences will be less than 

 those of what they are proposed to supersede. 



In the case in point, however, the confusion is really not so 

 great as it appears. 



There is but one known combination of phosphorus with 

 5 atoms of oxygen ; in which many chemists (chiefly in this 

 country) apprehend the phosphorus to enter as a single atom, 

 whilst others regard it as double, from its requiring 2 atoms 

 of alkali. The first class will write the P simple; the others 

 will bisect it: and as this difference of opinion is generally 

 known, the 5 atoms of oxygen, whether represented by dots 

 or initials, immediately distinguish the symbol as that of phos- 

 phoric acid. 



With hydrogen, the case is different: H may signify, ac- 

 cording to our atomistic notions, either pure or oxygenated 

 water; and considering the great number of compounds into 

 which water enters in definite proportions, it were to be 

 wished that Berzelius had adhered to his original decision of 



Third Series. Vol. 4. No. 1 9. Jan. 1 834. G 



