1814.] made during the Year 1813. IS 



2. Definite Proportions. 



For some years back the attention of chemists has been much 

 turned to the important fact that all bodies unite together in certain 

 definite proportions. The truth of this fact appears to me to be 

 put beyond all doubt, by the numerous and precise experiments of 

 Bcrzelius, Dalton, Davy, and several other chemists, both in this 

 country and on the continent. 1 cannot here attempt an outline of 

 the doctrine ; but must satisfy myself with referring to an essay on 

 the subject published in the 7th Number of the Anijab of Philoso- 

 pliy, to the essay of Berzelius on t^e same subject, which is inserted 

 in part in the present Number, and to the two parts of Mr. Dalton's 

 Chemiitry which have been for some years before the public. The 

 opinion is of such vast importance, that frequent opportunities will 

 occur during the course of the year of laying observations on it 

 before our readers. 



3. Simple Bodies and their Compounds. 

 This head comprehends under it a considerable part of chemical 

 bodies. Hence the number of facts belonging to it is considerable. 

 The following are the most important of them : — 



1. Phosgene gas was discovered by Mr. John Davy before the 

 period of which we are writing the history ; but it deserves to be 

 noticed on account of its remarkable properties. It is composed of 

 equal volumes of chlorine and carbonic oxide gases condensed into 

 half their bulk. It is colourless ; has a strong and disagreeable 

 smell. Its specific gravity is 3-6G9 ; and 100 cubic inches, under 

 a mean temperature and pressure, weigh 11 1-91 grains. Hence it 

 is by far the heaviest gas at present known. It reddens vegetable 

 blues. It combines with ammonia, condensing four times its bulk 

 of that gas, and forming a peculiar neutral salt. Phosgene gas is 

 decomposed by water, and by most metallic bodies. It is an acid 

 body ol a very i)eculiar nature, deserving a much more complete 

 examinati(;n. 



2. Mr. John Davy's paper on the combinations of chlorine and 

 metals deserves great praise, for the precision with which the expe- 

 riments were made, and for the many new facts which it exhibits : 

 but to enter ui)on a discussion respecting the truth of the theory of 

 the author wuidd lead into a field a great deal too wide for an his- 

 torical sketch like the present, it must be obvious to every chemist 

 thnt Sir H. Davy's explanation of the muriates, anes and anas, and 

 the extreme facility wjili which they are changed into each other 

 wuhoui atiy sensible chnriL'-e in tlitir properties, constitutes the 

 vulnerable part of his theory of chlorine. Indeed, his opinions 

 respecting these bjdies cannot be eniliraced vviihout overturning all 

 th( received doctrines resjieciiiig the neutral suits, doctrines upon 

 which every thing resembling theory in chemistry is foutided. The 

 two oppo-ite hypothc'-es of clilnrine and oxynuniatic acid are liable 

 eac h M> ol'jcctions, which in the present state of our knowledge it 

 is almost impossible to obviate. As chlorine cannot be decomix)sed 



