266 Scientific Reviews. 



It is strange that any man should place such reliance upen 

 forms deduced in the way above shown, as to permit himself to call 

 in question, or to modify the results of experiment. And yet there 

 is hardly a received atomic weight which the book before us does 

 not state to be more or less in error, and few chemical compounds 

 in which the ratio of the composing atoms has not been hitherto 

 misunderstood. Nay, the author has even found out new com- 

 pound bodies, and given them names, without having even seen or 

 knowing how to form them, and all because he finds that a certain 

 number of particles of two assumed forms, which he supposes to 

 represent certain substances, are capable of being built together 

 into a figure of more or less symmetry. To the knowledge of two 

 of these compounds, Citrogen and Pyragyne, or Pyragynic Acid, 

 Ave shall introduce our chemical readers. 



Of citrogen it is said, " We cannot avoid the conclusion that 

 particles of carbonic acid abundantly generated from a violent com- 

 bustion or otherwise, should apply themselves to each other in the 

 nascent state, so as to generate other molecules than those of mine- 

 ral fixed air. Thus two particles of fixed air might retain a par- 

 ticle of carbon in the cavity between them, which is conformable ; 

 and if the molecule only attained to this structure when escaping 

 from the region of combustion, in this state it might ascend into 

 the gasometer. Such a form is completely isamorphous with com- 

 mon fixed air, and none of the tests for carbonic acid would be 

 sufficient to distinguish it. To prevent circumlocution, it may be 

 called Citrogen, for a reason soon to be perceived. Its atomic 

 weight is 35." P. 336. 



And of pyragyne the author writes, " In all cases where oxygen i^ 

 supplied in abundance, and where the conditions are most favourable 

 to combustion, a completely burned sort of carbonic gas may be ex- 

 pected, in which there are three particles of carbon and four of oxy- 

 gen." This he calls pyragyne or pyragynic acid. Experimental che- 

 mists are content to wait for the discovery of substances before they 

 name them, but your theoretical men can give to any " airy no- 

 things a local habitation and a name." We dislike all prophetical 

 hints and anticipations either from practical or fanciful men ; and 

 we see no claim any philosopher, either ancient or modern, has to 

 the title of a wise man, merely because out of fifty idle guesses one 

 or two turn out at last to be true. 



The ratio of the elements of chemical compounds, is deduced by 

 our author after the following manner : — Silicon has a certain form 

 noticed above. Five particles of this form must be built up with 

 four of oxygen before any symmetrical figure can be obtained ; 

 therefore silica is a compound of 5 silicon -|- 4 oxygen. All known 

 combinations, and many unknown, are deduced in this way, and 

 were we sure of our fundamental forms, nothing could be safer or 

 "more accurate ; but while these forms are all fanciful, nothing can 

 be more useless or absurd. 



