Thomson's System of Chemistry. 163 



61 acid and water 



39 oxide 



If we suppose it a compound of 1 atom acid, 1 atom oxide, 



and 3 atoms water, its constituents will be, 



Acetic acid 25.12 



Peroxide of copper 39.41 



Water 35.47 



100.00 

 " / consider these to be its true constituents*." But there is not 

 a shadow of evidence for this random decision. If for 25 per 

 cent of acid, he had guessed 50 ; and for 35-| nearly of water, 

 one fourth of the quantity, he would have come pretty near 

 to the truth. Such temerity of error destroys all confidence 

 in the statements; nor can practical men derive any benefit from 

 them, in conducting their operations. 



Of the third volume, the first 160 pages, are taken up with 

 Dr. Thomson's notions of the philosophy of chemistry; or, " an 

 account of the nature of the power which produces combina- 

 tions," The following is the incipient sentence. " All the 

 great bodies which constitute the solar system, are urged towards 

 each other by a force which preserves them in their orbits 

 and regulates their motions." The force which urges them 

 together, preserves them in their orbits! Every school-boy 

 knows that the system of the world is sustained in order, by 

 the " blended powers of gravitation and projection," acting on 

 its revolving spheres. " Conantur ea omnia a centris orbium 

 recedere ; et nisi adsit vis aliqua conatui isti contraria, qua 

 cohibeantur, etin orbibus retiueantur, quamque ideo centripetam 

 appello, abibunt in rectis lineis, uniformi cum motuf." The 

 venerable words of Newton will atone to our readers, for 

 wasting a moment of their time with so plain a matter. 



In the section on gaseous constitution, to which no praise, 

 either for ingenuity or research, can be given. Dr. Thomson enu- 

 merates the solids, sulphur and iodine, among the simple gases. 

 Now surely, phosphorus, carbon, boron, mercury and all the me- 

 tals, have as good a claim to admission among the simple gases, 

 as the above two solids ; and indeed, had he been desirous to give 

 us a systematic view of combining volumes, he should have done 

 80. " Of these gaseous bodies," says he, " there is one whose 

 specific gravity is equal to the weight of its atom. This is 

 oxygen. 



Specific gravity oxygen being 1 Weight of an atom 

 Oxygen 1.000 1.000 



Sixteen of them have their specific gravity equal to half the 

 weight of their atoms. These are chlorocarbonic acid, chlo- 



• Siistem U. 644. 

 t Newloni Principia, 4to, cditio tertta. Definitio quinta. 



M 2 



