Notices respecting New Books. 301 



in weight unite with 20*1 of oxygen to' form pure potash; 

 and with 57'8 to form the orange oxide of potassium. 20'1, 

 the smallest number, is taken ; and as 20-1 : 100:: 15, the 

 number representing oxygen, to 74*99; or adding the mi- 

 nute fractional part to 75 ; and 57*8 is nearly 3 times 20. 

 And the difference may be easily explained by supposing 

 that in experiments on the ptroxide, it is scarcely possible to 

 convert the whole of the metal into potassium. 



*' To give another instance in which the datum is taken 

 from the peroxide : The peroxide of lead contains from 

 3 to 3*5 per cent more oxygen than minium ; and the first 

 oxide known, massicot, consists of about 100 of lead to 

 7*52 of oxygen; minium of 100 to between 10 and 12 j 

 and the puce coloured oxide of 100 of metal to about 15 j 

 and the smallest proportion amongst these is 3*76 of oxy- 

 gen ; and 3*76 : 100 : : 15 is to 398, the number represent- 

 ing lead ; and massicot is supposed to contain twice this 

 quantity of oxygen. 398 : 30 : : 100 is to 7*53. 



" It would be easy to bring forward a great collection of 

 evidences to show, that in all compound gaseous bodies, 

 the quantities of the elements are uniform for each species*, 

 and that, when two gaseous elements combine in more than 

 one proportion, the second or third proportion is always 

 a multiple or a divisor of the first; and the case seems to 

 be analogous with respect to all true chemical compounds, 



* That the proportions in compound gases are definite has long been ge- 

 nerally acknowledged ; but Mr. Higgins is, I believe, the first person who 

 coiceived that when gases combined in more than one proportion, all the 

 proportions of the same element were equal; and he founded this idea, 

 which was made public in l78y, on the corpuscular hypothesis, that bodies 

 combine particle with particle, or one with two, or three, or a greater num. 

 ber of particles. Mr. Dalton, about 18(;'i, adopting a similar hypothesis, 

 apparently without the knowledge of what Mr. Higgins had written, ex- 

 tende.l his views to compounds in general. Mr. Richter seems to have been 

 the first person to show, that in the decomposition of neutral salts by double 

 alTuiiiy, the neutral state is preserved; and likewise that, Vv'lien a metallic 

 salt is decomposed by a metal, all the oxygen and acid is transferred, and rhu 

 mei.il only changed, and that the new solution is as neutral as the former 

 one. It had been ascertained, by different experinients, that in certain cases 

 when solids dissolved in gaseS'.lhe volume is unchanged, and some instances 

 of the combination of gases were known, in which the volumes bore simple 

 ratios to each other, as in nitrous oxide, and water ; but .M. Gay Lussac it 

 the first philosopher who attempted to generalize on the phenomena, and 

 •flow that in all cases where gases unite, it is always in simple ratios of vo- 

 lume, 1 to l.or 1 to 2, or 1 to J, and that the condeneatinu,if any.isin a sim- 

 ple ratio. His very ingenious ideas on this subject nere made known to- 

 wards the close of 1808. Berzclius, in a work published in 1 810, has deter- 

 mined, very correctly, some of the definite proportions of several important 

 compounds. See Higgins's Comparative View. Dalton's New Chemical 

 Philosophy. Huhler Urber dit: niurm gegemtuiide iler Chemie. Mcmuires 

 iCAnntil, toin. ii. Ber»eUui, AnniUti tie Chimis, tom.lxvii. Thomson's System 

 of CheniitUy, val.iii. 



whether 



