348 Analysis of Scienl if tc Books. 



Of sheer effrontery, the following is a good example. He is 

 trying to palliate the absurdity of his claims, relative to sul- 

 phurous acid. " As for the experiments of Davy to which the 

 Reviewer refers, as the first which established the true com- 

 position of sulphurous acid, I am not acquainted with them * "' 

 Not acquainted with them ! They are quoted in the Review 

 from pages 273 and 274, of the Elements of Chemical Philo- 

 sophy. We shall here re-quote the passage for Dr. Thomson's 

 information. " If the specific gravities of sulphurous acid gas 

 and oxygen be compared, and the last subtracted from the first, 

 it will appear that sulphurous acid consists nearly of equal 

 parts of oxygen and sulphur by weight. In several experiments 

 in which I burned sulphur, procured from iron pyrites, out of 

 the contact of air or moisture, in dry oxygen over mercury, I 

 found that the volume of the oxygen was very little altered." 

 " These are experiments," adds the Reviewer, " in which the 

 world may confide. Dr. Thomson sinks them entirely, and 

 refers merely to his own, on which nobody can rely f. 



Under lithia, we find him re-asserting that 2.25, is the equiva- 

 lent number deducible from the mean of the foreign experiments. 

 Now, according to Gmelin, 100 parts of carbonate of lithia 

 consist of 45.54 lithia, and 54.46 acid. But 64.46 : 275 : : 

 45.54:2.299, or 2.3 as we stated in the Review. Again, 

 M. Vauquelin says, " that 100 parts of lithia contain 43.5 of 

 oxygen, and 56.5 of metallic base ; and 43.5 : 1 : : 56.5 : 1.299 

 for the atom of lithium, to which, adding 1 for oxygen, we have 

 that of lithia = 2.299 as above. 



He even defends his absurd method of preparing muriate of 

 barytes, by pouring muriatic acid on the calcined sulphuret, 

 instead of adding it to its filtered solution, on the score that the 

 muriatic acid of commerce is never free from iron. Chemists 

 who operate with pure acids (and the muriatic need never be 

 contaminated with iron,) will do well not to vitiate their pro- 

 duct, by following Dr. Thomson's mis-direction. We can 

 readily understand why he affects to prefer Mr. Dalton's table 

 of sulphuric acid, which at the specific gravity 1.8447 is, by 

 his own shewing, 4^ -per cent, wrong, to Dr. Ure's, which, at 

 the above density, must be right, since it agrees with his own 

 number, and which, in the other points, is probably never in 

 error to the amount of one-half per cent. 



The Doctor is peculiarly incensed at our exposure of the 

 bundle of errors in his paper on oxalic acid, inserted in the 

 Philosophical Transactions for 1808. We shall quote the pas- 



* Answei, 'p.ZG'd. f Review,^. \4'i. 



