on the Atomic Theory. 133 



In the 6th edition of his system, oxalate of ammonia is said 

 to consist of 4.5 oxalic acid + 2.125 ammonia. But no such 

 compound exists. In discussing ammonia, under azotic gas, he 

 now describes the oxalate as composed of 1 atom acid + 1 atom 

 ammonia, -f- 2 atoms water=8.875. This atomic weight of the 

 crystallized oxalate of ammonia was first given in the Philosophi- 

 cal Transactions for 1 822. 



Chapter 6th is occupied with the atomic weights of the acidi- 

 fiable combustibles, carbon, boron, silicon, phosphorus, sul* 

 phur, selenium, arsenic, and tellurium. 



The Doctor exposes calcareous spar to ignition in a platinum 

 crucible, and gets at once, as if by a wishing-cap, the absolute 

 atomic weight of carbonic acid. " The next object," says he, 

 " which engaged my attention was to disengage the carbonic acid 

 from 100 grains of calcareous spar, and collect it over mercury, 

 in order to ascertain its volume*." The manner in which he 

 tries to attain his purpose would ensure its failure, in any hands 

 but those of Fortunatus. He treats 100 grains of calcareous spar 

 with strong nitric acid in a retort, connected with a graduated 

 glass receiver nearly filled with mercury, and inverted in a 

 basin of that liquid. The beak of the retort has a stop-cock at- 

 tached to it, from which a bent glass tube proceeds to the top 

 of the receiver. The spar in three or four pieces is dropped into 

 the tubulure of the retort ; its stopper is inserted with all conve- 

 nient speed, and the stop-cock opened. We, who have made 

 many similar experiments, know well that so much carbonic acid 

 gas would escape in the time of introducing the spar and closing 

 the retort, and so much nitric acid vapour pass over with the 

 gas into the receiver, as would render the experiment nugatory 

 for all atomic determinations. It, moreover, occasions too many 

 chemical computations for the Doctor's arithmetic. On this oc- 

 casion, he acts with a prudent reserve. He takes care not to 

 state the experimental quantities, but pronounces the following 

 oracular response. u All the necessary reductions being made, 

 the volume of carbonic acid gas evolved from 100 grains of cal- 

 careous spar, supposing the barometer to stand at 30 inches, and 

 the thermometer at 60 , and the gas to be perfectly diy, amounts 

 from a mean of two experiments, both made, with very great care, 

 to 94.246 inchest." The Doctor has already drawn so freely on 

 our credulity, that we have really none to spare for the present 

 large demand. The result is plainly factitious. 



We cannot bestow a thought on his luminous details about the 

 compounds of carbon and hydrogen. In a paper published in the 

 Phil. Trans, for 1822, there are some facts relative to naphtha- 

 line, which he has carefully concealed from the readers of his 



♦ Attempt, i. HO, f Ibid. 1 IS. 



