24 Mj; Phillips's Reply to Dr. Hope. [July, 



Acidum Nitrosum. — In your reply to my objections to this 

 process, you say that I " have thought fit to condemn the propor- 

 tions directed in the Pharmacopoeia as unproductive and injudi- 

 cious on the result of a solitary trial." It is indeed true that I 

 stated the result of only one trial, but I have made many. I 

 thought it, however, sufficient to relate the results of that one 

 experiment, because it proved that I obtained the whole of the 

 nitric acid capable of being yielded by the nitre within l-39th 

 part, a loss unavoidable in experiment. I obtained 1 1*5 parts of ni- 

 tric acid by using your proportions of 24 parts of nitre and 16 

 of sulphuric acid. The nitric acid was nearly colourless, and 

 had a specific gravity of 1513 ; and I endeavoured to show, 

 according to Dr. Wollaston's scale, that the whole quantity of 

 nitric acid procurable from 24 parts of nitre could amount to 

 only 11*8 parts, because the sulphuric acid does not contain 

 water sufficient to condense a greater quantity. To this you 

 reply, that from the use of 24 parts of nitre and 16 of sulphuric 

 acid, the quantity of nitrous acid obtained by you amounts to 15 

 parts. Now permit me to examine what must occur in this case : 

 24 parts of nitre consist almost precisely of 12 8 of nitric acid 

 and 11-2 of potash: 16 parts of sulphuric acid are composed of 

 13-04 of dry acid and 2-96 of water ; but I will allow in your 

 favour, that sulphuric acid contains usually one-fifth of its weight 

 of water; we have then 16 parts of it composed of 12-8 dry acid 

 and 3*2 water. Supposing then you condense the whole of the 

 nitric acid, it could amount only to 12*75 parts ; and as nitric acid 

 cannot be procured stronger than two atoms of water to one of 

 acid, the nitrous acid which you procure must be composed of 

 9'55 nitric acid + 3*2 water = 12 - 75 nitric acid, specific gravity 

 15, and the remainder of the 15 parts = 2*25 must have been 

 deutoxide of azote condensed by, and converting of, a portion of 

 the nitric into nitrous acid. If then I heat 15 parts of red 

 nitrous acid (so, for distinction's sake, called, but not correctly), 

 I must expel 2 - 25 to procure pale nitric acid. In order to try 

 this, I put 150 parts of nitrous acid, specific gravity 1522, into a 

 retort to which a receiver was adapted, by the application of 

 heat 27 parts of nitrous acid were distilled, and 1 14 of pale nitric 

 acid, sp. gr. 1495, were left in the retort ; the loss was conse- 

 quently nine parts. As then 123 parts of red nitrous acid had 

 lost nine parts of deutoxide of azote, 27 the nitrous acid distilled, 

 would lose nearly two more. 



We may then, 1 think, fairly conclude, that 15 parts of red 

 nitrous acid would have lost 1*2 of deutoxide of azote, and 

 that there would have remained 13'8 of pale nitric acid, specific 

 gravity 1495. 



The small quantity of nitrous acid distilled had a sp. gr. of 

 1598, and it would lose, therefore, rather a greater proportion 

 of deutoxide of azote than that of 1522 ; but, making every al- 

 lowance, I think it improbable that the nitrous which you ob- 



