26 Sketch of the latest Improvements [Jan. 



acceded to ; yet it appears that it is not the true one. Mr. Vogel, 

 apothecary at Bayreuth, has lately published a very elaborate set of 

 experiments on this acid, which, as far as they go, appear decisive. 

 The following are the facts which he has established by his experi- 

 ments : Fuming sulphuric acid contains no sulphurous acid ; nor 

 can it be formed by uniting these two acids together, nor by dis- 

 tilling a mixture of sulphur and sulphuric acid. Fuming sulphuric 

 acid attracts no oxygen, nor does it produce any alteration on 

 atmospherical air. When mixed with water, it is converted into 

 common sulphuric acid. When combined with bases, it forms 

 common sulphates, it dissolves some sulphur, and acquires a 

 brown, green, or blue colour, according to the proportion of 

 sulphur which it holds in solution. It combines, likewise, with 

 phosphorus. Vogel considers it as common sulphuric acid united 

 witli some imponderable substance, and brought by its means to a 

 more powerful acid state. The direct consequence from his experi- 

 ments seems to be, that it is sulphuric acid free from water. There 

 is, however, a fact stated by Dobereiner, in a very long dissertation 

 which he has published on the action of the different kinds of sul- 

 phuric acid on nitric acid, which, if accurate, would require an 

 explanation. He says that when a mixture of fuming sulphuric 

 acid and nitric acid is heated, the nitric acid is decomposed into 

 nitrous gas and oxygen gas, but no such change is produced by 

 heating a mixture of common sulphuric acid and nitric acid. I do 

 not perceive very clearly how this fact was ascertained. Supposing 

 nitrous gas and oxygen gas to be evolved together out of the liquid, 

 they could not be collected, for they would instantly combine, and 

 form nitrous acid ; but supposing the fact correct, I can conceive 

 it to be owing to this circumstance. The fuming sulphuric acid 

 deprives the nitric acid of the whole of its water. Now in this 

 state it is probably much more easily decomposed than when it 

 contains water. Common sulphuric acid will not produce this 

 effect so completely, because it is already combined with an atom 

 of water. 



5. Prussic Acid. — Mr. Bergeman, apothecary ia Berlin, disco- 

 vered, in 1811, that the bark of the prunus padus contained a 

 notable quantity of prussic acid. Water distilled from this bark 

 proved fatal to animals when taken internally. 



6. Acetic Acid. — The following very extraordinary experiment 

 was made byNasse, one of the members of the Imperial Academy 

 of St. Petersburg, and is related by him in a letter to Professor 

 John. Take a glass vessel and fill it with a mixture of equal bulks 

 of carbonic acid gas and common air, and put into it a little water 

 so as hardly to cover the bottom of the vessel. Stop it up, and lay 

 it aside for some months, shaking it occasionally. Then open it, 

 and leave it for some weeks with the mouth slightly covered. Acetic 

 acid will be perceived formed in it, both by the taste and smell. 

 Nasse obtained his carbonic acid by the action of dilute sulphuric 

 acid on Carrara marble. Here is the formation of acetic acid %vitliout 

 the presence of any animal or vegetable substance: nothing else 



