l'2'2 FHILOSOFHICAL TKANSACTIONb. [aNNO 1725. 



not requisite to the peculiar constitution of brandy ; and consequently, that 

 the whole experiment, however plausible it may appear, is false, fallacious, 

 and useless; which he will farther show below. 



M. Neuman understood by a friend, who had tasted this proof-liquor at 

 Dantzic, that it was of a styptic savour: therefore, directing all his experiments 

 this way, he at length found, that it was no other than a mere solution of 

 iron, in a vitriolic acid; whether it consist of iron dissolved in spirit of vitriol, 

 and diluted with water, or of English vitriol, or some venereo martial vitriol, 

 prepared by precipitation, or of an extract of some iron-ore or earth, as the 

 Hessian, though the most elegant blue colour be produced from the last men- 

 tioned, namely, with the liquor of Hessian earth ; and the more saturated the 

 solution is, the less of it is required for making the experiment. 



That additament, which first communicates a yellow tincture to French 

 brandy, and then a blue, in the course of the experiment, is oak-wood, or the 

 shavings or chips of it, infused in brandy, or when the brandy is kept in a 

 new oak-cask, til! it has extracted a yellow tincture from the wood; and the 

 more yellow it is, the more blue it becomes by the martial liquor in the expe- 

 riment, unless it be tinged with saffron, or some other yellow body. 



That the whole is owing to nothing but the oak-wood, M. Neuman con- 

 firmed by the following experiments : he took malt-spirits, the same to which, 

 when the liquor is put, they neither exhibit a blue tincture, nor undergo any 

 other change; and therefore, reckoned pure malt spirits by the merchants; in 

 these he infused oak-chips, till the spirits had been almost as yellow as French 

 brandy; and after filtration, he poured into them some of the vitriolic liquor, 

 as is done into French brandy, and it produced the same elegant blue tinc- 

 ture, without any the least apparent difference; which abundantly shows, that 

 the change is entirely owing to the oak-wood. 



In like manner, may any other substance, resembling oak, as for instance, 

 galls, be infused in malt spirits; the experiment also succeeds in some measure 

 with pomegranate rind, and other astringent vegetables; yet best uf all with 

 oak, to which the pomegranate rind is far inferior, as exhibiting rather a violet 

 than a blue colour, and when stirred, appearing somewhat green. 



It is worth observing, that a very small quantity of the liquor, extracted 

 from oak, is sufficient to give a blue tincture, as the abovementioned liquor 

 does, to a large quantity of malt spirits; for, with a single drop of that infu- 

 sion, M. Neuman made the experiment answer in half an ounce of malt 

 spirits. 



That the liquor, or solution, should consist and be prepared of pure iron 

 vitriol, and not of that of copper, appears hence. 1. Because the experiment. 



