VOL. XXXIII.] PHILOSOPHICAL TRANSACTIONS. 123 



made with Goslar, Hungary, Dantzic, and all such mixed vitriols, that contain 

 any copper, more or less, does not succeed so well, and they produce a very 

 diluted blue, or grey tincture. 2. Because the experiment does not at all suc- 

 ceed with pure vitriol of copper, nor strike any blue tincture ; as M. Neuman 

 found by several experiments to this purpose, as will be shown below. 



It should still remain to explain the causes and origin of this blue tincture: 

 but because M. Neuman takes the composition to be the same with new or 

 diluted ink, whose chief ingredients, that produce the tincture, are the same, 

 namely, vitriol of iron, and an astringent vegetable, on which M. Lemery has 

 written a learned and copious dissertation (vide Hist, de I'Acad. des Sciences 

 pour I'An. 1707) to him he refers; and as to the optical and other philosophi- 

 cal reasons, consult Mr. Boyle, Sir Isaac Newton, and other authors who have 

 written on colours. 



In fine, M. Neuman briefly observes, that no other difference should be 

 sought for between French brandy and malt spirits, namely, such as are pure 

 and carefully distilled, than the peculiar flavour of French brandy; though the 

 same flavour may be several ways communicated to malt spirits, and thus be 

 adulterated into French brandy: so that the most skilful might take them for 

 genuine brandy, or at least, not for malt spirits ; whence it appears, that the 

 abovementioned, and other probatory experiments on spirits, are of no use, or 

 at least insufficient. 



An account of the experiments here follows : I. M. Neuman prepared eight 

 solutions of vitriol, taking for each solution 2 drachms of vitriol, and li oz. 

 of common distilled waters. The solutions were, 1 . Of Goslar vitriol. 2. Dant- 

 zic vitriol. 3. Hungary vitriol. 4. Cyprus vitriol. 5. English vitriol. 6. Of 

 iron prepared with oil of vitriol. 7. Of iron obtained by precipitation from 

 venereo-martial vitriol, and 8. A solution of Hessian earth; of which last he 

 only took 2 drachms to the abovementioned quantity of waters. 



II. He made 3 infusions of astringent vegetables; to each ounce of the ve- 

 getable putting one pound, apothecary's weight, of malt spirits, which received 

 no blue tincture from the proof-liquor: the infusions were, l.Oak. 2. lurkish 

 galls. 3. Pomegranate rind. 



III. With these three well saturated infusions, he made from malt spirits 

 3 sorts of adulterated French brandy, at least resembling it in the yellow tinc- 

 ture: and with each 8 oz. of malt spirits, he mixed an ounce of the infusion. 



IV. He took the common yellow French brandy, and also common malt 

 spirits, newly distilled, and with both, and the solutions of vitriol, he suc- 

 cessively made experiments, in the manner just mentioned. 



V. At each time he poured half an ounce of French brandy into a clean 



R 2 



