Page:Proceedings of the Royal Society of London Vol 1.djvu/429

Rh ascertained to yield one ﬁfth part of alcohol by distillation. When the same experiment was repeated on the same wine, to which one seventh part of alcohol had been previously added, still none was separated by subcarbonate of potash : but when so much as one third part had been added, then a very small proportion was found to ﬂoat upon the surface after it had stood twenty-four hours.

When madelra or sherry were employed instead of port, the re- sults were nearly the same. Since the method of Fabroni failed of detecting the presence of alcohol, unless the quantity was very considerable, it became necessary to have recourse to some other method of proving or disproving the presence of it as a product of fermentation; and Mr. Brande conceived, that if it were formed by the heat applied in distillation, the quantity should in that case be different when the same liquor was distilled at different temperatures.

In the ﬁrst of four processes of distillation, port wine was made to acquire the heat of 200° by addition of muriate of lime, and one half was quickly distilled over; and in the last, an equal quantity of port was kept for ﬁve days at the temperature of 180°, till half the quantity had passed Over into the receiver; but in all these experiments the speciﬁc gravities of the products were so nearly the same, that there did not appear to be any difference in the quantity of alcohol obtained.

Mr. Brande also attempted to separate alcohol from different kinds of wine by freezing; but the cake of ice produced was spongy, and would not allow any portion of alcohol to separate from it.

The author having thus, to his satisfaction, proved the existence of alcohol ready formed in fermented liquors, undertook, in the next place, to ascertain the relative strength of different kinds of Wine; and he concludes the present communication with a Table, in which is expressed the proportion per cent. of alcohol contained in a given measure of the several liquors that he has examined.

In this table the alcohol obtained from Port varies from 21 to nearly 26 per cent; Madeira 19 to 24; Sherry not so much as 20 per cent.; Claret from 13 to 16; Lisbon 19; Marsala nearly 26; Champagne from 11 to 13; Burgundy 12 to 14; Hock 9 to 14; Raisin wine 25%; Currant wine 20%; Cider and Perry nearly 10; Ale nearly 9 per cent.; good rum and brandy containing 53 per cent. of alcohol at the same standard of '825 speciﬁc gravity.

Norwithstauding the skill with which Dr. Maskelyne conducted the astronomical observations upon Schehallien, and the accuracy with which he may be presumed to have measured the deﬂection of his plumb-line from the perpendicular, whereby he discovered the actual attraction of that mountain; and although great ingenuity