290 



• KNOWLEDGE ♦ 



[Oct. 10, 1884. 



the paper all the guilty disturbing matter. I found it to 

 be a kind of argol, but containing a much larger proportion 

 of extractive and colouring matter, and a smaller propor- 

 tion of tartrate than the argol of commerce. I operated 

 upon rich new Catalan wine. 



This brings me at once to the source or origin of a sort 

 of wine-cookery by no means so legitimate as the 

 Pasteuriog already described, as it frequently amounts to 

 serious adulteration. 



The wine-merchants are here the victims of their cus- 

 tomers, who demand an amount of transparency that is 

 simply impossible as a permanent condition of unsophisti- 

 cated grape-wine. To anybody who has any knowledge of 

 the chemistry of wine, nothing can be more ludicrous than 

 the antics of the pretending connoisseur of wine who holds 

 his glass up to the light, shuts one eye (even at the stage 

 before double vision commences), and admires the brilliancy 

 of the liquid, this very brilliancy being, in nineteen samples 

 out of twenty, the evidence of adulteration, cookery, or 

 sophistication of some kind. Genuine wine made from 

 pure grape-juice without chemical manipulation is a liquid 

 that is never reliably clear, for the reasons above stated. 

 Partial precipitation, sufficient to })roduce opalescence, is 

 continually taking place, and therefore the brilliancy 

 demanded is obtained by substituting the natural and 

 wholesome tartrate by salts of mineral acids, and even by 

 the free mineral acid itself. At one time I deemed this 

 latter adulteration impossible, but have been convinced by 

 direct examination of samples of high-priced (mark this, 

 not cheap) dry sherries that they contained free sulphuric 

 and sulphurous aoid. 



The action of this free mineral acid on the wine will be 

 understood by what I have already explained concerning 

 the solubility of the bitartrate of potash. This solul^ility 

 is greatly increased by a little of such acid, and therefore 

 the transparency of the wine is by such addition rendered 

 stable, unaffected by changes of temperature. 



But what is the effect of such mineral acid on the 

 drinker of the wine ? If he is in any degree predisposed 

 to gout, rheumatism, stone, or any of the lithic acid 

 diseases, his life is sacrificed, with preceding tortures of the 

 most horrible kind. It has been stated, and probably with 

 truth, that the late Emperor Napoleon III. drank dry 

 sherry, and was a martyr of this kind. I rej eat emphati- 

 cally that high-priced dry sherries are far worse than cheap 

 Marsala, both as regards the quantity they contain of 

 sulphates and free acid. 



Anybody who doubts this may convince himself by 

 simply purchasing a little chloride of barium, dissolving it 

 in distilled water, and adding to the sample of wine to be 

 tested a few drops of this solution. 



Pure wine, containing its full supply of natural tartrate, 

 will. become cloudy to a small extent, and gradually. A 

 small precipitate will be formed by the tartrate. The 

 wine that contains either free sulphuric acid or any of 

 its compounds will yield immediateh/ a copious white 

 precipitate like chalk, but much more dense. This is 

 sulphate of baryta. The experiment may be made in a 

 common wine-glass, but better in a cylindrical test-tube, as, 

 by using in this a fixed quantity in each experiment, a 

 rough notion of the relative quantity of sulphate may be 

 formed by the depth of the white layer after all has come 

 down. To determine this accitrateli/, the wine, after apply- 

 ing the test, should be filtered through proper filtering 

 paper, and the precipitate and paper burnt in a platinum 

 or porcelain crucible and then weighed ; but this demands 

 ■apparatus not always available, and some technical skill. 

 The simple demonstration of the copious precipitation is 

 instructive, and those of my readers who are practical 



chemists, but have not yet applied this test to such wines, 

 will be astonished, as I was, at the amount of precipitation. 



I may add that my first experience was upon a sample 

 of dry sherry, brought to me by a friend who bought his 

 wine of a most resjiectable wine-merchant, and paid a high 

 price for it, but found that it disagreed with him ; since 

 that I have tested scores of samples, some of the finest 

 in the market, sent to me by a thoroughly conscientious 

 importer as the best he could obtain, and these contained 

 sulphate of potash instead of bitartrate. 



My friend, the sherry-merchant, could not account for 

 it, though he was most anxious to do so. This was about 

 three years ago. By dint of inquiry and cross-examination 

 of experts in the wine trade, I have, I believe, discovered 

 the origin of the sulphate of potash that is contained in 

 the samples that the British wine-merchant sells as he buys, 

 and conscientiously believes to be pure. I will state par- 

 ticulars in my next. 



FLIGHT OF A MISSILE. 



By Richard A. Proctor. 



{Continued from p. 253.) 



I PROCEED to follow the simpler course employed in 

 dealing with the flight of a vertical missile. 

 If V is the velocity, ; the elevation, v sin £ the vertical 



velocity, then the time t^ of ascent or of descent = ' 



the height attained h = !l_^' = AM, Fig. 2. 



The missile starts, then, from O in the real direction Op, 

 with velocity V ; and the resolved part of this velocity in 

 direction O / (in both figs.) is V. cos p I, or 



\/r- cos- e + u- + 2 ui- cos £ cos o. 



Suppose now a point to travel uniformly along I, Fig. 2, 

 with this velocity V cos pO I, while the body pursues its 

 course along the path O A a starting with velocity V, 

 and under the influence of terrestrial gravity (which, so far 

 as this motion is concerned, may be supposed to result 

 from the whole mass of the earth concentrated at S). Then 



Pig. 1. 



throughout these movements the missile travelling along 

 A a and the point travelling along 0/6 sweep out equal 

 areas, and each the same area per unit of time, around S. 

 Hence if the moving point reaches h when the missile 

 arrives at the ground again at a, we have 



Area S A a=sector S J 

 .•. area A a M= sector Sab 

 Or, appreciably, | O a . A M*=i S a . ab 



or a b=± O a . -=f 6.- 

 r r 



* It is clear that, for such an area as O A a mnst necessarily be, 

 the relations between a parabolic area such as A a (A M the axis) 

 and the enclosing rectangle, mnst be approximately folfilled, the 

 curve O A a not differing appreciably from a parabola when so 

 small an area as O A a is taken. 



