332 



♦ KNOWLEDGE ♦ 



[Oct. 24, 1884. 



o£ potash which is thus made to replace bitartrate is so 

 readily soluble that neither changes of temperature nor in- 

 crease of alcohol, due to further fermentation, will 

 throw it down ; and thus the wine-merchant, without any 

 guilty intent, and ignorant of what he is really doing, 

 sophisticates the wine, alters its essential composition, and 

 adds an impurity in doing what he supposes to be a mere 

 clarification or removal of impurities. 



I have heard of genuine sherries being returned as bad 

 to the shipper because they were genuine, and had been 

 fined without sophistication. Are we to blame the wine-, 

 merchant for this ? I think not. 



My own experience of genuine wines in wine-growing 

 countries teaches me that such wines are rarely brilliant ; 

 and the variations of solubility of the natural salt of the 

 grape, which I have already explained, shows why this is 

 the case. If the drinkers of sherry and other white and 

 golden wines would cease to demand the conventional bril- 

 liancy they would soon be supplied with the genuine article, 

 which really costs the wine-merchaut less than the cooked 

 product they now insist upon having. This foolish demand 

 of his customers merely gives him a large amount of un- 

 necessary trouble. 



So far, the wine-merchant ; but how about the consumer? 

 Simply that the substitution of a mineral acid — the sul- 

 phuiic for a vegetable acid (the tartaric) — supplies him 

 with a precipitant of lithic acid in his own body ; that is, 

 provides him with the source of gout, rheumatism, gravel, 

 stone, (fee, with which English wine-drinkers are prover- 

 bially tortured. 



I am the more urgent in propounding this view of the 

 subject because I see plainly that not only the patients, 

 but too commonly their medical advisers, do not under- 

 stand it. When I was in the midst of these experiments 

 I called upon a clerical neighbour, and found him in his 

 study with his foot on a pillow, and groaning with gout. 

 A decanter of pale, choice, very dry sherry was on the 

 table. He poured out a glass for me and another for him- 

 self. I tasted it, and then perpetrated the unheard-of 

 rudeness of denouncing the wine for which my host had 

 paid so high a price. He knew a little chemistry, and I 

 accordingly went home forthwith, brought back some chloride 

 of barium, added it to his choice sherry, and showed him a 

 precipitate which made him shudder. He drank no more 

 dry sherry, and has had no serious relapse of gout. 



In this case his medical adviser prohibited port and 

 advised dry sherry. 



The following from "The Brewer, Distiller, and Wine 

 Manufacturer," by John Gardner (ChurchiU's "Technological 

 Handbooks." 1883), supports my view of the position of the 

 wine-maker and wine-merchant. " Dupre and Thudicum 

 have shown by experiment that this j)ractice of plastering, 

 as it is called, also reduces the yield of the liquid, as a con- 

 siderable part of the wine mechanically combines with the 

 gypsum and is lost." When an adulteration — justly so- 

 called — is practised, the object is to enable the perpetrator 

 to obtain an increased profit on selling the commodity at a 

 given price. In this case an opposite result is obtained. The 

 gypsum, or Spanish earth, is used in considerable quantity, 

 and leaves a bulky residuum, which carries away some of 

 the wine with it, and thus increases the cost to the seller of 

 the saleable result. 



Having referred so often to dry wines, I should explain 

 the chemistry of this so-called dryness. The fermentation 

 of wine is the result of a vegetable growth, that of the 

 yeast, a microscopic fungus {Pencilliwm glaucum). The 

 must, or juice of the grape, obtains the germ spontaneously 

 — probably from the atmosphere. Two distinct effects are 

 produced by this fermentation or growth of fungus : first, 



the sugar of the must is converted into alcohol ; second, 

 more or less of the albuminous or nitrogenous matter of 

 the must is consumed as food by the fungus. If uninter- 

 rujjted, this fermentation goes on either until the supply of 

 suflicient sugar is stopped, or until the supply of sufficient 

 albuminous matter is stopped. The relative proportions of 

 these determine which of the two shall be first exhausted. 



If the sugar is exhausted before the nitrogenous food of 

 the fungus, a dry wine is produced ; if the nitrogenous food 

 is first consumed, the remaining unfermented sugar pro- 

 duces a sweet wine. If the sugar is greatly in excess, a 

 vin de liqueur is the result, such as the Frontignac, Lunel, 

 Rivesaltes, (fee, made from the muscat grape. 



The varieties of grape are very numerous. Rusby, in 

 his " Visit to the vineyards of Spain and France," gives a 

 list of 570 varieties, and as far back as 1827 Oavalow 

 enumerated more than 1,500 different wines in France 

 alone. 



From the above it will be understood that, cateris paribus, 

 the poorer the grape the drier the wine ; or that a given 

 variety of grape will yield a drier wine if grown where it 

 ripens imperfectly, than if grown in a warmer climate. 

 But the quantity of wine obtainable from a given acreage in 

 the cooler climate is less than where the sun is more 

 effective, and thus the naturalli/ dry wines cost more to 

 produce than the naiurallt/ sweet wines. 



This has promoted a special cookery or artificial drying, 

 the mysteries of which will be discussed in my next. 



NOTES ON COAL. 

 By Richakd A. Pboctoe. 



{Continued from page 297.) 



IF we now turn to the consideration of the extent of the 

 earth's surface occupied by those particular strata 

 which belong to the coal period, we find evidence of the 

 existence of enormous quantities of available coal. Pro- 

 fessor Ansted mentions that a quarter of a million of sqjiare 

 miles of the earth's surface " are covered with sandstones 

 and shales of the carboniferous period among which coal is 

 buried ; and this coal is for the most part accessible." Now 

 there are upwards of three million square yards of surface 

 in a square mile ; and, assuming an average total thickness 

 of ten yards for all the distinct seams of each coal-field, we 

 find for the total number of cubic yards of available coal 

 the enormous figure 7,500,000,000,000. As a cubic yard 

 of coal weighs nearly a ton, we may say that there are in 

 round numbers seven billions of tons of coal available for 

 the use of the human race. If we took the average number 

 of human beings living at each moment during the next 

 3,500 years to be 2,000,000,000, and the annual consump- 

 tion for all purposes to be at the average rate of one ton 

 per human being, the supply would last for that enormous 

 period. 



But let us consider what portion of this vast supply falls 

 to the share of this country — not including, of course, 

 those coal-fields which lie in countries forming British ter- 

 ritory, but not forming part of the British Isles ; and let 

 us compare our store of coals with our present rate of con- 

 sumption and with the probable rate of consumption during 

 coming years. 



Some difficulty arises at the outset in determining what 

 portion of the coal-fields actually existing in the British 

 Isles may be regarded as available. We might, indeed, 

 render the question more complicated by setting as a neces- 

 sary part of the inquiry the determination of the actnal 



