250 



♦ KNOWLEDGE 



[Sept. 2G, 1884. 



the high prices of old-fashioned old wines ; or of what I 

 <B»y novj cM the " traditional value " of wine. 



Of course, this is less when a man lays down his own 

 vine in his own cellar in obedience to the maxim " Lay 

 down good port in the d-iys of your youth, and when you 

 are old your friends will not forsake you." He may be 

 satisfied with a much smaller rate of interest than the man 

 ■engaged in business fairly demands. Still, when wine thus 

 aged was thrown into the market, it competed with com- 

 mercially cellared wine, and obtained remarkable prices, 

 ospecially as it has a special value for " blending " purposes, 

 /.«., for mixing with newer wines and infecting them with 

 its own senility. 



But why do I say that noiu such values are traditional ? 

 >?iinply because the progress of chemistry has shown us how 

 the changes resulting from years of celUiage may be 

 «fFricteH by seientitio cookery in a few hours or days. We 

 are indebted to Pasteur for the most legitimnte — I might 

 say the only legitimate — method of doing this. The pro- 

 aeas is accordingly called " Pasteuring." It cnsists in 

 simply heatiug the wine to the temperatu'e of 60°C =:140° 

 Fahr., the temperature at which, as will be remembered, 

 the visible changes in the cookery of animal food com- 

 laences. It is a process demanding considerable skill ; no 

 portion of the wine during its cookery must be raised above 

 this temperature, yet all must reach it ; nor must it be ex- 

 posed to the air. 



The apparatus designed by Rossignol is one of the best 

 suited for this purpose. This is a large metallic vat or 

 ><oiler with air-tight cover and a false bottom, fr^m which 

 rises a trumpet-shaped tube through the middle of the vat, 

 and passing through an air-tight fitting in the cover. The 

 chamber formed by the false bot'om is tilled with water by 

 means of this tube, the object being to prevent the wine 

 at the lower part from being heated dir<-ctiy by the fire 

 which is below the water chamber. A thermometer is 

 also inserted air-tight in the lid, with its bulb halt-way 

 down the vat. To allow for e.Kpansion a tube is similarly 

 fitted into the lid. This is bent syphon-like, and its lower 

 end dipped into a flask containing wine or water, so that 

 air or vapour may escape and bubble through, but none 

 «nter. Even in drawing off from the Pasteuring vat into 

 the cask the wine is not allowed to flow through the air, 

 but is conveyed by a pipe which bends down, and dips to 

 ihe bottom of the barrel. 



If heated with exposure to air, the wine acquires a 

 flavour easily recognised as the " gout de cuit," or flavour 

 of cooking. By Pasteur's method, properly carried out, the 

 rtttly changes are those which would be otherwise produced 

 by aga 



These changes are somewhat obscure. One eflPect is 

 probably that which more decidedly occurs in the maturing 

 of whisky and other spirits distil ed from grain — viz., the 

 reduction of the proportion of amy lie alcohol or fusel oil, 

 which although less abundantly prodncfd in the fermenta- 

 tion of grape juice than in gr-iin or potato spirit, is formed 

 ill varying quantities. Cup'oic alcohol and caprylic 

 alcohol are also produced by the fermentation of grape 

 juice or the " marc " of grapes — i «., the mixture of the 

 whole juice and the skins. These are aciid, ill flavoured 

 spirits, more conducive to headache than the ethylic alcohol, 

 •-vhioh is proper spirit of good wine. Every wine-drinker 

 knows that the amount of headache obtainable from a 

 given quantity of wine, or a given outlay of cash, varies 

 with the sample, and this variation appears to be due to 

 these supplementary alcohols or ethers. 



Another change appears to be the formation of ethers 

 having choice flavours and bouquets ; cenanthic ether, or 

 tJre ether of wine, is the most iniportau'. of th:se, and it is 



probably formed by the action of the natural acid salts of 

 the wine upon its alcohol. Johnstone says : — " So powerful 

 is the odour of this substance, however, that few wines 

 contain more than one- forty thousandth part of their bulk 

 of it. Yet it is always present, can always be recognised 

 by its smell, and is one of the general characteristics of all 

 grape wines." This ether is stated to be the basis of 

 Humjarian luine oil, which, according to the same authority, 

 has been sold for flavouring brandy at the rate of sixty- 

 nine dollars per pound. I am surprised that up to the 

 present time it has not been cheaply produced in large 

 quantities. Chemical problems that appear far more 

 diflScult have been practically solved. 



THE ELECTRO-MAGXET. 

 By W. Slingo. 



(Continued from p. 175.) 



AS I intimated in a previous article, an electro-magnet 

 is not necessarily a straight one. In fact, it may be 

 made to almost any pattern, although naturally the shape 

 and dimensions should be kept within certain bounds to 

 ensure the greatest attainable efficiency. Inasmuch as 

 electro-magnets are rarely used except where transitory 

 effects are requisite, they are generally made in one or 

 other of the many possible modifications of the so-called 

 horse-shoe shape. The object is to get the two poles near 

 each other, so as to influence a piece of iron placed across 



^ 



Fig- 1. 



them. In Fig. 1 we have the general form of an ele- 

 mentary electro-magnet, in which one end of the iron 

 core becomes a north pole and the other a south pole. 

 It is manifest that if with this we wish to exert 

 the greatest possible amount of attraction of which 

 it is capable we must utilise the two polar forces. The 

 piece of soft iron best adapted for this would be curved in 

 shape, the segment of a circle with one extremity on each 

 pole. This, however, would constitute an awkward arma- 

 ture, more especially where it is lequired to be light and 

 capable of moving freely. When, therefore, it is per- 

 missible to utilise both poles of the electromagnet, it is 

 bent into a more or less perfect \J shape. Fig. 2 represents 



aEb 



¥ 



Fig. 2. 



what we might get by bending a simple bar magnet. We 

 rarely, however, see a horse-shoe-magnet so constructed. In 

 the first place, a horse-shoe-magnet is manifestly only in- 

 tended for use at close quarters, because at even a short 

 distance, the two polarities become more nearly equidistant, 

 and we very soon reach a point where they are 

 practically equal, and where they, being opposite, 

 neutralise each other. Now it will be remembered that 

 in the preceding article it was demonstrated that when 

 experimenting with bar magnets, a magnet wound as 

 dep'cted in Fi^'. 3 gave g-eater results (at short distances) 



