42 
POPULAR SCIENCE REVIEW. 
tilled without decomposition. The amount of alcohol contained 
in the whole number of either class of compound ethers present 
can be estimated, but the determination of each individual 
compound ether cannot as yet be accomplished. Fixed ethers 
have, comparatively speaking, little influence on the character 
of the wine beyond neutralising part of the acid and facilitating 
the production of volatile ethers. Among volatile ethers, on 
the other hand, there are many possessing a very characteristic, 
and often, especially when much diluted, very agreeable smell ; 
and to them the wine owes a great part of its flavour and 
bouquet, and probably also some of its exhilarating and stimu- 
lating effects. 
As regards the proportion existing between the amounts of 
volatile and fixed ethers present, all pure natural wines, hitherto 
examined in this respect, contained a greater proportion of 
volatile than fixed ethers, in spite of the great preponderance of 
fixed acids ; nearly all fortified wines, on the other hand, con- 
tained a greater proportion of fixed ethers, although the pro- 
portion of volatile acids is generally higher than in the former. 
Sherries and Madeiras, however, although undoubtedly fortified, 
form an exception to this rule ; they contain, like the natural 
wines, more volatile than fixed ethers. Lastly, it appears that 
as the fortified wines get older, the proportion of volatile ethers 
becomes greater, so that at last they equal, or even exceed, the 
fixed ethers in amount, the wine gradually coming round to 
the natural standard. 
It seems very desirable that medical men should direct their 
attention to this difference among wines. By selecting, for 
example, such wines as contain the highest proportion of 
volatile ethers relative to their alcoholic strength, it may some- 
times be possible to produce the desired stimulating effect with 
the minimum amount of disturbance often following the admi- 
nistration of alcohol. 
The total amount of compound ethers present in any wine 
is extremely small. Thus in the highest case yet found (a 
Madeira, which had been 50 years in bottle) the alcohol 
contained in the compound ethers of the wine (both fixed and 
volatile) amounted to only one part in 800 parts of wine — equi- 
valent, roughly speaking, to about one part of compound ether 
in 300 parts of wine. 
Glycerine and Succinic Acid . — As previously explained, 107 
parts of cane sugar, when submitted to fermentation, yield, 
according to Pasteur, about 3*6 parts of glycerine and 0*60 
parts of succinic acid ; all fermented liquids should therefore 
contain small quantities of the.se two substances. At present, 
little is known as to the amounts actually present in dif- 
ferent sorts of wine. Succinic acid is probably without much 
