Next to water, sugar is the material which exists in the largest proportions in the must; it is, however, that peculiar kind of sugar termed "glucose," which may be described as uncrystallisable sugar, and as consisting of half grape sugar and half fruit sugar. It possesses the property of being able to ferment, which cane or crystallisable sugar cannot do, unless, indeed, it first be changed into glucose. Now, it is a curious fact that although cane sugar can be transformed into glucose, yet the latter form of sugar has never, so far, been changed into cane or crystallisable sugar. As Mr. J.A. Despeissis points out, the invention of a process that would achieve this would be worth more than all the mines of New South Wales put together. In the process of fermentation the glucose is broken up into a number of substances, which differ entirely from it; and as these different bodies are very important they deserve much attention. Under the influence of fermentation glucose undergoes a great change, of which the principal products are alcohol and carbonic acid gas. The alcohol is, of course, the one predominant feature in wine; and according to the amount of alcohol which wine contains, so it varies in strength. In addition to these two main products of glucose by fermentation, namely, alcohol and carbonic acid gas, there are glycerine and succinic acid, as well as a lesser proportion of other derivatives, very much akin to alcohol. Of all these glycerine is by no means unimportant, as it confers a blandness or mellowness upon the wine. The succinic acid, also, is distinctive for this reason, that it is the source of that characteristic flavour in wine known as "vinosity." Besides the water and the glucose, the must likewise contains quite an appreciable amount of those important bodies, the various acids. These consist of tartaric acid, so frequently met with all through the vegetable world; of malic acid, which is the acid almost distinctive of apples; of tannic acid or "tannin," and of other acids. These different acids play an important part in the production of wine; without them, in truth, it would be a mere admixture of spirits and water--a colourless, flavourless, and insipid product. By their assistance, however, wine is endowed with the brilliancy it possesses. And more than this, the action of the alcohol on these acids develops those exquisitely delicate ethers--the oenanthic and other ethers--which constitute, in fact, the bouquet of the wine. At the same time, it has also to be remembered that while these many acids constitute the life and soul, so to speak, of the wine, their very presence is absolutely necessary for the process of vinous fermentation. That is to say, the active agents of vinous fermentation are only enabled to work perfectly in a liquid which is somewhat acid.