398 



pasteurisation, has been over-heated. That point is reached at 

 about 70 C. (158 P.), and for that reason it is desirable not to go 

 much above 65 C. (149 P.). 



Each variety of grape has a special pigment of its own, par- 

 ticular to itself. 



Albuminoids or nitrogenous substances, resembling the white 

 of an egg, also occur in minute quantities, viz., '1 to '4 per cent., and 

 are important, as entering largely into the making up of the tissues 

 of the wine. To a certain extent, therefore, they are essential to 

 fermentation, but when constituting a surplus their presence in 

 wine is highly undesirable, and even dangerous, as they are very 

 unstable bodies, easily decomposed, causing many of the accidents 

 and diseases which occur in wines. 



Certain grapes, such as the Riesling, various white grapes, 

 and also Muscats, often contain a surplus of these albuminoid 

 bodies, and, especially so, grapes that mature very quickly, as in 

 hot climates ; and this is the case generally with grapes grown in 

 Australia. 



Such surplus albuminoid substances should be removed by all 

 possible means, in order to insure the safe keeping of wines ; and in 

 a subsequent paragraph I shall mention the object of aeration in 

 this respect. 



Another means we have of ridding white wine must of any 

 surplus albuminoid matters is to let it stand still for a day or two, 

 and then draw the clear liquid from over the muddy and viscuous 

 deposit just as the first indications of fermentation become notice- 

 able. In order to better effect this end in warm climates, where 

 fermentation starts very shortly after the grapes are crushed, the 

 liquid is treated with sulphurous acid fumes. Thus the must is 

 impregnated with the fumes of burning sulphur, or liquid sul- 

 phurous acid in small quantities is poured into it, or such salts a& 

 sulphite of potassium is added to it. The advantage of these last- 

 named methods over the first consist in the greater precision which 

 can be obtained in the matter of the dose used, and in the greater 

 convenience as well. 



WHEN TO PICK GTBAPES. 



In old-established districts experience has shown when it is 

 best to pick the grapes ; and at such places it is seldom that the 

 date of vintage alters more than a week or so from the customary 

 epoch for picking the different kinds of grapes grown. 



In other parts the vine- growers will have to depend, to a greater 

 extent, on other indications for determining the time when to begin 

 picking. These indications, although empirical, are sufficiently 

 reliable. 



They are afforded by the appearance of the bunch itself. The 

 stalk becomes woody, and loses its tender green look ; the berry is 



