28 Journal of Agriculture, Victoria. [to Jan., 191 t. 



Bisulphite of potash is a readily soluble crystalline salt which keeps 

 Tvell, especially when kept in corked bottles ; if left open it is apt to lose 

 portion of its SOo. The form in fairly large crystals is to be preferred. 

 In powder, it is liable to oxidation and transformation into sulphate. Dif- 

 ferent samples may vary a little in composition, but for practical purposes 

 it mav be looked upon as containing one half its weight of SOo. 



There are two forms in which this salt is known, viz., the ordinary 

 and the " meta " form. The salt, known is meta-bisulphite of potash, is 

 said to be more stable and less exposed to loss of SO2 on keeping. In 

 •other respects, the two may be looked upon as practically identical. 



A new proprietary compound has lately been placed on the market in 

 France under the name of suli)hophosphate of ammonia. It is a liquid 

 ■containing one quarter of its weight of SOv, as well as a certain propor- 

 tion of phosphate of animonia. a valuable yeast stimulant. (See Journal, 

 April. 1909, p. 229.) This substance is highly spoken of by leading 

 authorities. 



The close to use dej)ends. naturally, upon the percentage of sulphurous 

 acid contained in the product selected ; it can therefore be most satisfac- 

 torily stated in terms of SO^. Plven so, an arbitrarily fixed dose cannot 

 be laid down as being suitable for all cases. According to M. Dupont, 

 the proper dose may vary between 7.5 and 20 grammes of SO2 per hecto- 

 litre (ij to 3j oz. per 100 gallons) according to circumstances. The dose 

 is, in fact, very elastic ; some authorities have not hesitated to recommend 

 much heavier quantities — ev'en as much as 50 grammes per hectolitre (8 oz. 

 per ICO gallons). Such very heavy doses are not, according to ISI. Dupont, 

 to be recommended, unless in excejjtional cases, such as, for example, in 

 \'erv hot weather, when furtht-r ad.ditions may l)e given to check a rise 

 in temperature. 



The elasticity of the system is such that there is little danger of an 

 ■overdose. MM. Dupont and Ventre consider the most useful dose to 

 be from 10 to 15 grammes per hectolitre (i| to 2 J oz. per 106 gallons) of 

 SO2. This would necessitate an addition of the following quantities of 

 ^ach different form for every 100 gallons of grape juice : — 



5 to I5 ozs. of sulphur (combustion of). 



15 to 25 ozs. of liquified sulphur dioxide. 



16 to 24 fluid ozs. commercial sulphurous acid (aqueous solution of SOg)- 

 3 to 45 ozs. of bisulphite of potash. 



6 to 9 fluid ozs. of sulphophosphate of ammonia. 



As already pointed out, the form in which the sulphurous acid is added 

 appears to be immaterial. Exhaustive experiments have proved that wines 

 of equal quality can be obtained with any of the above substances. Ques- 

 tions of convenience and indi^•idual preference must decide the choice. In 

 a general way, commercial sulphurous acid is cheaper and, if fresh, quite 

 reliable in strength, whilst bisulphite of potash, though dearer, is more 

 con\enient to use and perniits the dose to be gauged more accuratelv. 



Practical Considerations. 



The practical application of the method presents no difficulties. All 

 that is necessary is to add the sulphurous acid to the fermenting mass, 

 whether this be crushed and stemmed grapes, in the case of red wine, or 

 pressed juice in the case of white. The two most vital points requiring 

 attention are, its early addition and the thorough mixing throughout the 

 fermenting mass. 



The advantages of an early start are obvious. From the moment the 

 ■grapes are crushed ; in other words, that the innumerable and varied ' 



