INDUSTRIES DKPKNDINr, ON PLANT PRODUCTS I349 



muting the must by a suitable process, which forms the very essence of 

 wine m^aking. 



^. — In order to increase the effect of ^refrigeration, ^eitherjce must 

 be used for storing cold, or the necessary cold nuist be produced on the spot 

 by means of a freezing machine. In either case, refrigeration may be effect- 

 ed in the vats direct, or outside, the usual refrigerating agents being retained. 

 (a) For refrigeration in the vats, the addition of ice to the must, which is 

 a watering prohibited by law, is not to be thought of. On the other hand ice 

 floats might be employed, as in breweries. The cooling effect, however, is 

 rather limited owing to the small bulk of the floats, and it is fairly dilhcult 

 to put the latter in owing to the cap formed b)' the grape skins. To over- 

 come this difficulty the method proposed by commandant Sigaut is sug- 

 gested, which consists in adding to the must to be cooled blocks of must 

 frozen in ice-making machines. There remain the stationary or detachable 

 devices for control of temperature. The fixed ones, which form an expensive 

 and troublesome method cannot be recommended ; the detachable 

 ones, similar to the " flags " utilised in breweries, might render very great 

 service on condition that the}' are designed in such a way that they can be 

 easily immersed in the small depth of liquid hdng above the crust. 



(b) The system of cooling outside the vats presents the advantage 

 that the already existing refrigerators can be used, it being sufficient to 

 increase their effect by feeding them with frozen water or even with 

 non-freezing brine. The carriage of the ice however in Tunis presents 

 some difficulty, so that it seems desirable to resort to the installation of 

 a small freezing machine in each cellar. 



(c) There remains the idea, again modelled on breweries, of cooling 

 the whole room in which fermentation takes place, in the hope of securing, 

 by low fermentation, an apparently more rational utilisation of the yeast 

 and smaller losses by evaporation (alcohol and bouquet). The writer, 

 after recording the failure of the attempts made in this direction, considers 

 this process as unrealisable both from the practical and economical point 

 of view. 



B. — Finally the industrialisation of the wine industr}', to be carried 

 on in big factories working throughout the year, appears to be the most 

 satisfactory solution as regards the future of the problem of the wine manu- 

 facture in hot countries. It is suggested that the preservation of the must 

 without antiseptics (or after slight sulphuring) might be ensured by keeping 

 in cold storage depots where it would wait for the favourable period for fer- 

 mentation, after which it would be brought back to the cellar. 



Immediate Solutions. — Until such time as the industrial methods of 

 breweries are adopted (the really rational solution of the problem), the Au- 

 thor suggests immediate solutions of the problem bv which, without heavy 

 cost, the recurrence of difficult seasons such as that of 1913 might be avoided. 



The idea of effecting a low fermentation in wine manufacture nuist be 

 dismissed completely. North African yeasts are excellent yeasts, and it 

 is not expedient to make them work at temperatures below 28-300C. On 

 the other hand, an increase of temperature in the vats must be prevented 



