344 FERMENTATION 



albuminoids occurring in worts of light gravities, arises simply from the fact that 

 for them the exhaustion of the malt is usually carried as far as possible ; the st r 

 worts consequently consisting of the more soluble saccharine constituents. 



From the foregoing remarks it will be seen that there is great difficulty in the 

 way of an attempt to give a reliable rule for apportioning the quantity of yeast to 

 a brewing, for there are many points to consider. These it will be well to recapitu- 

 late: 



1. The temperature at which it is intended to conduct the fermentation ; the lower this 

 is the more yeast must be used. 



2. The specific gravity of the ale to bo fermented ; the higher this is, the greater 

 must be the percentage of the yeast apportioned. 



3. The extent to which the exhaustion of the malt has been carried ; the more so that 

 this has been permitted, the less yeast must be used and the more slowly must the 

 fermentation be conducted. 



The extent to which granulation of the malt has occurred in the process of crushing ; 

 the more it has been pressed, the less yeast must be used, and the more slowly must 

 the fermentation be conducted. 



The character of the water used in the process of brewing, undoubtedly has its effect, 

 though it is but seldom taken into account ; the harder the water is, the more yeast by 

 a considerable proportion must be allowed. This latter consideration leads us on to a 

 subject, the importance of which cannot be over-estimated, however some may assume 

 to deride it ; but it does not require any elaborate reasoning to show that quality in 

 the water is an advantage almost equal to quality in the malt and hops. It cannot be 

 denied that the practical dyer must be master of the constituents contained in the water 

 he uses in his processes, before he can hope for unvarying success ; neither can we 

 disregard the well-known effect of drinking water in its hard state ; and recent re- 

 searches bear testimony to how small a quantity of organic impurity in any water makes 

 it extremely prejudicial as an article of food. These fects speak for themselves, and 

 point to the necessity there is that every brewer should have the means of readily 

 ascertaining the quality of the water he brews with. Amongst the most successful of 

 the trade this necessity is acknowledged and met as well as possible by a frequent 

 analysis of the waters supplied to the brewery ; but the ordinary brewer has very 

 seldom the time, the means, or the requisite ability to make a complete analysis 

 of the water ; but he may make an approximate analysis with rapidity and great 

 advantage, much oftener than is customary. Let him study the use of permanganate 

 of potash in the volumetric analysis for organic matter described in Mr. Button's 

 ' Volumetric Analysis.' The ordinary and permanent hardness can also bo easily tested, 

 as also the presence of ammonia-compounds, and those are perhaps the facts which 

 require watching in the waters supplied to breweries. 



In conducting a healthy alcoholic fermentation, the following general rules should 

 be observed : The wort should be purified as much as possible from gross con- 

 stituents and acetic tendency, first by using in its manufacture a water the lime- 

 salts of which will aid in their precipitation. (Of the beneficial influence of the hard 

 waters favoured by the brewer, Dr. Hassall suggests a theory which appears very 

 satisfactory. He says : ' During ebullition, the excess of carbonic acid in the water, 

 by which the carbonates of lime and magnesia are retained in solution, is expelled, 

 and those salts are precipitated. Again, the alkaline phosphates present in malt 

 have the power of converting the sulphate of lime into phosphate, which is thrown 

 down ; an alkaline sulphate, which is soluble, being synchronously formed. The 

 greater part of the phosphate of lime produced, is re-dissolved in the acid generated 

 during fermentation ; consequently, the water, from being hard, thus becomes soft, and 

 in this state is well suited for extracting the active properties of the malt and hops.') 

 Secondly. The wort should be cleared by every means that care and mechanical in- 

 genuity can provide. 



The yeast for setting-on should bo selected with every care, freed as much as pos- 

 sible from the gross flocks accruing in preceding manipulations, from tannic and gallic 

 acids (the product of the hop), from atmospheric contaminations, and from acetic and 

 butyric germs. It should bo as virgin as possible, and the lower the temperature at 

 which it was produced the better it will bo. When about to be applied, the wort with 

 which it is to bo mixed should bo of such a temperature as to induce immediately :ui 

 active fermentation ; this temperature must of course vary according to the gravity 

 and bulk of the wort, say for bulks of about 25 barrels of a gravity of 22 Ibs. por 

 barrel; the temperature for stone squares maybe from 67 to 70, and for v..ml 

 rounds from 64 to 67. Let the yeast bo added as soon as the wort begins to run 

 into the fermenting utensil, and decrease the temperature by the subsequent running 

 down, and the whole should bo most thoroughly roused many times during the process 

 of filling. 



