in Clearing Malt Liquor. 109 



ing or fining it, is by two properties of gelatine (the chemi- 

 cal principle of Isinglass). First, its solubility in weak or 

 dilute acids ; and, secondly, by being perfectly insoluble in 

 alcohol, and sparingly soluble in cold water. 



When clearings, or isinglass, in combination with sour 

 or acid beer, is applied to malt liquor in a state of vinous 

 fermentation, the alcohol of the liquor disengages the gela- 

 tine of the Isinglass from its solution in the acid porter, 

 and, being thus liberated, it carries with it the impurities 

 of the liquor which were suspended in it. 



The following experiments will better illustrate the 

 theory : 



Mix a small quantity of brewers' clearings with cold 

 water. In a short time the greatest part of the Isinglass 

 will be separated. 



Filter the mixture through paper, and if a few drops of 

 tincture of galls be added to the filtered liquor, a small 

 portion of gelatine will be precipitated. 



This shows that the acid of the clearings held a small 

 quantity of the gelatine in solution. This is further proved 

 by adding to the filtered solution as above, a few drops of 

 liquor of ammonia, instead of tincture of galls. The liquor 

 of ammonia should be cautiously added in sufficient quan- 

 tity, to neutralize the acid contained in the clearings, when 

 the gelatine, which was previously held in solution by the 

 acid, is liberated. 



By this experiment is shown, the solubility of Isinglass 

 in acid porter, and nearly its total insolubility in cold water. 



Again, dilate a small quantity of clearings with cold 

 water, until its acidity is so far overcome, as not to redden 

 litmus paper, when applied to it. The Isinglass of the 

 clearings will be completely separated from the mixture ; 

 for, if a few drops of the tincture of galls be added to the 

 filtered solution, it will remain unchanged. 



Add warm water, at about 180° F., to another small por- 

 tion of clearings, until the liquor is so much diluted as not 

 to affect litmus paper when dipped in it, as in the previous 

 experiment. Filter the liquor through paper, when cold. 

 Gelatine will be detected in this solution by adding a few 

 drops of tincture of galls. This shows the solubility of 

 Isinglass in hot water. 



