110 Notice of some Recent 



The next experiments will more clearly show the influ- 

 ence of alcohol in separating gelatine from its solution in 

 weak acid, by which its action in clearing porter in a state 

 of vinous fermentation, is explained. 



To sixty parts of cold water, add one part of alcohol, and 

 into this mixture put a small quantity of clearings. 



In a short time the Isinglass will be separated from the 

 mixture, and the liquor will be clear and bright. 



If, however, the liquor be filtered, and a few drops of 

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

 portion of gelatine will be disengaged. 



This is caused by the free acid of the sour porter, of which 

 the clearings are made, holding this small portion of gela- 

 tine in solution, as it may likewise be separated by adding 

 a few drops of liquor of ammonia, instead of tincture of 

 galls. 



Reverse the experiment by using hot water at 180° F., 

 instead of cold, adding the same quantity of alcohol and 

 clearings, as in the former experiment. 



After the mixture has been allowed to settle for a few 

 hours, it will be found that there is but a partial separation 

 of the Isinglass, and the liquor will not be so clear as in the 

 former trial, the reason of which is, that the hot water dis- 

 solves, and retains in solution a portion of the Isinglass of 

 the clearings, the remaining part being separated by the 

 alcohol, in which it is insoluble. The effect would be ex- 

 actly similar upon malt liquor, if clearings were applied to 

 it which had been made with an excess of acid beer. The 

 alcohol of the unfined porter would disengage but a small 

 portion of Isinglass from the clearings, the remainder being 

 held in solution by the excess of acid in the porter, the 

 disengaged gelatine carrying with it particles of vegetable 

 matter, which, when suspended in the liquor, rendered it 

 but semi-transparent. S. R. 



Article V. 

 Notice of some Recent Improvements in Science. 



I. ACOUSTICS. 



Nodes of vibration. — By comparing the theory of musical 

 strings and rods with that of musical pipes, Weber has 



