of Processes In the Fine and Useful Arts. 165 



genious practical men, they cannot find any objection to it;^*s6'' 

 I am emboldened to send you a description of it. 



2. On the evaporation of Wines, Alcohol, and other fluids by 

 means of bladders. By M. S(em:mering of Munich. 



M. Soemmering, in a memoir in the Academy of Sciences of 

 Munich, states that alcohol, in a vessel covered with bladder, 

 the latter not being in contact with the fluid, loses, when ex- 

 posed to a dry atmosphere, much of its water and becomes 

 stronger. But if the vessel thus closed be exposed to a damp 

 air, the alcohol attracts humidity and becomes weaker. 



In a second memoir the author states more particularly the 

 effect of bringing the alcohol into immediate contact with the 

 membrane. If a bladder be filled with 16 ounces of alcohol 

 at 75°, and be well closed and suspended over a sand bath, or 

 placed near a warm stove, so as to remain at the distance of 

 more than an inch from the hot surface, it becomes in a few 

 days reduced to a fourth of its volume, and is nearly or quite 

 anhydrous. 



M. Soemmering prepares for this purpose calves or beeves 

 bladders, by steeping them first in water, washing, inflating 

 and cleansing them from grease and other extraneous matters, 

 tying the ureters carefully, and then returning them to the 

 water in order to clear off" more fully the interior mucosityj 

 After having inflated and dried the bladders, M. S. covers 

 them with a solution of Ichthyocolla, one coating internally 

 and two externally. The bladder thus becomes firmer, and 

 the alcoholic concentration succeeds better. 



It is better not to fill the bladder entirely, but to leave a 

 small space empty. The bladder is not moist to the touch, 

 and gives out no odour of alcohol. If the latter be below 16° 

 Baume, the bladder then softens a little and appears moist to 

 the touch. 



Bladders prepared as above may be employed more than a 

 hundred times, though they at length acquire a yellowish- 

 brown colour and become a little wrinkled and leathery. 

 The swimming bladder of the salmon is not fit for these ex- 

 periments. Alcohol of 72° was put into one of them, and after 

 an exposure of thirty-two hours it had lost more than one-third 



