522 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



continually with a stick, the glue will immediately (when a 

 sufficient quantity of the solution has been introduced) co- 

 nsulate into nn elnstic mass, rubber-like when cold, which 

 Avill keep indefinitely without spoiling. 



If the glue thus prepared be now placed in pure water, it 

 swells, and will be found after a few hours not only not to 

 have lost its adhesive properties, but to have improved de- 

 cidedly in this respect. And, again, if it be melted (still con- 

 taining about 18 per cent, of moisture) with fresh glue-jelly 

 having 90 per cent, of water, a half-soft glue will be obtained, 

 easily soluble, and not spoiling readily. The saline solution 

 from which the coagulated glue has been removed, on evap- 

 oration, will yield the salt in its original form, and capable of 

 being used over again repeatedly. 



To make a practical application of this principle on a large 

 scale requires the use of a wooden box with low sides. The 

 bottom of the box is to be sprinkled with a layer of sulphate 

 of ammonia, Epsom or Glauber's salts, or hyposulphite of 

 soda, about half an inch in depth, and a moist linen cloth 

 laid over; upon this is to be placed a layer of glue-jelly, 

 which is to be covered with a moist linen cloth ; and thus 

 the alternation is to be continued until the box is full, after 

 which it is to be left for some hours, and the liquefied solution 

 allowed to drain off through a hole in the bottom, the drop- 

 ping ceasing in from twelve to eighteen hours. If, now, the 

 upper cloth is taken off with its layer of salt, the glue will be 

 found beneath it so far deprived of its moisture that, when 

 placed in the sun or exposed to other heat, it will become 

 completely dry in a short time without either melting or 

 spoiling, and in winter may be laid upon drying floors with 

 the same result. In this hint will be found the possibility of 

 preparing glue throughout the year without the use of drying 

 apartments or vacuum pans. 



This method has its defects as w r ell as its advantages. 

 Among the former may be enumerated a slight want of 

 transparency in consequence of the salt used in the process, 

 and the taking up of from three to six per cent, of salt. The 

 advantages, on the other hand, are in rendering the manufac- 

 ture independent of climate, and capable of being prosecuted 

 at any season of the year; and the fact that the salt employed 

 can be used over and over again with scarcely any loss. The 



