Mr. Bevan on the Adhesion of Glue. Ill 



tained a contrary opinion, we considered that the publication 

 of our experiments might not prove altogether useless. 



The compression of liquid bodies reducible to drops, is, as 

 far as our experience yet goes, subject to the same law. Here 

 too, the compression and the compressing power seem to bear 

 a direct relative proportion. We may therefore assume, that 

 the gases converted into liquids reducible to drops, begin again 

 to follow the same law to which they answered as gases. If 

 this should be confirmed by further experiments, it may be 

 said that the compression of a body ceases to conform to these 

 rules, only in its moment of transition from one state of 

 aggregation to another. 



XIV. On the Adhesion of Glue. By B. Bevan, Esq. 



To the Editor of the Philosophical Magazine and Journal. 

 *Sir, 

 T^ XPERIMENTS, when carefully made on the properties 

 -*-^ of substances which are daily used in large quantities, 

 cannot be altogether uninteresting, but may lead to improve- 

 ments in the arts. 



Having for some years been in possession of apparatus 

 for measuring with accuracy mechanical forces to a consider- 

 able extent, I avail myself of a leisure hour, when I can find 

 one, of trying various elementary experiments. I have lately 

 tried the force of adhesion of common glue. The method I 

 adopted was that of gluing together two cylinders of dry ash 

 wood, of 1 '5 in. diameter, and about eight inches long : 

 these were submitted to the lever apparatus after being 

 glued together twenty-four hours. To separate the cylinders 

 required a force of 1260 pounds; and as the area of the cir- 

 cular ends of the cylinders were 1*76 in., it follows that 

 the force of 715 pounds would be required to separate one 

 square inch. It is right to observe that the glue used in this 

 experiment was fresh made, and the season very dry. Upon 

 referring to some former experiments on this substance, made 

 in the winter season, and upon glue which had been frequently 

 melted, with occasional additions of glue and water, I obtained 

 a result of 350 to 560 pounds to the square inch. My present 

 experiment was conducted upon a larger scale, and with 

 greater care in the direction of the resultant of the force, 

 so that it might be, as near as was practicable, in a line 

 passing at right angles, through the centres of the surfaces in 

 contact; the pressure was applied gradually, and was sus- 

 tained two or three minutes before the separation took place. 



Upon 



