422 Miscellaneous Intelligence, 



nor fragments in the vessel beneath corresponding to it. If, on 

 the contrary, the stone yields to frost, then the salt, even in its 

 first appearance, will carry off with it fraj^ments of the stone, and 

 the cube will lose its angles and edges. The trial should finish on 

 the fifth day from the first appearance of the fine crystals upon the 

 stone ; at which time there will be found at the bottom of each 

 vessel the quantity of matter which has been detached from the 

 respective cube. 



The crystallization of the salt may be facilitated by dipping the stone 

 into the solution beneath so soon as the crystals have appeared upon 

 a few points, and repeating this shght operation five or six times in 

 one day. The observation already made that the solution is to be 

 saturated when cold, is highly necessary to be attended to, for expe- 

 riments have shewn, that stone which completely resisted the action 

 bf frost, and of a cold solution, was entirely disintegrated by the 

 use of a hot solution ; and the same effect takes place, though in a 

 less degree, if the trial be continued longer than the fifth day. 



X. To judge between two stones of the degree in which they 

 resist the action of frost, it is only necessary to collect the portions 

 of matter which have been detached in the above trials, from the 

 faces of the cubes, to dry and weigh them ; the greater the weight 

 of the matter separated, the more has the stone yielded. If a 

 cube 2 inches in the side, or having 24 square inches of surface, 

 loses 1 80 grains in this way, a cubical toise of the same stone would 

 lose 3 lb. 6 oz. in the same space of time. — Annales de Chimie, 

 xxxviii. 160. 



2. On the Compression of Water in different Vessels. — A series of 

 very interesting researches have been made lately by different philo- 

 sophers on the compressibility of fluids ; but a serious difference of 

 opinion has arisen relative to the effect of the pressure used upon 

 the vessel containing the fluid experimented with. The fluid is put 

 into a vessel, as a globe with a very narrow neck, and then this 

 vessel being immersed in water, or some other fluid, pressure is 

 applied to the latter in such a manner that it not only presses upon 

 the fluid in the first vessel, in consequence of the neck being open, 

 but also with an exactly equal force on the outside of that vessel ; 

 so that, in reality, the pressure on the inside and outside of the 

 measuring vessel is exactly equal. Then arises the question of what 

 alteration takes place in the form and capacity of this vessel in con- 

 sequence of the pressure. MM. CoUadon and Sturm, whose me- 

 moire has been rewarded by the Academy of Sciences, think that 

 the bulk and capacity of the vessel has been diminished in the same 

 proportion that would have occurred if it had been the outside 

 layer of a solid body of the same form and material ; whilst M. 

 Oersted, and others, reasoning upon the circumstance, that as the 

 pressure increases on the outside an equal increase on the inside 

 is opposed to it, think that, in reality, the capacity is increased^ 

 but by a quantity so small as not to be appreciable. The only 



