204 WRITINGS OF JOSEPH HENRY. [1855- 



place under the receiver of an air pump, a much greater re- 

 duction of temperature will be produced. 



Although we have not seen any account of the apparatus 

 for reducing to practice the plan above referred to, we can 

 readily imagine an arrangement which would produce the 

 result. For this purpose, it would be sufficient to put the 

 water to be frozen in thin tightly closed vessels, and place 

 them in a large receiver containing ether, the latter being 

 connected with an air pump, of which the upward stroke 

 should exhaust the atmosphere, and the downward stroke 

 re-condense the vapor in a separate vessel, to be again let 

 into the freezing receiver, and so on. 



The establishment of the ice trade, for which the present 

 age is chiefly indebted to an enterprising citizen of Boston, 

 must have a beneficial effect upon the sanitary condition of 

 the world. The white man is especially adapted by his 

 physical organization to the temperate regions, and succumbs 

 to the intensity of the prolonged heat of the tropics unless 

 through the agency of science he is enabled to ameliorate 

 the effects of the ardent rays of a nearly vertical sun. An 

 abundant supply of ice not only adds to the comfort of the 

 European in India, but is indispensable to the continuance 

 of his health. The use of this article will probably be very 

 much extended, and by a suitable system of ventilation ap- 

 plied to the cooling of the air of apartments in a manner 

 analogous to that of heating them during the rigor of winter 

 at the North. 



The expansion of a quantity of water passing into a solid 

 state will be in the direction of least resistance, and hence 

 we find a bulging up in the centre of the ice in a pitcher; 

 but if the freezing be continued the thickening of the ice in 

 this direction will produce a re-action in other directions, 

 which causes the rupture of the vessel. This expansion, as 

 we have stated before, only takes place while the water is in 

 the act of solidifying; and it is not the stratum of ice first 

 formed which causes the bulging up in this case, but the ex- 

 pansion of the water beneath. This is fully explained by 

 the plastic character of ice before mentioned. If the bulg- 



