204;' Exjierimeiils on Sca-ll'alcv. 



vvatei* with a stick. Thus lumps of ice are obtained sufTicieutly 

 hirge and thick to be taken out ol" the recipient and fit for re- 

 sisting fusion. The ice, once well fixed, may serve partly for 

 immediate use, and partly to reproduce ice without breaking 

 in upon the ship's store. The first liquefied ice may be useful 

 for cooling, were sea-water to be frozen in another recipient, if 

 it is no longer fit for the same purpose, and so on. 

 . The muriate of lime is easily collected for further use from 

 the sweet liquefied ice by evaporation ; but it is not so with 

 the muriate of lime dissolved by sea-water ice. It mixes then 

 with the salt of the sea-water, and after evaporation they re- 

 main united. But there is muriate of lime too in the sea- 

 water, and muriate of magnesia; and if the muriate of soda is 

 not so favourable to the frigorific mixtures as the others, it 

 will always be of some use when mixed with a sufticient quan- 

 tity of the muriates of lime and magnesia, as used by the con- 

 fectioners, and certainly will never be unfavourable to cooling. 

 The sweet ice ought to be kept in wooden cylinders within 

 leaden ones, with a sufficiently deep stratum of powdered char- 

 coal betvt'een them to preserve a constant temperature. The 

 iiuu'iate of lime ought to be put in earthen jars well corked up. 

 The driest and coldest place of the ship is the best for the ice ; 

 the driest and warmest for the muriate of lime. I shall not 

 recommend to seamen to collect the salt employed in a state of 

 crystallization ; they woidd scarcely understand the name, and 

 not at all the management, and not much more than the name 

 and the management of the air-pump for obtaining ice : but I 

 would recommend it to any chemical man on board liospital- 

 ships, for the use of which the proceeding is intended more 

 than for increasing the luxuries of vessels, as the effect of the 

 first part of water taken even by the deliquescent salts would 

 tend rather to increase the temperature. But the passage is 

 so rapid to the contrary effect, and such is the degree of its 

 power, that the circumstance is not worthy of notice with sea- 

 men. I said " sea-water ice might be obtained nearly de- 

 prived of salt," because it is impossible to separate it entirely 

 from it. The cold water would carry away the very salt 

 water adhering to its surface ; but it cannot carry away the si- 

 milar drops inclosed inside without destroying the ice itself. 

 These drops are found here and there in the thickest pieces of 

 ice ; and let the ice drain as it will, let it be washed and washed 

 again with cold water, and dried and dried again on blotting 

 paper, the greatest part of the internal drops will always remain 

 inside, at least in our laboratories, and particularl}' if the ice 

 has been obtained with agitation. 



Might nut diis observation shed some light on the origin of 



the 



