rxperiments on Sea- Water, 203 



without agitation, and well washed with cold water and dried 

 on blotting paper ; but animal and vegetable substances che^ 

 mically or mechanically dissolved, impart a ranch deeper 

 colour to the salt which remains after the complete evapo- 

 ration of the washed liquefied ice, than of an ecjual quantity of 

 the sea-water fiom which it oi-iginates. Therefoi-e, if they are 

 not more accumulating in the ice, they are at least the same 

 quantity in a less proportion of salt; and consequently the co- 

 louring must be more sUong. The colour of the dry salts cer- 

 tainly did not depend iipon iron, as their solution in distilled 

 water was not sensible in the lea^it, either to the gallic acid or 

 to the prussiate of potash. It follows naturidly liom these 

 trials, that fresh water for kitchen uses and washing may be 

 obtained Irom sea-water better by distilJation than by freezing ; 

 and particularly if care be taken to purily tlie distilled water 

 further by filtering it through sand and powdered charcoal, 

 and to unpregnate it aftei^wards with a small tjuantity of car- 

 bonic acid gas, which would take off its flatness, and make it 

 more palatable. By these precautions perhaps all bad effects 

 woiUd be better avoided, should they even be as great as those 

 described by some physicians of the South, who had an op- 

 portunity of seeing the effects of the long-protracted use of 

 that water on some criminals, and which have never been ob- 

 served in England upon any occasion of its use, not even when, 

 at a large dinner of two hundred persons, South-End water 

 was the only water used even for ices. But sea-water taken 

 at the same depth in the soudiern seas might perhaps be more 

 charged with noxious substances than the sea-water of South- 

 End : and, besides, there is a wide difference between the use 

 of it for one day at a great dinner, and foi" weeks together 

 with frugal fare. But, be that as it ma}^, it will always be of 

 some interest to know that with a small quantity of ice, and 

 muriate of lime, a great deal of ice might be produced in a 

 vessel without any waste of fresh water or ice fit for use. 



Some couj)Ies of thin lead cylinders, or perhaps better pa- 

 rallelopi|)eds, placed the one wiUiin the other, would suffice. 

 Fill the internal one with sea-water; fill with alterniite layers 

 of pounded ice and muriate of lime, wjiich needs not absolutely 

 to be powdered, the little s[)ace between the two; and keep them 

 quiet. After sometime, always depending on the more or less 

 advantageous disposition of the chmensions of the rccij)ients, on 

 the general temperature of the air, and the Ibrmer temperature 

 of the water (which ought to be taken as little warm and salt 

 as is allowed by the means at hand and the depth of the sea) 

 light clouds shall be seen floating all along the water. This is 

 the mouicnt of helping the crystalli/ation by lightly moving the 



C c 2 water 



