VOL. LXXI.] PHILOSOPHICAL TRANSACTIONS. J 6 1 



The proportion between the quantity of the ether and of the water that ma)' 

 be frozen by it, seems to vary according to the quantity of water; for a larger 

 quantity of water seems to require a proportionably less quantity of ether than a 

 smaller quantity of water, supposing that the water is contained in cylindrical 

 glass vessels; for I have not tried whether a metal vessel instead of a glass one, 

 and whether some other shape besides the cylindrical, might not facilitate the 

 congelation. In the beginning of the spring I froze about a quarter of an ounce 

 of water with nearly half an ounce weight of ether, the apparatus being larger, 

 though similar to that described above. Now as the price of ether, sufficiently 

 good for the purpose, is generally between 18 pence and 2 shillings per ounce, 

 it is plain, that with less than 2 shillings a quarter of an ounce of ice, or ice 

 cream, may be made in every climate, and at any time; which may afford great 

 satisfaction to those persons who, living in places where no natural ice is to be 

 had, never saw or tasted any such delicious refreshments. 



When a small piece of ice, for instance, of about 10 grains in weight, is 

 wanted, the necessary apparatus is very small, and the expense of the ether not 

 worth mentioning. I have a small box, which is 4-L inches long, 2 inches 

 broad, and 1-^ inch deep, which contains all the apparatus necessary for this pur- 

 pose, viz. a bottle capable of containing about 1 ounce of ether, 2 pointed tubes, 

 in case that one should break, a tube in which the water is to be frozen, and 

 the wire. With the quantity of ether contained in this small and very portable 

 apparatus, the experiment, when carefully performed, may be repeated about 10 

 times. A person who wishes to perform such experiments in hot climates, and 

 in places where ice is not easily procured, requires only a large bottle of ether, 

 besides the small apparatus described above. 



It is a known fact, that the moment a quantity of water becomes ice, a ther- 

 mometer kept immersed in it, rises a few degrees, and accordingly this is observed 

 in our experiment, viz. the mercury of the thermometer, which is immersed in 

 the water of the tube ab, will suddenly rise, sometimes as much as 10 degrees, 

 when the water becomes first opaque. Electrization increases very little the de- 

 gree of cold produced by the evaporation of ether. Having thrown the electri- 

 fied and also the unelectrified steam of ether on the bulb of a thermometer, 

 the mercury in it was brought down 2 degrees lower in the former than in the 



latter case. 



As various persons may, perhaps, be induced by this paper to repeat such ex- 

 periments, and as ether is a fluid which can with difficulty be preserved, it may 

 be useful to mention, that a cork confines ether in a glass bottle much better 

 than a glass stopple, which it is almost impossible to grind so well as entirely to 

 prevent the evaporation of ether. When a stopple, made very nicely out of a 

 uniform and close piece of cork, which goes rather tight, is put on a bottle of 



vol xv. Tt 



