436 Nfw Method of congealing }-fater in a Vacuum. 



within the limits mentioned by him. This induced me to make 

 a calculation of the time of bej^inning for Leighton ; and I was 

 surprised to find the time differ more than foiu- minutes from 

 the time given by so good an observation. I take it for granted, 

 thar Mr. B. has been misled by the equation of time in the 

 Nautical Almanac being marked Add, instead of Sub. 



I hope, if this has been the case, Mr. B. vviil have the good- 

 ness to give the times thus corrected in the same explicit man- 

 ner in which he sent you his former observations. 



In a calculation of this eclipse bv Mr. MacGregor, noticed in 

 your last Magazine, and upon which you have bestowed such 

 merited encomiums, I have observed that he has made the equa- 

 tion of time rather too great ; but his 14th and Slst equations 

 of longitude, being respectively 0"-78, and 0"-9 too small, will 

 very nearly balance the error in the equation of time. 



Your inserting the above will oblige. 



Sir, your most obedient iervant, 

 Aberdeen, Nov. 10, 1820. Geo. Innes. 



LXXI. New Method of cov sealing Water in a Vacmim. By 

 M. T. Grothuss*. 



Xhe beautiful discovery of Professor Leslie on the artificial 

 congelation of water has successively engaged the attention of 

 many learned philosophers and chemists. They have sought to 

 give to this discoverv a more extended application, in order to 

 convert it to some great object of utility; and already their la- 

 bours have led to the discovery of some particular results which 

 might otherwise have remained long concealed. In the mean 

 time it must be useful to make known all the facts connected 

 with this discovery ; and I am therefore induced *o publish the 

 result of an experiment by which I effected the congelation of 

 water promptly and witli the greatest facility. 



Into a metal vase half filled with water, I poured very gently 

 an eqwal quantity of etiicr, so that no mixture might take place 

 of the two liquids, Tiie vase was placed under the receiver of 

 an air-pump, which was so fixed uj)on its su|)i)ort as to remain 

 quite steady when the air was pumped out. At the first strokes 

 of the piston the ether became in a state of cljullition ; it wjjs 

 evaporated totally in less than a minute, and tlie water remained 

 converted into ice. I made this experiment for the first time at 

 Mittau, in an apartment the temperature of which was 16° R. 



• Annak's Generates des Sciences Physif/nes. By MM. Van Mons, &c. 



LXXII, Cal- 



