1 823.] Enquiry relative to theExperimenl of Freezing on theAir-Pump. 389 



producing ice i« vacuo than this. I 

 have been repeatedly informed, by 

 those wlio have witnessed it, that Mr. 

 Nichol, successor to Dr. Moyes, pro- 

 duces in a few minutes, be the tempe- 

 rature of the room what it may, solid 

 pieces of ice about the size of a com- 

 mon tea-cup. Now, if this be the case, 

 there must be some other ingredient 

 made use of besides the sulpiiuric 

 acid, if indeed that be used at all. 



1 have tried the other method, but 

 without success, mentioned in Mac- 

 kenzie's One Thousand Experiments, 

 and said to have been practised by M. 

 T. Grothus: the ether was quickly 

 evaporated, but the water remained 

 in a perfectly fluid state. Dried Trapp 

 rock and oatmeal I have often tried, 

 but never could produce congelation 

 with either of them. I observe a very 

 great dificrence between the directions 

 given for the performance of this ex- 

 periment by different writers, with re- 

 gard to the nature of the vessel into 

 which the water to be fiozen is to be 



have been that of a dictator, — dwin- 

 dled down to the office of a humble 

 friend, trying to wheedle Spain out of 

 half her liberties, lest France should 

 take the other half; and paltering to 

 France, who, backed by Russia, cared 

 not one straw for our interference. 

 Thus have we sown : but there is con- 

 solation to the i)eople, if not to their 

 rulers, in reflecting that the season by 

 which the bud harvest may be averted 

 rests not upon the diplomatic powers 

 of the Duke of Wellington. 



The avowed policy of tiiC Liberales 

 of Spain has hitherto been to allow the 

 French to advance, till they shall be 

 consumed by famine, disease, and the 

 Guerillas, — three powerful foes, in 

 whose hands the latest reports say 

 " the work goes bravely on." 



+ 



To the Editor of the Monthly Magazine. 



SIR, 



WELL knowing your readiness 

 to afford information on any 

 subject that may tend to the promo- 

 tion of science, I have taken the liberty 

 of troubling you with this, to request 

 that either you or some of your scien- 

 tific correspondents would favour me 

 with a statement of the most effectual 

 and easiest method of performing 

 Leslie's beautiful experiment, — freez- 

 ing on the air-pump. I have tried the 

 experiment at least an hundred times, 

 and all under the same circumstances, 

 on a pump in excellent condition; hut 

 I never yet found the results agree. 

 Sometimes the congelation has taken 

 place in fifteen minutes after the re- 

 ceiver was exhausted ; sometimes in 

 twenty minutes. At other times it has 

 required an hour, and, in some cases, 

 «venlwo; while in others the water 

 has totally evaporated without any ap- 

 pearance of congelation. The appa- 

 ratus I make use of is made after 

 Leslie's ; and my pump, which is made 

 by Hurter and Haas, admits of a sur- 

 face of acid of ten inches diameter: 

 the receiver which 1 use is very low. 

 These things being so, and using 

 highly concentrated acid, if the ac- 

 counts that are often published of this 

 experiment be correct, surely I ought 

 to expect that two table-spoonsful of 

 water should congeal much sooner 

 than I have ever yet found to be the 

 case. But my principal r,:,)live for 

 making this public enquiry is to ascer- 

 tain, if possible, whether there be not 

 a much more expeditious method of 



put. Some direct that it sliould be 

 glass, and others say porous earthen- 

 ware. If the latter is to be preferred, 

 the particular kind ought to be speci- 

 fied, and perhaps the most convenient 

 form also pointed out. The whole 

 process, I doubt not, sir, is familiar 

 enough to youiself, and also to many 

 of your able correspondents; any of 

 whom will, I dare say, feel a pleasure 

 in communicating it. 



I should not have intruded on you 

 with this, could I have obtained the 

 desired information from any of the 

 popular works on chemistry and natu- 

 ral philosophy that have lately appear- 

 ed. Perhaps, after all, the desideratum 

 may be as simple as that which has so 

 long been sought after by the electri- 

 cian, viz. to make his machine work 

 equally well in the lecture-room when 

 crowded, as in the parlour, where 

 there is not a breath save his own. 

 This difficulty is now obviated ; and it 

 was but the other nif;ht that 1 worked 

 for two hours a ten-inch cylinder, in a 

 rainy night, and in a room, '-rough 

 the walls of which the damp had visi- 

 bly penetrated, which was nearly filled 

 with people, and was in every respect 

 unfavourable for my experiments : yet, 

 at the conclusion of the whole, my 

 conductor emitted, from a ball fixed 

 in it, fine strong zig-zag sparks, to the 

 distance of eight inches. i. M. 



Market Harburough. 



TADl/LAR 



