Dr. WoUastorCs Chryophorus. — Sitgarfrom Starch. 155 



present. When the surrounding temperature Is unfavour- 

 able, the success ot" the experiment may be facihtated by 

 first dipping the clothed bulb in water, and, after freezing 

 this bv means of the air pump, pouring a few drops of ether 

 upon it, and again exposing it to exhaustion. 



In another part of the present number will be found an_ 

 interestins: notice by Mr. Hutton of Edinburgh respecting 

 some experiments on alcohol, effected by means of artificial 

 eoid. The author, in giving his resuJts, has been silent re- 

 specting the method employed for reducing the temperature 

 of the alcohol ; but Dr. Marcet^s process, described above, 

 would certainly answer the purpose. Indeed iTiany new- 

 results, obtained by -means of th'fS powerful agent, may be 

 speedily expected. 



DR. wollaston's chryophorus. 



In a paper read some weeks ago before the Royal Society, 

 Dr. VVollaston describes a new instrument, to which he has 

 given the above name. It consists of a tube, terminated at 

 «ach end by a ball, and bent like the letter U, having one 

 of these half full of water, the other empty, and the whole 

 exhausted of air. If the empty ball be plunged into a mix- 

 ture of salt and snow, the water in the other ball will be 

 •frozen in a few minutes, though several inches, or evea 

 some feet, distant from the cold mixture. 



In the communication alluded to in the preceding notice. 

 Dr. Marcet states, that, by a process similar to that de- 

 scribed for the congelation of mercury, the water in Dr» 

 Wollaston's instrument maybe frozen without any cooling 

 mixture in less than a minute, and with a pump of very 

 XDoderale power. 



SUGAR FROM STARCH. 



In the preceding volume of the Philosophical Magazine 

 some account was giveii of this process, the discovery of 

 M. Kirchoff" of the academy of Pelcrsburgh. M. KiichofF 

 employs sulphuric acid, one part diluted with 200 parts of 

 water, which is made to boil in a wcll-linned co[)per vessel. 

 Starch 100 pans, mixed with 200 parts of water and passed 

 through a sieve, is then gradually and in small quantities 

 mixed with the boiling diluted acid; and the whole is kept 

 in a state of ebullition for 36 hours, water being added for 

 what is evaporated : some powdered charcoal is then added, 

 and, lastly, chalk sufficient to saturate the acid. It is then 

 fillertd through a cloth, and afterwards evaporated gently 

 to the state of a syrup, and set aside for crystallization, 

 which takes place ia three or four days, 



M. Vogel 



