Chemical Science* 149 



2. Oersted on Accelerating Distillation. — In Gehlen*s Journal^ i. 

 277, I have related a few experiments which demonstrate that the 

 disengagement of gas in a fluid resulting from chemical decom- 

 position, never takes place, except in contact with some solid body. 

 This principle may, without doubt, be applied to the disengage- 

 ment of vapours. If a metallic wire be suspended in a boiling 

 fluid, it instantly becomes covered with bubbles of vapour. Hence 

 it might be concluded that a large number of metallic wires, in- 

 troduced into a fluid which we wish to distil, would accelerate the 

 fonnation of vapours. To prove this opinion, I introduced ten 

 pounds of brass wire, of one-fifth of a line in diameter, loosely 

 rolled up, into a distillatory vessel, containing 20 measures (about 

 10 pints) of brandy ; the result was, that seven measures of brandy 

 distilled over with a heat which, without the wire, was capable of 

 sending over only four measures. 



An expedient similar to this has been long in common use in 

 England. "When a steam-boiler has become incrusted with so 

 much earthy matter that the contained water ceases to boil with 

 rapidity, it is customary to throw in a quantity of the residue ob- 

 tained from malt, by extracting its soluble portion, and which 

 chiefly consists of small grains or fibres. Here the disengage- 

 ment of vapour is promoted by the large number of thin and solid 

 particles. — Ann. Phil. N.S. ix. 157. 



The Editor of the Annals considers it probable that M. Oersted 

 refers to the statement made by Mr. Bald in the Edin. Phil. Jour. 

 ii. 340. That gentleman states that comings are used for this pur- 

 pose ; they are the radicles of barley produced by malting, and 

 separated before the malt is sent to market. About a bushel of 

 these is thrown into the boiler, and when the steam is raised there 

 is not only a plentiful supply to produce the full working speed 

 of the engine, but an excess going waste at the safety valve. 

 This singular effect will continue several days. 



3. Maximum Density of Water. — Professor Hallos trom, in a 

 memoir which has appeared in the Swedish Transactions for 1823» 

 deduces the temperature of the maximum density of water, as 

 39.394° Fahrenheit. Endeavours were made to estimate every 

 cause which interfered with the experiments, such as dilatation 

 of glass, ^-c, and he thinks the limits of uncertainty are 0.428° 

 Fahrenheit on either side of the above number. 



4. On the substitution of Tubes for Bottles, in the 'preservation of 

 certain Fluids, such as Chloride of Sulphur, Proiochlorides of 

 Phosphorus, and Carbon, &c. — There are many fluids^in the labo- 

 ratory, which are much more conveniently retained in tubes, such as 

 that depicted in the margin, than in bottles, and from which they 

 may be taken in a less wasteful manner when required for tlie pur- 

 pose of experiment. A piece of glass tube, a quarter of an inch ov 



