Intelligence and Miscellaneous Articles. 315 



bitartrate of potash, and 30 grammes of potash. This solution when 

 filtered is of an intense blue colour, and ought to be kept in the dark. 

 The trials made with this solution proved that cane-sugar or beet- 

 sugar may produce the same reaction as glucose on the alkaline 

 solution of oxide of copper, according to the conditions of operating 

 and the modifications which this kind of sugar may undergo by the 

 influence of heat alone, or with water. 



M. Lassaigne thinks he has ascertained that glucose acts more 

 readily, and at a lower temperature, on the copper reagent than 

 common sugar does ; but the latter, if heated till it begins to assume 

 an amber colour of less or greater depth, then acts like the former. 

 In fact, an aqueous solution of glucose artificially prepared with, 

 starch, and containing one-fiftieth of its weight of this sugar, treated 

 with the copper test at a heat of 64° to 68° F., reacts in less than 

 three or four minutes, or by holding the tube inclosed in the palm 

 of the hand. Under similar conditions cane-sugar produces no effect 

 on the solution of copper ; but it may be kept for some time near 

 212° without giving any appearance of reduction. By prolonging 

 the time of boiling, action is at first perceived by change in the 

 blue colour of the solution, slight turbidness, and the separation of a 

 pulverulent yellow precipitate, which eventually becomes brick-red. 

 The action of cane-sugar, not modified by heat, is slow upon the 

 alkaline solution of copper ; whereas when it has been subjected to 

 a more or less high temperature, the action is often as prompt as 

 that of glucose on the same reagent. 



Heat, by its action on cane-sugar, ought naturally to put us on 

 our guard in employing the solution of copper above mentioned for 

 determining glucose in manufactured products in which it is sup- 

 posed to exist. The employment of this reagent is to be suspected 

 of inducing error in certain cases ; thus barley-sugar and pate de 

 gomme, prepared with cane-sugar slightly caramelized by heating 

 the substances which enter into their composition, acted as readily 

 on the test as pure glucose. 



It has also been proved that potash, which acts in so characteristic 

 a manner upon glucose, and which has been proposed for distin- 

 guishing this kind of sugar from cane or beet-sugar, often gives with 

 these latter sugars reactions analogous to those developed by glucose. 

 In the examination of sugars, and various alimentary or medicinal 

 preparations into which they enter, the influence which heat may 

 produce on these products, and the modifications which result from 

 it, should be considered. — Journ. de Chim. Med., Juillet 1850. 



NEW REAGENT FOR OXIDE OF CARBON. 



MM. Stas, Dogere and Felix Leblanc, wishing to determine the 

 oxygen in carburetted hydrogen by ammoniacal protochloride of 

 copper, found that this reagent dissolved a great quantity of oxide 

 of carbon and even of olefiant gas. M. Leblanc, having undertaken 

 the investigation of this property, obtained the following results ; — 



