CHEMISTRY. 231 



candles at 8d. will cost only l$d.- which is less than one-fifth the price of 

 candles. Compared with wax candles the cost of gas light will be one- 

 sixteenth. 



In comparison with the cheapest kind of lamp oil, the cost of light from 

 gas will be loss than one-fifth, and'compared with sperm oil only one-ninth. 

 Gas is admirably adapted, and is coming extensively into use, for warming, 

 ventilating, and cooking ; and for many other purposes both domestic and 

 commercial. Cooking by gas is easily understood, and is very cleanly and 

 convenient. In many other respects it possesses advantages so peculiarly its 

 own, that it needs only to be fairly tried to realize all that can be said in its 

 favor. Roasting by gas is the perfection of that part of the culinary art. 

 The meat thus prepared, both in flavor and nutritive properties, is superior to' 

 that cooked by an open fire ; and this is as applicable to the smallest, as it is 

 to the largest joints. In baking cakes, or pastry, the requisite knowledge is 

 acquired in a few hours ; the heat being regulated with such accuracy as 

 always to insure success. In warming by gas it is desirable that the stove 

 should communicate with a flue or chimney ; but always in such a manner as 

 that, whilst the products of combustion escape, as much as possible of the 

 heat might be retained in the apartment. 



INVESTIGATIONS IX CHLOEIMETRY. 



The anomalies presented at times in the process of treating with hypochlo- 

 rite of linie (commonly called chloride of lime) the standard test liquors of Gay 

 Lussac. have just been explained by MM. Fordos and Gelis. A normal solu- 

 tion of the hypochlorite having, at the end of some time, lost its standard 

 value without having lost its bleaching power, these chemists examined the 

 liquid and found that a part of the hypochlorous acid was changed to chlorous 

 acid, which bleaches indigo well, but does not act on the arsenous acid 

 employed in the process of Gay Lussac. 



This fact is of great importance in commerce ; for on examining a hypochlo- 

 rite of lirne or soda, the merchant or dyer is not anxious to learn the quantity 

 of hypochlorous acid present, but wishes to know the quantity of coloring 

 matter a given weight of the hypochloric will bleach. 



MM. Fordos and Gelis have therefore sought for a better process ; and after 

 employing it for four years in the fine establishment founded by them on the 

 Seine, they publish it for the benefit of the trade. They replace the arsenous 

 acid with hyposulphite of soda, a salt that is definite hi composition and 

 unalterable of itself, and which chlorous acid destroys easily. It is very 

 soluble in water, and not poisonous, and therefore every way preferable to 

 the arsenous acid. 



Excepting this substitution, the process resembles that of Gay Lussac. 

 2'77 grammes of crystallized hyposulphite of soda dissolved hi 1 litre of water, 

 constitutes the test liquor, corresponding to the arsenical solution of Gay 

 Lussac. After having taken 10 cubic centimetres of this normal liquor, 100 

 parts of water are added and some drops of indigo ; and as the hypochlorites 

 are generally alkaline, and since the hyposulphite of soda does not decompose 

 readily except in an acid liquid, some drops of sulphuric acid are added. As 



