270 BALARD’S RESEARCHES CONCERNING THE NATURE OF 
deprived of its hurtful properties, while it retained only those which 
are useful, were soon generally employed in the art of bleaching. They 
were at first prepared with the solution, and as the first trials were made 
in the manufactory of Javelle, the new liquid with which industry was 
enriched was called eau de Javelle. But in 1798, Tennant and Knox 
of Glasgow attempted to substitute hydrate of lime, which forms a solid 
bleaching compound, while chlorine retains its power only when diluted 
with a large quantity of water. This substitution was generally adopted, 
and the new compound, which is more easily preserved and prepared, 
and at a less price, and more easy of transport, soon became an article 
of manufacture and considerable commerce, under the name of bleach- 
ing powder. 
The employment of these compounds of chlorine was further ex- 
tended in 1822. M. Labarraque, an apothecary of Paris, proved at this 
period, by numerous trials, that these compounds, which had rendered 
so many services to the art of bleaching, might be as successfully used 
for disinfecting. His own trials, and the fresh proofs that his example 
incited, placed the decolorizing compound of chlorine decidedly among 
the most valuable resources of the art of preserving health. 
We should be at first inclined to believe that the nature of these 
eompounds, which had rendered us such various services, was perfectly 
understood by chemists; but it is not at all so; and notwithstanding 
the researches which they have occasioned, the place which they ought 
to oceupy in a classification is not clearly determined. It is, indeed, 
true that their elementary composition and immediate analysis are well 
known. In fact, obtained by the action of chlorine upon a metallic 
oxide, they evidently must be formed merely of chlorine, oxygen, and 
a metal; on the other hand, the experiments of several chemists have 
proved that in these compounds, for every two atoms of chlorine*, there 
is one atom each of oxygen and metal. But how are these three ele- 
ments arranged? This is not at present known with certainty ; and 
yet this knowledge is indispensable for determining by what reactions 
they serve in decolorizing and disinfecting. 
§ 1. Of the Opinions which have been entertained as to the Nature of the 
decolorizing Compounds of Chlorine. 
The opinions of chemists on this subject are divisible into two hy- 
potheses. According to some, these compounds are merely chlorides 
of oxides ; according to others, they are to be considered as mixtures of 
metallic chlorides with a salt which contains an acid of chlorine, less 
oxygenated than the chloric, and which it has been proposed to call 
chlorous acid. 
* Not so in England, but foreign chemists reckon the weight of chlorine only 
half that of English chemists, hence the author states two atoms.—Ep. 
