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European, is owing to the former being cleansed withoutany soap. In a French dissertation on this subject, towhich a premium was adjudged by the academy of Lyons,in 1761, the ill qualities of soap are attributed to its oil,and a solution of simple alcaline salt, made so dilute asnot to corrode the silk itself, is recommended in its place:the salt of soude or bariglia, as being the mildest of thealcaline salts, is for this purpose justly preferred to thecommon more corrosive alcalies. Alcaline salts, eitherin their pure state or made into soap with oils, are theonly known menstrua that extract the matter whichgives harshness and colour to raw silk.

What this matter is, has not been sufficiently ex-amined. As it is not dissolved by water, spirit of wine,or by acids so far diluted as not to destroy the silk itself,Mr. Macquer supposes it to be either a concrete oilysubstance, whose oil is of the nature of expressed oils ; ora compound of oily and gummy matter, so proportionedand combined, as to protect one another from the actionof their respective dissolvents. Whatever can be said ofthe composition of this matter, may perhaps be saidequally of that of silk itself, which is not an organisedsib re like wool, but is in its whole substance a concreteanimal juice : naturalists observe, that on opening thelilk-worm at a proper season, the yellow silky juice maybe readily distinguished, and drawn out into fine flexiblefilaments. Alcaline salts, which when diluted with water,or sheathed with oil, to a certain degree, are sound theproper menstrua of the harsh and tinging part of rawsilk, in a purer or less dilute state, or by longer boiling,dissolve also the matter on which the tenacity or cohesionof the silk depends. Some of the spun silk called in theshops raw silk, but which has been boiled with soap pre-vious to the spinning, and suffered the diminution of

weight