The next point was to find some substance that would prevent this rapid drying, and it was very soon discovered that those soaps that contained an excess of lye retained moisture longer. Henceforth it was only necessary to use lyes of extra strength so as to obtain a large yield of soap containing an excess of water. The results of this ingenious method are before us; in the shops of the soap dealers the bars of soap become coated with a crust of white crystals, which is nothing but soda. If a few drops of corrosive sublimate be dropped on these crystals, a red spot will at once be produced by the formation of mercuric oxide. In addition to the deception of the public who buy such soaps, this alkali destroys clothes washed with it, as the fiber of the tissues is directly attacked by it, while the proper action of the soap depends on its enveloping the particles of dirt and carrying them off. Soap is subject to another kind of adulteration called filling, or weighting. Soapstone and similar mineral substances are added to the finished soap to increase its weight. But it may be added that this fraudulent weighting is rare. Large establishments cannot take the risk of being detected in such avaricious practices, and small ones scarcely have the apparatus at their disposal for making a uniform mixture which will not arouse suspicion. Now soaps are frequently found in the market that scarcely deserve this name. Mineral soap, cold water soap, etc., are the names inscribed on the placards behind which is buried a preparation consisting for the greater part of water-glass. The well-known water-glass is a silicate of soda or potash dissolved in free or caustic soda, or potash. There was a time when it excited great hopes, and its introduction into the household for washing was dreamed of, but it was soon found that its caustic properties made their appearance at a relatively low temperature. Hence we often find the notice, "TO BE USED COLD," printed in bold letters on the wrappers. This product is obtained by thickening water-glass with stearine, oleine, or any other easily saponifiable fat. As it takes but very little of the substances named to make an article closely resembling soap, of course the product is very cheap. There does not seem to be any limit to the amount of water in it; at least the author found in one kind of mineral soap from Berlin 58 per cent. of water. Water-glass soaps do not dissolve readily in water, they make but little suds, and render the skin hard and unpliable. Admitting that they are suitable for many purposes, nothing can be said against their sale so long as they appear under names which preclude their being confounded with other soaps. Nevertheless, there is always this danger--that water-glass may come into general use in making soap, and this is to be deplored. Water-glass soaps are easily recognized by their insolubility in moderately strong alcohol, the water-glass remaining behind in a gelatinous form.