The hand-book of household scienceA popular account of heat, light, air, aliment, and cleansing, in their scientific principles and domestic . ater. The soap is either applied directly to the article itis desired to cleanse, or it may be first dissolved in water. As soapand water thus act jointly, it is proper to inquire as to their behaviortoward each other. If the water be pure or soft, soap dissolves in itentirely ; if it be hard, that is, if it contains sulphate of lime or mag-nesia, the soap, when added, instead of dissolving, curdles or is de-composed, and a new soap is for
The hand-book of household scienceA popular account of heat, light, air, aliment, and cleansing, in their scientific principles and domestic . ater. The soap is either applied directly to the article itis desired to cleanse, or it may be first dissolved in water. As soapand water thus act jointly, it is proper to inquire as to their behaviortoward each other. If the water be pure or soft, soap dissolves in itentirely ; if it be hard, that is, if it contains sulphate of lime or mag-nesia, the soap, when added, instead of dissolving, curdles or is de-composed, and a new soap is formed, which contains lime instead ofpotash or soda. This new lime soap will not dissolve, and may beseen upon the surface of the water as a kind of srieasy scum. Itadheres to whatever is washed in it, and gives that unpleasant sensa-tion called harshness when we wash our hands. Hence, with hardwater, an excessive quantity of soap is required, while the operationis much less aj^Tceablc and satisfactory than with soft water. To testits quality of harshness, dissolve a little soap in alcohol and put a few STEUCTUKE OF THEIR ULTIMATE FIBEES. 429 Fig. drops ia the water it is wished to examine. If it remains clear, thewater is perfectly soft; if it becomes cloudy or opaque, the water isranked as hard, and according to the degree or density of the cloudi-ness, is the hardness of the water. 795. Cotton, Linen, and Woollen articles.—All textile articles are,however, not to be treated alike in cleansing. There is a radical dif-ference in the structure of the fibre between woollen fabrics on theone hand, and cotton and linen on the other, which makes it necessarythat they should be differently man-aged. Fig. 125 rep resents the straightsmooth form of linen and cotton fila-ments, while Fig. 126 exhibits thetoothed and jagged structure ofwoollen fibres. It is evident thatthese, by compression and friction,will mat and lock together, whilethe cotton and linen fibres, havingno such as
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectfood, booksubjecthome
