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67

66 TECHNICAL TREATISE ON SOAP AND CANDLES. to be added, so that 1800 cubic centimetres (1.689 quarts) soap solution are formed, which accordingly is ready for use. Since tho waters which are -o be tested as to their decrees of hardness, almost without exception, contain larger or smaller quantifies of bicarbonate of lime, which reddens the ti net tire of litmus, only by boiling can the carbonic acid as an insoluble carbonate of lin^e separate. The waters niunt be boiled about five minutes before commencing to add the soap solution,and thei be mixed with so much nitric ncid that the liquid obtains a light red color. If a nitric acid of a certain strength is applied—for instance of one-tenth equiva-lout to the liter (1.05 quart) (hi : 10,000)—then the quantity of the nitric acid used, will also prove the hardness of the water, since 1 cubic centimetre (0.27 flu. dr.) of such an acid corresponds «> about '2 cubic centimetres (0.54 flu. dr.) of the normal soap solution. If, therefore, in the testing of a well-water 8 cubic centimetres (0.270 flu. oz.) of the latter acid have been used, while, on the other hand, for the solution of the carbona:e of lime 4 cubic centimetres (O.I3i> flu. oz.) of the ,'„ standard nitric acid hud been npplied, it follows, therefore, that 2 ;ubic centimetre* (0.-S4 flu. dr.) of the soap solution have to be brought int> account for the carbonate and nitrate of H:ne, and '5 cubic centimetres (0.203 flu. oz.), hence 6° for the permanent degree of hardness. Every decree of hardness corresponds to 100 cubic ceuti-mctrus (3.38 tlu. oz*.) 12 milligrammes (0.18 grains) gypsum, or 5 milligrammes (0.077 grain) of pure lime, so that for the single degrees of hardness the following values are proved, wh'ch permit an approximate conclusion a* to tho eoup which is

water decani

lies*.

witli 2S |i.c. Dem. wild 2S p.c.

Lime. Gypsum. water.

Lime. I Gypsum. wnter. 20 1.01kg. 2.4.)ks. 14.75kg. 10 0.50 k g. 1.23 kg. 7.31 klj. 19 0.96 ' • 2. S3 ? 14.03 '

9 0.45 ' - 1.10 '

6.5H -

18 0.91 *

2.21 ' 1 13.H0 l 8 0.40 ? ' 0.98 '

5.85 '

17 0.8(1 '

2.08 ' 1 12.57 ?

? 7 0 35 ' - 0.8fi l 5.12 '

16 0.81 '

1.1H3 ' 1 11.85 '

6 0.80 l ' 1 0.74 '

4.r» ' 15 0.76 '

1.84 ' ' 11.12 '

5 11.25 ' 4 0 01 ?

14 0 71 '

1.73 1 10.39 '

4 0 2fl ' 0.40

2.93 '

13 0.66 l

1.5

3 n.ir, > ' n.37 2.10

13 o.ei ' 1.47 ' * 8 04 '

2 0.10 ' ' o.a.i ' 1.4(1 '

11 0.58 '

1.85 ' ' 8.21 " 1 0.05 ' ' 0.13 1 0.73 *

But there are some waters the hardness of wnich exceeds 20°, i. eM such, as besides a large amount of gypsum contain also chloride of calcium and dolomite salts, which decompose a larger amount of ?oaj_. The purest waters are rain and snow waters. Kiver water is generally sufficiently pure for making soap and lye. A simple remedy for waters containing lime, is a solution of silicate of poda of 20° B., 5 per cent, of which added to the wa*er will cause the lime to precipitate and leave the clear water sufficiently pure for use. SALT. Culinary salt or sodium chlorkh playing an important ptrt in the manipulation of soup it in necessary to give some ot its characteristics and the impurities that impair its usefulness and cause a loss of soap. Most of the salt of commerce contains foreign salts such as chloride of magnesium, sulphate of soda, gypsum, etc. These inipuritiea decompose a large proportion of soap, forming metallic and insoluble soaps that are either precipitated or if held in the soap impair its detersive qualities and injure ita appearance. The salt furnished by the evaporation of sea water is so very impure that it should be entirely avoided. That from mineral springs is very much better though often contaminated with organic matter, while that made from the salt mines or rock salt baft, as a rule, the fewest imparities, although it ia never entirely pure. 08 TSCHSICAT. TREATISE OS SOAP AND CANDLES. In boiling sDap, salt is so important a material for refining that the soap-maker should pay proper attention to procuring it reasonably pure, otherwse he may fail in obtaining a good color, or he may lose by the decomposed soap and alkali carried off with the waste lye. Should he Buspect that his salt has many impurities he can ivtine it in the manner indicated for hard water, viz., with silicate of soda. This process ia quite simple, it being only necessary to dissolve the salt in a suitable quantity of warm water and to add the solution of silicate of soda in the proj>ortion of say b per cent., when after stirring for a time and being left to rest, it will carry down with the precipitate almost all of the lime and other pal:s, and tlic soap-maker may use the upper clear portion with confidence. By means of the crystal carbonate of soda a solution of culinary salt can also be somewhat purified, as t:ie contaminating salts nre thereby ch tinged into insoluble carbonates which precipitate and can easily be separated. FATS ASD OILS. Both fats find oils occur as the constituents of animals as well as plants; in animals theso substances are deposited in particular tissues in larger quantities, and are found in all parts of plants, principally in the seeds and fruit; and are characterized by tlicir physical anil chemical properties. Such as are liquid at on Unary temi>eratures are termed, fat oil?, those that have a soft consistency are called lard or butter, while those that have ;i higher melting point and are solid at the normal temperature, a re classified with tallow and suet. Tn u pure state they are generally colorless and hut of faint odor and are of an average specific gravity of 0.9. They are insoluble in water and but slightly soluble in alcohol, but freely ii ether and carbon bisulphide and in volatile oils. Some fat oils absorb oxygen and dry up and are called drying oils, others only assume a rancid Btate when exposed to the air. When heated to 250° or 300° C. (482° or 572^ F.) they