SOAPNAKIUG IN COLONIAL DAYS The housewife made her own lye by leaching wood ashes mixed with quicklime in a n open cask packed with layers of straw. She collected fat from the kitchen and boiled it together with the homemade lye in an iron kettle over an open 5re in the yard.
HE detergent industry directly concerns few of the inidwestern cities, conveniently located between our entire population. Few things have the large supply of western range cattle on the one hand and more primary importance to the individual the consuming public on the other, gave rise to a new anti than soap. Food, clothing, and fuel, for warmth in cold large supply of soap-making fats. This rupply made POW weather, are absolute necessities to all of us, but so also is sible the development of soap factories of larger capacity soap for cleansing body and clothes and the maintenance of than had been possible theretofore, since the nianufacturers sanitary conditioiis necessary to health. had formerly been forced to glean their fats in small amount. Soap has been in use so long in our homes, in laundries, and over scattered areas. in textile inills that it is taken as a matter of course. The deThe successful recovery of refined glycerol from spent soap velopment of the soap industry has been so gradual and has lyes that had formerly been wasted was a decided advance to extended over so long a period that it has none of the glamour the industry since it made more of this valuable material of some of the newer cheinical industries that have been built available to its varied users and lessened the cost of making up to large proportions within the last few years. soap. It is worth mentioning that competition in the soapUp to the beginning of the nineteenth century practically making field has usually been sufficiently active to cause soapall the soap used in this country was made by housewives makers to figure most of the Peturn from the sale of glycerol from fat scraps and fats recovered from cooking. Hardwood as a credit against the cost of making soap, with the result was then the Conimoii fuel, and that the puglic has benefited the wood a s h e s w e r e saved in lower prices for soap than and mixed with quicklime and they might have otherwise enthen leached for the producjoyed. K i t h the i n c r e a s e i n o u r tion of lye Tvhich was used to population, the consumption s a p o n i f y t h e f a t s to soap. In the early part of the last and exportation of edible fats c e n t u r y a few s m a l l soap has left an inadequate domestic f a c t o r i e s were s t a r t e d , supply of soap-making fats for flourished, and were gradually use in the soap kettle. Heretofore, t h e soap-rnaker h a s enlarged; they collected fats been able to supplement the from near-by b u t c h e r shops inadequate supply of domestic and sold most of their output fats by the importation of to i n h a b i t a n t s of cities, who foreign vegetable oils, notably did not have facilities for makcoconut and palm oils. Aling soap. T h e d e v e l o p m e n t of the though these oils c a n n o t be alkali industry, especially the produced in this countrys and BIARTIY HILL ITTXER discovery of a cheap way of although GUY domestic edible making soda ash and caustic f a t s h a v e continued to eolgate-Palmolive-Peet Company, c o m m a n d a p r e m i u m both soda from salt, did much i n t h e home m a r k e t a n d t o a d r a n c e t h e soau inT e i - c ~ vVitv. N e T.
etersive ndustr
I
has recently been placed on most of these imported soapmaking oils. Without these foreign oils there would not be sufficient fats to supply soap to fill the demand.
Alkaline Builders Coincident with the increasing demand for soap and for fats for edible purposes, and with increasing prices for soap fats, the soap-maker has been forced to incorporate alkaline detersive agents or “builders” in most of the household soaps on the market. This has become necessary to supply sufficient 3oap to meet the demand and also to avoid any sharp rise in the sales price of soap. Whatever the primary cause for using alkaline builders may have been, it transpires that there is another cause, dependent on the soap consumer, that is more cogent than all other causes put together. Soaps and soap powders used for household cleaning purposes are priced closely proportionate to their cost of manufacture; those containing alkaline builders are correspondingly cheaper than pure soaps. The “builders” most commonly used are sal soda (sodium carbonate) and sodium silicate and, to a lesser degree, sodium phosphate. Extensive detergency tests prove conclusively that, for a given unit of cost, soaps containing a moderate addition of alkaline builders give more actual washing value than pure soaps. This is especially true in water that is somewhat hard, since the alkaline builders now in use have water-softening qualities in addition to detersive properties and exert an appreciable effect in saving the amount of actual soap necessary in use. It is significant that the average consumer reaction discovered and proved the greater value per unit cost of soaps containing alkaline builders before soap-makers were sure of it themselves. Household soaps containing a moderate amount of sodium carbonate and/or sodium silicate, with perhaps some sodium phosphate, are the products which persistently enjoy the widest sales and command repeat orders. High-pressure sales may place a fair amount of pure household soap or of highly filled cheaper soap, but neither of these classes will enjoy any amount of natural repeat business. When the sales pressure is discontinued, the great mass of the consuming public will return t o soap products containing a moderate amount of alkaline soap builders-the kind that is proved to be best by careful detergency tests.
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The better toilet soaps are usually pure soap for the reason that pure soaps are found to be best for toilet soap purposes and command the largest repeat business. Although it has already been stated that for many purposes soap with a moderate addition of alkaline “builder” gives an efficient, egonomical detersive agent, and although it is well known that pure soap by itself is a most efficient cleansing agent, it is worthy of note that the so-called alkaline soap builders have very limited use as detergents except in conjunction with soap.
Improvements in Soap Making Considerable effort has been directed towards improvements in soap making through the aid of chemistry, and other improvements have been brought about with the aid of chemical engineering. The conversion of soft, unsaturated oils to saturated, or more nearly saturated, fats by means of hydrogenation is now well known. Various types of aqueous saponification of fats using little or no alkaline or acid catalytic saponifying agent and resulting in fatty acids and glycerol, have commanded the attention of soap- and candle-makers for more than seventy-five years, and gradual improvements have rewarded their efforts. The distillation of fatty acids has gradually been improved upon until now there are several systems of obtaining high-grade distilled fatty acids, each system being so satisfactory that its advocates are inclined to ignore the success of others in the same field. Methods for the recovery and refining of glycerol have improved until refined glycerol stands a t the present time as one of the purest chemicals on the market. The demand for glycerol is now greater and more diversified than ever. Glycerol is an important article of commerce and its sales price is free from manipulation and entirely controlled by the demand that is largely independent of various substances which might be used as substitutes for it in one use or another, Up to the present, nothing has been found that can replace it in all of its important uses, and, if such a substance should be found, glycerol would still be made and sold unless its price declined to the price of soap and remained there. During the last few years unusual attention has been given
BATTERY OF LARGE SOAPKETTLES IN
A
MODERN FACTORY
Each kettle yields a half-million pounds of finished soap at a batch.
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INDUSTRIAL, AND ENGINEERING CHEMISTRY
to the physical form of soaps t o facilitate solution in use and for the convenience of the consumer. It is worked into chips and shavings of wafer-like thinness or into tiny beads that dissolve almost instantly. Enormous amounts of soap are sold in sealed cartons for use in the kitchen and especially for use in home washing machines that are very much in vogue and are used in millions of homes. The process of saponification is old and is generally looked upon as susceptible of little change or improvement. Chemists refer to it as “hydrolysis.” Hydrolysis has been performed heretofore in the presence of liquid w a ter-aqueous solutions of alkalies to make soap, and liquid water with alkaline or acid catalyzers to make fatty acids. It has now been found that what might be called “dry saponification” is altogether practicable and that dry fats may be saponified by anhydrous alkaline materials with the aid of dry superheated steam, in the absence of liquid water, giving anhydrous soap and concentrated glycerol; the saponification is rapid and complete, and the recovery of glycerol is complete,
Sulfate and Sulfonate Detergents Another group of detergents is in its early stages of development and differs chemically from soaps; this group constitutes salts of certain organic sulfonic acids, or salts of sulfates of certain alcohols, Most of them are open-chain bodies, and their sodium salts are the kind most commonly employed. These sulfate and sulfonate salts differ greatly in their efficiency but the best of them are readily soluble in water and make suds that resemble ordinary soapsuds in appearance. One desirable property is that they work, n-ell in neutral solu-
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tion and are almost as efficient in solutions that are either slightly acid or slightly alkaline. These sulfate or sulfonate solutions do not commonly possess the smooth lubricating feel characteristic of soapsuds but are good emulsifiers of most kinds of dirt and are particularly usefui in the cleansing of materials which should not be subjected to the action of alkaline solutions. They possess some advantage for use in cleansing natural silk and wool and in preparing some fibers preparatory to dyeing. Another desirable quality is their suitability for use in hard water without the formation of objectionable precipitates of calcium or magnesium, In soft or in only moderately hard water they possess little, if anys advantage over soap for most uses. But for use in water having, for instance, a hardness equivalent to 200 parts calcium carbonate per million, they possess a distinct and decided advantage over soap for the washing of textile fabrics. However, the greater part of OUT population is located where the water is soft or not more than moderately hard, and this fact lessens the necessity for the new type of detergent. The long-proved value of soap is so well known and the price of soap is so uniformly low that there is little possibility of any large proportion of soap, as now used for general cleansing purposes, being displaced by the sulfate or sulfonate cleansers. On the other hand, the manufacture and sale of this class of detergents will undoubtedly enjoy wider use for many special purposes and will e\Ten gradually enter as an active competitor of soap for general purposes in districts where the vater is very hard, RECEIVED April 24, 1935.
This, No. 55 in the Berolzheimer Series of Alchemical and Historical Reproductions, presents the right half of the pen-and-ink drawing by the famous German painter, Wilhelm Trautschold, of Justus von Liebig’s Laboratory at the Universityof Giessen. The left half was reproduced last month. Evidently, Liebig had not yet invented the condenser which bears his name, as none is shovn in either portion of this drawing.
A detailed list of the first thirty-six regroduotions in the series, together with full particulars for obtaining photographic copies of the originals, appeared in our lssue for January, 1934, page 112. A eupplementary liat of Nos, 37 t o 48 is in our January, 1935, issue, page 102. Nos. 49 t o 64, inclusive. appear in our issues for January bo June of this y e a , respectively, o n pages 86, 204, 314, 409, 516, and 631.
