Cooley's Cyclopaedia of Practical Receipts Volume Ii Part 234

of alkali to each gallon of liquid, is employed to facilitate the disintegration and separation of the gluten and other nitrogenised matters. A weak solution of ammonia, or sesquicarbonate of ammonia, is also similarly employed with advantage. The gluten may be recovered by saturating the alkali with dilute sulphuric acid. Such starch does not require boiling, and is less apt than wheat starch to attract moisture from the atmosphere. Most of the so-called 'wheaten starch' of commerce used by laundresses is now prepared from rice.

To whiten the starches made from damaged roots and grains, and the coa.r.s.er portions of those from sound ones, a little solution of chloride of lime is occasionally added to the water, followed by another water containing a very little dilute sulphuric acid; every trace of the last being afterwards removed by the copious use of pure soft or spring water.

The bluish-white starch used by laundresses is coloured with a mixture of smalts and alum in water, and is regarded as unfit for medicinal purposes.

_Prop., &c._ Starch is insoluble in cold water, and in alcohol and most other liquids, but it readily forms a gelatinous compound (amidin) with water at about 175 Fahr.; alcohol and most of the astringent salts precipitate it from its solutions; infusion of galls throws down a copious yellowish precipitate, containing tannic acid, which is redissolved by heating the liquid; heat and dilute acids convert it into dextrin and grape sugar; strong alkaline lyes dissolve it, and ultimately decompose it. Sp. gr. 153.

To the naked eye it presents the appearance of a soft, white, and often glistening powder; under the microscope it is seen to be altogether dest.i.tute of crystalline structure, but to possess, on the contrary, a kind of organisation, being made of mult.i.tudes of little rounded transparent bodies, upon each of which a series of depressed parallel rings, surrounding a central spot or hilum, may be traced. The starch granules from different plants vary both in magnitude and form. Those of potato starch and canna starch (tous les mois) are the largest, and those of rice and millet starch the smallest, the dimensions ranging from 1/200 to the 1/10000 of an inch. The granules of arrow-root and tous les mois are ovoid, those of potato starch both oblong and circular those of tapioca muller-shaped, and those of wheat starch circular.

_Identif._ One of the commonest frauds practised upon the profession and the public is the admixture of the cheaper kinds of starch, chiefly potato farina, with arrow-root, and vending manufactured for genuine tapioca, sago, and other articles of diet, used for invalids and children. These sophistications are most easily detected with a good microscope.[193]

[Footnote 193: Drawings of the princ.i.p.al starches will be found under the substances from which they are obtained, as "arrow-root," &c.]

=Starch, I'odide of.= _Syn._ AMYLI IODIDUM, AMYLI IODATUM, L. _Prep._ (Ph.

Castr. Ruthena.) Iodine, 24 gr.; rectified spirit, a few drops; rub them to a powder; then add of starch, 1 oz., and again triturate, until the ma.s.s a.s.sumes a uniform colour. Recommended by Dr A. Buchanan, of Glasgow, as producing the alterative effects of iodine, without the usual irritant action of that medicine.--_Dose._ A teaspoonful, or more, in water-gruel, or any bland liquid, twice or thrice a day.

=Starch, Soluble Iodide of.= (Pet.i.t.) _Prep._ Iodine, 12 grammes; starch, 100 grammes; ether, q. s. Dissolve the iodine in the ether, pour the resulting solution over the starch, and triturate until the ether has sufficiently evaporated. Put the product in a porcelain capsule and expose it to the heat of a boiling water bath for half an hour, with occasional stirring. This treatment is sufficient to render it entirely soluble in hot water.

Dr Bellini strongly recommends iodide of starch as a valuable antidote in cases of poisoning by caustic alkalies, alkaline, or earthy sulphides, and vegetable alkaloids. The advantages attending its employment, he says, are: that it may be administered in large doses; that it does not possess the irritating properties of free iodine; and that it readily forms harmless compounds with the substances named. To avoid the subsequent decomposition of the latter, he advises its administration to be followed by an emetic. As an antidote to alkaline and earthy sulphides, the author thinks it preferable to all others. In cases of poisoning by ammonia, caustic potash, or soda, it is applicable when acid drinks are not on hand.

=STARCHING (Clear).= Muslins, &c., are 'clear-starched' or 'got-up' by laundresses in the following manner:--Rinse the articles in three waters, dry them, and dip them into thick-made starch, which has been previously strained through a piece of muslin; squeeze them, shake them gently, and again hang them up to dry; when they are dry, dip them twice or thrice into clear water, squeeze them, spread them on a linen cloth, roll them up in it, and let them lie an hour before ironing them. Some persons put a morsel of sugar into the starch, to prevent its sticking whilst ironing, and others stir the starch with a candle to effect the same end; both these practices are as injurious as unnecessary. The best plan to prevent sticking is simply to use the best starch, and to make it well, and to have the irons quite clean and highly polished. Mr W. B. Tegetmeier recommends the addition of a small piece of paraffin (a piece of paraffin candle-end) to the starch, to increase the glossiness of the ironed fabric.

=STARS.= (In pyrotechny.) _Prop._ 1. (Brilliant--Marsh.) Nitrate, 52-1/2 parts; sulphur and black antimony, of each 13 parts; reduce them to powder, make them into a stiff paste with isingla.s.s, 1-1/2 parts, dissolved in a mixture of vinegar, 6-1/2 parts; and spirits of wine, 13 parts; lastly, form this into small pieces, and whilst moist, roll them in meal gunpowder.

2. (WHITE--Ruggieri.) Nitre, 16 parts; sulphur, 7 parts; gunpowder, 4 parts; as the last.

3. (GOLDEN RAIN.)--_a._ (Ruggieri.) Nitre and gunpowder, of each 16 parts; sulphur, 10 parts; charcoal, 4 parts; lampblack, 2 parts; mix, and pack it into small paper tubes.

_b._ (Ruggieri.) Nitre, 16 parts; sulphur and gunpowder, of each 8 parts; charcoal and lampblack, of each 2 parts; as the last.

_c._ (Marsh.) Mealed gunpowder, 66-3/4 parts; sulphur, 11 parts; charcoal, 22-1/4 parts; as before. Used for the 'garniture' of rockets, &c. See PYROTECHNY.

=STAVES'ACRE.= _Syn._ STAVESACRE SEEDS; STAPHISAGRIae SEMINA, STAPHISAGRIA (Ph. L. & D.), L. "The seed of _Delphinium Staphisagria_, Linn." (Ph. L.) This article is powerfully emetic and cathartic, but is now scarcely ever used internally. Mixed with hair powder, it is used to kill lice. An infusion or ointment made with it is said to be infallible in itch, but its use requires some caution.

=STAYS.= _Syn._ CORSET. Stays, "before womanhood, are instruments of barbarity and torture, and then they are needed only to give beauty to the chest. It is the duty of every mother, and every guardian of children, to inquire the purpose for which stays were introduced into female attire.

Was it for warmth? If so, they certainly fulfil the intention very badly, and are much inferior to an elastic woollen habit, or one of silk quilted with wool. Was it to force the ribs, while yet soft and pliable, into the place of the liver and stomach, and the two latter into the s.p.a.ce allotted for other parts, to engender disease and deformity to the sufferer and her children for generations? Truly, if this were the object, the device is most successful, and the intention most ingeniously fulfilled." (Eras.

Wilson.)

"Only observe," exclaimed Dr John Hunter--"only observe, if the statue of the Medicean Venus were to be dressed in stays, and her beautiful feet compressed into a pair of execrably tight shoes, it would extort a smile from an Herac.l.i.tus, and a horse-laugh from a Cynic."

"The Turkish ladies express horror at seeing Englishwomen so tightly laced." (Lady M. W. Montague.) See DISTORTIONS.

=STEAM.= The application of steam of the laboratory, as a source of heat, is commonly effected by means of double pans, to the s.p.a.ce between which steam, at a moderate pressure, is introduced, the arrangements being such as to permit of the condensed steam, or distilled water, being removed, by means of a c.o.c.k, nearly as soon as formed, or as may be desirable. Another plan is to place coils of metal pipe along the bottom of cisterns, vats, &c., formed either of wood or metal, and to keep them supplied with high-pressure steam.

"It is quite susceptible of positive proof that by no arrangement yet discovered, can more than two thirds of the heat generated by a given quant.i.ty of coal, during combustion, be fairly absorbed and utilised in any of our manufactories; and, moreover, there are undeniable facts, which demonstrate that seldom, in the burning of coal, are more than three fourths of the total heat, which might be eliminated, actually obtained; thus justifying the supposition that one half of all the coal now consumed is virtually wasted and lost to society." To lessen, as much as possible, this loss various improvements have been made, "which, for the most part, have consisted in lengthening the flues, and exposing a larger surface of the boiler to the action of the heated air pa.s.sing from the furnace to the chimney." "Remembering that air is an extremely bad conductor of heat, and that water about to be converted into steam is also a bad conductor, it is evident that time must form an important element in the perfect transmission of heat from one of these to the other; and hence, with a great velocity of current existing in the flues, very little heat would pa.s.s from air, however high its temperature, to water contained in a boiler, and so circ.u.mstanced with respect to its all but gaseous condition." The results of the experiments on fuel made at the Museum of Practical Geology by Sir H. de la Beche and Dr Lyon Playfair go clearly to show that "to open the damper of a steam-boiler furnace is pretty generally to diminish the effective power of the fuel." "Great waste of coal now arises from this simple circ.u.mstance; and much of the heat of the fire, which ought to go to the boiler, is lost by its (too) hasty transmission up the chimney. If, however, there be thus far room for improvement in the direction just indicated, still wider is the vacant s.p.a.ce, caused by imperfect combustion, or, in technical phrase, 'bad stoking,' merely because the stoker, to economise his labour, and to avoid trouble, throws on to the bars of his furnace a thick layer of fuel, by which loss is caused in two or three directions." These are, princ.i.p.ally, imperfect combustion, and the volatilisation of fuel, as smoke, &c., from an insufficient supply of air, and from a ma.s.s of mere red-hot c.o.ke or cinder, two or three inches thick, lying between the boiler and the hottest part of the furnace; which last, according to Dr Kennedy, is about one inch above the fire-bars. Besides which, "in pa.s.sing over this red-hot c.o.ke, the carbonic acid would be converted into carbonic oxide, and thus not only remove a quant.i.ty of carbon equal to its own, without yielding any additional heat, but actually with the production of cold, or, in other words, the absorption of heat." ('Dict. Arts, Manuf., and Mines.') This points to the evident policy of using a smoke-consuming furnace, as noticed elsewhere.

Another matter worthy of remark is the constant waste of heat, and, consequently, of fuel, in laboratories and manufactories in which steam is employed, owing to the exposed condition of the pipes, boilers, and pans.

All of these should be well 'clothed' or covered by some non-conducting medium, to prevent loss of heat by radiation, and by contact with the atmosphere. Not only does economy dictate such a course, but the health and comfort of the workpeople demand that the atmosphere in which they labour should be as little heated and poisoned as possible.

TABLE _of corresponding Pressure and Temperatures of Steam_. By ARAGO and DULONG.

+------------------+------------++------------------+------------+ Pressure Temperature, Pressure Temperature, in in Atmospheres.[194] Fahr. Atmospheres.[194] Fahr. ------------------+------------++------------------+------------+ _Degrees._ _Degrees._ 1 212 13 38066 1-1/2 234 14 38694 2 2505 15 39286 2-1/2 2638 16 39848 3 2752 17 40383 3-1/2 285 18 40892 4 2937 19 41378 4-1/2 3003 20 41846 5 3075 21 42296 5-1/2 31424 22 42728 6 32036 23 43142 6-1/2 32626 24 43556 7 3317 25 43934 7-1/2 33686 30 45716 8 34178 35 47273 9 35078 40 48659 10 35888 45 49914 11 36685 50 5106 12 374 +------------------+------------++------------------+------------+

[Footnote 194: Estimating 146 lbs. = 1 atmosphere.]

A cubic inch of water, during its conversion into steam, under the ordinary pressure of the atmosphere, expands into 1696 cubic inches, or nearly a cubic foot.

One part, by weight, of steam, at 212 Fahr., when condensed into cold water, is found to be capable of raising 56 parts of the latter from the freezing to the boiling point. See FUEL, PIT-COAL, SMOKE, &c.

=STEAR'IC ACID.= HC_{18}H_{35}O_{2}. _Syn._ STEARIN (Commercial). This is obtained from stearin (see _below_), by saponification.

_Prep._ 1. Repeatedly dissolve and crystallise commercial stearic acid in hot alcohol, until its melting point becomes constant at not less than 158 Fahr. Pure.

2. (Chevreul.) Saponify mutton suet with caustic pota.s.sa, and dissolve the newly formed soap in 6 times its weight of hot water; to the solution add 40 or 50 parts of cold water, and set the mixture aside in a temperature of about 52 Fahr.; after a time separate the pearly matter (stearate and margarate of pota.s.sa) which falls, drain and wash it on a filter, and dissolve it in 24 parts of hot alcohol of sp. gr. 820; collect the stearate of pota.s.sa which falls as the liquid cools, recrystallise it in alcohol, and decompose it, in boiling water, with hydrochloric acid; lastly, wash the disengaged stearic acid in hot water, and dry it.

3. (Commercial.) Ordinary tallow is boiled in large wooden vessels, by means of high pressure steam, with about 16% of hydrate of lime (equiv. to 11% of pure lime), for 3 or 4 hours, or until the combination is complete, and an earthy soap is formed, when the whole is allowed to cool; the product (stearate of lime) is then transferred to another wooden vessel, and decomposed by adding to it 4 parts of oil of vitriol (diluted with water) for every 3 parts of slaked lime previously employed, the action being promoted by steam heat and brisk agitation; after repose, the liberated fat is decanted from the sediment (sulphate of lime) and water, and is then well washed with water, and by blowing steam into it; it is next allowed to cool, when it is reduced to shavings by means of a number of knives worked by machinery, and in this divided state is placed in canvas bags and submitted to the action of a powerful hydraulic press, by which a large portion of the oleic acid which it contains is expelled; the pressed cakes are then a second time exposed to the action of steam and water, again cooled, and coa.r.s.ely powdered, and again submitted to the joint action of steam and pressure; they are, lastly, melted, and cast into blocks for sale.

_Obs._ This product is a more or less impure mixture of stearic acid and other fatty bodies, particularly the so-called margaric acid, now generally regarded as a mixture of palmitic and stearic acids. The hard, fatty acids of vegetable origin (palmitic, cocinic, myristic, &c.), now so extensively used as candle materials, are obtained from the natural oils and b.u.t.ters by the process known as 'sulphuric acid saponification,' which consists in treating the fatty bodies with 5 or 6% of concentrated sulphuric acid at a high temperature (about 350 Fahr., produced by superheated steam), and distilling the resulting ma.s.s by the aid of steam heated to about 560 Fahr. Frequently the operations of hot and cold pressing are resorted to in order to free the product from the softer fats.

By a patent process employed at Price's candle works the natural vegetable fats are decomposed into their const.i.tuents (fatty acids and glycerin) by the action of superheated steam alone, without previous 'saponification'

with lime or sulphuric acid.

Another method for the preparation of commercial stearic acid is that of Messrs Moinier and Bontigny. This process is thus described in the 'Chemical Technology' of Messrs Ronalds and Richardson:--Two tons of tallow and 900 gall. of water are introduced into a large rectangular vat of about 270 feet capacity.

The tallow is melted by means of steam admitted through a pipe coiled round the bottom, and the whole kept at the boiling heat for an hour, during which a current of sulphurous acid is forced in. At the end of this period 6 cwt. of lime, made into milk with 350 gall. of water, are added.

The mixture soon acquires consistence, and becomes frothy and viscid. The whole is now agitated in order to regulate the ebullitions, and prevent the sudden swelling up of the soapy materials. The pasty appearance of the lime soap succeeds, and it then agglomerates into small nodular ma.s.ses.

The admission of sulphurous acid is now stopped; but the injection of the steam is continued until the small ma.s.ses become hard and h.o.m.ogeneous. The whole period occupies eight hours, but the admission of the sulphurous acid is discontinued at the end of about three hours. The water containing the glycerin is run off through a tube into cisterns prepared to receive it.

The arrangements for preparing sulphurous acids are retorts, into which are put sulphuric acid and pieces of wood; upon the application of heat the sulphurous acid pa.s.ses off, and is conveyed by leaden pipes into the vessels containing the tallow. The lime soap formed is then moistened with 12 cwt. of sulphuric acid, at 150 Fahr., diluted with 50 gall. of water.

The whole is thoroughly agitated and the steam cautiously admitted, so as not to dilute the acid too much until the decomposition is general at all points. This occupies about 3 hours, and in 2 or 3 hours more the sulphate of lime has collected at the bottom, while the fatty acids are floating on the surface of the solution of the bisulphate of lime. Several processes of was.h.i.+ng with steam and water are necessary to ensure the removal of the sulphate of lime, &c., and after settling for 4 hours the fatty acids are forced through a fixed siphon, into a vat, where they are again washed with water; they are then siphoned at last into a trough lined with lead, on the bottom of which are placed leaden gutters, pierced below by long pegs of wood. The fatty acids are then placed in clothes and subjected to pressure in the stearin cold press.

In 1871 Professor Boek of Copenhagen, after a careful microscopic and chemical investigation, discovered that the neutral fats were composed of a congeries of little globules enclosed in alb.u.minous envelopes. To the presence of these latter substances in the fat he attributed the difficulty of eliminating the fatty acids from it by means either of sulphuric acid, except in excess, or of alkali, except under great pressure; conceiving that both these agents as employed under the usual methods were expended in rupturing and destroying the alb.u.minous coverings.

The inconveniences arising from the above processes are, in the case of the excess of the sulphuric acid, a considerable destruction of the fatty acid, as well as the necessity of its distillation, and the consequent danger of conflagration; whilst in the case of the alkali, this must either be used in quant.i.ties much greater than theory requires, or else be heated under great pressure, at the risk of giving rise to an explosion.

In Professor Boek's process these dangers, together with the waste of material, are avoided. By submitting the fat for a limited time and at a given temperature to the action of a small quant.i.ty of sulphuric acid, the alb.u.minous envelopes are broken and partly destroyed. The neutral fat thus liberated is then placed in open tanks in water, by which, after the expiration of several hours, it becomes decomposed. When this is completely effected the glycerin, dissolved in the water used for the decomposition, is removed; the fatty acids which remain behind, and which amount to 94 per cent. of the original fat, being at this stage of the operation dark brown or blackish in colour.

In this condition they are placed in open tanks, and dilute solutions of certain agents are poured upon them, whereby the alb.u.minous debris as well as the colouring matters with which they are a.s.sociated become oxidised, whilst the specific gravity of these latter is in consequence so increased as to cause them to subside to the bottom of the tank, leaving the fatty acids, now greatly whitened, on the upper part of the liquid.

The acids after being washed 2 or 3 times with dilute acid and water are then cooled, and hot-pressed in the usual manner, and the stearic acid thus obtained is said to have a higher melting point, and to be larger in yield than that obtained by any other method, an oleic acid of excellent quality being at the same time produced.

In 1874 a French patent was taken out for an improvement in the manufacture of stearic acid. The patentee employs carbon disulphide to increase the fluidity of the oleic acid, so that the warm pressure of the crude stearic acid is avoided. The addition of the carbon disulphide may be made either before or after the cold pressing of the stearic acid. The crude fat acid is melted in a special apparatus, and 20 per cent. of the disulphide is mixed with it whilst in the fluid state. It is then left to cool and subjected to cold pressure. The stearic acid thus obtained should be free from oleic acid.

_Prop., &c._ Pure stearic acid crystallises in milk-white needles, which are soluble in ether and in cold alcohol, and forms salts with the bases, called stearates. The commercial acid is made into candles. See CANDLES, FAT, OILS (Fixed), and TALLOW.

=STE'ARIN.= C_{57}H_{110}O_{6}. The solid portion of fats which is insoluble in cold alcohol.

_Prep._ Pure strained mutton suet is melted in a gla.s.s flask along with 7 or 8 times its weight of ether, and the solution allowed to cool; the soft, pasty, semi-crystalline ma.s.s is then transferred to a cloth and is strongly pressed as rapidly as possible, in order to avoid unnecessary evaporation; the solid portion is then redissolved in ether, and the solution allowed to crystallise, as before. The product is nearly pure.