Part 2 (2/2)

or crude sodiue cylindrical revolving furnaces, through, which flaaseous fuel, pass; the waste heat is utilised for boiling down ”black ash” liquor, obtained by lixiviating the black ash A mixture of salt-cake, limestone or chalk (calciued into the revolving cylinder; during the process the lomerated, and the final product is what is known as a ”black-ash ball,” consisting chiefly of crude sodiu smaller quantities of many other substances The soda ash or sodiu ater, and after various purification processes, the solution is boiled down, as previously stated, by the waste heat of the black-ash furnace The alkali is sold in various for soda, etc

Caustic soda is manufactured fro, that is, treatment with caustic lime or quicklients in the Leblanc process is the sulphur used in the for vitriol in the first stage; this sulphur goes through the entire process; frooes to form a constituent of the salt-cake, and afterwards of the calcium sulphide contained in the black ash This calcium sulphide remains as an insoluble mass when the carbonate of soda is extracted from the black ash, and forms the chief constituent of the alkali waste, which until the year 1880 could be seen in large heaps around cheases containing carbonic acid, the sulphur is extracted froen sulphide, which is burnt to for pure sulphur; and so as once waste is now a source of profit

_Ammonia-Soda Process of Alkali Manufacture_--This process depends upon the fact that when carbonic acid is forced, under pressure, into a saturated solution of ammonia and common salt, sodium bicarbonate is precipitated, whilst ammonium chloride or ”sal-ammoniac” remains dissolved in the solution The reaction was discovered in 1836 by a Scotch chemist named John Thom, and small quantities of ahton & Thoe scale depends principally upon the coent, ammonia, and this problem was only solved within comparatively recent years by Solvay The process has been perfected and worked with great success in England by Messrs Brunner, Mond, & Co, and has proved a successful rival to the Leblanc process

Alkali is also produced to so upon the splitting up of a solution of common salt into caustic soda and chlorine by the use of an electric current

LECTURE VI

BORIC ACID, BORAX, SOAP

_Boric Acid_--At ordinary temperatures and under ordinary conditions boric acid is a very weak acid, but like silicic and some other acids, its relative powers of affinity and coh tely heated boric acid can decompose carbonates and even sulphates, and yet a current of so weak an acid as hydrogen sulphide, passed through a strong solution of borax, will decompose it and set free boric acid Boric acid is obtained chiefly from Italy In a tract of country called the Mare an area of about forty square miles, are nuases and springs of water spurt The steas contains s one of those solid substances distilling to some extent in a current of stea to some kind of constant volcanic disturbance, are also as, cohbourhood These phenomena were at first looked upon by the people as the work of the devil, and priestly exorcis the at the present tin competition and its evils, and the dulness of trade, the artificial coeneral lamentation, etc, are essayed in the atteth a kind of prophet arose of a very practical character in the form of the late Count Lardarel, who, mindful of the fact that the chemist Hoffer, in the time of the Grand Duke Leopold I, had discovered boric acid in the volcanic steam jets, looked hopefully beyond the exorcisms of the priests and the superstitions of the people to a possible blessing contained in what appeared to be an unholy confusion of Nature He constructed tanks of from 100 to 1000 ft in diameter and 7 to 20 ft in depth, of such a kind that the steam jets were surrounded by or contained in them, and thus the liquors formed by condensation becaed at different levels, so that the liquors could be run off fro cisterns Subsequently the strong liquors were run to lead-lined, wooden vats, in which the boric acid was crystallised out Had the industry depended on the use of fuel it could never have developed, but Count Lardarel ingeniously utilised the heat of the steam for all the purposes, and neither coal nor as required Where would that Tuscan boric acid industry have been now had merely the lamentations of landowners, fears of the people, and exorcis the work of the arch-enemy of h and difficult step in an upward direction towards the attaine and skill, of a blessing for the whole province of Tuscany? What was true in the history of that industry and its develop of trade through foreign co hoher platform to which it was somewhat difficult to step up, but upon which the battle her scientific and technological education and training The chemist Hoffer made the discovery of boric acid in the vapours, they would no doubt take note; but Hoffer went no further; and it needed the man of both educated and practical mind like Count Lardarel to turn the discovery to account and extract the blessing In like manner it was clear that in our educational schemes for the benefit of the people, there ator of abstract truth, but also the scientific technologist to point the way to the practical realisation of tangible profit Moreover, and a still more important truth, it is the scientific education of the proprietors and heads ant--educated capital rather than educated workood deal of the Tuscan boric acid is used in France for the manufacture of borax, which is a sodium salt of boric acid Borax is also manufactured from boronitrocalcite, a calcium salt of boric acid, which is found in Chili and other parts of South America The crude boronitrocalcite or ”tiza” is boiled with sodiu, the borax is obtained by crystallisation Borax itself is found in California and Nevada, USA, and also in Peru, Ceylon, China, Persia, and Thibet The commercial product is obtained fro in water and allowing the solution to crystallise The Peruvian borax so the purity of refined borax the following simple tests will usually suffice A solution of the borax is1 part of borax to 50 parts of water, and small portions of the solution are tested as follows: _Heavysulphuretted hydrogen into the solution, no coloration or precipitate should be produced _Calciuive a precipitate with ammonium oxalate solution

_Carbonates_--The solution should not effervesce on addition of nitric or hydrochloric acid _Chlorides_--No appreciable precipitate should be produced on addition of silver nitrate solution and nitric acid

_Sulphates_--No appreciable precipitate should be produced on adding hydrochloric acid and barium chloride _Iron_--50 cc of the solution should not immediately be coloured blue by 05 cc of potassium ferrocyanide solution

_Soap_--Soap is a salt in the chemical sense, and this leads to a wider definition of the term ”salt” or ”saline” compound Fats and oils, from which soaps are manufactured, are a kind of _quasi_ salts, composed of a fatty acid and a chemical constant, if I lycerin When these fats and oils, often called glycerides, are heated with alkali, soda, a true salt of the fatty acid and soda is forlycerin relycerin is soluble in water containing dissolved salt (brine), whilst soap is insoluble, though soluble in pure water The lycerin produced from the fat and soda is therefore treated with brine, a process called ”cutting the soap” The soap separates out in the solid form as a curdy mass, which can be easily separated Certain soaps are able to absorb a large quantity of water, and yet appear quite solid, and in purchasing large quantities of soap it is necessary, therefore, to determine the a out ten or twenty grams of the soap, cut in sas flalass held over the dish no longer beco, the dry soap is weighed, and the loss of weight represents the a about 83 per cent of water has been sold at the full market price Some soaps also contain more alkali than is actually combined with the fatty acids of the soap, and that excess alkali is injurious in washi+ng silks and scouring wool, and is also not good for the skin The presence of this free or excess alkali can be at once detected by rubbing a little phenolphthalein solution on to the freshly-cut surface of a piece of soap; if free alkali be present, a red colour will be produced

LECTURE VII

ShellAC, WOOD SPIRIT, AND THE STIFFENING AND PROOFING PROCESS

_Shellac_--The resin tribe, of which shellac is a ree of si substances insoluble in water, but soluble in alcohol and wood spirit In many cases the alcoholic solutions show an acid reaction The resins are partly soluble in alkalis, with formation of a kind of alkali salts which we may call resin-soaps

Shellac is obtained fros and branches of various tropical trees by the puncture of the female ”lac insect” (_Taccardia lacca_) The lac is re” in water; the woody matter floats to the surface, and the resin sinks to the bottom, and when removed forms what is known as ”seed-lac” For matter dissolved from the crude ”stick-lac,” was evaporated for recovery of the so-called ”lac-dye,” but the latter is no longer used technically The seed-lac is bleached by boiling with sodium or potassiuh, is further bleached by exposure to sunlight It is now dried, melted, and mixed with a certain proportion of rosin or of orpi to the purpose for which it is desired After further operations of , the lac is melted and spread into thin sheets to form ordinary shellac, or is melted and dropped on to a smooth surface to form ”button-lac” Ordinary shellac alood button-lac is free from this substance

The presence of 5 per cent of rosin in shellac can be detected by dissolving in a little alcohol, pouring the solution into water, and drying the fine impalpable pohich separates This powder is extracted with petroleu a trace of copper acetate If rosin be present, the petroleureen

Borax, soda crystals, and ammonia are all used to dissolve shellac, and it may be asked: Which of these is least injurious to wool? and why? How is their action modified by the presence of dilute sulphuric acid in the wool? I would say that soda crystals and a, are sure to do a certain amount of injury to the fibre of wool, and more if used hot than cold Of the two, the ammonia will have the least effect, especially if dilute, but borax is better than either

The influence of a little sulphuric acid in the ould be in the direction of neutralising some of the ammonia or soda, and shellac, if dissolved in the alkalis, would be to some extent precipitated on the fibre, unless the alkali, soda or ammonia, were present in sufficient excess to neutralise that sulphuric acid and to leave a sufficient balance to keep the shellac in solution Borax, which is a borate of soda, would be so acted on by the sulphuric acid that so some of that borax of its soda This boric acid would not be nearly so injurious to wool as carbonate of soda or ammonia would

The best solvent for shellac, however, in the preparation of the stiffening and proofing mixture for hats, is probably wood spirit or methylated spirit A solution of shellac in wood spirit is indeed used for the spirit-proofing of silk hats, and to some extent of felt hats, and on the whole the best work, I believe, is done with it Moreover, borax is not a cheap agent, and being non-volatile it is all left behind in the proofed material, whereas wood spirit or methylated spirit is a volatile liquid, _ie_ a liquid easily driven off in vapour, and after application to the felt it ain for re-use

In this way I conceive the use of wood spirit would be both more effective and also cheaper than that of borax, besides being most suitable in the case of any kind of dyes and colours to be subsequently applied to the hats

_Wood Spirit_--Wood spirit, the pure form of which is methyl alcohol, is one of the products of the destructive distillation of wood The wood is distilled in large iron retorts connected to apparatus for condensing the distillation products The heating is conducted slowly at first, so that the maximum yield of the valuable products--wood acid (acetic acid) and wood spirit--which distil at a low temperature, is obtained When the condensed products are allowed to settle, they separate into two distinct layers, the lower one consisting of a thick, very dark tar, whilst the upper one,also the wood spirit), and is reddish-yellow or reddish-brown in colour This crude wood acid is distilled, and the wood spirit which distils off first is collected separately from the acetic acid which afterwards comes over The acid is used for the preparation of alumina and iron mordants (see next lecture), or is neutralised with lirey acetate of lime, from which, subsequently, pure acetic acid or acetone is prepared The crude wood spirit isfor several hours is distilled in a rectifying still The distillate is diluted ater, run off from any oily impurities which are separated, and re-distilled once or twice after treat Process_--Before proceeding to discuss the stiffening and proofing of hat forms or ”bodies,” it will be well to point out that it was in thoroughly grasping the i out this process that Continental hat lish rivals in competition as to a special kind of hat which sold well on the Continent There are, or ought to be, three ai, all the three being of equal importance These are: first, to waterproof the hat-forms; second, to stiffen them at the same time and by the same process; and the third, the one the ilish hat manufacturers have frequently overlooked, at least in the past, is to so proof and stiffen the hat-forms as to leave the process In proofing the felt, the fibres becolaze which is insoluble in water, and this varnish or proof is but imperfectly removed from the ends of the fibres on the upper surface of the felt The consequence is a too slight penetration of the dyestuff into the inner pores of the fibres; indeed, in the logwood black dyeing of such proofed felt a great deal of the colour becomes precipitated on the outside of the fibres--a kind of process of ”sreening” of the black hats after a short period of wear is simply due to the ease hich such badly fixed dye rubs off, washes off, or wears off, the brownish or yellowish substratureenish shade to at length appear If we examine under the microscope a pure unproofed fur fibre, its characteristic structure is quite visible Exawood black shows again the same characteristic structure with the dye inside the fibre, colouring it a beautiful bluish-grey tint, the inner cellularblack A proofed fur fibre, on the other hand, when examined under the laze, which cos showing the scaly structure of the fibre fro seen Finally, if we examine microscopically a proofed fibre which has been dyed, or which we have attewood black, we find that the fibre presents an appearance sih soment or black mud, and then dried

It is quite plain that no lustrous appearance or good ”finish” can be expected from such material No did the Continental hateither with logwood black or with coal-tar colours, and also getting a high degree of ”finish”? They attained their object by rubbing the proofing varnish on the inside of the hat bodies, in sou the lac-varnish rubbed inside Thus the proofing could never reach the outside On throwing the hat bodies, thus proofed by a logical and scientific process, into the dye-bath, the gums on the outer surface are dissolved and removed, and the dye strikes into a pure, clean fibre, capable of a high degree of finish This process, however, whilst very good for the softer hats used on the Continent, is not so satisfactory for the harder, stiffer headgear demanded in Great Britain What was needed was a process which would allow of a through-and-through proofing and stiffening, and also of satisfactory dyeing of the stiffened and proofed felt This was accomplished by a process patented in 1887 by Mr

FW Cheetha” process The hat bodies, proofed as hard as usual, are thrown into a ”bu hot water rendered faintly acid with sulphuric acid, and mixed with short-staple fur or wool, usually of a finer quality than that of which the hat bodies are coree the felting powers of the short-staple wool or fur, and, to a lesser extent, the thinly proofed ends of the fibres projecting from the surfaces of the proofed hat-forms Thus the short-staple wool or fur felts itself on to the fibres already for part of the hat bodies, and a new layer of pure, unproofed wool or fur is gradually wrought on to the proofed surface The hat-forreatest ease and with excellent results, as will be seen fro 15) This successful invention emphasises the value of the microscope in the study of processes connected with textile fibres I would strongly advise everyone interested in hator similar industries to make a collection of wool and fur fibres, and mount them on microscope slides so as to form a kind of index collection for reference

[Illustration: FIG 15