Latex

“ It is assumed that all estates, not only in the preparation of sheet rubber, but also in the making of crepe rubber, always employ the system of standardising latex in order to obtain uniformity. They are ill-advised if they do not follow this practice; but in case average undiluted latex is treated in coagulation, the quantity of acetic acid to be used should be calculated from the ratio 1:1,000. ”

“ In the Factory.—As a general rule it may be understood that the mischief has been done before the latex is handled at the factory. Sometimes it is perceptible from the peculiar appearance of the latex, and in such case the batch should not be used for the preparation of sheet-rubber. Often it is found that only the last to arrive at the store is visibly affected. ”

“ Latex tubes function both as storage and as conducting cells. They, like the sieve tubes, contain proteid substances chiefly, yet frequently starch is found. The cells bordering the latex tubes absorb from them, as needed, the soluble food material. While our knowledge concerning the function of latex in some plants is meagre, still in other plants it is practically certain that the latex is composed of nutritive substances which are utilized by the plant as food. In certain other plants the latex appears to be used as a means of resisting insect attacks and as a protection against injury. ”

“ Rubber is chiefly composed of the soft, solid, elastic substance known as caoutchouc. It is usually assumed that this substance is present as such in the latex. The globules in the' latex, however, consist more probably of a distinct liquid substance which readily changes into the solid caoutchouc. The coagulation of the latex often originates with the “curding” of the proteids present, and this alteration in the proteid leads to the solidification of the globules into caoutchouc. ”

“ The presence of more than a small percentage of resin in the latex leads to the production of rubber containing much resin, which seriously depreciates its commercial value for most purposes. The percentage of resin in a good rubber should be as small as possible, and should in any case be less than 10%. There is no feasible method at present known of preventing the inclusion of the resin of the latex with the rubber during coagulation, and although the separation of the resin from the solid caoutchouc by means of solvents is possible, it is not practicable or profitable commercially. ”

“ Colour of Smoked Sheets.—It may be of interest to note that the effect known as oxidation is attributed to the presence of micro-organisms called enzymes (ferments) in the latex. It can also be produced artificially in various ways—e.g., by the use of the crude product of wood-distillation (pyroligneous acid) as a coagulant, or by the addition to the latex of small quantities of a phenol such as carbolic acid. It is thus possible to prepare in sheet form a rubber which has the appearance of having been smoke-cured, although it may never have been in a smoke-house. ”

“ As a matter of fact, up to certain limits of added water, the reverse is actually the case—i.e., the more water in the latex the less acid must be added, assuming that for pure latex the proportion of pure acid to latex is taken as 1 part to 1,000 parts. This was found to be the case up to dilutions of three or four times the volume of latex. To take concrete examples which will perhaps make the truth more clear:
Assuming we commence by making up our stock solution of acid by adding 100 parts of water to 1 part of pure acid, this gives us a mixture of 1 to 100. ”

“ Quantities Necessary for Modern Requirements.—It may be commended to the notice of the beginner that any further experimental work as to the quantity of acetic acid necessary for complete coagulation would only involve a waste of time and energy.
The general figure given in a preceding paragraph (1 part pure acid to 1,000 parts of latex) may be accepted as the rough basis for working. In modern practice, however, undiluted latex is usually diluted to a standard which may vary on different estates from 11⁄4 lbs. to 11⁄2 lbs. dry rubber per gallon. ”

“ When such a plant is punctured or torn the latex flows out, and as soon as it is exposed to the air it becomes more and more sticky until it hardens. It is from the latex of certain trees that India rubber is obtained, but it may be observed in many plants, notably the milkweeds, which have received their popular name on account of it. ”

“ There are two types of latex tubes common to plants, namely, latex cells and latex vessels. Latex tubes developing from a single cell do not differ materially from a latex tube originating from the fusion of several cells. ”

“ Of this solution 1 gallon is required for 50 gallons of standardised latex.
In noting this formula the writer gives no recommendation regarding its use. Whatever may be the actual facts regarding the effect of formalin upon the vulcanisation of rubber, when used in minimum proportions, there can be no question concerning its injurious effect if used in excess. Beyond this the factors of cost and loss militate against its wider employment. ”

“ Under certain conditions, as when latex is allowed to stand or is centrifugalized, a cream is obtained consisting of the liquid globules, which may be washed free from proteid without change, but, either by mechanical agitation or by the addition of acid or other chemical agent, the liquid gradually solidifies to a mass of solid caoutchouc. ”

“ Where uniform jars or tanks are in use, the majority of which will contain uniform quantities of latex daily, the practice of using the chemical can be made almost fool-proof even in the hands of coolies. A calculation is made of the quantity of powder required for each vessel daily. ”

“ It is a cheerful sight to see the workers, men and women, dressed in all the colors of the rainbow, trooping out from their quarters to begin the day's work. The tapping must be done early in the day, for the latex or rubber juice stops flowing a few hours after sunrise. ”

“ The possibility of obtaining the ideal knife, which will go to sufficient depth into barks of varying thickness to yield the maximum quantity of latex without wounding, is quite as remote at the present time as it was some years ago. Meanwhile the search for that ideal knife continues, and occasionally one learns of the alleged merits of some new instrument which, it is said, fulfils all requirements. It is only to be regretted, both for the sake of the inventor and for the expectant buyers, that the claims always fail in some one or more particulars. ”

“ In the ordinary way the method of excision is practised in such a manner that the “cut” gradually descends to the base of the tree.
Planters with original views, and of an enquiring nature, often query the common practice; and it has been suggested that “as the latex descends by the force of gravity,” one’s paring should be done in an upward direction, thus obtaining a greater pressure of latex—and hence a greater flow. ”

“ The best type of strainer has yet to be evolved. Usually it consists in principle of a piece of fine brass mesh contained in some form of holder. Theoretically such a strainer should [68] work well, but in actual practice nearly all strainers are a source of continual worry. Undiluted latex, as received at the factory, is of a rich consistency, containing very fine particles of dirt and often minute particles of prematurely coagulated rubber. ”

“ In the case of sheets prepared from less rich latex, the surface film naturally is extremely thin, and no cracking is observed.
If the fresh sheets are placed in a smoke-house, the drying film will take up colour from the constituents of the smoke, and it will be invisible. Somewhat analogous to the instance of a transparent glass giving a visible and opaque powder when crushed, so the transparent film on stretching breaks up into a visible powder which is lighter in colour than the rubber on which it is superimposed. ”

“ The figures show, however, that the variation in breaking strain is relatively small, and not very different for crepe and sheet rubber. In our opinion, undue importance should not be attached to very high or exceptionally high figures for breaking strain, which are occasionally met with. Provided the figure does not fall much below the average, the sample may be regarded as satisfactory. It is very seldom that any sample of first latex estate rubber does not show satisfactory figures. ”

“ The coolies often feed into the machines lumps which are too large, with the result that portions are thrust under the cheek-blocks and become stained.
When a sheet-coagulating tank is used all labour of cutting the coagulum is obviated. The long strips are handled and fed into the rolls easily. It may be seen, likewise, that actual work is thus saved in machining.
Quantity of Coagulant.—For a general discussion on the coagulant and quantities employed, the reader is referred to Chapter VIII. It is there recommended that for latex standardised to a level of 11⁄2 lbs. ”

“ Vulcanising in its simplest aspect consists in mixing the rubber with sulphur and heating the product under regulated conditions. The effect of heat on the inferior grades of “wild” rubber is very marked. A soft, sticky, and resinous material is transformed into a relatively tough and elastic product. The effect of vulcanising on the better grades is less marked, but immediately apparent. On the other hand, the effect of vulcanising is least apparent on first latex plantation grades, because in these we have a raw rubber prepared in a manner best suited to retain its natural characteristics. ”

“ In a second part of his work, M. de Vries treats of the function of the juices analogous to the resins which are found in other plants, and seeks to assimilate to the resins, from different points of view, the latex, some of the gums, caoutchouc, and waxy matters, lie shows that these substances also exude for the occlusion of wounds, even in herbaceous plants like the northern chicories and spurges, and cites some recent experiments by M. Moll in favor of his view. ”

“ It was proved by the witnesses, and found by the jury, that, although made of silk, the laces in question were commercially known as thread laces. Whether an article is thread lace, it was shown, depended upon the mode of its manufacture,-as upon a cushion, from thread wound on bobbins moved by hand; and that it was equally thread lace whether made of cotton or silk, and whether white or black; and that there are also articles commercially known as silk laces, and articles commercially known as cotton laces; and that thread lace made of linen had been practically unknown for many years. ”

“ I hated and detested Charles Latisse at that moment more that I had thought it possible to or detest any one. Through his devilish machinations he had succeeded in getting his sister—the only woman in the whole world for me—into the clutches of that cold-blooded monster at the Casque and Gauntlet!
Morris, of all men in the world! Was he to rob me a second time, this time of Elise? I could not bear the thought. Had I been alone I must have gone raving mad. A film of red danced before my eyes and my fists clenched in a sudden ecstacy of horror and anger. ”

“ For this reason every amateur mechanic and wood-worker who has a workshop, no matter how small, is anxious to possess a lathe of some sort. A good and substantial homemade lathe, which is suitable for woodturning and light metal work, may be constructed from pipe and pipe fittings as shown in the accompanying sketch.
The bed of this lathe is made of a piece of 1-in. pipe, about 30 in. long. It can be made longer or shorter, but if it is made much longer, a larger size of pipe should be used. The headstock is made of two tees, joined by a standard long nipple as shown in Fig. ”

“ If there are shovels to be mended, the lathe will drill the holes and turn the rivets. If the handle of the saucepan is loose, it will do the same. If scissors or knives want grinding, there is the lathe; if the castors on the sofa break down, there is the lathe; if skates need repairs, either of grinding or of any other kind, there is the lathe. In short, it ought to be as much a part of domestic economy as the sewing machine, for it takes the odd stitches in the mechanical department that save money. ”

“ By a simple change of tool, it can also face off any casting, and can easily be made to cut a thread, of a given pitch, by any ingenious workman. Not only this, but it can also be made without planing; or other work most amateurs have no facilities for. It is within the range of ordinary lathe work, and will be found indispensable. The T-head may be of cast iron, but the spindle should be steel, with a brass nut let in the back end for the screw to work in. ”

“ Lacquer is coloured or opaque varnish applied to metallic objects as well as wood. The name is obtained from "resin lac," the material which is used as the base of all lacquers. In the East Indies the whole surface of wooden objects, large and small, is covered with bright-coloured lacquers. The Japanese lacquers are the finest that are made. They excel in the variety and exquisite perfection of this style of [Pg 5] work, and under their skilful manipulation it becomes one of the choicest forms of decorative art. ”

“ Of course a bench with a vise and a few wood working and iron working tools will be required; but the most expensive as well as the most essential tool is a lathe. With this tool, not only turning in wood, metal, ivory, rubber, etc., can be accomplished, but it may also be used for screw-thread cutting, gear cutting, drilling metals, boring wood, spinning metals, milling, sawing metal and wood, grinding, polishing, moulding, shaping, and other purposes. A first class plain lathe of small size cannot be purchased for less than $50 or $60, and one of inferior quality will cost $20 to $30. ”