The above mixtures fairly represent some of the best sizing compositions, but there is no posi tive formula in the matter. Every man modifies these according to the dictates of his experience, and this is never uniform.
The manner in which these compounds have to be put together is also of importance. The water ought to be quite pure, as the presence of orgauic matter greatly increases the risk of mildew. But every sizing-room in which the cylinder sizing-machines are used can furnish a supply of pure water from the condensed steam, which is the result of the operation.
Modern sizing-rooms are supplied according to their magnitude, and the system of sizing pur sued, with a series of tanks called " becks." These are furnished with " agitators "—vertical dashers with centre shafts, on the top of fitted bevel wheels, gearing into similar ones on a hori zontal driving-shaft, extending the length of the becks. These becks communicate with each other, so as to allow the size to flow from one end to the other, as required.
In mixing, it is usual to allow 20 gal. water to each sack (280 lb.) flour. This is thoroughly and subsequently allowed to stand and ferment for about a week. The fermentation is promoted and hastened by keeping the mixture at a temperature of F.), but the latter degree should not be exceeded, as it would have a tendency to destroy the fungoid germs to which fermentation is due. After fermentation has ceased, the size is pumped into the succeeding becks, where it is agitated for a period varying from a few days to 5-6 weeks, and in some instances for a greater length of time. The longer it is kept, the more finely disintegrated the flour becomes, fitting it the better for its purpose, which is to penetrate to the core of the yarn in the sizing process. The granules of all starches, when heated with water, swell, and the pellicle bursts, and discharges its contents of granulose. This is requisite to accomplish 'the sizer's end. The size is passed through the series of becks at such a rate as to reach the machines at a uniform age.
The sizing-machine in most general use in this country is that known as the cylinder drying machine. Its origin is clearly traceable to the inventions of Radcliffe of Stockport, and his assistant Johnson, to whom the cotton trade owe the dressing-frame. The defects of the latter machine led to many efforts to improve upon it the first which achieved any considerable success being the tape-frame of Hornby and Kenworthy, of Blackburn, which was invented in 1839. This constituted a great advance, but about 14 years subsequent to that date it was superseded by the " slasher" sizing-machine, the invention of Bullough and Whittaker, the production from which was much greater. It is the perfected form of this machine which is uow in general use, and which is known as the " cylinder sizing-machine " to distinguish it from the more recently introduced hot or cold air drying-machines.
The cylinder-frame is made by numerous machinists with their own improvements, which aro claimed as special excellencies. Figs. 558 and 559 show elevation and plan of a very effective frame made by Howard and Bullough, of Accrington. The creel a is constructed for the reception of 6 warpere' beams, or any less number required for a weaver's warp. The size-box b contains the immersion-roller n, the size-roller J, and the finishing-roller I, with their pressure-rollers. The first named, by means of a rack, can be submerged in the size. The eiziug-roller J may be of wood or copper, but it is usually of the latter, when the slow-motion doffing arrangement is adopted, aud the pressure-roller is of iron. The bottom roller of the second pair I is always of copper, and the top one of iron. The pressure-rollers are covered with flannel. The acid of the size quickly corrodes these rollers, producing irregular sizing at the inequalities, and it would be an improvement if they were covered with brass. Their function as pressure-rollers necessitates their being solid, their weight usually being 2-4 owt., according to the counts of yarn in use. Size-boxes are now made with a second compartment, into which the size is fed at the bottom, and boiled before overflowing into the principal oompartmeut, where it oomes into contact with the size. By this means is prevented the use of raw size, which would make the warp hard and rough. In this machine, this plan ie improved upon. As will be seen from the drawing, the size-box ie divided into two parte, the partition being shown by the dotted lines between N and M. The small division M contains a float, regulating the admission of size, aud a single pipe, for boiling purposes, at the bottom. The size enters at one side, towards the top, ae seen at K, and only reaches the principal compartment after traversing the width of the machine, and sinking to the bottom, where it passes through an opening in the parti tion, shown at L. The boiling-pipe, at the bottom of the small compartment, being constantly supplied with steam, and fho top being covered with a lid, the heat is retained, and the contents are kept boiling violently, so that the newly introduced size, slowly and regularly admitted by the float, has to cross the width of the machine, and descend through the boiling mass, before it can come to the opening L at the bottom of the partition. It can only enter the next division as the size is carried away by the yarn. Experiments show that, if the size in the small compartment be coloured, it will require 20-30 minutes to reach the second division, which shows the length of time it undergoes boiling before admixture with the bulk, where it is further subjected to the same process before it is taken up by the yarn.