The percentage of size put on cotton goods is calculated according to the increase of weight on the warp only. Thus if the warp in a piece of cloth be composed of 10lbs. of cotton covered with 4lbs. of size, the warp will have been sized to the extent of 40 per cent. The amount of size on cotton warps varies from 3 to 200 per cent. In those classes of goods which are intended for dyeing or bleaching, and which are generally sold by the counts of yarn, it is obviously not wise to add foreign matter to be washed out again, but in those exported goods which have to be made of a fixed weight, or certain feel, heavy sizing is adopted. In the chapter treating of cloths, fuller information on this point is given. Up to 20 per cent. are termed light sized goods, from this to 50 per cent. medium, and above 50 per cent. heavily sized. YARN FOR WARPS. The selection of suitable yarn is obviously important. Warp yarn is generally stronger than weft, and the hardness is obtained by extra twisting of the thread: owing to this peculiarity, warp yarn is generally called “twist.” For heavy sizing purposes, a soft spun twist is advisable, and one made out of the harder and wiry stapled cottons. Brazilian is of this character, and is often mixed with American for “shirting” warps. The spongy and size-absorbent properties are obtained at the expense of the strength of the yarn, and therefore a good sizing twist often winds badly. The colour of the warp yarn is not important, and therefore whiter cottons are often reserved for weft. Fine twists are spun out of longer and finer cottons forming a close spun thread, which is used for better classes of cloth lightly sized. Strength and elasticity are great advantages in twist, and these properties should be obtained and preserved for the last process of weaving. SIZING MATERIALS. Many points distinguish a good size-mixing from a bad one, and the leading qualifications for a suitable one are adhesive properties--it is no use sizing warps if the substance falls off at the loom--good colour, and uniform consistency. Mealy cloth is often produced by lumpy size. Yarn, even with a heavy coat of size, should remain tenacious, pliable and smooth.