When canvas became more general, the sizings which had been used for wood panels were continued, and it is on the same concoctions of paste and chalk that the first canvas pictures were painted. These concoctions were afterwards abandoned by degrees -i.e., the sizings of paste, getting thinner and thinner, were re-covered by others made of oil and white lead, and finally no paste was used at all. But it was soon observed that canvas, in direct contact with oil, burned and became like touchwood. This sad fact established, artists returned to the use of a first coating of paste, merely to separate the canvas from the oil coating; but this first coating was of a gelatinous substance susceptible to damp, and the canvas became rotten. Another method was then tried -viz., putting behind the canvas another coating of separating paste re-covered with a second coating of oil and passing them between two cylinders to press them. But, thus imprisoned, the canvas lost all suppleness, and could no longer be stretched on the frames; then they stretched the canvas first, and the coatings put on the stretched canvas were merely numerous coatings of oil white, and by therewith entirely covering the grain of the texture, manufacturers tried to get a surface as smooth as that of a panel. This method had the inconvenience of encumbering the studios with frames, each canvas requiring two or three years of constant exposure to the air for its preparation; trying to shorten this time, siccative means were used -such as replacing a portion of the oil with essence of turpentine, using oil prepared with litharge, umber, or red earth mixed with white and sometimes even using no oil at all. These practices were not calculated to improve the qualities of a coating already doomed to scale off fatally- quite the contrary; but they facilitated the manufacture of a kind of canvas which assured to artists a rapid and valuable execution in great favour for a long time especially amongst portrait painters whose supreme ambition was to imitate porcelain.,Did they suspect they they would imitate even its cracks? In any case, time has amply revenged the flimsiness of those guilty pretensions: to-day a portrait of an ancestor that is cracked loses much of its value! After this period of brittle canvas, the ordinary laws of reaction brought on a taste for supple canvas, and much ingenuity was excercised in procuring this quality. A sizing was added of mucilage paste, such as linseed, snail-slime, honey, fig-juice, etc. An oil was also used, rendered viscous by rancidity -i.e., acidified and never drying. For reasons of economy, manufactures substituted for white lead, chalk, whites of Troyes, whiting, white of Meudon, white of Bougival, pipeclay, etc., which gave them results just as good in the matter of suppleness, none of the carbonates of lime ever drying thoroughly when they are ground with oil. Everyone knows that glazier's putty, which is made of oil and whiting, will remain soft for many years under a hard and wrinkled coating. It is easy to understand, therefore, that painting must crack when done over coatings that continue to shrink long after the painting is dry. The invention of railroads, which has changed so many things, is also not without influence on painting-canvas, for like all other things pictures also now travel, and the constant rolling and unrolling necessitates the use of more and more supple canvas, until suppleness is now the chief property considered in its manufacture. This is the present state of the manufacture. By an inexplicable anomaly, unbleached canvas costs more at the French custom-house than prepared canvas does. Now, painting-canvas being made chiefly in Holland, and hand labour costing less there than at Paris, it has become the custom to apply the coating at the place of manufacture and to send the canvas ready prepared in large rolls: this has the double advantage of costing less and of not encumbering the shops. Further, the canvas being rolled as quickly as possible, the oil deprived of the light before becoming dry, gets rancid and diminishes the suppleness of the coating, as has been said above. This canvas is therefore perfect? For the tradesman, yes! But it is yellow, it has a disagreeable odour, and pictures painted on it remain to posterity blackened and cracked. Of course manufacturers do not work for posterity. By comparing the works which remain to us and by examining the materials on which they are painted, it is easy to convince ourselves that the best preserved pictures have been painted on paste sizings. Is that to say that all those which are on paste sizings are well preserved? Assuredly, no. But that does not affect the principle, because, very often, the cause of destruction is independent of the sizing, and sometimes the paste used was of bad quality. Paste should be incorruptible, supple, perfectly neutral, and not susceptible to damp. In this condition it isolates the colours from all chemical reaction liable to result from the support; neither contracting nor expanding, it occasions no cracks, and its suppleness enables it to follow the movements of wood and canvas; whilst oil sizings*, on the contrary, oxidise, get yellow, produce chemical reaction on certain colours, shrink, and in the end invariably become brittle. The conclusion of all this is, therefore, that oil sizings should be rejected and paste used. But it must be carefully chosen.