Even in the normal expansion of the drops of color, it often happens, that the rim of the drop is jagged, the cause being that the size already possessed a thin top, which was not yet sufficient to prevent the expanding of the colors. If the size be left standing for a half-hour or an hour before throwing on the color without having at first removed the top of the size, the drop will tear a hole into this film and will sink, even if quite a large quantity of gall had been added. This explains the contraction and the sinking down of colors on a still warm size, inasmuch as the top is formed by evaporation of the warm mucilage, so quickly and so thick, that the color which had already begun to spread out is pressed together by it and is forced to sink. The greater the difference of temperature between the size and air, the quicker is the top formed. It is therefore a rule, that the size should be allowed to cool off in the same room, in which the marbling occurs, because in this way a symmetrical degree of heat or cold of the size and air will be gained. On such a size, the formation of the top is much slower and thinner, so that even after one to one and a half minutes after removal of the top of the size, the colors can be thrown on without the occurrence of the starry formation. I will here mention a fact to show the importance of temperature. As this point has given me much trouble and has taken much time and labor, it was my aim to find that mysterious effect which I was unable to overcome despite my numerous chemical experiments, until my eyes became opened and I saw accidentally that this obstacle was the difference of temperature of size and air. From that time on I was able to prosecute my labors without the slightest difficulty. To show the excellence of my marbling colors, I used a great number of samples, perhaps several thousand, and in order to produce them I worked on Sunday so that I could employ my whole time to the good purpose. It was winter; on every Saturday I ordered two pots of size to be boiled, and to cool them off I placed them in a room, in which there was no heat. On Sunday morning I filtered the size through a loose linen cloth; it was as clear as crystal, it possessed the necessary consistency, and I was much pleased with the results, which I had expected to achieve. I commenced the preparation of the colors in a separate flat vessel, using but little size, so as to keep the rest from being soiled, but I was greatly astonished, when the colors in spite of the addition of gall, which of course was carefully done by drops, first spread out and then again were contracted, the starry formation of the colors took place, whenever I was not quick enough after the taking off of the top to throw on the colors.