| to shake the bottle containing this black oil before using. The best expedient is to decant the oil into another bottle after it has had several days to settle, and to filter it in the process. Filtering paper and a funnel can be used. Filtering the oil makes it more limpid and it seems to improve its siccative quality. It must always be kept tightly closed to protect it from the air.. There are certain precautions that must be taken in making this oil. These must be stressed even at the cost of repetition. In the first place, it is necessary to use a receptacle of a capacity six to eight times greater than the volume of the contents to be cooked. And it is important that the receptacle should be perfectly dry, for a drop or more of water, on reaching too to 150 degrees, could vaporize and cause a small explosion which would violently project the oil into the air. It must always be remembered that the oil must be cooked very slowly and the container be isolated from the fire by asbestos mats. in the case of white lead, it must be remembered that this product is hydrated and consequently contains a certain amount of moisture which causes an abundant foam during the cooling and which might display the same phenomenon mentioned above if the receptacle is not dry.. A lid for the receptacle should be placed at hand before the operation is begun, and if by chance the oil should happen to catch fire in cooking, a11 that is necessary is to cover the receptacle quickly--at the same time turning off the heat. The receptacle should be left covered for a few minutes. Such accidents will only happen through the negligence of the operator. The phenomenon of auto-inflammation does not take place under 35o degrees and it is always preceded by an abundance of sharp, acrid smoke. So the margin of security is relatively great.. The black oil (after it has completely settled and been strained find re bottled) is used for grinding the colors. The only exception is the white which, being itself a lead, does not require the siccative properties of the oil, and would only lose its pure whiteness by being mixed with it. It is therefore ground in raw oil. In grinding the colors, it is better to be fairly generous with |