As dry white lead supplied by the corroders is never adulterated, it is not necessary for paint grinders or other consumers to go to the expense of having elaborate chemical tests made, but still there are a few that under certain conditions can hardly be dispensed with. One of these is to ascertain the presence of lead acetate in objectionable proportion. It may be done in a simple way. Grind a small portion of the dry lead with distilled water to paste, throw it on a wetted filter and wash with freshly boiled distilled water. The clear filtered liquid must show nothing more than a slight cloudiness on the addition of a little dilute sulphuric acid. Another and more difficult test, requiring the services of an expert chemist, is to ascertain the proportion in white lead of lead carbonate and lead hydrate, as much depends upon the pigment having these constituents within the right limit. An excess of lead carbonate and consequent deficiency of lead hydrate means lack of spreading power and oil absorption, while on the other hand an excess of lead hydrate means deficiency of body (hiding power) due to too great absorption of oil. In either case the life of paint made from such white lead in oil is shorter by far than when the lead is normal in every way. This test is made by taking a weighed portion of the dry lead, having previously been dried at 212 degrees F., carefully roasting it in a current of dry air and the water evolved intercepted by means of a weighed calcium chloride absorption tube. Unless, however, this test is made accurately it is liable to lead to erroneous conclusions.