Take one gram of powdered spice which will pass a 60-mesh sieve and dry at 150 degrees to 110 degrees C. in an air bath provided with a regulator, until a successive weighing shows a gain, which denotes that oxidization has begun, which takes about 12 hours, or over night; the loss is water, together with the largest part of volatile oil. Deduction of the volatile oil, as determined in the ether extract, will give a close approximation of water. The ash portion is determined by incineration at a very low temperature, such as may be attained in a gas muffle, which is the most convenient arrangement for work of this kind. The proportion of ash insoluble in acid may be determined where there is a reason to believe that sand is present. To find the amount of volatile oil by ether extract: Two grains of substance are extracted for twenty-four hours in a siphoning extraction apparatus, being first placed in a test tube, which is inserted into a continuous extraction apparatus of the intermittent siphon class, the tube used being an ordinary test tube, the bottom of which has been blown out. A wad of washed cotton of sufficient thickness is put in the lower end of the tubes to prevent any solid particles of the sample from finding their way into the receiving flask; another wad of cotton is packed on top of the sample, and the apparatus is then so adjusted that the condensed ether drops into the tube and percolates through the sample siphons into the receiving flask. In this way the operation is continued the length of time named. The best ether should be used to avoid extracting substances other than oil soluble in alcohol, and to continue the extraction for at least the time named, as piperine and several other proximate principles are not extremely soluble in ether. On stopping the extraction, the extract is washed into a light, weighed, glass dish, and the ether is allowed to evaporate spontaneously, but not too rapidly, for the reason that water, which is difficult to remove, might be condensed into the dish. In a short time the ether will disappear, and the dish is placed in a dessicator with pumice and sulphuric acid, not with chloride of calcium, which has been shown to be useless. It is allowed to remain over night to remove any moisture; the loss of oil by this process is scarcely appreciable. The dish is next weighed and afterward heated to 110 degrees C. for some hours, to drive off the volatile oil, beginning at a low temperature, as the oil is easily oxidized, and then is not volatile oil. The residue is weighed, the difference being calculated to volatile oil and examined as to its composition of purity. [Illustration: Fig. 11. _Tumeric_ Fig. 12. GINGER ADULTERATED Fig. 13. PURE GINGER Fig. 14. _Ginger_ Fig. 19. _Nutmeg_ Fig. 24. _Buckwheat_ Fig. 34. _Rye_]