It is absolutely essential for obtaining the best results to see that all vessels are perfectly clean. Always employ alcohol, 90 per cent, deodorized by means of charcoal. When grain musk is used as an ingredient in liquid perfumes, first rub down with pumice stone, then digest in a little hot water for 2 or 3 hours; finally add to alcohol. The addition of 2 or 3 minims of acetic acid will improve the odor and also prevent accumulation of NH3. Civet and ambergris should also be thoroughly rubbed down with some coarse powder, and transferred directly to alcohol.

Seeds, pods, bark rhizomes, etc., should be cut up in small pieces or powdered.

Perfumes improve by storing. It is a good plan to tie over the mouth of the containing vessel some fairly thick porous material, and to allow the vessel to stand for a week or two in a cool place, instead of corking at once.

It is perhaps unnecessary to add that as large a quantity as possible should be decanted, and then the residue filtered. This obviously prevents loss by evaporation. Talc or kieselguhr (amorphous SiO2) are perhaps the best substances to add to the filter in order to render liquid perfumes bright and clear, and more especially necessary in the case of aromatic vinegars.

The operations involved in making perfumes are simple; the chief thing to be learned, perhaps,is to judge of the quality of materials.

The term "extract," when used in most formulas, means an alcoholic solution of the odorous principles of certain flowers obtained by enfluerage; that is, the flowers are placed in contact with prepared grease which absorbs the odorous matter, and this grease is in turn macerated with alcohol which dissolves out the odor. A small portion of the grease is taken up also at ordinary temperatures; this is removed by filtering the "extract" while "chilled" by a freezing mixture. The extracts can be either purchased or made directly from the pomade (as the grease is called). To employ the latter method successfully some experience may be necessary.

The tinctures are made with 95 per cent deodorized alcohol, enough menstruum being added through the marc when filtering to bring the finished preparation to the measure of the menstruum originally taken.

The glycerine is intended to act as a "fixing" agent—that is, to lessen the volatility of the perfumes.