Page:Eleanor Gamble - The Applicability of Weber's Law to Smell.pdf/38

34 warm or cold water. All the odorous substances in this group were melted in a water-bath. We crumbled or shaved them into a small beaker, which we floated by means of a ring of cork in a large beaker of water over a Bunsen burner, We tried to melt the gums in a sand-bath, but succeeded only in charring them. The mass which we obtained by melting the gum ammoniac and gutta-percha together was of lighter color than that sent from Holland, and was not entirely free from the fibres of the gutta-percha. It was spongy and easily moulded by the fingers into any desired shape. The soap, paraffine, cocou-butter and tallow are readily manipulated. They solidify in a very few moments if the outer tube is immersed in col water, and the removal of the inner mould presents no difficulty. Tubes of these materials were kept all the summer in a room of which the temperature occasionally rose to 94° F., and sustained no damage by the heat. The tubes of soap, however, sometimes shrivel in a few days independently of the temperature. The longer the paraffine is heated the stronger the odor. Zwaardemaker succeeds in giving it an odor as strong as that of tallow or musk-root. We did not try beating it longer than an hour and a half, and our paraffine tubes gave the weakest of all our scents. Tubes of tallow are easy to make and to keep, and do not exhaust the subject's sense-organ to any appreciable extent, and are therefore especially to be recommended.

The oil of mace has a consistency like that of table-butter. It melts rapidly, and solidifies almost instantly when the outer mould is pinnged into ice water, but tends to stick to the inner tube, and to come out with it in perfect shape. To remove the inner tube by itself, we filled it with ice water, and then hastily poured little hot water over the outer mould. When once made, the mace tubes should be kept in a cool place, and the jar in which they stand should not be set on end. While they are in use, they must be grasped only with the tips of the fingers, and must be cooled every few moments with ice or snow. The juice of asafœtida, when pure, never becomes solid enough to be moulded. We poured small quantities of it, when melted, upon a mass of pulverized carbonate of magnesia, and worked the two materials together with our fingers, as one works flour into a very soft dough. We put lumps of this mixture into an outer mould, heated it in the water bath for a few moments, and then forced the inner tube down through the mass as nearly parallel with the outer mould as possible. After many attempts, we succeeded in making several satisfactory cylinders. Their odor, in spite of the adulteration of the asafœtids, is only too strong.

The gums never become very liquid in melting, and they solidify almost instantly when removed from the heat. We found it difficult to pour the gnm benzoin,and impossible to pour the toln and the mixture of gutta-percha and ammoniac, into the space between the inner and outer moulds. We poured this mixture and the tolu into the outer tube when empty, and then forced the inner tube into its place, as in the case of the asafcetida. When the fragrant substance is a gum, this inner tubs must be greased. We coated it rather thickly, but evenly, with lanolene, which is as nearly odorless as grease can easily be found, and which evaporates quickly. All these tubes of gum retain their odors well, but the tolu is likely to melt out of shape in a hot room.

Before these cylinders are used, the section of odorless substance exposed at the outer end must be covered. We employed a little ring or cap of glazed paper gummed to the surface. Even with this precaution, the odor of the asafœtida, mace, butter and Russian leather, is quite apparent when the instrument is closed by pushing the odorous tube