The formula for water mattresses and cushions—(India-rubber) is:—
| s. | d. | |||
|---|---|---|---|---|
| 1 lb. | Fara Gum (in sheet,) | 2 | 0 | |
| (Present cost, 1s. 7d., per lb.) | ||||
| 6 oz. | Oxide Zinc, | 0 | 1½ | |
| 1 oz. | Pure Sulphur, (common equally good,) | 0 | 1½ | |
| Mill costs, | 3 | |||
| 2 | 5 | |||
| Or 1s. 7d. per lb. | ||||
| Say of the above compound, | 1 | 0 | ||
| Making waste, | 0 | ⅓ | ||
| Grinding, running, cleaning and vulcanizing, | 0 | 6 | ||
| Add 36⅓ mill profit, or | 0 | 10 | ||
| is | 3 | 2 | per lb. | |
This is the price per pound the weight should be estimated at. The mattresses vary in size from 8 + 14 inches to 48 + 72—some with cells—some without cells. The retail profits on these goods, over the manufacturer’s prices, in 1856, ranged from 13s. 6d. to £7, 6s.—according to the size of the mattress. Or in American currency, from about $3.00 to $36.00 profit on single mattresses.
Should so serviceable an article be thus clogged and fettered by such immoderate charges by the retail shop-keepers? It may probably be a guide to some of our readers to state, the best size pillow is 17 + 22, and that the celled mattresses 27 + 30, and 30 + 40, are found most useful, and of adequate length to support the trunk of invalids, and admit the other portion of the body to rest upon the usual feather bed, and thus steady a weak patient; as a full length mattress of elastic gum, 33 + 72 is beyond the safe control of such invalids.
The retailer, for obvious reasons, recommends the larger mattresses, and which are not returnable, even if the patient dies before they reach him.
CHAPTER VI.
VALUABLE RECIPES, ETC.
PURIFYING GUTTA-PERCHA.
H. H. Day, of New York, has obtained a patent in England for extracting from gutta percha a peculiar etheric oil which it contains, preparatory to its being subjected to the process of vulcanization, by submitting it to the action of a liquor which dissolves out the etheric oil, and also, at the same time, by acting upon the woody matter, disengages the sand or other foreign substances held therewith. This liquor is composed of caustic potash (hydrate of potassa) dissolved in water, with an ether formed from a solution of chloride of lime and alcohol added, and after the crude gutta-percha is placed therein the whole mass is heated to a boiling point, and so kept for about nine hours, and then treated between rollers under water, in the ordinary manner. When taken out, the gum will consist of a pure and solid mass, resembling India-rubber, and fully equal to it in fineness, and in the readiness with which it may be worked to prepare it for the additional process of vulcanization.
PURIFICATION OF GUTTA-PERCHA,
By James Reynolds, of New York City. Gutta-percha, in the raw state in which it is imported, contains large quantities of bark, dirt, and foreign substances. In the common processes of manufacture these cannot be extracted, and bad results often ensue. For example, in the covering of telegraph wires, holes are often left wherever foreign substances are present, and thus the insulation is impaired. The only method heretofore employed, for preventing the quality of the manufactured article from being too much injured by the presence of these impurities, has been to reduce the bark and dirt into fine particles, by long-continued and tedious grinding, and then incorporating them with the gum.
The object of the present improvement is to effect the entire extraction of the bark and other foreign particles, and thus improve to a very great degree the quality of the manufactured article. The invention consists in first cutting the gutta-percha into extremely thin slices or sheets, and then submitting it to heating, rubbing, and screening operations. Under this treatment the foreign matters, are almost entirely extracted, and the gutta-percha left pure. This is a valuable invention.