Alcoholic liquors are most generally used for the preservation of animal substances, if they are more costly, they are liable to fewer objections. Brandy, rum, tafea, are coloured by a resinous substance, which clouds their transparency, and which is liable to be deposited. The alcohol of cherries, of grain, of cider, or of wine, is preferred at present, which can be procured well rectified and transparent, and which may be afterwards weakened with distilled water, so as to obtain alcohol very limpid, marking from 22° to 30° of Baumè’s areometer.
Some years since, alcohol was still employed, in which was dissolved certain transparent resins; such as camphor, but it has since been ascertained, that animal substances which have remained in this liquor, contract such a disagreeable and nauseous odour, that it becomes very painful to keep them long uncovered for examination, consequently, pure alcohol is preferred.
Nevertheless, when it is desirable to preserve the preparations of the nerves, it is better to put a few drops of muriatic acid into the jar along with the spirits of wine: this mixture bleaches and renders more visible the nervous fibres, on which the acid appears to act more specially. The yellow tinge, which the parts sometimes assume in the end, may sometimes be removed by pouring a small quantity of muriatic acid into the jar which contains them: this precaution occasionally gives a new aspect to the parts.
We have chosen this passage of M. Dumèril’s pamphlet, because it gives with sufficient accuracy all the liquids employed by preparors, and because it indicates a part of the inconveniences which we have experienced from them.
We shall see to what extent the more recent additions made to sublimated alcohol, of hydrochlorate of soda, (chloride of sodium,) of the hydrochlorate of ammonia, of the muriate and nitrate of alumine, can contribute to the wants of the collector of pathological anatomy.
Before entering into this critical examination, it remains for us to describe the processes employed by naturalists for preserving the different species of animals. The excellent manual of M. Boitard, so useful to preparors, will furnish us with this information.
Means of preparing and preserving practised by naturalists.—The soap of Bècoeur enjoys with naturalists a great reputation as a preservative. It is this preservative, then, that we should recommend as the most approved by experience: the following is the receipt:
| ℞. | Arsenic pulverized, | 2 ℔. |
| Salt of tartar, | 12 ℥. | |
| Camphor, | 5 ℥. | |
| White soap, | 2 ℔. | |
| Powdered lime, | 8 ℥. |
In the original, four ounces of lime is recommended, and we have given this dose in our first edition; but it has since been found by doubling it, the preservative is less pasty, and less difficult to use, more abundant and equally good.