As the specific gravity of nitro-glycerin is 1·6, one part by bulk will yield by combustion:—
| Aqueous vapour | 554 | volumes. |
| Carbonic acid | 469 | ” |
| Oxygen | 39 | ” |
| Nitrogen | 236 | ” |
| ——— | ||
| 1298[48] | ” |
Other experimenters affirm that, instead of free oxygen, nitrous oxide is one of the products of the combustion of nitro-glycerin. According to Nobel the heat liberated when nitro-glycerin is exploded, causes the expansion of the gases to be eight times their original bulk; therefore, one volume of the substance will yield 10,384 volumes of gas, whilst one part by bulk of gunpowder only yields 800 volumes of gas. If these data be correct the explosive force of nitro-glycerin is thirteen times greater than that of powder, bulk for bulk, and eight times greater weight for weight.
Böttger has devised a process for the preparation of nitro-glycerin, which being, as he affirms, entirely free from danger, adapts it for lecture experiments:—A few grains of pure
glycerin, free from water, is poured into a test-tube, which is surrounded by a freezing mixture, and containing a mixture of one volume of the most concentrated nitric acid (1·52 sp. gr.), and two volumes of the strongest sulphuric acid (1·83 sp. gr.). Then, as quickly as possible, the whole is poured into a larger quantity of cold water. The nitro-glycerin, which has formed like oil drops, sinks rapidly to the bottom, being specifically the heavier liquid. It is then washed several times by decantation with fresh water, and, lastly, with a weak solution of soda.
Remove the water with a few pieces of fused chloride of calcium. Then the nitro-glycerin is in such purity that it may, without danger, be kept any length of time for lecture experiments.
NITRO-HYDROCHLO′RIC ACID. Syn. Nitro-muriatic acid; Aqua regia, Acidum nitro-hydrochloricum (B. P.), A nitro-muriaticum, L.; Eau régale, Fr. Prep. 1. (B. P.) Nitric acid, 3; hydrochloric acid, 4; water, 25. Mix the acids twenty-four hours before adding the water. (This precaution is necessary to allow of the development of the chlorine, and the chloronitrous and chloronitric gases which result from the mutual decomposition of the two acids, and upon which the therapeutic activity of the agent depends). Colourless. Keep the mixture in a cool and dark place.
2. (Ph. D. 1826). Nitric acid, 1 part; hydrochloric acid, 2 parts (both by measure); mix in a refrigerated bottle, and keep the mixture in a cold and dark place. Used to dissolve gold and platinum; and in medicine, in liver complaints, syphilis, the exanthemata, &c., either externally, in doses of 5 to 15 drops in water, or externally, as a foot- or knee-bath. It is also occasionally employed as a caustic.
3. (Aqua regia with sal ammoniac.) Nitric acid (sp. gr. 1·2), 16 fl. oz.; sal ammoniac, 4 oz.; dissolve. Occasionally used by dyers; does not keep well.
4. (Dyers’ aquafortis.) Colourless nitric acid (sp. gr. 1·17), 10 lbs.; hydrochloric acid (sp. gr. 1·19), 1 lb.; mix. Used by dyers.