His name is chiefly known in connexion with ozone, which he began to investigate in 1839, and with guncotton, which he prepared and applied as a propellant in fire-arms early in 1846.
GUNCOTTON, an explosive substance produced by the action of strong nitric acid on cellulose at the ordinary temperature; chemically it is a nitrate of cellulose, or a mixture of nitrates, according to some authorities.
The first step in the history of guncotton was made by T.
Schonbein of Basel published his discovery of guncotton in 1846 (Phil.
The chemical composition and constitution of guncotton has been studied by a considerable number of chemists and many divergent views have been put forward on the subject.
The oldest and perhaps most reasonable idea represents guncotton as cellulose trinitrate, but this has been much disputed, and various formulae, some based on cellulose as C, 2 H200 10, others on a still more complex molecule, have been proposed.
The constitution of guncotton is a difficult matter to investigate, primarily on account of the very insoluble nature of cellulose itself, and also from the fact that comparatively slight variations in the concentration and temperature of the acids used produce considerable differences in the products.
Guncotton is made by immersing cleaned and dried cotton waste in a mixture of strong nitric and sulphuric acids.
Cellulose sulphates are one, and possibly the main, cause of instability in guncotton, and it is highly desirable that they should be completely hydrolysed and removed in the washing process.
Guncotton in an air-dry state, whether in the original form or after grinding to pulp and compressing, burns with very great rapidity but does not detonate unless confined.
Immediately after the discovery of guncotton SchOnbein proposed its employment as a substitute for gunpowder, and General von Lenk carried out a lengthy and laborious series of experiments intending to adapt it especially for artillery use.
The employment of guncotton as a propellant was possible only after the discovery that it could be gelatinized or made into a colloid by the action of so called solvents, e.g.
When quite dry guncotton is easily detonated by a blow on an anvil or hard surface.
Compressed dry guncotton is easily detonated by an initiative detonator such as mercuric fulminate.
Guncotton containing more than 15% of water is uninflammable, may be compressed or worked without danger and is much more difficult to detonate by a fulminate This formula is retained mainly on account of its simplicity.
A small charge of dry guncotton will, however, detonate the wet material, and this peculiarity is made use of in the employment of guncotton for blasting purposes.
A charge of compressed wet guncotton may be exploded, even under water, by the detonation of a small primer of the dry and waterproofed material, which in turn can be started by a small fulminate detonator.
The explosive wave from the dry guncotton primer is in fact better responded to by the wet compressed material than the dry, and its detonation is somewhat sharper than that of the dry.
It is not necessary for the blocks of wet guncotton to be actually in contact if they be under water, and the peculiar explosive wave can also be conveyed a little distance by a piece of metal such as a railway rail.
The more nearly the composition of guncotton approaches that represented by C6H702(N03)3, the more stable is it as regards storing at ordinary temperatures, and the higher the igniting temperature.
Carefully prepared guncotton after washing with alcohol-ether until nothing more dissolves may require to be heated to 180-185° C. before inflaming.
Assuming the above formula to represent guncotton, there is sufficient oxygen for internal combustion without any carbon being left.
The gaseous mixture obtained by burning guncotton in a vacuum vessel contains steam, carbon monoxide, carbon dioxide, nitrogen, nitric oxide, and methane.
Dry guncotton heated in ammonia gas detonates at about 70°, and ammonium hydroxide solutions of all strengths slowly decompose it, yielding somewhat complex products.
Alkali sulphohydrates reduce guncotton, or other nitrated celluloses, completely to cellulose.
A characteristic difference between guncotton and collodion cotton is the insolubility of the former in ether or alcohol or a mixture of these liquids.
If guncotton be correctly represented by the formula C 6 H 7 0 2 (NO 3) 3, it should contain a little more than 14% of nitrogen.
Generally speaking, the lower the nitrogen content of a guncotton, as found by the nitrometer, the higher the percentage of matters soluble in a mixture of ether-alcohol.
Another heat test, that of Will, consists in heating a weighed quantity of the guncotton in a stream of carbon dioxide to 130° C., passing the evolved gases over some red-hot copper, and finally collecting them over a solution of potassium hydroxide which retains the carbon dioxide and allows the nitrogen, arising from the guncotton decomposition, to be measured.
It has a strong and characteristic odour, and a hot sweetish taste, is soluble in ten parts of water, and in all proportions in alcohol, and dissolves bromine, iodine, and, in small quantities, sulphur and phosphorus, also the volatile oils, most fatty and resinous substances, guncotton, caoutchouc and certain of the vegetable alkaloids.
One of the most important of his investigations had to do with the manufacture of guncotton, and he developed a process, consisting essentially of reducing the nitrated cotton to fine pulp, which enabled it to be prepared with practically no danger and at the same time yielded the product in a form that increased its usefulness.