Chemical impurity

“ To destroy organic matter the most powerful oxidizing agents are required. We must boil it with nitric acid and chloric acid and the most perfect chemical agents. To think to get rid of organic matter by exposure to the air for a short time is absurd. ”

“ When oxygen combines with a single element, what is the compound called? We have found that O makes up a certain portion of the air; later, we shall see how large the proportion is. Its tendency to combine with almost everything is a reason for the decay, rust, and oxidation of so many substances, and for conflagrations, great and small. New compounds are thusformed, of which O constitutes one factor. Water, H2O, is only a chemical union of O and H. Iron rust, Fe2O3 and H2O, is composed of O, Fe, and water. The burning of wood or of coal gives rise to carbon dioxide, CO2, and water. ”

“ The peculiar manner in which hydrogen gas appears to dissolve solid substances,—as iron, potassium, sodium, sulphur, phosphorus, selenium, and arsenic, may be explained by regarding the results as a manifestation of the powers of chemical affinity over the forms of bodies. In like manner, the solution of salt in water, or the mixture of alcohol in that fluid, may be viewed as chemical phenomena, although usually considered as simple cases of solution or mixture: alterations of temperature and other physical changes taking place in either. ”

“ The destruction of organic matter through simple distillation by means of pure hydrochloric acid is at least equal to that by sulphuric acid, chlorate of potash, and the carbonisation methods. The object of the chemist not being to dissolve every fragment of cellular tissue, muscle, and tendon, but simply all mineral ingredients, the less organic matter which goes into solution the better. ”

“ Again, the greenish-yellow and intensely poisonous gas, chlorine, unites in definite proportions by weight with the soft, wax-like, and highly poisonous metal sodium to produce the white crystalline solid chloride of sodium (common salt) , a compound which, except in very large quantities, is not only not poisonous, but actually beneficial to health.
Such combinations are called chemical compounds, and the force which binds their constituents together is distinguished from all other attractive forces by the term affinity or chemical affinity. ”

“ Spots of acid on clothing fall too often under the observation of all those engaged in practical chemical work. However quickly a spot of acid is wiped off, unless it is immediately neutralised by ammonia, it ultimately makes a hole in the cloth; the spot, as a rule, whatever the colour of the cloth, is of a blotting-paper red.
Sulphuric acid dropped on iron, attacks it, forming a sulphate, which may be dissolved out by water. If the iron is exposed to the weather [81] the rain may wash away all traces of the acid, save the corrosion ”

“ When the body of a man, or of an animal, is exposed to the combined influences of air, of water, and of a moderately high temperature, it undergoes a series of chemical decompositions, whose final term is its transformation into carbonic acid gas, and some compounds, gaseous or solid, which represent the less advanced products of destruction. Gases of various kinds, carbonic acid, hydrosulphuric, and ammoniac, and the vapour of water, spread themselves through the atmosphere, or dissolve into the humidity of the soil. ”

“ Hence, as putrefaction is impossible in the absence of moisture, and the active agent, albumen, equally reduced, decomposition of such substances that remain ensues only by a process of decay, slow combustion or oxidation, the slowly uniting of oxygen with the substance. In this the constituent parts of the animal tissues break up into simpler compounds by the chemical changes that nature produces, and differs from other forms of putrefaction only by the length of time employed. ”

“ In addition to the sources of pollution of the atmosphere which we have been considering, there are various trades and manufactures in which poisonous matters are given off. Some of these are of an organic nature, as in the melting of fats, in the making of size and glue, in the boiling of oil, in the boiling of bones, and in many other processes carried out on a considerable scale, where the emanations are highly offensive and often of unknown chemical composition. ”

“ In the whole range of artistic colours there is no pigment less [111] affected by chemical or physical agents. Acid and ammoniacal fumes, foul gases, and exposure to damp, air, light, or sunshine, equally fail to injure it. The perfect impunity with which it bears the action both of sulphuretted hydrogen and sulphide of ammonium is remarkable. The former gas may be continuously passed into the colour suspended in water, or a strong solution of the latter sulphide be poured upon it, and the yellow remains unchanged. ”

“ It appears from some experiments by Schlöpfer that the fluid preparations act rapidly through the lining membrane of the air-passages. Six grains of corrosive sublimate in solution will thus kill a rabbit in five minutes. [966] But the effects of mercury through this channel are much better exemplified when its preparations are inhaled in the form of vapour. Corrosive sublimate when incautiously sublimed in chemical experiments has been known to cause serious effects. ”

“ The Decomposition of any remaining Portion, and the adoption of measures best calculated to obviate its absorption. Where the substance is in a solid form, and acts by absorption, we should be very cautious how we favour its solution; while, if it exists in a liquid state, our object must be to render its active portion insoluble; this problem involves a series of questions which are wholly chemical. In order to prevent, or retard, the absorption of the active matter, we must, to a great degree, depend upon the agency of vital adjuvants ”

“ Thus we find 'inflammable air* as the name for hydrogen, 'fixed air* for carbonic acid gas, and 'dephlogisticated marine acid air' for chlorin. That no better principle of classification of substances from a chemical standpoint than that of superficial outward appearance was demanded is not strange, when we recollect that at this period and, indeed, down to the close of the eighteenth century, the transmutation of metals was a popular belief of the common people and was not disproved by the chemist. ”

“ It brings home to me what an unstable chemical compound man is. Here are the stage accessories as good as ever, while the players have all split up into hydrogen and oxygen and nitrogen and carbon, with traces of iron and silica and phosphorus. ”

“ Many volatile substances destroy the luminous appearance of phosphorus vapour, e.g., chlorine, hydric sulphide, sulphur dioxide, carbon disulphide, ether, alcohol, petroleum, turpentine, creasote, and most essential oils. On the other hand, bromine, hydrochloric acid, camphor, and carbonate of ammonia do not seem to interfere much with the phosphorescence. ”

“ In larger works where dust is generated this should be drawn away at the point where it is produced. This applies also to processes in the chemical industries where lead or lead compounds are used, seeing that no substitute is possible. ”

“ Such an arrangement, if erected upon a scale sufficiently extensive, with the medium of a neutro-saline solution, would, in his opinion, produce large quantities of acids and alkalies with very little trouble or expense.
249 Alterations in chemical equilibrium are constantly taking place in Nature, and he thinks it probable that the electric influence, in its faculties of decomposition and transference, may considerably interfere with the chemical changes occurring in different parts of our system. ”

“ Among his minor chemical researches were his experiments showing that the slow oxidation of phosphorus by air is arrested by the presence of even mere traces of olefiant gas, and that the spontaneous inflammability of phosphuretted hydrogen is due to the presence of a small proportion of nitrous acid. ”

“ The comparatively fixed class, as regards diffusion, is represented by a different order of chemical substances (marked out by the absence of the power to crystallise) , which are slow in the extreme. Among the latter are hydrated silicic acid, hydrated alumina, and other metallic peroxides of the aluminous class, when they exist in the soluble form; with starch, dextrine, and the gums, caramel, tannin, albumen, gelatin, vegetable and animal extractive matters. Low diffusibility is not the only property which the bodies last enumerated possess in common. ”

“ It hence follows, that mere qualitative tests for these elements in the tissues or fluids of the body are of not the slightest use, for they are always present during the life of the healthiest individual, and can be found after death in persons dying from any malady whatever. To establish the fact of a person having taken an unusual dose of any of the alkali salts, by simply chemical evidence, it must be proved that the alkalies are present in unusual quantities or in an abnormal state of combination. ”

“ By a suitable movement of the flask, the acid ferrous chloride is allowed to come in contact with the tissue, a gentle heat applied to the flask, and gases are evolved. These may be carbon dioxide, nitrogen, and nitric oxide. On the evolution of gas ceasing, the carbon dioxide is absorbed by passing up under the mercury a little caustic potash. When absorption is complete, the gas, consisting of nitrogen and nitric oxide, may be measured. A bubble or two of oxygen is now passed into the eudiometer; if nitric oxide is present, red fumes at once develop. ”

“ They who gape, horror-struck, at the endless revelations of chemistry, without giving reason time to act, err in the second manner. Led away by the brilliant hues and wonderful transformations of the laboratory, they forget the size of the world outside, in which these changes are enacted, and the quiet way in which Nature works. The breath of chlorine is deadly, but we daily eat it in safety, wrapped in its poison-proof envelope of sodium, as common salt. Carbonic acid is among the gases most hostile to man, but he drinks it in soda-water or Champagne with impunity. ”

“ Expert Analysis.—A modification of this experiment is employed by experts to test for AS2O3 poisoning. The organs.— stomach or liver—are cut into small pieces dissolved by nascent Cl, or HClO, made from KC1O3 and HCl, and the solution is introduced into a H generator, as above. AS2O3 preserves the tissues it comes in contact with, for a long time, and the test can be made years after death. All the chemicals must be pure, since As is found in small quantities in most ores, and the Zn, HCl, and H2SO4 of commerce are very likely to contain it. ”

“ It is a colourless or faintly-yellow acid liquid, the depth of colour depending on its purity, and especially its freedom from iron. The liquid is volatile, and can be separated from fixed matters and the less volatile acids by distillation; it has a strong attraction for water, and fumes when exposed to the air, from becoming saturated with aqueous vapour. If exposed to the vapour of ammonia, extremely dense clouds arise, due to the formation of the solid ammonium chloride. The acid, boiled with a small quantity of manganese binoxide, evolves chlorine. Dioxide of lead has a similar action ”

“ Millions of them may be lying packed in a gun cartridge, as quiet as you please, but let a little disturbance start in the neighborhood—say a grain of mercury fulminate flares up—and all the nitrogen atoms get to trembling so violently that they cannot be restrained. The shock spreads rapidly through the whole mass. The hydrogen and carbon atoms catch up the oxygen and in an instant they are off on a stampede, crowding in every direction to find an exit, and getting more heated up all the time. ”

“ A chemist, given a liquid to examine, would naturally test first its reaction, and, if strongly alkaline or strongly acid, would at once direct his attention to the mineral acids or to the alkalies. In other cases, he would proceed to separate volatile matters from those that were fixed, lest substances such as prussic acid, chloroform, alcohol, and phosphorus be dissipated or destroyed by his subsequent operations. ”

“ The third step in the manufacture is purification, which removes from the gas the noxious elements, chiefly carbonic acid and sulphuretted hydrogen. The first lowers the illuminating power very greatly: one per cent, being sufficient, it is said, to diminish it five per cent. The sulphuretted hydrogen and other sulphurous compounds give rise in burning to sulphurous and sulphuric acids which may injure, by their corrosive action, delicate structures, such as books, gilding, silks, etc., that are exposed to the air of the room in which the gas is burned. ”

“ The air may be contaminated by the disengagement of poisonous gases, or by the propagation of miasms.
The decomposition of bodies in the earth is a real organic combination; its products are quite well known. The principal and most abundant of them is carbonic acid, a substance that is generated by the slow combustion of the carbon contained in all organic matter, vegetable or animal, whether it be a blade of grass, a leaf, wood, manure, or a dead body. ”

“ By the combustion of bodies, substances are generated that are either gaseous or solid, whence arises the variety of products. Of aëriform fluids, some are coloured, as nitrous acid vapour, (nitrous gas and oxygen) , chlorine, and the protoxide and deutoxide of chlorine. The first is red, the rest yellowish-green, or yellowish. Some relight a taper, provided the wick remain ignited, as oxygen gas, protoxide of azote, and the oxides of chlorine. Others produce white vapours in the air, as muriatic acid, fluoboric, fluosilicic, and hydriodic. ”