INCINERA′TION. The reduction of organic substances to ashes by combustion. See Calcination.
INCOMBUSTIBIL′ITY. The property of being incapable of being kindled, or of being consumed by fire. Substances possessing this property are said to be ‘incombustible’ or ‘fire-proof.’
INCOMBUST′IBLE FAB′RICS. Syn. Non-inflammable fabrics. The fashion of wearing light gauzy dresses extended by hoops or crinoline has made death from fire a common casualty. With a view of diminishing the danger to which women expose themselves, chemists have lately devoted considerable attention to the problem of rendering muslin and other light fabrics non-inflammable. This object may be attained by steeping the fabric in almost any saline solution. Thus, cotton or linen stuffs prepared with a solution of borax, phosphate of soda, phosphate of ammonia, alum, or sal ammoniac, may be placed in contact with ignited bodies without their suffering active combustion or bursting into flame. The salts act by forming a crust of incombustible matter on the surface of the fibres. They do not, however, prevent carbonisation taking place, when the temperature is sufficiently high. It is by a knowledge of this property of culinary salt that jugglers are enabled to perform the common trick of burning a thread of cotton while supporting a ring or a small key, without the latter falling to the ground. The cotton is reduced to a cinder, but from the action of the salt its fibres still retain sufficient tenacity to support a light weight.
The addition of about 1 oz. of alum or sal ammoniac to the last water used to rinse a lady’s dress, or a set of bed furniture, or a less quantity added to the starch used to stiffen them, renders them uninflammable, or at least so little combustible that they will not readily take fire; and if kindled, are slowly consumed without flame. None of the above-named salts are adapted for fine soft muslins, which mostly require chemical treatment, because they injure the texture, rendering the fabric harsh and destroying all its beauty. The salt which is found to answer most completely all the required conditions is TUNGSTATE OF SODA. “Muslin steeped in a solution containing 20% of this salt is perfectly non-inflammable when dry, and the saline film left on the surface is smooth and of a fatty appearance like talc, and therefore does not interfere with the process of ironing, but allows the hot iron to pass smoothly over the surface. The non-fulfilment of this latter condition completely prevents the use of many other salts—such as sulphate or phosphate of ammonia, which are otherwise efficacious in destroying inflammability—for all fabrics which have to be washed and ironed.” (Watts.)
The addition of a little phosphoric acid or phosphate of soda to the tungstate is recommended, for without this addition a portion of the tungstate is apt to undergo a chemical change and become comparatively insoluble. Messrs Versmann and Oppenheim, the introducers of tungstate of soda, give the following formula for a solution of minimum strength:—
Dilute a concentrated solution of neutral tungstate of soda with water to 28° Twaddell (sp. gr. 1·14), and then add 3% of phosphate of soda. This solution is found to keep and to answer its purpose very well; it is now constantly used in the Royal Laundry.
Paper, WOOD, &c., may be also rendered comparatively incombustible by soaking them in saline solutions. See Asbestos, Fire, &c.
INCOMPAT′IBLES. In medicine and pharmacy, substances which exert a chemical action on each other, and cannot, therefore, with propriety, be prescribed together in the same
formula or prescription. The principles on which we should act to avoid prescribing or dispensing incompatibles, are briefly developed under the heads Affinity and Decomposition. To this we may add that, if a substance is endowed with well-marked therapeutical or poisonous properties, independent of those which may exert a chemical effect upon the tissues, its mode of action will neither be changed nor destroyed by the combinations which it forms, provided always that the new compounds are not insoluble in water.
“It is not necessary to give two incompatible medicines at the same time, in order to produce decomposition; it is sufficient if they are given within a very short interval of each other. Thus, a sick person, who has been treated with lead externally, or even internally, will present a discoloration of the skin, if he takes a sulphur bath four or five days after the lead treatment has been discontinued. If a person is rubbed with iodide of potassium shortly after having applied Vigo’s plaster (plaster of ammoniacum with mercury), or the Neapolitan ointment (mercurial ointment), iodide of mercury and caustic potash will be formed, which will cause vesication. So also vomiting occurs if lemonade made with tartaric acid is taken five or 6 days after the administration of white oxide of antimony.” (Trousseau and Reveil.)