The product obtained by skilful manipulation are—from good dry sugar, 128%; from
good treacle, 107%.—“One cwt. of good treacle will yield about 116 lbs. of marketable oxalic acid, and the same weight of good brown sugar may be calculated to produce about 140 lbs. of acid.” “As a general rule, 5 cwt. of saltpetre, or an equivalent of nitrate of soda, with 21⁄2 cwt. of sulphuric acid, will generate sufficient nitric acid to decompose 1 cwt. of good sugar, and yield, as above, 140 lbs. of fair marketable oxalic acid, free from superfluous moisture.” (Ure.) On the small scale, 5 parts of sugar yield nearly 6 parts of crystallised acid.
Chemically pure oxalic acid is best prepared by precipitating a solution of binoxalate of potassium with a solution of acetate of lead, washing the precipitate with water, decomposing it, whilst still moist, with dilute sulphuric acid or sulphuretted hydrogen, and gently evaporating the filtrate so that crystals may form as it cools.
OXALURIA. Also known as the oxalic-acid diathesis; is an abnormal condition of the system, marked by the presence in the urine of crystals of oxalate of lime. The crystals occur as minute transparent octahedra, and sometimes in the form of dumb-bells. They can be easily recognised under a microscope with a power of from 200 to 250 diameters, when they present a very beautiful appearance. They differ from phosphatic deposits in being insoluble in acetic acid. Their presence is mostly indicated by the appearance in the urine of a cloud of mucus, which forms after the urine has stood some little time.
Oxaluria most generally affects persons of dyspeptic and sedentary habits and of nervous temperament; those suffering from skin affections and neuralgia are also occasionally attacked by it. In ordinary cases the treatment consists in the administration of the nitro-hydrochloric acid, in infusion of gentian two or three times a day, or of a course of quinine and iron, aided by plenty of exercise in the open air, care being taken to avoid fatigue. If it can be borne the shower bath should also be had recourse to. Rhubarb tarts and tomatoes, which contain oxalic acid, must be excluded from the diet; so also should aerated water and too much sugar.
If after a short time the oxalates should not disappear from the urine under this treatment, the patient should seek proper medical advice; since the persistent presence of this deposit is of very serious significance, as indicating the existence in the bladder of that dangerous form of urinary concretion known as ‘mulberry calculus.’
OXIDA′TION. Syn. Oxydation. The combination of bodies with oxygen, forming oxides; the operation or process adopted to induce or facilitate such conversion.
OX′IDE. Syn. Oxyd; Oxydum, L. A compound formed by the union of oxygen with another body.
OXYCHLO′′RIDE. Syn. Oxichloride;
Oxychloridum, L. A term often loosely applied to compounds of an oxide and chloride, whether in definite or variable proportions. See Antimony (Oxychloride), &c.