Isinglass-The swimming bladder or sound of various species of Acipenser, prepared and cut into fine shreds.

Characters.-Light, coriaceous, whitish or yellowish, semi-transparent, inodorous, tasteless; insoluble in cold water, soluble in 24 parts of boiling water, forming a transparent jelly on cooling.

From Isinglass is made: Solution of Gelatine.

Use

Isinglass is nutrient, Gelatine is used in chemical testing.

Oleum Morrhiiae-Cod-Liver Oil.-The oil extracted from the fresh liver of the cod, Gadus Morrhua, by the application of a heat not exceeding 180°.

Characters and test.-Pale yellow, with a slight fishy-odour, and bland fishy taste. A drop of sulphuric acid added to a few drops of the oil on a porcelain slab develops a violet colour, which soon passes to a yellowish or brownish-red.

Composition.-Cod-liver oil consists chiefly of olein and margarin, but contains as much as 5 per-cent. of free fatty acids (oleic, palmitic, stearic), traces of iodine and bromine, the ordinary inorganic salts of animal tissues and products, and trimethylamin N(CH3)3. Some authorities give bile as a constituent of cod-liver oil, others deny this entirely.

Impurities.-Inferior oils.

Dose.-l to 8 fl.dr.

Action And Uses. 1. Immediate Local Action And Uses

The action and uses of oils externally have been fully discussed under the head of Oleum Olivoe, page 284.

Cod-liver oil is sometimes rubbed into the skin of wasting children as a nutrient, and with perfect success; but it imparts an objectionable colour and smell to the body.

With a little perseverance, it is as easily taken as other oils, and more easily digested, on account of the amount of free acid which it contains, and which greatly facilitates saponification and emulsion, as well as ahsorption.

2. Action On The Blood

Like olive and other oils, it enters the circulation, carrying with it traces of the other constituents. Increasing the richness of the chyle, it improves the quality of the blood, especially as regards the corpuscles, and is thus a haematinic.

3. Specific Action And Uses

Passing into the cells, cod-liver oil is a nutrient of the first importance, whilst the traces of iodine, bromine, phosphates, other salts, and the trimethylamin doubtless produce a slight specific action when the oil is given continuously for months. The latter effects are, however, quite secondary to those of the oil proper, that is, to its effects as a food. Thus cod-liver oil differs from other oils (olive and almond oils, cream, butter, etc.), chiefly, but not solely, in respect of the ease with which it is digested and absorbed.

Cod-liver oil is very extensively used in almost all kinds of chronic disease attended by wasting. The chief of these diseases are scrofula in its various forms, phthisis, rickets, tertiary syphilis, chronic rheumatism, and general debility referable to misery, over-work, and under-feeding. In convalescence from acute illness it is of much service. It is also one of the best restoratives of the nervous functions, and of great value as a tonic in neuralgia, headache, mental irritability, despondency, and other less definite disorders, referable to exhaustion or inherent debility of the nervous centres.

In every instance where cod-liver oil is indicated, the first point to be determined is whether it can be taken and digested. Besides the difficulty of taste, two conditions distinctly contra-indicate the exhibition of the oil, namely, diarrhoea and considerable fever. Gastric dyspepsia also suggests hesitation in the use of oil, but if alkaline stomachics are given before meals, and the oil after, it will be found to agree perfectly in most cases. If oil be persistently rejected, it should be stopped for a time, and again cautiously tried, or given with ether (10 minims of pure ether to 1 drachm of oil) or as an emulsion.