« PreviousContinue »
and variety of our food, it is yet extremely improbable that they are all essential or constituent parts of the vital fluid. On this head we know enough of the character of Fourcroy, to regard his avowedly imperfect experiments on the blood of the foetus, as a jeu d'esprit. The membranous matter, or fibrin, of the blood, is separable by rubbing the coagulum between the fingers in water; which carries away the colouring matter, and leaves the real fibrin, that has sometimes been confounded with the coagulable lymph. According to physiologists, fibrin is destined for the purpose of forming and repairing the substance of the muscles. Our author details the causes of the coagulation of the blood (allowing it a vital principle), after the French chemists Parmentier and Deyeux; whose speculations contain nothing which cannot be traced to those of Hunter, Hewson, &c. Dr Johnson seems not to have known the experiments on muscular irritability with the galvanic fluid.
The examination of milk, and its acetous and vinous fermentations, shews, according to Stipriaan, that the greatest quantity of spirit is obtained from the milk of the cow; while Plenek affirms that of the mare, as containing the greater abundance of sugar. The remote component parts of milk are oxigen, hydrogen, carbon, soda, azote, phosphorus, and lime, and some chemists add iron. Then follows (admirable arrangement!) a history of milk,' with more desultory experiments, and a pompous account of the peculiar excellence of the Roquefort cheese, made of sheep's and ass's milk. As the author has never tasted it at Roquefort, we can assure him from experience that even there, if he has the palate of an Englishman, he would esteem it very inferior, both in flavour and texture, to the common cheese in Wales.
On the gastric juice, or menstruum in the stomach that facilitates digestion, the experiments of the Italian chemists Carminati, Brugnatelli, and Scopoli, particularly the latter, drawn from French accounts, are very incorrectly related. This fluid, taken from the human body in health, is composed of water neither acid nor alkaline, muriat of soda, and an animal substance said to afford phosphat of ammonia. We subjoin the following extract; which, if not useful against the prevalent disease of empiricism, may perhaps amuse some of our sedentary readers who are troubled with indigestions, &c.
Substances insoluble, or that were not digested in the usual time (three hours) in the stomach, according to Gosse of Geneva.
Animal substances:-1. Tendinous parts: 2. Bones: 3. Oily or fatty* parts: 4. Indurated white of egg. Vegetable substances:
*This is not to be understood of fat meat. REV.
1. Oily or emulsive seeds: 2. Expressed oils of different nuts and kernels: 3. Dried grapes, and the skins of fish: 4. Rind of farinaceous substances: 5. Pods of beans and pease: 6. Skins of stone fruits: 7. Husks of fruits with grains or seeds: 8. Capsules of fruit with grains: 9. Ligneous stones of fruits, &c.
Substances partly soluble, or parts of which were digested.
Animal substances:-1. Pork dressed various ways: 2. Black puddings: 3. Fritters of eggs, fried eggs and bacon. Vegetable substances:-1. Sallads of different kinds, rendered more so when dressed: 2. White cabbage less soluble than red: 3. Beet, cardoons, onions, and leeks: 4. Roots of scurvy grass, red and yellow Carrots, succory, are more insoluble in the form of sallad than any other way: 5. The pulp of fruit with seeds, when not fluid: 6. Warm bread and sweet pastry, from their producing acidity: 7. Fresh and dry figs. By frying all the substances in butter or oil they became still less soluble (digestible). If not dissolved in the stomach, they are, however, in their passage through the intestines. Substances soluble or easy of digestion, and which are reduced to a pulp in an hour and half.
Animal substances:-1. Veal, lamb, all gelatinous substances, and in general the flesh of young animals, are sooner dissolved than that of old: 2. Fresh eggs: 3. Cow's milk: 4. Perch boiled with a little salt and parsley: when fried or seasoned with oil, wine, and white sauce, it is not so soluble. Vegetable substances:-1. Herbs, as spinach mixed with sorrel, are less soluble. Celery, tops of asparagus, and hops: 2. Bottom of artichokes: 3. Boiled pulp of fruits, seasoned with sugar: 4. Pulp or meal of farinaceous seeds: 5. Different sorts of wheaten bread, without butter, the second day after baking, the crust more so than the crumb. Salted bread more so than that without salt; brown bread in proportion as it contains more bran is less soluble: 6. Rapes, turnips, potatoes, parsnips, not too old.
Substances which facilitated the menstrual power of the gastric juice, are sea salt, spices, mustard, scurvy-grass, horse-radish, radish, capers, wine, spirits in small quantities, cheese, particularly when old, sugar, various bitters.
Substances which retarded the gastric power, are water, particularly hot, all acids, astringents, Perùvian bark taken after dinner : unctuous substances, kermes, corrosive sublimate, &c. Gosse likewise observed, that employment after a meal suspended or retarded digestion, as well as leaning with the breast against a table, and that repose of mind, vertical position and gentle exercise facilitated it." Vol. I. P. 210.
It appears that Carminati, by digesting two drachms of fresh veal in an ounce of spring water, adding five grains of common salt, exposing it to the heat of about 100° of Fahrenheit for sixteen hours, and decanting the liquor, imitated the gastric juice of carnivorous animals. By repeated digestion with fresh flesh, he found it became much stronger, and more similar to the natural gastric juice. Struve, with phosphoric acid and CRIT. REV. Vol. 4. April, 1805.
volatile alkali, made a liquor which produced an effect similar to the gastric juice on aliments.
The bile, considered as a necessary stimulus to the intestines, keeping up their energy and peristaltic_motion, and thereby facilitating digestion, according to Dr. Saunders, contains: 1. Water impregnated with the odorous principle: 2. A mucilaginous substance, resembling the albumen: 3. A resinous substance containing the colouring principle and bitter taste: and 4. The mild mineral alkali. The combination of the bitter resin with the alkali, he supposes, forms the saponaceous matter. Fourcroy calls it a biliary or real animal soap. Our author here offers his own opinion, and considers it, with Galen and Paracelsus, merely an excrement.
If I may be permitted to hazard a conjecture upon the use of the bile, and the viscus that secretes it, it would appear, as Fourcroy has well observed, that the liver has a great connection with the Jungs, not only from the facts already mentioned, but from the large size of this viscus in the fetus which has not yet respired; and that whatever action the bile may have upon the food, or on the intestines in digestion, there is reason to believe that the liver deprives the blood which passes through it of some of its noxious parts, performing an excrementitious operation in the abdomen, whilst the lungs are acting to the same end in the thorax. This appears probable, not only from the large size of the liver in those animals of limited respiration, but even the extent of this viscus in man and quadrupeds, which is by far the most voluminous gland in the body, indicates, that its action must be of greater extent than that of furnishing a mere secretion. All the glands form their secretions from the blood in its most perfect state, or as it circulates through the arteries; whilst, on the contrary, the liver makes use of the inpure venous blood, supplied by the vena porta; which blood has been said by some, although denied by others, to be in a state of greater fluidity, and to have a putrescent tendency, so as scarcely or not at all to be coagulated; or in other words, possessing a superabundance of soda, which preserves its fluidity, and of carbon and hydrogen, which give it a dark colour. If this be the case, it is probable, that as this blood circulates through the liver, this viscus deprives it of hydrogen and carbon, which, united to a little oxygen, form an oily matter, and meeting with the soda, a saponaceous substance is produced, which forms the principal character of the bile. Hence arises the necessity of this fluid being made with constancy and regularity, for the integrity of all the functions; and the reason of its existing in all animals, and of its being as necessary as the evacuation of the lungs during respiration. In those animals whose respiratory organs are very small in comparison to their body, and where the carbon and hydrogen must be in large quantity in their blood from the want of proper evacuation, the liver is remarkably capacious and great in proportion, by which means these substances are evacuated in the form of bile, the act of respiration being incon
venient to their mode of life. It is by such means that these two viscera assist each other. To this opinion of its being an excre mentitious matter, may be added several other properties of a like nature, viz. its nauseous and disgusting smell and taste.
It appears from the experiments of Fourcroy, that the oily part of the bile is nearly in the state of spermaceti, preserving its fluidity during a state of health. When, however, this matter is too abundant to remain in solution in the bile, it becomes crystallized, forming the calculi of the gall bladder, or gall stones, which, on analysis, evidently appear to owe their formation to this oily concrescible matter; and this matter being contained either in the pores or parenchymatous substance of the liver, often proves the source of several of its diseases.' P. 234-5.
Dr. Johnson concludes, that whatever may be the functions of the liver, and use of the bile, many experiments are necessary before any satisfactory proof can be had: and that the liver fulfils an operation, the whole of which science has not embraced.'
Saliva, tears, nàsal mucus, pus (scrofulous, venereal, cancerous and hospital-sore), synovia, sperma virile, humor à vesicatorio, humor hydrops, and the liquor amnii, complete the catalogue of fluids, in which we find no mention of the humors of the eye, so inestimably important to the animal economy. This omission is the more extraordinary, as ample information on the analysis of these humors is to be found in Plenck's Hygrology, which our author has oftener quoted than read. Nor has Dr. Johnson, though a mere historian, rarely or never ventur ing his own opinion of facts, paid any more attention to the wax of the ear, or that unctuous, ceraceous matter found in the meatus auditorius externus.
The examination of the solids cannot but be highly interesting to the experimentalist, as it presents him with a vast field unexplored by any of his predecessors. It is in this point of view that the history and actual state of any science may be useful. The desultory and incoherent speculations that are here offered on the muscle or flesh of a few animals; liver of the skate, brain, skin, and process of tanning membranous, tendinous, and ligamentous parts, with the art of making glue and isinglass;'-evince the imperfection of our analytical (as well as synthetical) knowledge of the constituent parts of animal bodies. Notwithstanding the author's partiality to the labours of Fourcroy and the French chemists, he is indebted to the excellent experiments of Mr. Hatchett on the muscular fibre, for all that is worthy attention on the solids.
Synovia, or the liquor of the joints, by the analysis of Marqueron gave parts of phosphat of lime; by that of Hatchett only
We have a detailed account of Seguin's method of tanning, which, though generally abandoned in France, might yet with attention facilitate the improvement of that art. The germ, however, of Seguin's discovery is to be found in the experiments of Macbride. This account is rendered interesting by Mr. Biggin's table of the relative quantities of the tanning principle in the different barks, most of which are superior to that of the oak.
Hard and external parts'-bones, horns, shells, zoophytes : hair, wool, feathers, silk, &c. are yet far from being accurately analyzed, and still farther from being elucidated by the confused medley of experiments and opinions here introduced. According to Mr. Hatchett, bones neither contain alumen nor magnesia, but are composed of two earthy neutral salts, a large quantity of phosphat of lime, a small proportion of sulphat of lime, some carbonat of lime, and gelatin. Merat-Guillot found 100 parts of hard bones from the church-yard contain 16 gelatin: 67 phosphat of lime: 1.5 carbonat of lime: loss 15-5: and common dry bones, 23 gelatin: 63 phosphat of lime: 2 carbonat of lime: 2 loss. The original and accurate experiments of Mr. Hatchett on these subjects stand unrivalled. The feathers of geese are said to be preferable to those of other fowls for beds, being less disposed to felt.
The second volume opens with an examination of the animal oils, soaps, and acids, which is in a great measure but a repetition (sometimes a contradiction) of the experiments detailed in the first. In the actual state of our chemical knowledge of acids, we should have expected to see some attempt at classification, either by their quantities, affinities, the strength of their acidifying principles, or by some generic character that would have relieved the memory, and avoided the disgusting tautology of the present chaos. We shall extract our author's observations on the nature of corpulency, as a fair specimen of his manner of compiling, and also a proof of the alarming progress of modern empiricism.
According to the theses of Dr. Beddoes, whenever there is a certain diminution of oxygen in the animal system, fat will be produced. The following observations, according to Coindet, seem to support this assertion. The chemical analysis of fat shows, that six parts of it contain nearly five of carbon, and one of hydrogen, and some sebacic acid. The fat parts of animals only differ from
* Taken from that scientific work, Nicholson's Journal.
† A Spanish chemist has discovered a process of making soap, by adding farinaceous matter to the alkaline lye and oil, which forms a soap that in the course of a year will double its original weight by absorption from the atmosphere. REV.