CHEMISTRY. 



147 



VJiemical 

 Examina- 

 tion of 

 Nature. 



Mucus of 

 the nose. 



Liquor of 

 the peri- 

 cardium. 



Ii proper- 

 ties. 



1. Water. 4. Soda. 



2. Mucus. 5. Phosphate of lime. 



3. Muriate of soda. 6. Phosphate of soda. 



The saline parts amount only to about 0.01 of the 

 whole, or probably not so much. 



2. The mucus of the nose has also been examined by 

 Fourcroy and Vauquelin. They found it composed of 

 precisely the same ingredients with .the tears. As this 

 fluid is more exposed to the action of the air than the 

 tears, in most cases its mucilage has undergone less or 

 more of that change which is the consequence of the ab- 

 sorption of oxygen. Hence the reason of the greater 

 viscidity and consistence of the mucus of the nose; hence 

 also the great consistence which it acquires during colds, 

 where the action of the atmosphere is assisted by the in- 

 creased action of the parts. 



3. As to the mucus which lubricates the alimentary 

 canal, the trachea, the bronchi's, the urethra, and all the 

 different cavities of the bjdy, nobody has hitherto sub- 

 jected it to analysis, because it cannot be obtained in suf- 

 ficient quantity. It is viscid, and no doubt contains 

 a mucilaginous substance, similar to that contained in the 

 saliva, the tears, and the mucus of the nose ; as, like 

 these liquids, it is liable to become much more thick by 

 exposure to the air. 



SECT. XV. Liquor of the Pericardium. 



This is a liquor which lubricates the heart. It has 

 been lately examined by Dr Bostock, having; been ob- 

 tained from the pericardium of a boy who had died sud- 

 denly. 



It had the colour and appearance of the serum of the 

 blood. Evaporated to dryness, it left a residue amount- 

 ing to -^th of its weight. When exposed to the heat of 

 boiling water, it became opakc and thready. It was co- 

 piously precipitated by oxymuriate of mercury before, 

 boiling ; but when boiled, evaporated to dryness, and re- 

 dissolved, the solution was not affected by oxymuriate 

 of mercury. These experiments show us that it con- 

 tained albumen. When saturated with oxymuriate of 

 mercury, infusion of galls produced no effect, indicating 

 the absence of gelatine. It was copiously precipitated 

 by neutral acetate of lead, even after being boiled to dry- 

 ness, and the residue re-dissolved in water. Nitrate of 

 silver indicated the presence of muriatic acid. Dr Bog- 

 tuck, from his experiments, considers it composed of 



Water 92.0 



Albumen 5.5 



Mucus 2.0 



Muriate of soda 0.5 



100.0 



SECT. XVI. Of the Humours of the Eye. 



Humour* Thc . e 7 e is one of tlle most delicate and complicated 

 f the eye. o r g an8 in the body ; at the same time its structure, and 

 the uses of its parts, are better understood than almost 

 any of the other innrumenis of sensation. It is compo- 

 sed of several concentric coats, which have not been che- 

 mically examined; but, fromthet-xperimentsof Hatchett 

 on similar substances, we may consider it as probable that 

 th.-y po-sess the properties of coagulated albumen. The 

 internal part of the e)e is chiefly tilled with three trans- 

 parent substances, which have been called humours by 

 anatomist*; namely, 1. The aqueous humour, immediate- 

 ly behind the cornea; 2. The crystuUvic humour, or 



Examina- 

 tion of 

 Nature. 



OompoH- 

 tion. 



lens ; and, 3. The otlreans humour, behind the lens, and 

 occupying the greatest part of the eye. 



1. The aqueous humour of the eye of the sheep is a 

 clear transparent liquid like water, which has very little 

 smell or taste when fresh. Its specific gravity is 1.0090 

 at the temperature of 60. It appears to be water slight- 

 ly impregnated with the following substances : 



1. Albumen. 2. Gelatine. 3. Muriate of soda. 



2. The vitreous matter possesses the very same proper- 

 ties as the aqueous ; even its specific gravity is the same, 

 or only a very little greater. 



3. The crystalline lens is solid : densest in the centre, 

 and becoming less solid towards the circumference. It 

 is composed of concentric coats, and is transparent. Its 

 specific gravity is 1 . 1000. When fresh, it has little taste. 

 It putrefies very rapidly. 



It is almost completely soluble in water. The solu- 

 tion is partly coagulated by heat, and gives a copious 

 precipitate with tannin, both before the coagulation and 

 after it. It gives no traces of muriatic acid. Hence it 

 is composed of albumen and gelatine united to water. 

 According to Nicholas, the quantity of gelatine dimi- 

 nishes as we approach the centre of the lens, where it is 

 very small. He detected phosphate of lime likev/ise in 

 every part of the lens. 



The humours of the human eye are composed of the 

 same ingredients as those of the sheep ; the only percep- 

 tible difference consists in their specific gravity. The 

 specific gravity of the human aqueous and vitreous hu- 

 mours is 1.0053 ; that of the crystalline 1.0790. 



The humours of the eyes of oxen resemble those of 

 the sheep in their composition. The specific gravity of 

 the aqueous and vitreous humours is 1.0088 ; that of the 

 crystalline 1.0765. 



SECT. XVII. OfSinovia. 



Within the capsular ligament of the different joints of Sinovia. 

 the body there is contained a peculiar liquid, intended 

 evidently to lubricate the parts, and to facilitate their 

 motion. This liquid is known among anatomists by the 

 name of sinofia. 



The sinovia of the ox, when it has just flowed from t ts proper- 

 the joint, is a viscid scmitransparent fluid, of a greenish ties, 

 white colour, and a smell not unlike frog-spawn. It very 

 soon acquires the consistence of jelly ; and this happens 

 equally whether it be kept in a cold or a hot temperature, 

 whether it be exposed to the air or excluded from it. 

 This consistence does not continue long ; the sinovia soon 

 recovers again its fluidity, and at the same time deposites 

 a thready-Tike matter. 



Sinovia mixes readily with water, and imparts to that 

 liquid a great deal of viscidity. The mixture froths when 

 agitated ; becomes milky when .boiled, and deposites some 

 pellicles on the sides of the dish ; but its viscidity is not 

 diminished. 



When alcohol is ponred into sinovia, a white substance 

 precipitates, which has all the properties of albumen. 

 One hundred parts of sinovia contain 4.52 of albumen. 

 The liquid still continues as viscid as ever s but if acetic 

 acid be poured kito it, the viscidity disappears altogether, 

 the liquid becomes transparent, and depositi-s a quantity 

 of matter in white threads, which possesses the following 

 properties : 1. It has the colour, smell, taste, and elasti- 

 city of vegetable gluten. 2. It is soluble in concentra- 

 ted acids and pure alkalies. 3. It is soluble in cold wa- 

 ter ; the solution froths. Acids and alcohol precipitate 

 the fibrous matter in flakes. One hundred parts of sino- 

 via contain 11.86 of this matter. 



