HARDWICKE' S SCIENCE-GOSSIP. 



3 



states that it " resembles cows', except in its greater 

 consistence ; like that, milk, it throws up abundance 

 of cream, from which butter is easily obtained." Its 

 cheese was solid and elastic ; its general charac- 

 teristic, a richness only equalled by that of the ewe's 

 milk. 



Howard (vol. ii. p. 1066) writes of domestic goats : 

 li They are recommended to lie among horses, their 

 smell, as is supposed, preventing many diseases 

 in those animals. The blood of the he-goat, dried, 

 has been recommended for the pleurisy and inflam- 

 matory disorders." The celebrated Dr. Mead, in his 

 treatment for pleurisy, prescribed, " for dissolving 

 the sizy blood that obstructs the small canals, wild 

 goat's blood and volatile salts." 



The diacopraegire were preparations of goat's dung, 

 but for what purposes they were administered, and 

 what were their reputed qualifications therefor, I am 

 as yet unaware. 



The suet of goats, and perhaps the hair and horns 

 likewise, were also made available by the faculty. 

 The bezoar of the domestic goat shall be treated of 

 under the head of the Bezoar-goat. 



Chamois. — This all but inaccessible animal subject 

 was still, as the provider of" shamoy leather," made 

 to pay his slight tribute to the tyrant surgeon. The 

 use of this material will be best illustrated by the 

 incidental mention made of it in treatments quoted 

 elsewhere. 



The chamois-stone is deserving of separate mention. 

 This stone, alias the German bezoar (writes Howard, 

 vol. i. p, 333), " is called by some cow's egg, said to be 

 found in the stomach of cows, but more frequently in 

 that of the chamois or wild goat. These are sup- 

 posed to be caused by the hair of those creatures, 

 which they lick off by the tongue, and, being 

 swallowed clown and impregnated with the saliva, 

 etc., is condensed into balls. Some of them weigh 

 eighteen ounces, and, though used in some medicines, 

 are not much esteemed. 



EXPANSION OF AIR BY HEAT. 



THE expansibility or distension of solids, fluids, 

 and gases by heat is a very extensive physical 

 law, although generally unobserved, and is of the 

 greatest importance in chemistry. Examples of the 

 expansion of air by heat are very numerous ; the 

 following are some of the more simple processes of 

 this kind, which I have found will illustrate this law 

 as plainly as possible. 



A small stoppered bottle of two or three cubic 

 inch capacity, is to be filled with pure air (at a low 

 temperature), which may be practically done by the 

 application of the lips to the mouth of the bottle, so 

 that one half only of it is covered (the other part 

 remaining open), and the air drawn out by suction ; 

 its volume is then replaced by external air drawn in 



through the remaining aperture to supply its place. 

 This being done, the stopper can be wetted and 

 loosely replaced. The bottle should now be tightly 

 held in the warm hand, and the stopper will then be 

 seen to pop up two or three times, emitting a jet 

 of expanded air each time. If under the same 

 circumstances, the stopper, instead of being loosely 

 replaced, is a little tightened, it will completely jump 

 out by the application of the heat as above. Now if 

 oxygen, or hydrogen gas (both of which are very 



Fig. 1.— A glass bulb immersed in hot water with a piece 

 of wet membrane over its mouth, blown out by the 

 dilation of the contained ■air. 



Fig. 2. — A glass vessel after being immersed in boiling 

 water. The air has been reduced to less than half its 

 volume, as shown by the contained fluid. 



combustible) is substituted for common air, the 

 same experiment repeated, and an ignited match 

 held over the stopper, each jet of gas will produce a 

 small blue flame. 



A second simple method is to take a thin glass 

 bottle, loosely tie a thin piece of caoutchouc, or wetted 

 membrane over the mouth, and then immerse it in 

 water at the temperature of ebullition (ioo° C), the 

 membrane will bulge out, and ultimately burst if it 

 be very thin (Fig. 1). On the other hand, if the 



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