OSTREA EDULIS. 



unjoined, but swimming by one another, where they seemed 

 in a more perfect state, and were judged by Lewenhock to be 

 the animalcules in the roe or melt of the oyster. 



CHEMICAL AND MEDICAL PROPERTIES AND USES. 



The officinal parts of oysters are the SHELLS, Testce Ostrece. 

 The hollow valves are preferred. The shell is composed of 

 carbonate of lime and animal matter, and was at one time 

 supposed to possess peculiar medical properties ; but analysis 

 has shown that the only advantage of these animal carbon- 

 ates of lime over those from the mineral kingdom arises from 

 their containing no admixture of any metallic substance. 



Oyster-shells require to be reduced to an impalpable pow- 

 der before they are fit for medicinal employment, and their 

 preparation in this way constitutes their sole pharmaceutical 

 use. When thus prepared they form TESTA PILEPARATA, 

 Prepared Oyster-shell. Take of oyster-shell a convenient 

 quantity, free it from extraneous matter, wash it with boiling 

 water, and reduce it to powder. Throw this into a large ves- 

 sel of water, stir it, and after a short interval pour off the su- 

 pernatant turbid water into another vessel, and set it apart, 

 that the powder may subside ; lastly, let the water be poured 

 off, and dry the powder. 



Prepared oyster-shell differs from prepared chalk in contain- 

 ing animal matter, which, being very intimately blended with 

 the carbonate of lime, is supposed to render the preparation 

 more acceptable to a delicate stomach. It is given as an 

 antacid in diarrhoea, in doses of from ten to forty grains or 

 more, frequently repeated. A preparation has been intro- 

 duced within a few years, under the name of Castilleri's pow- 

 ders, consisting of sago, salep, and tragacanth, each in pow- 

 der, a drachm, prepared oyster-shell a scruple, and sufficient 

 cochineal to give color to the mixture. A drachm of this is 

 boiled in a pint of milk, and the decoction used ad libitum as 

 a diet in chronic bowel affections. 



The flesh of the oyster furnishes a delicious article of food, 

 and is more digestible in the raw state than when cooked, for 

 the heat employed coagulates and hardens the albumen, and 

 corrugates the fibrine, which are then less easily soluble in the 

 gastric juice, and the heated butter generally used as an ac- 

 companiment adds still more to the indigestibility of the oyster. 



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