PHARMACY. 



The excise officers in this country collect 

 the duties paid by spirituous liquors, by 

 estimating the proportion which they 

 contain of a standard spirit, about 0.933 

 in specific gravity, which they call hy- 

 drometer proof, and they express the re- 

 lation which spirits of a different strength 

 have to the standard spirit, by saying 1 that 

 they are above or under hydrometer 

 proof. Thus one in six, or one in seven, 

 below hydrometer proof means that it is 

 equal in strength to a mixture of six parts 

 of proof spirit with one of water. 



The only other mode of expressing 

 specific gravities which it is necessai*y to 

 notice is 'that of Baume's areometer, as it 

 is often used in the writings of the French 

 chemists, and is little understood in this 

 country. For substances heavier than 

 water he assumes the specific gravity of 

 distilled water as zero, and graduates the 

 stem of his instrument downwards, each 

 degree being- supposed by him to ex- 

 press the number of parts of muriate of 

 soda contained in a given solution, which 

 however is not at all the case. For sub- 

 stances lighter than water the tube is 

 graduated upwards, and this zero is af- 

 forded by a solution of 10 of salt in 90 

 water. 



Mechanical Division. By this process 

 substances are reduced to a form better 

 adapted for medical purposes; and by the 

 increase of their surface their action is 

 promoted, both as medical and chemical 

 agents. It is performed by cutting, bruis- 

 ing, grinding, grating, rasping, filing, 

 pulverization, trituration, and granulation, 

 by means of machinery or of proper in- 

 struments. 



Pulverization is the first of these ope- 

 rations that is commonly employed in the 

 apothecary's shop. It is performed by 

 means of pestles and mortars. The bot- 

 tom of the mortars should be concave ; 

 and their sides should neither be so in- 

 clined, as not to allow the substances ope- 

 rated on to fall to the bottom between 

 each stroke of the pestle, nor so perpen- 

 dicular as to collect it too much toge- 

 ther, and to retard the operation. The 

 materials of which the pestles and mor- 

 tars are formed should resist both the 

 mechanical and chemical action of the 

 substances for which they are used, 

 Wood, iron, marble, siliceous stones, 

 porcelain, and glass, are all employed : 

 but copper, and metals containing cop- 

 per, are to be avoided. They should be 

 provided with covers, to prevent the finest 

 and lightest parts from escaping, and to 



defend the operator from the effects of 

 disagreeable or noxious substances. But 

 these ends are more complete!) attained 

 by ty'mg a piece of pliable leather round 

 the "p ( - st 'e and round the mouth of the 

 mortar. It must be closely applied, and 

 ut the same time so large, as to permit 

 the free motion of the pestle. In tcme 

 instances it will be even necessary for the 

 operator to cover his mouth and nostrils 

 with a wet cloth, and to stand wiin his 

 back to a current of air, that the very 

 acrid particles which arise may be carried 

 from him. The addition of a little water 

 or spirit of wine, or of a few almonds, to 

 very light and dry substances, will pre- 

 vent their flying off. But almonds are 

 apt to induce rancidity, and powders are 

 always injured by the drying which is 

 necessary when they have been moisten- 

 ed. Water must never be added to sub- 

 stances which absorb it, or are rendered 

 cohesive by it. 



All vegetable substances must be pre- 

 viously dried. Resins and gummy resins, 

 which become soft in summer, must be 

 powdered in very cold weather, and must 

 be beaten gently, or they will be convert- 

 ed into a paste instead of being powder- 

 ed. Wood, roots, barks, horn, bone, ivory, 

 &c. must be previously cut, split, chipped, 

 or rasped. Fibrous woods and roots 

 should be finely shaved after their bark 

 is removed, for otherwise their powders 

 will be full of hair-like filaments, winch 

 can scarcely be separated. Some sub- 

 stances will even require to be moistened 

 with mucilage of tragacanth, or of starch, 

 and then dried before they can be pow- 

 dered. Camphor may be conveniently 

 powdered by the addition of a little spirit 

 of wine, or almond oil. The emulsive 

 seeds cannot be reduced to powder un- 

 less some dry powder be added to them. 

 To aromatic oily substances sugar is the 

 best addition. AH impurities and inert 

 parts having been previously separated, 

 the operation must be continued and re- 

 peated upon vegetable substances till no 

 residuum is left. The powders obtained 

 at different times must then be intimately 

 mixed together, so as to bring the whole 

 to a state of perfect uniformity. 



Very hard stony substances must be re- 

 peatedly heated to a red heat, and then 

 suddenly quenched in cold v/ater, until 

 they become sufficiently friable. Some 

 metals may be powdered hot in a healed 

 iron mortar, or may be rendered brittle by 

 alloying them with a little mercury. 



Tiititratton is intended for the still more 



