274 



B. — Drying Apparatus. 



Freshly-gathered plants or parts of plants are freed from 

 adhering impurities, as earth, sand, or dust, by beating, dusting, or 

 quickly washing with water. Thick roots, stems, branches, or 

 fleshy fruits, are first split or cut into pieces of a proper size, and 

 afterwards spread on wooden sieves, previously covered with 

 printing paper, and thus exposed on warm days to the action 

 of the air and the diffused sunlight, or, if the temperature should 

 be below 10°, they are dried by artificial heat not exceeding 40°, 

 but carefully screened from steam and smoke. The drying is 

 finished, and the so treated substance called air-dried, when it does 

 no longer incur loss of weight. 



With the exception of certain succulent fruits, which on drying 

 undergo a partial decomposition, all vegetable substances are 

 submitted to analysis aii'-dried. 



To estimate the water still retained by the air-dried material, a 

 small sample of the latter is properly comminuted as described 

 under C, and intimately mixed. Two to five grams of the 

 substance thus treated are then put into a platinum crucible, 

 and the latter iilaced into an air-hath made of copper, and 

 provided with a thermometer. The whole apparatus is now 

 heated to a temperature of 110° to 120° by means of a small 

 spii-it (or gas) lamp. (For particulars see Div. III., 1.) 



Vegetable substances in the natural state less than those educts, 

 obtained in the course of the analysis, and which, on account of 

 their liability to decompose under the influence of heat, atmo- 

 spheric air, or moisture, cannot be dried in the air-bath, must have 

 the last traces of water removed under the jar of the air-pump 

 with the simultaneous application of watex'-absoi'bing substances, 

 such as quicklime, fused chloride of calcium or concentrated s\il- 

 phuric acid, any of which are placed close to the substance in 

 question, under the receiver of the air-pump. 



C. — Comminuting Apparatus. 



Thick or woody roots, stems or large branches, are at first thinly 

 split with an axe; the single pieces are then cut up transversely 

 on the cutting-hoard and separated by means of a sieve of ivire 

 gauze, with apertures not larger than one-sixth of an inch; the 

 coarser parts are further comminuted in the stamping-hox by 

 means of cross-knives provided with a long handle, and again 

 passed through the sieve. To reduce vegetable parts of this kind 

 to a still finer or powdery state, will generally require much time 

 and labour, but this is essential for a satisfactory final result. 

 Often the operation is greatly facilitated by successively exposing 

 the substance to a gentle heat and then pounding it in a metal mortar. 



