32 SUBSTANCES SOLUBLE IN ET HEIL 



alloAv the solvent to act at the ordinary temperature. Some 

 instances of special estimations may be excepted in which separate 

 portions of the material may be extracted warm. 



After allowing the maceration with ether to proceed for about 

 eight days, the first estimation to be made is that of the total 

 substances dissolved, which may be effected by evaporating 

 an aliquot part, or the whole of the extract, in a flat-bottomed 

 glass dish. I usually employ a measured quantity of ether, say 

 5 to 10 cc, for every gram of substance under examination, 

 macerate in a well-closed flask, and replace any ether that may 

 have been lost by evaporation dui'ing the process. After well 

 shaking I take a certain number of cc. of the clear or (cf. § 9) 

 filtered liquid for evaporation. The residue must be dried at 

 100" to 110°, till the weight is constant, and this then noted. 

 It should be ascertained whether any fatty matter which has 

 escaped extraction with petroleum spirit is mixed with the residue, 

 and if this is the case it should, if possible, be removed by wash- 

 ing with the latter liquid, its weight noted, added to the amount 

 found in § 9, and subtracted from the substances dissolved by 

 ether. It must also be borne in mind that all fats are not neces- 

 sarily soluble in petroleum spirit. It is well-known that castor oil 

 forms clear mixtures with certain, but not all proportions of that 

 solvent.^ 



The remainder of the ethereal extract is filtered from the 

 residual powder, the latter washed, and extract and washings 

 allowed to evaporate at the ordinary temperature. The residue 

 of the substance is freed from ether at the same temperature as 

 speedily as possible. 



§ .37. Chlorophyll. — The ethereal extract may also be tested 

 before evaporation for chlorophyll, as described in §§ 20, 132, et seq. 

 I have already observed that this substance is more easily and 

 completely removed by ether than by petroleum spirit. 



§ 38. Portion Soluble in JFafer. — That part of the ethereal 

 extract which has been evaporated at the ordinary temperature 

 may, if possible, be powdered or brought into as fine a state of 

 division as practicable by triturating with washed sand or pure 

 siliceous earth (Kieselgvhr), and treated with cold water. In the 

 aqueous solution substances solul)le in water, such as hcerriatoxylhiy 

 gallic acid, caieclnn, pjrocatccliin, salicylic acid, benzoic acid, 

 1 Jahrb. f. riiarm. 1876, p. 369 (Ye.ar-book Pharm. 1876, p. 356). 



