313 



III. — Tbeatment with Alcohol. 



Rettu'ii tlie substance, exhausted by ether, to the dry flask 

 used before, pour on it as much alcohol of 95°/^ as will cover the 

 well-soaked substance one-half to one inch high, secure the flask with 

 a cork, perforated lengthwise by a canal of about 1 millimeter in 

 width, digest for three days at a temperature not exceeding 70°, 

 let stand cold for one day, transfer the contents to a displacement 

 apparatus, and wash thoroughly with alcohol of the same strength. 

 But, should the alcohol have formed a deposit on the top of the sub- 

 stance, after having been kept cold for one day, then the flask 

 must be warmed for half-an-hour before filtering and the washing 

 is performed also with warm alcohol. 



The contents of the displacement apparatus, after being washed, 

 are spread out thinly in a shallow porcelain-dish and dried, at last 

 with a very gentle heat. Weigh the substance, after it has been 

 left cold for one day, determine the amount of hygroscopic water 

 of a sample of 2 or 5 grams and calculate from this the weight 

 of the whole substance in the dry state. The latter valvie deducted 

 from that found under II, represents the weight of the portion 

 dissolved by alcohol. 



Concentrate the solution under addition of the alcohol, vised 

 for washing the insoluble part, by evaporation in a weighed 

 beaker at the open air, and finally at a gentle heat. Larger quan- 

 tities, consisting of more than half a litre, are distilled in a retort 

 until seven-eighths have passed over. Then pour the remnant into a 

 beaker, rinse the retort a few times with a little alcohol, and gently 

 heat the solution. Mix the residue, after the odour of the alcohol 

 has almost disappeared, with 10 grams water, heat until the 

 last traces of alcohol are driven ofi", and let cool. 



The contents of the beaker will now consist of a liquid and of a 

 sediment, which in some cases may be very slight or even wanting 

 altogether. Before separating the solid from the liquid portion, 

 try if an addition of more Avater will produce any turbidity. If 

 this should be the case — which generally takes place in the 

 presence of much resinous matter — the liquid must be mixed with 

 an equal volume of water, warmed for a few minutes and left to 

 cool. It is afterwards tried again with more water, and, if it 

 becomes turbid again, the same process is rejieated as before, and 

 so on, until a liquid be obtained which remains clear by mixing 

 with water. The liquid, together with the whole sediment, is now 

 brought on a weighed filter, washed thoroughly with cold water, 

 and left to dry; while the solution is examined as follows: — 



Ä. — Examination of the aqueous solution of the alcoholic extract. 

 Try the united filtrates in regard to taste, odour, colour, &c., 

 and reaction towards litmus-paper, evaporate a small sample to a 



