302 



on sulphuric and hydrochloric acids, as in their presence the 

 alkaloid would be in combination with any of them. 



If the alkaloid be present in the state of a salt, precipitable by 

 an alkali, and soluble in an excess of the latter, it can only be 

 obtained by cautiously adding of the alkali until the liquid just 

 begins to exhibit an alkaline reaction towards litmus-paper. If, 

 on the contrary, it is precipitated permanently, the same precaution 

 need not be taken, and the alkali may be added in a slight excess. 

 Collect the precipitate, after it has completely subsided, in a filter, 

 wash with water and dry at ordinary temperature or at a very 

 gentle heat. It has to be tested as indicated in the preceding 

 paragraph. 



If the alkaloid be present as a salt and not precipitable by alka- 

 lies, it is most effectually isolated in the following way. Convert 

 the chloride into the sulphate by precipitating its solution with 

 just a sufficient quantity of sulphate of süver, filter off the chloride 

 of silver, mix the filtrate intimately with carbonate of baryta equal 

 in weight to the alkaloid salt employed, digest for one day at 

 ordinary temperature, and filter. If the alkaloid be soluble in 

 water, it will now be j^resent pure in the filtrate ; if it be insoluble 

 in water, it remains in the filter mixed with the sulphate of 

 baryta, from which it may be obtained after drying by means of 

 alcohol. 



Should the alkaloid prove new and unknown, its elementary 

 analysis, determination of atomic weight, and the preparation and 

 examination of some of its salts are required. 



If the material should be insufficient for these experiments, the 

 continuation and conclusion must be defei-red to sections IX. or X., 

 when larger quantities of raw material are taken in hand. 



(b) The substance is non-nitrogenised and is indifferent. It 

 belongs to this category if, besides being non-nitrogenised, it has 

 no acid taste and no or only slightly acid reaction. Test like the 

 substances under a, on its physical properties, behaviour in the 

 heat towards indifferent solvents, to alkalies, to acids, and to tannin. 



Of great importance is treating with dilute sulphuric acid, as 

 it shows if the substance is a ghicosid or not. For this purpose 

 the acid must be diluted with ten times its weight of wateu. 

 Digest the body with it for an hour at a temperature of about 

 100°, and let cool down. If the substance remains undissolved, 

 or if, in consequence of the treatment, a new body is formed, 

 ocular inspection will show if it be the original body or a product 

 of it. The whole must be filtered and the contents of the filter 

 washed until all the acid is removed. From the united filtrates 

 or, should the whole have been dissolved, from the liquid as it is, 

 take a small sample and over-saturate with caustic soda, add a 

 few dro]5S of the alkaline copper solution ; heat and proceed as 

 indicated under A with a resin. 



