vi A UTHORS PREFA CE. 



of one hundred dissertations or communications published by 

 myself or by my scholars. 



Comparatively few chemists will have learnt, as I have done, 

 that nothing can tend so much to the end aimed at as increased 

 activity in this much-neglected branch of chemistry ; and it was 

 the hope of stimulating young chemists to steady, persevering 

 work in testing the methods now placed before them, and devis- 

 ing better ones, that finally decided me. I doubt the possibility 

 of making, without assistance, such progress as I think necessary; 

 and I trust, therefore, that the publication of this little work will 

 be followed by an increase in the number of my fellow-workers. 



As will be explained in the introduction, I have endeavoured 

 to construct a method that shall comprise at once both the qualita- 

 tive and the quantitative, micro- as well as macro-chemical 

 analysis of plants and their constituents. All widely distributed 

 vegetable substances are to be included, the detection of rarer 

 ones facilitated, and the method so arranged that other principles 

 not hitherto observed shall, if present, attract the attention of the 

 investigator. 



An exhaustive treatise on all the known constituents of plants 

 would naturally have obscured the method of examination. This 

 result I have endeavoured to avoid by compressing the method 

 of examination proper (Part I.) into the smallest possible limits ; 

 and by following it up with further observations (Part II.) on the 

 characters, etc., of the substances there mentioned. Numerous 

 notes and a systematic, as well as alphabetical, index will guard 

 the reader from confusion. 



I have been compelled to restrict myself to the treatment of 

 the more important constituents of plants, that is, those that are 

 of importance to the plant itself, or that play an important part 

 in its economical application. The extracts in which rarer or 

 less important substances are to be looked for have been pointed 

 out, but it has been left for the reader himself to gain further 

 information about them from other sources. Numerous refer- 

 ences will aid him in his search, and also direct his attention to a 

 number of analyses that may be of service to him in modifying or 

 extending the process here recommended. 



