118. CONCLUDING REMARKS. 97 



CONCLUDING REMARKS. 



118. In compiling the foregoing method of analysis, one 

 object that I had in view was to show how, when working upon 

 a small quantity of material, say 30 to 50 grams, an insight into its 

 composition might be gained, so that at least the presence or 

 absence of the more important constituents of plants might be 

 ascertained. T wished to show further how the constituents 

 actually present might be estimated, even if no more than the 

 above-mentioned quantity was available. I had therefore to 

 devise a combination of qualitative and quantitative analysis, and 

 the fact that a considerable number of the same constituents occur 

 in the majority of plants justified me in making the attempt. 



Means have also been indicated by which attention would be 

 drawn to the presence of substances that occur only in single 

 plants or in smaller groups of the vegetable kingdom. In this 

 respect the foregoing method is of course but an introduction, the 

 special application and perfection of which for each separate case 

 must be left to the investigator himself. Processes for the quan- 

 titative estimation of certain substances, and especially such as 

 are of considerable practical importance in medicine, agriculture, 

 etc., have already been recommended, and will be followed by 

 others in the second part of the work. 



119. It must be admitted that many of the proposed methods 

 of detection and estimation cannot boast of the accuracy attain- 

 able in the analysis of some inorganic substances. For this 

 reason I advise beginners to refrain from calculating their analyses, 

 as is frequently done, to the fourth and even fifth place of deci- 

 mals. Such calculations often mislead readers less acquainted 

 with the subject to attach to the separate determinations an im- 

 portance to which they are not entitled. I consider it ample to 

 carry the calculations to the second decimal place. 



To those who ask of what use analyses are, the accuracy of 

 which I have myself this moment questioned, I reply that the 

 object of analyzing a vegetable substance, as for instance ergot, is 

 not so much to ascertain the exact composition of a fungus pro- 

 duced on a certain ear of rye in a certain field, but to obtain 

 information as to the approximate composition of ergot in general, 

 the specimen under examination being taken as a representative 

 of the drug. Attention must be specially drawn to the fact that 



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