In the preceding six paragraphs, on which it would be easy to 

 enlarge, I have explained sufficiently, that the execution of a 

 phjrto-chemic analysis is one of those operations, the just perform- 

 ance of wliich demands in a high degree circumspectness and 

 accm'acy. But the real value of such work is only obtained, when 

 the necessary chemical elementary knowledge is previously gained ; 

 and as sixch I must designate the complete theoretical and prac- 

 tical acquaintance with the qualitative and quantitative inorganic 

 analysis, with the principal laboratary operations, with the charac- 

 teristics of the most important groups of organic bodies, and with 

 their elementary analysis. He, who undertakes a phyto-chemic 

 analysis without being furnished with these treasui'es of knowledge, 

 enters helpless the field of research, and has, irrespective of loss of 

 time and means, no chance of results, while he may introduce 

 dubious or incorrect data into science. Ancient phyto-chemic 

 analysts have sometimes in these respects committed themselves 

 enormously; but the modei-n operators ought not on that account 

 to relax, but ought to remember, that we are justified in de- 

 manding from them something better than from their predecessors, 

 and that perhaps the limits of their own exertions may in not too 

 distant a time be considerably surpassed. At all events, the 

 endeavours of the chemical worker must be incessantly dii-ected 

 towards the goal of perfection, and in this spirit I shall welcome 

 also every contribution to the improvement of this work. 



