366 Report on a re-examination of the 



hence to determine their amount is an important point in agricul- 

 tural chemistry. And the differences which are so obvious in 

 soils derived from different rocks, do not depend entirely upon 

 the different proportions of the earths which they contain. For 

 the quantity and nature of the salts resulting from the decompo- 

 sition of rocks are considerably different. Thus we should ex- 

 pect, that the gneiss and granite soils would contain a larger 

 amount than usual of the salts of potassa, and where sulphuret 

 of iron prevails, of the salts of iron ; the porphyry soils, of the 

 salts of soda ; the graywacke and sandstone soils, of the salts of 

 lime, magnesia, and perhaps potassa and soda ; the mica slate 

 soils, of the salts of magnesia and potassa ; the talcose slate soil, 

 of the salts of magnesia : or perhaps more commonly we should 

 find the lime and magnesia uncomhined with an acid,' (we do 

 not perceive how this can be.) 



' Such differences as these in the constituents of soil, will un- 

 questionably affect their fertility ; and it would be desirable to 

 ascertain how far they exist in the soils of Massachusetts. I had 

 hoped to accomplish this object ; but it will require a great num- 

 ber of delicate and accurate analyses, demanding far more time 

 than has yet been allowed me. As will be seen in the sequel, I 

 have attempted to determine the amount of the salts of lime in 

 all the soils that I have collected ; but it will need comparative 

 trials by the ordinary modes of analysis before the peculiar char- 

 acteristics of the different classes of our soil can be pointed out ,• 

 and besides I have made no attempt to determine the existence 

 and amount of potassa and soda in my specimens.' p. 27. 



Prof H. next proceeds to the developement of a new method of 

 analysis derived from Dr. Samuel L. Dana of Lowell, Mass., and 

 which Prof H. regards as a most important contribution to agri- 

 cultural chemistry. The account is prefaced by the following 

 remarks from Dr. D. 



•'' Geine forms the basis of all the nourishing part of all vegetable manures. The 

 relations of soils to heat and moisture depend chiefly on geine. It is in fact, under 

 its three states of ' vegetable extract, geine, and carbonaceous mould,' the principle 

 which gives fertility to soils long after the action of common manures has ceased. 

 In these three states it is essentially the same. The experiments of Saussure have 

 long ago proved that air and moisture convert insoluble into soluble geine. Of all 

 the problems to be solved by agricultural chemistry, none is of so great practical 

 importance as the determination of the quantity of soluble and insoluble geine in 

 soils. This is a question of much higher importance than the nature and propor- 

 tions of the earthy constituents and soluble salts of soils. It lies at the foundation 



