125 



writings upon the subject of mineral fertilizers, to note the fact of th© 

 injurious action of caustic magnesia upon vegetation, and in fact the 

 only writer who seems to have recognized it is Sir Humphrey Davy,* 

 who reports experiments upon this subject made by himself, and others 

 made previously by Mr. Tenuant. He explains the injurious efitects 

 upon the theory, since confirmed by experiment, that caustic magnesia 

 in presence of caustic lime absorbs carbonic acid very slowly, and that 

 on this account remaining a longtime in the soil iu the caustic state 

 exerts the deleterious infiueuce noticed in the limes mentioned above. 

 The limes in question were applied to rather light sandy or gravelly soil, 

 but, according to Davy, the same lime might bo applied to heavy soils, con- 

 taining considerable quantity of organic matter with decidedly good re- 

 sults, and that upon light soils, where pure lime is not obtainable, the 

 magnesian limestone should be applied in small quantities. The caus- 

 tic action of the magnesia may in such cases be very materially amelio- 

 rated by a tolerably heavy application of stable-manure. In the local- 

 ity in New Jersey referred to, however, we would advise those farmers 

 who have suti'ered the inconveniences and losses resulting from the use 

 of magnesian limestones to employ the other, even though they may be 

 subjected to greater expense in the matter of transportation. 



It has been suggested that the magnesia combining with water and 

 silica forms a hydraulic cement iu the soil, and that the injurious eifects 

 are due to such a combination. 



This can not, however, be considered a correct theory, since these 

 magnesian limestones have been used upon clay soils and their applica- 

 tion to such soils has no deleterious effects. It would seem that the 

 magnesia reacting upon the silicate of alumina forms a double silicate of 

 alumina and magnesia, thus neutralizing its causticity, and that the 

 injury consequent upon the application of magnesia lime to sandy or 

 gravelly soils is to a large extent due to a deficiency of clay. 



The following are the results' of a sample of dark-colored cranberries 

 from Xew Jersey : 



Moisture 85. 50 



Organic matter 13. 25 



luorgauic matter 0.25 



100. 00 



The inorganic matter contains : 



lusoluble silica 0. 874 



•Soluble silica 2. 5G3 



Lime 2] 710 



Magnesia trace. 



Peroxide of iron 1. 253 



Pbosplioric acid . . = 19. JiOS 



Sulphuric acid 5. 870 



Chlorine 1. 260 



Potassa .' 56.683 



Soda 9.333 



99. 860 



W"- The supplement to the Mark Lane Express for February, 1875, con- 

 tains an interesting paper communicated by Professor Church to the 

 members of the Cirencester Chamber of Agriculture, showing the results 

 of a number of analyses made in the interests of agriculture. The sub- 

 stances analyzed consist principally of fertilizing and feeding mate- 

 rials. One peculiarity in mixed-seed cakes analyzed, which had an 



'Elements of Agricultural Chemistry, London, 1814. 



