solution was obtained, which contained a liberal amount of free sul- 

 phuric acid, besides a considerable quantity of the combination of 

 tliis acid with lime (gypsum), and with oxide of iron (green cop- 

 peras) . The presence of these compounds was evidently due to the 

 action of air and of moisture on iron pyrites — a combination of 

 sulphur and iron — contained in the rocks and the soils through which 

 the water percolated which fills the muck-bed. 



Wells located in rocks containing iron pyrites are apt to show a 

 similar alteration in their character during the earlier part of the 

 spring after a dry summer and autumn, when in consequence of a 

 lower level of the water sup[)ly a more extensive exposure of adjoin- 

 ing rocks have favored the oxidation of both iron and sulphur. This 

 change may assume such proportions at times that the water of these 

 wells will curdle fresh milk, and produce a more or less iuklike 

 abstract of green tea. 



A repeated pumping out in most instances removes the cause of 

 these reactions. An actual .observation in this direction at Amherst 

 a few years ago, after several years of dry seasons, furnished a strik- 

 ing illustration of the previous statement. 



A muck like No. III. is decidedly injurious to vegetation, and 

 needs an exceptionally large addition of lime or ashes, and a h)uger 

 exposure to the air than the average material of this kind, to prepare 

 it for manurial purposes. 



319-320. FERTILIZING MATERIALS. 



The materials are evidently mixtures of refuse from various 

 sources, and contain large quantities of insoluble matter. No. 319 

 is worth from $7 to $8 per ton, and No. 320 from $2.50 to $3. 



321. REFUSE LIME. 



Sent on for examination from Lowell, Mass. 

 Moisture at 100° C, 33.54 per cent. 



Phosphoric acid, 1.62 " 



Magnesium oxide, 8.30 " 



Calcium oxide, 40.57 " 



Insoluble matter, 0.40 " 



