183 



the loss sustained is ^vater. 2d, Put the sample then in a wine glass 

 and pour hot water over it — stir it well for two minutes, then allow it to 

 settle — then pour off the liquid carefully — add hot water again, and 

 proceed as before — then pour a small qantity of muriatic or nitric acid 

 into the ^lass; the acid will dissolve all the undissolved salts, and noth- 

 ing will remain of the guano hwi pure sand — wash this dry and weigh 

 it, the quantity of sand in the sample will be thus ascertained. 



3d. Take a fresh sample of guano, weigh it and place it in an evap- 

 orating basin, and heat it over a spirit lamp so long as the fumes are 

 given oft', and the guano appears black ; weigh it again, deduct the 

 water from the volatized portion, and the remainder of the loss consists 

 of ammoniacal salts; the smaller the quantity remaining in the basin 

 the better is the guano. The admixture of saio dust will be detected 

 by the second test, as it will float on the water in the glass. By these 

 simple tests the farmer will be enabled to 2>'f'ove the quality of guano 

 and detect imposition. 



GYPSUM OR PLASTER OF PARIS. 



This valuable manure is found in large quantities in Michigan. It is 

 much used through various parts of America, as a top dressing for clo- 

 ver, wheat, and also for old meadows. Gypsum is sometimes called 

 plaster of paris, from its abounding in the quarries of Montmartre, nea? 

 the French Metropolis. It is found in New Brunswick and Nova Sco- 

 tia, and large quarries of it have been opened at Grand Rapids in this 

 State. In its crystalized form, it is sometimes called "Selenite." 100 

 pounds of gypsum consists of 



Sulphuric Acid, - - - 46 lbs. 



Lime, 33 lbs. 



Water, _ 21 lbs. 



100 



It dissolves with difficulty in water, and requires 500 times its own 

 weight to effect its solution ; by burning it is reduced in weight, the 

 water being driven oft", and it is then easily reduced to powder, which is 

 perfectly white, and much used in stucco, cement, etc. 



On soils which contain all the other ingredients necessary to supply 

 the food of plants, except srdphate of lime, gypsum has a powerful ef- 

 fect, particularly if applied to clover, or any of the leguminous crops. 



