284 APPENDIX TO PART I. 



convert the contents of 1 gallon of gas liquor into sulphate 

 of ammonia, and accordingly, 50 gallons will require 70 

 lbs. of gypsum, and will produce about 60 lbs. of the am- 

 moniacal sulphate. 



**Now since the price per ton of gypsum is from 2Z. to 

 3/., the cost of 70 lbs. of it cannot exceed 2«., and the 

 labor of mixing the materials may be reckoned at about as 

 much more ; so that to a gas company, where this liquor, 

 not being employed for manufacturing any of the salts of 

 ammonia, has hitherto been regarded as so much refuse, 

 and where the heat requisite for evaporating and crystal- 

 lizing the product can be obtained with scarcely any in- 

 creased expenditure, the cost of the impure sulphate would 

 not exceed one penny per pound. 



'* This then is less than half the cost of an equal quantity 

 of nitrate of soda, which at its present price (23s. per 

 cwt.) may be reckoned at two-pence-halfpenny a pound, 

 and yet it may be shown, that a given weight of sulphate 

 of ammonia contains more ammonia, and consequently 

 ought to yield more nitrogen, than nitrate of soda."^ 



" Sulphate of ammonia 75 pis. contain of ammonia 17 = nitrogen 14, 



whilst 

 Nitrate of soda .... 86 pts 17= 14. 



"So far as theory goes, therefore, the balance would 

 seem to be in favor of the efficiency of sulphate of am- 

 monia over nitrate of soda, in the proportion of 15 to 86. 



"These considerations are merely offered, by way of 

 encouragement to those who may be disposed to make trial 

 of this promising kind of manure, and of course will go 

 for little until they have been tested by experiment. 



"There are other materials also employed as manure, 

 which appear to owe their efficacy to the presence of am- 

 monia, — such, for example, as soot, which contains a con- 

 siderable proportion of this principle united with carbonic 

 acid, and which accordingly has for a long time been ad- 

 vantageously employed as a top-dressing to land. 



"Lastly, the foregoing considerations point out the de- 

 cided superiority of human to other sorts of animal manure. 



" Independently of its being richer in most of those in- 

 gredients on which the fertilizing property of manure de- 

 pends, the following circumstance gives it an advantage. 



" * Nitrate of potass ought to contain ten per cent, less nitric acid 

 than nitrate of soda, but, as it is a less deliquescent salt, the difference 

 between the two, as obtained in commerce, is not very considerable." 



