VEGETAliLE M a:> .. .w..-. I ^J5 



Ten opinions given ; unanimously, no. 3(1, Will it supply the 

 place of organic manure? or, will a barren soil be converted 

 into a fertile soil by the use of it? Seven answers given; 

 unanimously, no. 4th, Does gypsum sensibly increase the 

 crops of the Cereals ? Of 32 opinions, 30 are negative, and 

 2 affirmative." 



259. Gypsum may be applied either in the burned or 

 unbumed state, the only change produced by buniing it being 

 the expulsion of the water which it contains. It is sparingly 

 soluble in water, and is usually applied as a top-dressing in 

 calm, moist weather; and its effects are said to be more 

 apparent when the white powdered gypsum adheres to the 

 leaves and stalks of the young gi-asses (Mr. C. Johnson). It 

 is said that its presence in the soil causes the seeds of 

 peas and beans to become hard, so that they are not 

 easily boiled. As this mineral manm-e exists in considerable 

 quantity in the north of Ireland, and can be obtained from 

 England at a very cheap rate, it should receive more attention 

 in this countiy. 



260. The refuse lime of the gas-works has lately been em- 

 ployed as a manure, in the neighbourhood of towns where esta- 

 blishments for the manufacture of gas exist. From a half to 

 two-thirds of its weight usually consists of carbonate of lime, 

 and it also contains variable proportions of caustic lime, gypsum, 

 coal-tar, and compounds of sulphur. It may be interesting to 

 mention the purpose for which so much lime is used in the 

 gas-works. When coal is distilled, along with the illuminating 

 gas produced, certain volatile bodies are also evolved, which, 

 as they would interfere with its purity, it is necessary to re- 

 move ; thus carbonic acid gas (24) and ammonia, and the disa- 

 greeable smellmg gas, sulphuretted hydrogen, are given off {set 

 page 57). The manufacturer, however, by passing the mixetl 

 gases over slaked lime, is enabled to detain the carbonic acid 

 and sulphuretted hydrogen, and, as it were, sifts the illumi- 

 nating gas from these impurities. The compounds of sulphur 

 and lime which are produced, dissolve in water, and exercise 

 an injurious effect upon plants; but, by exposure to the air, 

 these salts are converted into gypsum, and are thus rendered 

 nsefol applications to the soil; so that if gas-lime is to be 

 used as manure, this precaution should always be adopted. 

 It has been used, with great advantage, in the neigh bourhooi' 

 of '' ''' ' made into a compost with weeds, the seeds (•' 



