Manurial f/vjjej-iics of Ci ay from Gas-Works. 307 



save upon some slightly risings parts, near which I understand 

 two or three drains were inserted some years aso. Tlie spring of 

 1855 v.as exceedingly dry, and the field was generally very brown 

 on the 1st of Alay, wlien I cut excellent green succulent grass 6i 

 inches in length from the plot to which the new manure was 

 applied. In the winter of 1855-6 the same farmer dressed the 

 whole of the meadow, and obtained so remarkable a crop, that 

 the field became a place of resort and surprise to most of the 

 small farmers in the neighbourhood. Upon the rising portions 

 the grass was laid like corn, and was so thick that it was rotting 

 in the bottom when mown. The aftergrass was sold for 30s. 

 per acre to an adjacent farmer, named Harrison, who keeps 

 much stock, and who informed me that he never saw sheep and 

 cattle thrive faster than they did upon that aftergrass. A larger 

 quantity could not have been produced upon the land. 



Some instructive facts were noted during the use of this 

 manure upon grass, which seem to show that plants take up 

 their food in the same state as that in which it is presented to 

 them ; and that, like animals, they may be gorged to repletion 

 and die of excess of food, which they are unable to assimilate. 

 A blue compound of cyanogen and iron, analogous to Prussian 

 blue, has been mentioned as existing in the saturated clay in 

 considerable quantitv. AVhen a plot of broccoli was manured 

 with the manure which tlie gardener at the Wakefield Union 

 Workhouse had ol)tained from the gas-works, I was surprised to 

 see the plants grow well and yet gradually become blue. The 

 colour was quite different from the blue of stagnation from 

 drought and poverty, which is often seen in cabbages ; and the 

 fact of these broccoli plants growing vigorously while they 

 gradually became more and more blue, negatived the supposition 

 that here was notliing but a familiar phenomenon. Feeling 

 much interest, 1 watched the matter closely, and was amused at 

 length to see the whole become as blue as if the leaves had been 

 painted. The fragments of the gas refuse lying upon the sur- 

 face among the plants showed the origin of the colour, and the 

 question to be solved was, is this temporary or permanent? 

 Will the absorbed substance prove food or poison? A short 

 time showed that, though taken up in its integrity, decomposi- 

 tion was proceeding, and in about a fortnight the blue had 

 changed to that dark luxurious green which always accompanies 

 an abundant supply of salts of ammonia. This brought to mind 

 some experiments on celery, in which the like taking up of more 

 manure than could be assimilated was accompanied with rapid 

 growth and apparently perfect health. In one case, common 

 salt was applied in enormous quantity in a wet season, and during 

 any dry intervals tlie plants were freely watered. So much salt 



