Intelligence and Miscellaneous Articles, 149 



One half of a wheat field was manured with sulphate of ammonia, 

 at the rate of 1^ cwt. to the acre, and at a cost of 1/. 2s., the other 

 half with the ordinary manure ; the latter produced only 23|hushels, 

 but the former under the treatment of sulphate of ammonia produced 

 32| bushels. In the discussion that ensued, in which Prof. Graham, 

 Mr. Cooper and many members took part, the advantages of the 

 system were confirmed, and the necessity for its extension insisted 

 upon. The various modes of purifying gas, and the value of tiie pro- 

 ducts obtained for agricultural purposes, were canvassed at length. 

 It was stated that seeds steeped for forty hours in a solution of one 

 pound of sulphate of ammonia to one gallon of water, sown in un- 

 manured land, produced a heavy crop, and remained green during a 

 dry season, when every other kind of vegetation became yellow and 

 withered. Another remarkable feature was, that faded flowers, when 

 plunged in a weak solution of sulphate of ammonia, were in a short 

 time restored, and that plants watered with it attained extraordi- 

 nary health and beauty. The great loss resulting from the leak- 

 age of the gas through the joints and the pores of the cast iron pipes, 

 was incidentally mentioned, and it was stated that in some instances 

 it had amounted to from 25 to 75 per cent, of the total quantity 

 produced. 



XXIII. Intelligence and Miscellatieons Articles, 



ANALYSIS OF A PORCELAIN CLAY DISCOVERED AT HOWTH, NEAR 

 DUBLIN. BY ROBERT MALLET, ESQ. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 



I BEG to transmit you the results of my analysis of a porcelain clay 

 discovered some years ago by me at Howth, near Dublin, and since 

 extensively brought into use for the manufacture of crucibles. The 

 clay is found upon the southern side of the peninsula of Howth, which 

 consists principally of quartz rock ; it exists in large concretionary 

 masses or highly irregular beds, and appears to have reached its pre- 

 sent position by the transport of water. It is found of every degree 

 of fineness, from a coarse gritty mass of decomposing pebbles, with 

 occasional large nodules of friable felspar, to that of an impalpable 

 colourless clay, like that of Dorsetshire, known as pipeclay : this is 

 soft, ductile, adheres to the tongue, and forms a strongly adhesive 

 and plastic mass with water, capable of being moulded upon the 

 potter's wheel into the finest forms. 



It bakes perfectly white, or occasionally of the slightest possible 

 rosy tint of white ; some of the masses of this mineral are strongly 

 discoloured by iron and manganese, and imbedded in the finer parts 

 are occasionally found a few fragments of marine shells and bits of 

 wood. 



By washing with abundance of water, a fine quartzose sand is se- 

 parable from even the finest portions of this clay ; this sand is white, 

 but water separates from it a little sand of a darker colour, like 



