TRANSACTIONS OF SECTION B. 



313 



mineral constituents of the water are, iron — calcium, magnesium, in the form of 

 sulphates. 



This water when heated quickly throws down a copious ochreous deposit. The 

 deposit found in the engine boilers after having used the water in them for steam 

 purposes was of the composition given below. 



The boiler residue from which this sample was taken, consisted of an in- 

 crustation about one inch thick, which had adhered to the bottom of the boiler. 



The incrustation was of a light reddish yellow colour in the bulk, it was very 

 hard and tough, and not easily broken in pieces. 



The iron work in connection with this colliery engine and boilers, in any way 

 exposed to the action of either the acid water itself, or the steam generated from it, 

 becomes corroded and partially dissolved. The most effectual remedy against this 

 corrosive action and deposit, is that described in my letter to the Chemical News, 

 June 15, 1877. 



Analysis of Boiler Deposit, from Wortley Silkstone Colliery Boilers, Sep- 

 tember 15, 1875. 



Moisture ; 6-85 per cent. 



Combined water, organic matter, &c. . 5*80 „ „ 



Silicious matter 1-80 „ „ 



Per-oxide or iron and alumina con-"\ fi ,„ 



taining phosphoric acid 0-76 per cent. ./ " " 



Sulphate of lime 78 - 55 „ „ 



Magnesia 0-65 „ „ 



99-75 



Some curious balls of mineral matter are occasionally found in the feed tank of 

 the colliery boilers, which are supplied with this water. The water is pumped up 

 from the engine pond into a cylindrical feed tank, and is there heated by the 

 exhaust steam from the engine playing on its surface (not blowing through it). 

 The water in this feed tank has an average temperature of 164° F. 



It sometimes happens that during the short space of even two or three weeks, 

 great numbers of these balls are formed, varying in size from about three and a half 

 inches in diameter to five-eighths of an inch diameter, and in weight from about 

 one and a half pound to a quarter of an ounce. 



The author has many of these in his possession. They are perfectly hard and 

 compact when taken from the tank, and are no doubt formed from the deposit 

 thrown down when the mineral water is heated. 



The action of steam playing on the surface of the water probably causes circular 

 eddies, and when a nucleus has thus once been formed, it is easy to conceive of the 

 gradual formation and consolidation of these balls. 



The author suggests that the conditions of formation of natural nodules of iron 

 ore, pyrolusite, &c, may be similar to those observed by him in the foregoing cases. 



The following is the analysis of the balls formed in the feed tank, from which 

 it will be seen that they are quite different in composition to the residue deposited 

 in the boilers, owing probably to the difference in the temperature between the feed 

 tank and the boiler. 



Analysis of a Concretion Ball, found in the Engine Feed Tank. Wortley Silkstone 



Colliery. 



Moisture 2-30 per cent. 



Loss on ignition, organic matter, &c., 



contains matters extracted by ether, 



5-8 per cent. . 

 Silica 



Per-oxide of iron 

 Alumina . 

 Phosphoric acid 

 Lime 

 Magnesia .... . trace 



■}' 



24-10 



1-80 



62-86 



5-43 



2-81 

 0-40 



100-00 



