66 Oii the Conversion of Cast-iron Pipes [Jan. 



Dec. 16. — The needle vibrated 15'; wind liigh and squally from 

 the S.W., followed by rain. 



r, . - „ (Between noon of the 1st Nov.) „ „„.t • i 

 Ram fallen < ,, , c ^i i . r. f 2-207 incites. 



I Between noon of the 1st Dec. ^ 



Article V. 



On the Conversion of Cast-iron Pipes into a Substance hearing 

 some resemblance to P Lumbago. By William Henry, M.D. 

 F.R.S. &c. 



I WAS lately requested by a gentleman who resides in the neigh- 

 bourhood of Newcastle-upon-Tyne, to examine the nature of tlie 

 change effected in a cast-iron pipe, placed' in the shaft of a coal 

 mine near that town. In sinking the shaft, it was necessary, as 

 sometimes happens, to put down a airb, or cylinder, of cast-iron, 

 in order to support a bed of quicksand ; and into a suitable opening 

 in this cylinder, the cast-iron pipe, three inches diameter, was 

 bolted by means of ajlanche at its extremity. Its use was to allow 

 an exit to the water and gas, which issued from the stratum of 

 quicksand. 



The fragment of the pipe, with which I was furnished, was of a 

 dark grey colour; its inner surface was smooth and black ; and its 

 outer surface had a thin ochrey incrustation, The usual fracture of 

 cast-iron was exchanged for an earthy one, except near the centre 

 of the mass, where somewhat of the usual texture of cast iron was 

 still visible. It was soft enough to be easily scraped by a knife ; 

 and was readily broken by a slight blow of a hammer. Some parts 

 of it left a black trace on writing paper, but destitute of the lustre 

 which the traces of plumbago exhibit. 



The specific gravity of the specimen was 2*008; and, after being 

 soaked an hour or two in water, it became 2* 1.05. 



Twenty grains of the powdered substance were projected upon 

 200 grains of melted nitre. The combustion was very feeble, 

 compared with that which happens to plumbago under similar cir- 

 cumstances. After washing off the nitre, there remained 14^ 

 grains, which were almost entirely oxide of iron, consisting pro- 

 bably of 1 1'2 iron and 3-3 oxygen. 



A small piece of the pipe, weighing 6^ grains, was passed into a 

 glass tube containing diluted sulphuric acid over mercury. The 

 acid acted very slowly ; and, in eight days, when its etTect seemed 

 to be complete, only half a cubic inch of hydrogen gas was formed. 

 This was only about -'jth of what would have been obtained from 

 the same quan'iity of cast-iron.* There remained a black and 



* A jiitce of plumbago from Bovrowdalc, kept eight dajs in dilute sulphuric 

 acid, tiud evolved no gas. 



