Chemical Science. 



395 



Experiments five, six, seven, eight, and nine correspond closely 

 with two, three, four, and five of the last table, and show that, at the 

 comparative temperature, iron in this form, as well as in plate, pro- 

 duces 1 Ib. of steam for 9 Ibs. of metal. 



By a third series of experiments, with cast-iron, it was found that, 

 at the comparable temperature, it could generate more steam than 

 wrought-iron, 8 Ibs. nearly being sufficient to produce 1 Ib. of 

 steam. This effect is, perhaps, attributable to a difference in the 

 specific heat of the two substances, which may well exist, considering 

 the difference of their composition*. 



2. DISCHARGE OF LIGHTNING OVER A LARGE SURFACE. 



The following interesting electrical account is given by Mr. 

 Bryant, clerk in the State Prison at Charles Town, Massachusetts : 

 * Yesterday,' July 30, 1829, 'we had a severe shock of lightning at 

 the prison. It rained in torrents, and a dense mass of highly- 

 charged clouds spent their embosomed electricity on and about us. 

 I was looking out of my office window to discover the direction in 

 which the clouds were moving, when a flash, accompanied by a 

 rustling noise like that of small shot thrown upon stiff paper, and 

 a feeling as if all the energy of my muscles was at once withdrawn, 

 and an almost insuperable inclination to fall back on the floor, con- 

 vinced me that I had been struck with lightning. But I only 

 tottered back a few steps, and recovered myself immediately. On 

 leaving my office to inquire what mischief had been done, I learned 

 of the officers that almost all of them, as well as many of the con- 

 victs, had been affected like myself. My office is in the brick build- 

 ing directly south, and in front of the prison, about three hundred 

 and sixty yards from the north wall of the prison yard. Between 

 the office and the prison building is a large yard, perhaps one lum- 



* Silliman's Journal, xix. 292. 



