Intelligence and Miscellaneous Articles. 71 



prevent the precipitation of the iron by ammonia, which was then 

 added in considerable excess, and a current of SH passed through 

 the solution for several hours. The solution was then allowed to 

 stand in a warm place until it had become of a clear light yellow 

 colour, when it was quickly filtered and washed with water con- 

 taining a little hydrosulphate of ammonia. The solution was then 

 evaporated to dryness, the ammoniacal salts driven off by ignition, 

 and the residue, consisting of phosphoric acid, with minute portions 

 of lime, alumina and alkalies, fused with a little carbonate of potash 

 and soda. [This fusion sometimes required repeating once or twice 

 before the whole of the phosphoric acid was detached as tribasic 

 alkaline phosphates.] The PO^ was then determined in the usual 

 manner as the ammonio-phosphate of magnesia. 



Determination of Carbon. — The iron was reduced to a moderately 

 fine powder by being turned in a lathe. A still finer powder was 

 obtained from this by sifting through lawn. About 30 or 40 grs. 

 of this were rubbed for a considerable time in an agate mortar along 

 with about its own weight of hard white sand, which had been pre- 

 viously mixed with a little oxide of copper, and ignited to destroy 

 any traces of organic matter. When an almost impalpable powder 

 was thus obtained (care being taken to avoid any loss by rubbing 

 over a sheet of glazed paper), it was mixed with 6 or 8 times its 

 bulk of chromate of lead, and introduced into a combustion-tube, at 

 the extreme point of which a few grains of chlorate of potash had 

 been placed ; the combustion was conducted with the usual precau- 

 tions, and the carbon calculated from the carbonic acid formed, the 

 latter of course being passed through a CaCl tube previous to absorp- 

 tion. Trials were made with the substances remaining in the com- 

 bustion-tube, to ascertain if any trace of carbon remained thei'ein ; 

 but no trace of carbonic acid was obtained by attempted recom- 

 bustion of substances again powdered. 



Nitrogen was sought for in the iron by mixing the powder with 

 soda-lime, &c. ; but none, or only such minute traces of ammonia 

 were obtained as to render it questionable if they might not have been 

 derived from the atmosphere of the laboratory. I append a com- 

 parison of the proportions of phosphorus in the hot and cold blast 

 iron, taken from this and the series of analyses before alluded to. 

 No. V. is generally considered the best in quality for forge iron, 

 Nos. VII. and VIII. being too brittle,this in all probability arising from 

 the different mode in which the carbon is combined. The difference 

 in appearance between these two irons and the others is remarkable, 

 being of a much whiter and finer fracture, with only a few grayish 

 specks in the centre of the "pig.' In No. V. these are much increased, 

 and the colour is of a mottled gray ; in Nos. IV. and III. the colour is 

 still darker. These different appearances can be caused in the same 

 iron simply by altering the time of cooling ; if, for example, when 

 the iron of the gray or mottled kind is running, a portion just set be 

 thrown into cold water, it becomes pi-ecisely similar to No. VII. or VIII. 



