C1IKMISTKY. 



113 



ward it takes fire. If ground, however, after 

 nit interval of tluvo day-, tli.-ri! is no percvpti- 

 liU- rUo ot' temp. r:itur.-. r'n>m ;i leriea of ex- 

 piM-im.-nts ma.lu by Mr. lliir^iviivi-s, it wmiM 

 app.-ar t!i:it rhaivoal roiitimu-s to absorb oxy- 

 tfi-n l..r thirty-six hours after it has been burnt, 

 and tho full amount of hygroscopic moisture is 

 mily attained after exposure to the air for about 

 two weeks. 



<on in Colored Tapers. The presence 

 of poisonous coloring-matters in green and 

 ivtl \\ a\ tapers has been proved by Mr. James 

 MfFarlane. Green tapers owe their color to 

 arsonito of copper (Soheele's green). The allia- 

 ceous odor evolved during the combustion of 

 th-.'si- tapors left no doubt as to the presence 

 of ur^-iiu 1 . The quantity was estimated to 

 be 0.60 per cent., equal to 0.35 gramme of 

 arsenious acid in each 2-gramme taper quite 

 enough to poison two people if taken directly 

 in the solid form. The red tapers weighed, 

 on the average, 8.94 grammes, and the ash, 

 weighing 3 milligrammes, was totally devoid 

 of metallic appearance. Mercury, existing as 

 \vrmilion, was found by Reiusch's process, and 

 its quantity was carefully determined. The 

 amount of mercuric sulphide ultimately col- 

 lected, washed, and dried, was 1.66 per cent. 

 White, yellow, and blue tapers were found to 

 he harmless, the blue being colored with ultra- 

 marine, and the yellow with chromate of lead. 

 Silicon in Pig-iron. Having observed that 

 silica, instead of silicon, is obtained in the in- 

 soluble residue when pig-iron containing a 

 large quantity of silicon is dissolved by dilute 

 sulphuric acid, E. Ilandfield Morton, of the 

 London Chemical Society, was led to call in 

 question the received theory of the silicon 

 being intimately mixed with the pig-iron. 



To determine this point he made a number of ex- 

 periments with a No, 1 Bessemer iron, containing 

 4.612 per cent, of silicon. Weighed quantities of 

 this pig-iron were placed in sealed, tubes with Nord- 

 hausen sulphuric acid, in atmospheres of carbon di- 

 oxide and hydrogen, and also in vacuo ; the tubes 

 were then heated in an air-bath by two Bunseu burn- 

 ers fpr twenty-four hours, but in every case the sili- 

 con contained in the pig-iron had been converted 

 into silica, and a small quantity of sulphur dioxide 

 found in the tube, which occasioned sufficient press- 

 ure to blow the top off the tube when cracked with 

 a file. On examining the insoluble residue from 

 these experiments, under the microscope, perfectly 

 transparent crystals of silica were observed, inter- 

 spersed with opaque pieces of the same substance. 

 When these insoluble residues were treated with hy- 

 drofluoric acid, complete solution was effected. The 

 next attempt to isolate the silicon in this pig-iron 

 was made by heating weighed quantities of the latter 

 with an excess of pure iodine in sealed tubes, all air 

 being first displaced by carbon dioxide ; the same 

 heating arrangement being used as in the sulphuric- 

 acid experiments. At the end of twenty-four hours, 

 all iodine-vapor having disappeared, one of the tubes 

 was opened and the contents analyzed, with the fol- 

 lowing results : 



Iodine 7B.432 per cent 



Iron 20.013 " " 



Silica 1.709 " 



Carbon 0.759 " 



Total 98.918 



VOL. xiv. 8 A 



Directly the tube was crocked, the preMure of gat 

 blew tho top off. The content* coiitutod of dull-red 

 lumps, the whole of the iron having been converted 



into tho furrous iodido, at the above figure* corre- 

 spond to the formula, K.I,. There can be little doubt 

 but that the silica which wan formed in thui experi- 

 ment was duo to a blight decomposition of the car* 

 bon dioxide, with which tho tube was filled ; the 

 greatest part of the silicon having been converted, in 

 ull probability, into an iodine compound; for, al- 

 though iodine-vapor is without action upon silicon 

 under ordinary conditions, it is highly probable that, 

 when silicon in the nascent state is presented to 

 iodine-vapor, a compound of iodine and silicon may 

 be formed. These results were confirmed by several 

 other similar experiments. This pig-iron was also 

 carefully tested for graphitoidal silicon, by treating 

 the iron with hydrofluoric acid : the insoluble residue 

 was filtered off, and ignited to get rid of the carbon, 

 when a mere trace of a dark powder remained, which 

 proved to be iron. 



From these results it may fairly be concluded that 

 the silicon contained in pig-iron does not exist in a 

 state of mechanical mixture, but exists combined 

 with a portion of the iron as a cilicide of iron, in the 

 same manner that carbon exists as a carbide of iron, 

 only differing from carbon in so far that it does not 

 exist in a graphitoidal form in pig-iron. If the pig- 

 iron used had contained any unoombined silicon, it 

 would have been found in the insoluble residue from 

 the experiments with Nordhausen sulphuric acid and 

 hydrofluoric acid, as it is insoluble in even the latter 

 acid atter having been strongly heated ; and, as any 

 uncombined silicon must have been heated intensely 

 in the blast-furnace, there can be little doubt that, 

 as a rule, pig-iron does not contain any uncombined 

 silicon. 



The author then experimented to ascertain 

 whether or no the supposition of the combina- 

 tion of the silicon with the iron was correct, 

 and the result proved a confirmation of his hy- 

 pothesis. Experiments with white pig-iron 

 gave identical results. 



New Method of separating Calcium from 

 Magnesium. For the complete separation of 

 these two substances, which, by the ordinary 

 method, is a very difficult operation, E. Son- 

 stadt proposes the following process : 



In the course of recent experiments on theiodates, 

 I have found that iodate or calcium is not sensibly 

 soluble in a saturated solution of iodate of potassium, 

 whereas iodate of magnesium is not precipitated 

 from solution in any degree by iodate of potassium. 

 If to 10 or 12 c.o. of a saturated solution of iodate 

 of potassium a lew drops are added of solution of 

 sulphate of calcium, and after two hours the liquid 

 is filtered, and oxalate of ammonium added to the 

 filtrate, a slight opalescence appears after a while, 

 due to the presence of a trace of calcium. But if 

 the iodate of potassium solution to which the cal- 

 cium salt was added is allowed to stand twenty 

 hours, and is then filtered, and oxalate of ammonium 

 added to the filtrate, not the slightest opalescence 

 appears even after many hours. A slight crystalli- 

 zation takes place, owing to a diminution of the solu- 

 bility of the iodate of potassium by the presence of 

 oxalate of ammonium, out the crystals entirely dis- 

 appear, leaving the solution perfectly limpid, on ad- 

 dition of a very small proportion of water. The 

 precipitation of calcium by saturation of the solu- 

 tion with iodate of potassium does not appear to be 

 affected by the presence of alkali and magnesium 

 salts, in whatever proportion those may be present. 

 If. for instance, a small quantity, as a decigramme, 

 of ordinary Epsom salts is dissolved in the least 

 possible quantity of water, and four or five timeaiU 

 bulk of a saturated, solution of iodate of potasaittm 



