An Attempt to avahjse Silica. S09 



was collected over waler previouslv made use of in several 

 similar experiments with malleable iron and cast iron, in 

 hope thai It would take up less of the evolved gas, being 

 Dreviouslv saturated. Burnt in pure oxvgtn gas, free of 

 carbonic ac.d, over lime water, it produced 07 of a gramme 

 of carbonate of lime which contained 0*305 gr. of carbonic 

 acid, which according to Allen and Pepvs's experiments 

 correspond to o Ob7 of carbon. The solution with muriatic 

 acid lett a gray siliceous powder, which was collected on a 

 weighed filter, and when dried (in a vessel secured from 

 access of air) in a dark red heat weighed 0"355 of a gratnme. 

 Heated to white in an dpen crucible, ii lost 00 2 of a gramme 

 more, and bi came white. When these are added to what 

 was before obtained, the whole quantity of carbon proves 

 to be 0-107 of a gramme, or 3 percent, of the weight of the 

 iron. I oxygenated the solution of iron by boiling it with 

 nitric acid, and precipitated with caustic ; mmonia. The 

 Stroiiglv ignited proci[-iiare weighed 4'71 erammes, cor- 

 responding to 3"266 grammes of iron. When the iron 

 and the c-arbon (.^'SfiG > 0"I07) are added together, we 

 have 3-3 73. The siliceous base will therefore be 0-127 

 gr. These 0-1 27 had produced 0*335 of a gramme of silica, 

 and (>f course hari taken up O'OOS oxygen. The siHca 

 therefore appears to be composed of 38 parts base and 62 

 parts oxygen. This quantity ol oxygen in the silica, although 

 agrerini! well with its insolubility in acids, on applying the 

 rule that the metallic oxides, in proportion to their charge 

 of oxvgen, are less soluble in acids, was unexpectedly grear, 

 and led me to su>^pect that, in the treatment of the gas, 

 sonieihinti might have escaped my notice, and rendered 

 the charge of carbon too high. 



e. Ten grammes of silicated iron of a mixed nature, 

 partlv malleable and partly like cast iron, produced, during 

 a dissolution in concentrated muriatic acid, 163 cubic 

 inches of gas, including the air contained in the vessel. 

 The last portion of gas was expelled by boiling. The wateT 

 had a disagreeable smell, from adherent new formed oil, 

 showing a loss of carbon which could not be calculated. 

 The gas burned in oxvgen gas over lime water yielded 0*782 

 carbonate of lime, corresponding to 0341 carbonic acid, 

 and ()Uij7 carbon. The solution left a white, light, and 

 porous siliceous earth, which after a strong drying weiifhed 

 O'fiOS gr. By itjnitiou it at first blackened, but on con- 

 tinuing, the heat became white, and lost 0-02. I consider 

 two-thirds of ihe loss to be carbon, since the earth before 

 the ignition was without smell and colour, and since the 



oleaginous 



