As evidence of the accuracy of the method, I subjoin the results I obtained on a sample whose gangue was free from all organic and other impurities, consisting chiefly of quartz: 

New Method.  Combustion in Oxygen, Weighing CO_{2}.
  15.51 15.54

It is plain that such a result leaves nothing to be desired for the accuracy of the method, while, as regards time and trouble, the advantage lies on the side of the new method.  I have completed a determination in less than two hours from the start, and did not hurry myself over it in any degree.

Fine pulverization of the sample is not essential, and in fact is rather detrimental, as the graphite, when fine, is more difficult to wash without loss.  When operating on a coarse sample more time is necessarily taken, but the resulting graphite shows the manner of occurrence better, whether in scales or in the amorphous form.

In consulting the literature bearing on the subject, I cannot find any mention of this method employed as an analytical process; it has, however, been previously described as a commercial method for the purification of graphite,[1] and I understand has been tried on a small scale in this country.  The method, though inexpensive, yet seems to have been abandoned for some reason, and I am not aware that it is now employed anywhere.—­Sch.  Mines Quarterly.

[Footnote 1:  Schloffel, Zeitschrift der K.K. geolog.  Reichanstalt, 1866, p. 126.]

* * * * *

SULPHOCYANIDE OF POTASSIUM.

The elements of cyanogen, combined with sulphur, form a salt radical, sulphocyanogen, C_{2}NS_{2}, which is expressed by the symbol Csy.  The sulphocyanide of potassium, KCsy, is prepared by fusing ferrocyanide of potassium, deprived of its water of crystallization, intimately mixed with half its weight of sulphur and 17 parts of carbonate of potassa.  The molten mass, after having cooled, is exhausted with water, the solution evaporated to dryness, and extracted with alcohol, from which the crystals of the salt are separated by evaporation.

It is also made by melting the ferrocyanide of potassium with sulphide of potassium.  It is a white, crystallizable salt of a taste resembling that of niter, soluble in water and alcohol, and extremely poisonous.  It dissolves the chlorides, iodides, and bromides of silver, is, therefore, a fixing agent, but has not come in general use as such.  Vogel speaks highly of it as an addition to the positive toning bath, although he prefers the analogous ammonium salt in the following formula: 

Chloride of gold solution.... (1:50) 3 c. cm. (46-1/5 grains).  Sulphocyanide of ammonium ... 20 grammes (308 grains).  Water........100 c. cm. (3 ounces 5 drachms 40 grains).

Ferrocyanide of Potassium—­K_{2}Cfy+3HO, or K_{2}C_{8}N_{3}Fe+3HO, is generally known by the name of yellow prussiate of potassa.  It contains ferrocyanogen, a compound radical, consisting of 1 eq. of metallic iron and 3 eq. of the elements of cyanogen, and is designated by the symbol Cfy.