114 ON HYDRARGYRUM CUM CRETA. 
in contact with the glass, had the proper bluish color, 
characteristic of the preparation, whilst the upper disturbed 
portion, and indeed the whole mass excepting the part 
alluded to had a light reddish tinge, such as would be pro- 
duced by incorporating a small portion of burnt umber with 
white lead. The idea at once occurred that some unknown 
circumstances had caused the per oxidation of the mercury, 
and should this be true, the inordinate effects of the prepa- 
ration noticed above, would be satisfactorily accounted for. 
That thissupposition was correct let the following investiga- 
tion witness, viz. 
1st. One hundred grains of the specimen of mercury with 
chalk was placed in a vial, an excess of aqueous hydrocy- 
anic acid added, and the mixture shaken occasionally for 
ten hours. The whole was then thrown on a filter, the 
undissolved portion lixiviated and the clear filtrate evapo- 
rated in a capsule, until evidences of crystallization were 
manifest around the edges of the liquid, when the vessel 
was set aside. In half an hour the mother liquid was de- 
canted from a mass of brilliant acicular crystals, weighing, 
with that contained in the mother liquid, subsequently iso- 
lated, more than 26 grains. These crystals were color- 
less, had a strong metallic taste like corrosive sublimate, 
and when dissolved in dilute muriatic acid the odor of 
hydrocyanic acid was observable. Several grains of these 
crystals were placed in a sealed tube, the open end drawn 
out to a fine open point and the closed end containing the 
saline matter heated to redness, whilst a lighted taper was 
held at the orifice. Soon a jet of purple flame was seen 
issuing from the tube, whilst the interior surface of the tube 
beyond the heated end was coated with globules of mer- 
cury, thus completing the chain of evidence that the crys- 
talline matter is bicyanuret of mercury, which could only 
have been formed by deutoxide of mercury in the hydrarg. 
cum creta. 
2. Sixty grains of the cretaceous mercurial powder was 
boiled in distilled water acidulated with muriatic acid until 
