4 DR. ANGUS SMITH ON THE COMPOSITION 
resin took place. Even after several hours no colour was 
observed. This tube was kept for some days, and along 
the whole of it the rose colour appeared, gradually deep- 
ening for some weeks. 
As it seemed from these experiments to be produced by 
the oxidation of carbolic acid, and as the above method 
was tedious, I heated carbolic acid with caustic soda and 
black oxide of manganese so highly that the carbolic acid 
began to evaporate. In this manner it was formed with 
great rapidity; the melted mass became of a fine iridescent 
appearance ; it was dissolved in water, and after a time, 
the manganate of soda having expended its oxygen, the 
oxide of manganese fell and the rosolic acid remained 
with the soda. The rosolate of soda was then decomposed 
with acid; a large quantity may in this way be procured 
with very little trouble. 
The hypochlorites also cause the formation of a rosolate, 
but the process did not seem to promise so well as the one 
given. 
To ascertain its composition, the resin obtained from 
the lead-salt was dried in a water-bath: it then becomes 
brittle, as Runge states, and may be powdered, but much 
drying destroys it. Many analyses, made at various 
stages of the drying, and too tedious and uninteresting 
to enumerate, showed a gradual rise of carbon in the 
composition and also a loss of hydrogen. The following 
analyses were made with chromate of lead and a stream 
of oxygen. Grains are used as weights : 
Substance, Carbonic acid. Water, 
uF 3.017 7.802 1.661 
2. 3.007 7.795 1.528 
3. 3.861 10.087 2.029 
4, 3.077 7,983 1.565 
These are by per centage : 
18 Il. III. IV. 
Carbon ......... 70.527 70.698 71.256 70.875 
Hydrogen...,.. 6.116 5.646 5.839 5.651 
