Into the end of one of the ignition tubes thus formed, when it is cool, put one-fourth of a gram of arsenic trioxide, As2O3, using paper to transfer it.
"An Introduction to Chemical Science"
R.P. Williams
If this foil be dried, cut up, put in a reduction-tube, and heated, crystals of arsenious trioxide will be deposited on the cold part of the tube.
"Aids to Forensic Medicine and Toxicology"
W. G. Aitchison Robertson
It has been suggested that if igneous emanations contain free oxygen and sulphur, or sulphur dioxide, it would be expected that as they become cool sulphur trioxide would be formed which would result in the sulphate at suitable temperature.
"The Economic Aspect of Geology"
C. K. Leith