Improved apparatus for trapped radical and other studies down to 1.5 K.
This note describes a Dewar system and associated apparatus for trapped free radical and other studies at temperatures down to 1.5 K. Cylindrical and rectangular microwave cavities can be used.
AN OPTICAL CELL FOR USE WITH LIQUID HELIUM
A low temperature cell is described that permits spectral absorption and emission measurements, as well as high energy irradiation of materials held at liquid helium temperatures. The liquid helium capacity of one liter is sufficient for up to 24 hours of continuous operation. Any substance whether it be solid, liquid, or gas at room temperatures can be studied. The all‐metal cell is entirely portable and can be employed with a number of instruments without modification. A sylphon bellows arrangement permits vertical displacement within the cell of the samples under study.
THE IRON-ACETOCARMINE METHOD OF FIXING AND STAINING CHROMOSOMES
A short description of this procedure was given in Vol. 55 of the American Naturalist, pp. 573â€”574. The method has now been used almost daily for five years, and certain improvements have suggested themselves. The solution can be prepared by mixing about equal volumes of glacial acetic acid and water. To this is added powdered carmine in excess. The liquid is then â€ ? just brought to boil, cooled, and decanted. To the red solution there are then added a few drops of a solution of ferric hydrate in 50 per cent. acetic acid, to act as a mordant. The amount of iron varies with different objects. Too much produces a precipitate in a short time. The more