1903] Robinson, — Insecticides used at Gray Herbarium 243 
apparently dead when taken out, became active again after two or 
three hours in air and sunshine. It is thus clear that carbon bisul- 
phide fumigation to be effective must be conducted in metal cases. 
Partly for this reason and partly with a view to the improvement 
of the fire precautions at the Gray Herbarium, much thought 
was devoted to the construction of a case for ordinary use in the 
herbarium, which should be at once gas-tight and fireproof. ‘These 
features, which seemed simple enough, proved in combination rather 
difficult to realize, especially in a case which must open and close 
readily. -After the supposed advantages of an all-metal case and a 
wooden case covered outside and in with sheet iron had been carefully 
weighed, sixteen trial cases of the second type were installed about a . 
year ago. The doors, hinged at the side as usual, closed upon a con- 
tinuous soft rubber buffer to render the fitting as air-tight as possible. 
These cases have proved satisfactory for purposes of fumigation, 
although they cannot be regarded as absolutely air-tight, a relatively 
small quantity of the vapor of the sulphide escaping around the doors. 
It is believed that they are also as fire-proof as cases can well be made. 
Unfortunately, however, it has been found impossible to treat the 
tinned sheet-iron covering in any way which does not make the case 
a crude and unsightly object. When, during the spring of the present 
year, it was again necessary to add a block of cases it was decided to 
have them made entirely of sheet steel, the plates of metal, wherever 
they came on the outside, being double with an air space of about five 
eighths of aninch intervening. This feature not only adds, on the well 
known principle of the hollow column, much strength to the structure 
as a whole, but is believed to insure practically as great protection 
against fire as the metal-covered wooden construction. Through 
the generosity of a liberal but anonymous friend of the Gray Herba- 
rium it has been possible to have a trial block of eight such steel 
cases manufactured and recently set up in the main working room. 
They were made by the Art Metal Construction Company of James- 
town, New York, and the Gray Herbarium is much indebted to 
Messrs. Hine and Sullivan, the Boston representatives of the com- 
pany, for their painstaking attention to this new application of their 
methods in steel work. In these cases, as in many safes, the doors 
fit with pressure against a smooth strip of piano felt, making a junction 
which is probably quite as effective as the rubber buffer above men- 
tioned. ‘The cases are handsomely japanned in light gray, are 
