256 REPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 
injurious or objectionable than Paris green, other arsenical poisons, 
hellebore, &c, which are in common use. The sulphuric acid should 
be labeled — 
POISON ! ! 
SULPHURIC 
ACID. 
In case it gets upon clothing it burns a hole through, and should be 
treated quickly with bicarbonate of soda, hartshorn, or soap. When 
upon the skin the same may be applied or it can be washed off quickly 
by water, but if by accident it be drunk, avoid taking water, but swallow 
quickly either raw eggs, any albuminous substances, carbonate of mag- 
nesia, of calcium, of potassium, or of soda ; also, chalk, soap, or whiting in 
milk may answer 5 but finally in all cases oil should be taken in full dose. 
The acid ought never to be left in a vessel such as a child or grown person 
might suppose to contain water or some beverage; also a card bearing all 
the above instructions ought to be given with each vessel containing the 
acid, and be always carried with, but not in contact with, the vessel or 
the acid which would destroy it. The materials for generators are pref- 
erably glass or lead, substances which are not impaired by the acid. 
Glass is liable to breakage, but very stout glass may be used and it is 
more satisfactory to be able to see the interior readily to observe the action 
and quantities of the substances within, and especially the amount of 
acid being poured. To render the glass less likely to break, each vessel is 
protected by a frame to deaden the impact of any blows it may receive. 
The vessel is guarded as lanterns are by a metallic frame, or as coal- 
oil cans are now made of glass with corrugated sheet-metal cages, as 
carboys are by a net-work of cordage, as demijohns are by wicker- 
work, though preferably of a more open character. But simple wooden 
enoesements are easily made of end-blocks connected by longitudinal 
stlats, as in Plate XXXV, Pig. 4«, or otherwise. When either vessel or 
chamber is made of metal it is preferably a lead cylinder, tube, bottle, 
or can. Although any metallic acid receptacle is necessarily of lead, 
that for the generator is kept alkaline by the excess of bicarbonate in 
it, so it corrodes far less and endures a long time of whatever metal it 
be composed. There are several ways in which the apparatus is made 
of metal, and some of these must be noticed briefly. A good metallic 
chamber as acid bottle or generator, or both, is made of a cylinder or 
section of pipe constructed to open at one or both ends by a plug or 
cap. A screw-cap is generally preferable. Beneath it a packing ring 
or plate may be clamped. This, if iron be used, will keep the acid 
from eating the screw-thread and the other thick parts of the iron en- 
dure a long time. The cap is perforated by a tube, or tubes, to com- 
municate with the other vessel or vessels. 
