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 — 



POISO:t^!! 



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; 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 sui^pose 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 

 encasements are easily made of end-blocks connected by longitudinal 

 silats, as in Plate XXXV, Fig. 4<x, 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. 



