on Mosquito Extermination. 29 



For the benefit of those who may not have read Dr. How- 

 ard's paper on this subject, I quote as follows: 



"Before performing the operation the house must be 

 vacated, and it is well to do this just before nightfall. It is 

 not necessary to remove any of the furniture or household 

 belongings unless of polished nickel or brass, which may 

 tarnish a little. Liquid or moist foods, as milk or other larder 

 supplies that are not dry and might absorb the gas, should 

 be removed from the house. All fires should be put out, for 

 v»'hile the gas will not burn under ordinary conditions, it is as 

 well to take no risks. 



On the floor of each room should be placed a large porce- 

 lain wash basin, and into each wash basin should be poured 

 the proportionate amount of water and sulphuric acid. It may 

 be well to place under each wash basin a thick layer of news- 

 papers, in order to avoid damage to carpet or rugs by the 

 possible spattering of the acid acting upon the cyanide. All 

 windows must be closed, and if they are not tight they should 

 be calked wnth thin paper or cotton batting. Then tbe operator, 

 beginning at the top of the house, drops the proportionate 

 amount of cyanide of potassium, previously weighed out into 

 thin paper sacks, into each washbowl, running rapidly from 

 room to room and instantly closing the door behind him, 

 descending ultimately to the ground floor or even to the 

 cellar, running finally into the open air through the open door, 

 which is instantly closed. 



Hydrocyanic acid gas is lighter than air and consequently 

 rises. Therefore, the operation must be begun at the top of 

 the house. The next morning the operator returns to the 

 house, opens the last door, allows a certain amount of airing ; 

 then enters hurriedly and opens the windows of the first room or 

 floor ; then, after the thorough airing of this one, another in 

 turn, thus gradually airing the whole house. The fumes quickly 

 overcome and are fatal to human beings ; hence the necessity 

 for the utmost care and greatest speed in the initial operation 

 and in the subsequent airing, and the undesirability of per- 

 forming the experiment alone. The house should not be re- 

 inhabited until all trace of the odor of the gas has disappeared. 

 This odor resembles that of peach kernels." 



Dr. Fernando Lopez, of Mexico, at a recent meeting of the 

 American Public Health Association, presented a paper on the 



