PUBLISHER’S PREFACE 
m was the original plan of the author to have 
Bu used as a frontispiece in this work a portrait 
of Mr. D. W. Coquillett, who discovered the 
economic value of hydrocyanic acid gas asan 
insecticide. Mr. Coquillett prefers to be remembered 
by the discovery he made in his experimental and prac- 
tical work with hydrocyanic acid gas. The publishers 
therefore take pleasure in introducing this volume 
with a portrait of the author, who has done so much 
to utilize in a practical way the discovery made by Mr. 
Coquillett. 
ORANGE JUDD COMPANY. 
