Circular 21 - Insecticides and Srfcsidiary Materials 44 
is called lamp black. It has a blue undertone 
and varying amounts of oily matter, and is 
used in paints, varnishes, and printers ink 
and as a filler for rubber, etc. 
The cost of lamp black is from 2.7 to 
3.B cents per pound in carload lots of 12^ 
pound paper bags. 
For manufacturers and distributors see 
numbers ^4, 71, and 112 of list at end of 
this circular. 
LARKSPUR 
A solution of larkspur is used as one 
treatment for human hair in the control of 
the head louse. 
The principal alkaloid, Delphinine 
(probably C31H; nOyN) , a white, crystalline, 
poisonous substance, soluble in ether and 
alcohol, is extracted from the larkspur herb.' 
It is used as an ointment or lotion to destroy 
lice and to relieve neuralgia. 
This material may be bought in pint 
bottles for i?1.75. 
For manufacturers and distributors 
see number 85 of list at end of this circular. 
