SPRAYING AND FUMIGATING. 537 



to give more body to the mixture ; sometimes glue is added 

 also. There is some tendency in tents treated with the 

 cactus decoction, to become moldy when not in use, to pre- 

 vent which some prepare a tannin solution to add to the 

 mixture. The decoction may be applied to the tents with 

 a brush, but a, better way is to soak them during the night 

 in a trough containing the mixture. In the morning they 

 can be raised by means of ropes and pulleys and allowed 

 to drain for some time and then spread out to dry. Tents 

 treated with this mixture are scarcely at all stiffened and 

 seem to be satisfactorily tight." 



In treating cloth so as to render it gas-tight, Prof. 

 H. A. Gossard used and recommends the following: 



"Five pounds white lead, fifteen pounds of laundry 

 soap, chipped, ten pounds of lampblack, two gallons of 

 boiled linseed oil, six gallons of water. Heat to boiling 

 two vessels of water, having three gallons in each. In one 

 dissolve the soap and keep the other hot. Thoroughly pul- 

 verize the lampblack by stirring and mixing well with one- 

 half gallon of vinegar. Now add the lampblack to the 

 linseed oil, stir, and pour into the soap solution. Add 

 the white lead, mix the whole thoroughly, using all the 

 water, and apply to cloth with brush, keeping the paint 

 hot enough to just show steaming while being used. If 

 the first coating is not sufficient, reverse the tent and give 

 an application to the opposite side." 



The manipulation of tents is a matter requiring con- 

 siderable skill, and as a rule it is best to secure skilled 

 labor in first undertaking the work. Excellent directions 

 are given by Prof. Woodworth in Bulletin 122, California 

 Experiment Station. The following on the form and 

 handling of sheet tents is taken from that publication: 



