The spectator., 1921-11-29
Stump Successfully Requires E.peenc. Judgment

(Prsparsd by tho United States Department
 of AgriCulture)
 Distribution by the United States Department of Agriculture of 12,5oO,- O0O pounds of picric acid salvaged from the war stores and designed to be used for farm explosives will arouse interest in the desirability and practieabllity of blasting stumps to clear off old wood lots for crop pur- poses.
 The picric acid for distribution has been allotted to the states according to areas of cut-oyer lands. It Is planned to establish an agency in each state to cooperate with the depart ment, and the agricultural college in each state has been asked to net in that capacity.
 Not Commercially Available.
 Picric acid is rather higher in eX- plosive power than ordinary conner cial dynamite ens used In agriculture, but for manufacturing reasons Is not likely to be on the market after the governments supply is disposed of. For stump and rock blasting work ii Is used In practically the same way, being exploded by detonating cap, either with fuse or an electric det Onator.
 In blasting stumps, the proper loca- tion and size Of the charge depend upon the kind, size and age of the stump; the kind of soil and the amount of moisture In It; and the method of firing the charge which is to be used.
 For tap-rooted stumps good meth cd is to dig away enough earth at the side 10 permit boring an tpelined hole we'll down past the center at the depth where 1t is desired 10 cut the root on The hole should be at least eight inches deeper than the length of the cartridge 10 allow for tamping This charge may be fired by fuse or electricity, or two or moro charges may be placed In holes around the outside of the root and fired with an electric blasting machine. Sometimes even one large charge, planted deep on the outside of the root, will do the work
 Where stumps have lateral roots, some experience and judgment will be necessary in placing the explosive. es- peciauy If only one charge is used. Generally the center of resistance will be the center of the stump, although sometimes roots on one side are much stronger than on the other.
 The depth requires careful consid eration. For small Stumps the charge should be at least two feet deep while larger stumps with wide spreading roots should be loaded deeper Sandy soil requires deeper charge than clay or loam.
 Size of Charge
 The size of the charge cannot be specified briefly, but one authority recommends roughly one-half pound of 70 per cent dynamite for each square foot of stump, With picric acid, cooperative investigations by the United States Department of Agrlcul- ture and other institutions indicate that success can be attained with one fourth of pound for each square foot of white-pine stumps. with larger charges for hardwood stumps. The inexperienced plaster should begin ex- periments with small stumps and ad- just the charge.
 Holes In soil may usually be made | by driving 1ia-inch crowbar with maui. In wood, of course, | tn auger Is required. Sometimes 1t is l wise 10 set off small charge in the | bottom of the hole to form chamber | and after the hole has cooled tamp 1t | full of slit cartridges. If the soil is | tridges may be slit with sharp knife | and the cartridges tan1ped into solld | mass with wooa, II sick. Cartridges | nay be divided hy sitting the paper around and kreakiue Never attempt | to slit a frozen cartridge.
 To prime the charge, cut off the proper length of fuse, allowing at least feet per minute required to get to safety after firing.
 Open the cap box and allow one cap to slide into the hand. Never pick or pry out cap with stick or wire, as they are very sensitive. Slip the end of the fuse snugly into the open end of the cap. Crimp the cap on with a crimper. If the charge is to be fired In water. apply a little grease around the top of the cap.
 With the crimper handle, or q stick the size of lead pencil, make hole h the side of the cartridge. inclning t 80 the part to be occupied by the zap win be parallel with the side of he cartridge If the cartridge is te be