503 



by 11 feet high ; No. 3 covers trees 104 feet diameter by 12 feet 

 high. This diagram is taken from Mr. A. Benson's paper in the 

 Queensland Agricultural Journal. 



CAUTION TO OPERATORS. 



Those using the process of fumigation for the treatment of scaly 

 trees should bear in mind that they are handling, probably, the most 

 insiduous and deadly of poisons. 



The gas inhaled in a close chamber produces sudden death ; 

 when largely diluted with air it is harmless. Thousands of thou- 

 sands of trees are now-a-days fumigated every year, and accidents 

 are rare. With proper precautions there is no danger whatever. 



Unless handling small tents covering trees 5ft. or 6ft. high, 

 not less than two men should operate. 



Not only is the hydrocyanic acid gas highly poisonous, but the 

 ingredients or chemicals used in its production are also dangerous 

 poisons. These ingredients are : 1 potassium-cyanide, of which a 

 piece of the size of a grain of wheat would prove fatal to an adult 

 or an animal ; 2 sulphuric acid or oil of vitrol, which is eminently 

 corrosive, and every precaution should be taken to guard against 

 its spurting 011 the face, hands, or clothes. 



When operating, hold your breath when dropping the cyanide 

 into the acid, and also when removing the tent and uncovering the 

 tree. See that the tents are always gas tight. Should the acid 

 accidentally spurt on your hands or face, wash at once in water. 



Do not handle a clean tree after having examined a diseased 

 one, without previously washing your hands, as the eggs and larvae 

 of some of the scales are so small that they are easily carried from 

 one tree to another by the growers themselves, or their men. I have 

 often seen people crush scale insects on branches of trees, between 

 their fingers, and then go to the adjoining tree and carelessly handle 

 it and examine it for scales. Trees infested with the San Jose and 

 the more dangerous sorts of scales should not be handled unless it 

 is found necessary to do so. 



FUMIGATING OUTFIT 



consists of gas-tight tents made of light, strong canvas, cut 

 and sewn together in a bell shape, and painted with raw linseed 

 oil. A little turpentine added to the oil will cause it to dry quicker. 

 When painting, spread the tent well by hanging it to theVafters of 

 a shed or the branches of a tree, and leave it to dry thus spread out, 

 lest the tissue of the canvas should heat and rot.' Calico is rather 

 a light material for the manufacture of tents ; it wears badly, and 

 requires constant patching up. Eight-ounce duck or ordinary blue 

 or brown drilling, sewed carefully, are good materials. It is advisable 

 to have rings at the sides and top of the tent, bo ease it over trees 

 by means of a light pole with a fork at the end. A light ^-inch 

 gas piping hoop, rung through rings at the base of the bell-shaped 



