191 



Brunnich (J. C). A new dipping fluid. — Queensland Agric. Jl, 

 Brisbane, iii, no. 4, April 1915, pp. 161-163. [Received 25th 

 September 1915.] 



Tar and soap are much the most costly ingredients of arsenical dip 

 mixtures and this fact is believed to have led to the diminution of the 

 recommended proportions by some manufacturers of concentrates. 

 Their cost, and particularly the difficulty now experienced in obtaining 

 Stockholm tar of good quality, determined the author to experiment 

 with commercial bone-oil as a substitute. Bone-oil is a by-product in 

 the manufacture of animal charcoal, and procurable in sufficient 

 quantities from the sugar refineries in Australia. Experiments showed 

 it to be in the main readily emulsifiable by boiling with alkali, and the 

 resulting solution possessed marked detergent properties, and retained 

 these, in common with Stockholm tar, when compounded with hard 

 water. It was therefore expected that arsenical solutions of standard 

 strength containing bone-oil would prove fully effective in tick 

 destruction, and trials with a dip containing J per cent, of bone-oil 

 supported this. On the seventh day after spraying, the cattle were 

 clean and showed no indications of scalding. Most of the ticks were 

 dead on the third day. The trials proved the complete efficacy of the 

 bone-oil arsenical dip, and also that bone-oil has a decidedly beneficial 

 and emollient effect. The strong, though not objectionable, odour 

 imparted by the oil, leaves dipped animals within 24 to 48 hours and 

 did not communicate a noticeable odour or taint to the milk produced. 

 The cost of the chemicals in the bone-oil dip is only about half of 

 those in the old standard dip and the process of manufacture is much 

 simpUfied, the concentrate being rapidly and easily prepared as 

 follows : The required amount of bone-oil (at the rate of 1 gal. to 

 400 gals, of dipping fluid) is heated in an open pan with one-quarter 

 of its weight of caustic soda and stirred. After a quarter of an hour, 

 the mass being still in condition of active frothing, the flame is with- 

 drawn and the arsenic, previously intimately mixed in the dry powder 

 form with a quarter of its weight of caustic soda, is stirred into the oil in 

 small portions. On partial cooling, the mass receives the addition of 

 sufficient water to form a soft homogeneous paste, which can be 

 immediately dissolved in more water to produce the dipping fluid ready 

 for use, or can be tinned as a concentrate. To make 400 gals, of dip, 

 the proportions of constituents recommended are : — Arsenic, 8 lb. to 

 8| lb., according to quality ; bone-oil, 1 gal. (from 9 to 9i lb.) ; caustic 

 soda, 4 lb. As a mean of several laboratory trials, the following figures 

 may be taken as a guide in preparation of concentrate on a large 

 scale :— Bone oil, 95 parts by weight ; caustic soda, 25 parts ; arsenic, 

 100 parts ; and caustic soda, 25 parts. This gives a total of 245 parts, 

 which after boiling and cooling, were reduced to 200 parts, so that 

 50 parts of water were added to make 250 parts of paste. For final 

 fluids the latter is diluted in the proportion of 1 part concentrate to 

 200 parts of water. The paste form is recommended, as pastes possess 

 the following advantages over fluids : perfect homogeneity, allowing 

 the amount of arsenic to be accurately gauged ; no liabiHty to 

 exude from the containers, which are therefore less expensive to 

 construct ; generally greater concentration and consequent saving of 

 freight. 



