-181 



Williams (C). The Control of Fluid in Cattle Dipping Tanks. — Agric. 

 Jl. Union S. Africa, Pretoria, viii, no. 1, July 1914, pp. 12-17. 



In this paper the results of a number of analyses of tank fluids 

 are given, with the object of showing the effect of temperature 

 upon the dip and the oxidation of the arsenite it contains to 

 arsenate [see above, p. 172]. There appears to be no doubt that 

 this process takes place more rapidly in summer than in wmter, 

 but at the same time very little use was being made of these tanks 

 during the winter, and, as it has already been shown that the 

 constant use of a tank promotes the efficiency of the dip, the 

 question of summer oxidation is probably not of great consequence. 

 It is again pointed out that samples of dip kept in the laboratory 

 undergo change very much more rapidly than the same fluids in 

 tanks in use, and it is stated that the result of the analyses for 

 farmers of tank liquor, during the past three or four years in the 

 province of Natal, shows that in very few cases had the oxidation of 

 arsenite to arsenate been at all serious. Dr. W. Pitchford maintains 

 that any arsenate which may be produced in a tank by means of 

 oxidation is relatively harmless to ticks and to the skins of the animals. 

 Cooper and Laws [see this Review, Ser. B, i, pp. 133, 152-153 and 

 214-215] have practically estabhshed the fact that arsenate has only 

 half the tick-killing property of arsenite, and in any case it is important 

 that the quantity of arsenate present in the tank liquor should be 

 more or less accurately known so as to keep the tank in efficient 

 working order. The results of the addition of disinfectants to tank 

 liquor in arresting oxidation have been investigated, and are briefly 

 as follows : — Ten parts of sodium sulphite in 2,000 of dip 

 had very little effect in arresting the oxidation, and one part each of 

 carbolic acid and of c-ommon commercial coal tar disinfectant were 

 also quite ineffective, but when the proportion was raised to 10 parts 

 each in 2,000, oxidation was very largely arrested. As these results 

 were obtained under laboratory conditions, in which oxidation has 

 been shown to be much more rapid than in the tank itself, it is probable 

 that a much smaller proportion in the tank would have an important 

 effect, and it is suggested that the addition of a gallon or two of some 

 of the ordinary coal tar disinfectant products now on the market to 

 if 'every thousand gallons of tank liquid would very materially reduce, 

 not entirely arrest, oxidation of arsenite to arsenate in the tank itself. 



Many of the proprietary arsenical cattle dips at present on the 

 market are said to be very efficient, but the farmers in South Africa 

 generally prefer the use of arsenite of soda, either alone or in conjunction 

 with paraffin or soft soap, forming what is known as the " Laboratory 

 Dip." Although much of the arsenite of soda sold in South Africa 

 for dipping purposes is well up to standard, in some instances it is 

 very much below, and contains a varying proportion of arsenic oxide. 

 The need of periodical analysis of dipping fluids and tank hquors is 

 emphasised. 



LouNSBURY (C. P.). Warble Flies: a Danger with Imported Cattle, 



— Agric. Jl. Union S. Africa, Pretoria, viii, no. 1, July 1914, 

 pp. 61-64, 1 fig. 

 There is no known record of warble ffies being bred anywhere in 



