210 
Theory and Practice of Dippiny 
The animal was infested with Blue ticks ( Boophilus decoloratus ) 
which are easy to kill, and whereas all the ticks on the sprayed area 
and within a margin of six inches surrounding this area, were killed, 
none of the ticks distributed over the unsprayed part of the animal’s 
skin was in the least affected. 
In other cases, in which we had the misfortune to cause the death 
of the animal, the autopsies showed that the cutaneous vessels in the 
scalded areas were much congested and there was some considerable 
extravasation of blood. This, together with the fact that the animals 
exhibited symptoms of acute arsenical poisoning prior to death, indicates 
that arsenic was absorbed, but in quantities insufficient to affect ticks 
attached at a distance of six inches or more from the sprayed area. 
Appendix VI. 
The Quantity of Arsenic retained in the Skin of Oxen 
after Dipping. 
Watkins-Pitchford has given data (1911a, Schedule “E,” pp. 58-61) 
relative to the amounts of arsenic retained by the skin (hair and hide) 
of dipped animals; these figures are tabulated below and some further 
calculations, based on these, have been added in the last three columns. 
The animals under investigation were dipped for varying periods; 
some every five days for many months, others once only (see Column 4 
of table). After the lapse of different intervals (Col. 5) the animals 
were killed, and from each one square foot of skin was taken. The 
hair was removed and the arsenic contents of both hair and hide were 
separately determined (Cols. 6 and 7). 
It appeared to us, however, that the results would be more com¬ 
prehensive if the amount of arsenic in the entire skin of the animal 
was estimated. Several measurements made on three animals of normal 
size established the fact that the mean area of the skin, inclusive of 
the head and legs, was about fifty square feet, and the figures given in 
the last three columns of the table represent Watkins-Pitchford’s data 
multiplied fifty times. 
