28 
Indian Forest Records. [Vol. Ill- 
experiment cannot be considered as conclusive. On the other hand, 
sulphate of copper has in itself many drawbacks, the most important of 
which is that it is very liable to be washed out of the timber, For this 
reason the tendency both in Europe and America has been to discontinue 
its use, and this after prolonged experience as to the value of this salt as 
a preservative for timber. 
With reference to the process itself it has the disadvantage that only 
green wood or wood which has been kept fresh in water can be used 
and that a considerable loss is caused by having to treat those portions 
of the log which on conversion have to be discarded as off-cuts and butt- 
ends. 
( 4 ) THE BURNETT1ZING PROCESS. 
Process. 
The process by which chloride of zinc is injected into converted 
timber was started by Sir William Burnett and the process now bears the 
inventor's name. It consists in subjecting the timber to a partial 
vacuum and then immersing it in the solution varying in strength from 
1 in 50 to 1 in 100, by measure, according to the quality of the timber. 
It was observed in Germany that a 3 per cent, solution was generally 
too strong, in that it injured the timber by its action on the iron fasten¬ 
ings. It was. found that on the Brunswick lines, where a solution of 
1 part in 30 of the chloride of zinc of commerce was used, that the 
sleeper-woods, after 5 years, showed discolouration and softness round 
the spike-holes causing the fastenings to become loose. Dr. Warth 
states that after the ill-effects caused by using a solution as strong as 
I in 30 had become apparent the strength was reduced to 1 in 60 and 
contained 0-66 percent, of metallic zinc by weight, or 264 percent, 
of chloride of zinc of commerce. In the experiments carried out by 
H. B. Eastman of the American Forest Service, a 6 per cent, solution 
was taken, the Open Tank method being probably employed* 
The Use of Chloride of Zinc as an Antiseptic. 
As was explained in Chapter I, page 8, the process has certain disad¬ 
vantages such as the corrosive action of the salt on iron fastenings, 
besides which it is a highly hygroscopic substance. To overcome these 
drawbacks attempts have been made to use chloride of zinc together 
( 101 ) 
