"It is noticable [sic] that about all of the recent improvements in cyanide practise [sic] have been along mechanical rather than chemical lines. the use of oxidizers such as air, ozone, sodium peroxide, etc., the use of the salts of lead, and even the addition of a coating of lead to the zinc shavings in the extractor boxes were all recommended when the process was first advocated but sometimes for different reasons. In the early days of the process the addition of hypochlorites, alkaline persulphates, and the use of mercuric cyanide was also investigated but has not proven satisfactory owing to the increases [in] cost. If, however, there has been no advance made along the chemical side of the process the reverse is certainly true of the mechanical side. Whereas in the past the attempt of everyone was to crush coarse and make as few fines and possible, now, owing to the improved machinery for the treatment of slime, the tendency is to slime all the ore as this has been found in a majority of cases to give a higher extraction and less cost than the former practise [sic] did" – Introduction, p. 3.