THIRTY-FOURTH FRUIT-GROWERS ' CONVENTION. 



105 



In this respect he agreed with Morse. His dosage, however, was some- 

 what greater than Morse's, being at the rate of practically 1 ounce of 

 cyanide per hundred cubic feet enclosed space. 



In 1891 Alexander Craw proposed a dosage system. Trees 6 feet 

 liigh were given 1 ounce of cyanide, 8 feet high 2 ounces, 10 feet high 

 3 ounces, and so on, the largest trees mentioned, 30 feet high, receiving 

 11 ounces. This dosage table was probably scheduled without regard 

 as to what the volumetric measurement of trees of the dimensions given 

 actually was. From a computation of the volumetric values of trees 

 from 6 to 30 feet in height, and a comparison of these volumes with 

 the dosage scheduled, we find that for trees 6 feet high the dosage 

 was at the rate of l^o ounces of cyanide per hundred cubic feet. 

 As the trees became larger the rate clecreased, until for trees 30 feet 

 high the rate was Init slightly more than i/4 of an ounce per hundred 

 cubic feet. Hence, from this schedule, the gas would be six times as 

 concentrated or strong for the 6-foot tree as in case of the 30-foot. 



A dosage table in the "Rural Calif ornian," which was considered so 

 excellent as to be placed in Professor Johnson's book, "Fumigation 

 ]\Iethods, ' ' the most extensive practical treatise on fumigation in print, 

 was carefully examined. In this table a tree 6 feet high is given 1/2 

 of an ounce of cyanide; one 30 feet high Sy.^ ounces; with trees of 

 intermediate size receiving a dosage between these limits. A normal 

 shaped orange tree 6 feet high enclosed in a tent represents about 

 70 cubic feet: one 30 feet high represents practically 8,375 cubic feet. 

 From this fact we see that in this particular table the tree 6 feet high 

 would be receiving practically .seven tenths of an ounce of cyanide per 

 hundred cubic feet, whereas the tree 30 feet high would be receiving 

 but one tenth of an ounce of cyanide per hundred cubic feet. This 

 results, that the gas for the 6-foot tree would be seven times as strong 

 as for the 30-foot tree. 



Analyses of other dosage tables, with a single exception, show a 

 non-proportionate variation of dosage usually as great as in those 

 already mentioned, and in some cases even greater. In brief, a com- 

 jjarative analysis of the dosage systems proposed by fumigation experts 

 in the past reveals that no two are in exact accord as to what amount 

 of cyanide should be used for a tree of given size. The range of this 

 amount with different authorities is indeed great, some using for a 

 certain sized tree as much as ten times the dosage that others use. And 

 this is not all. for not only do these authorities disagree with each other, 

 but many of them have displayed lack of uniformity in their individual 

 tables. 



Can we wonder, then, that to this chaotic condition of fumigation 

 dosage the practical fumigator fails to resort ^ AYhat satisfaction would 

 he receive were he to turn to it for assistance? None, but rather per- 

 plexity. The problem has resolved itself into the fumigator 's de- 

 termining his o^vn dosage from practical experience and results secured. 

 If he fail to destroy the scale on a 6-foot tree in using one ounce of 

 cyanide, he increased his dosage for the next 6-foot tree, and so on. 

 He has also gradually learned that the dosage required to destroy 

 some scales must be stronger than that for others. 



Most fumigators have worked out their own dosage individually, 

 and consequently the dosage used -by some fumigators differs notice- 



