344 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



ground sulfur of the best quality will show from 60 to 70, and those of 

 ordinary quality 43. 1 



All the sulfurs examined, with the exception of two of the ground 

 samples (Nos. 8 and 14), contained sufficient fine material to do effec- 

 tive work, but the amount it would be necessary to use of the various 

 grades would vary considerably. If the sulfur is applied by hand or 

 with perforated cans, any of the sulfurs except Nos. 14 and 8 would 

 probably be nearly equally good, and therefore the cheapest would be 

 best. If we use several times as much as is needed, as w r e must \vith 

 these methods, it matters little if 25 per cent, or 50 per cent, of the 

 sulfur is useless. 



When using an effective sulfur machine it is possible to utilize the 

 superior^ of the finer grades, and in this case it is undoubtedly ad- 

 visable to use the better qualities. (See figs. 13 and 15.) 



A few simple directions for the examination of sulfur may be of 

 use to the grower. 



1. The finer the sulfur the more bulky. Therefore if several sul- 

 furs are in sacks of equal weight, the largest sack will contain the 

 finest sulfur. A 110-pound sack of good flow r ers of sulfur is twice as 

 large as a 110-pound sack of very coarse ground. The difference in 

 bulk between equal weights of sulfurs of various qualities is shown in 

 fig. 17, representing the Chancel test. 



2. The color of sublimed sulfur is a clear, bright yellow. The 

 color of ground sulfur will vary with the fineness. Coarsely ground 

 sulfur is almost of the same color as sublimed. When finely ground, 

 the color becomes whitish. The whiter a ground sulfur, the finer it is. 

 provided the color is not due to adulterants. 



3. A good sublimed sulfur should feel as soft as flour when rubbed 

 with the fingers in the palm of the hand. If hard particles are felt, 

 the sulfur is not of the best quality. Ground sulfur always feels a 

 little gritty, but the hard particles should not be large or numerous. 



4. A very good idea of the fineness of a sulfur can be obtained by 

 the use of an ordinary good hand magnifying glass costing about $1. 

 A magnification of 10 or 20 diameters is sufficient. With a little expe- 

 rience sublimed and ground sulfur can be distinguished by this means. 

 The particles of sublimed sulfur are all nearly spherical with smooth 

 outlines. Those of ground sulfur are irregular and with sharp edges. 



The sulfur is most easily examined when spread on a piece of glass 

 over a dark background. A good way to spread the sulfur is to place 



Yiala, P., Les Maladies de la Vigne, p. 53. 



