88 HYDEOCYAISTIC-ACID GAS FUMIGATION IN CALIFORNIA. 
extent in fumigation work in California. An examination of the 
data in this table shows that only Nos. 6523, 6525, 6527, and 6528 
are suitable for use in fumigation. Each of these is a high-grade 
article and each contains less than 1 per cent of sodium chlorid. 
The other three samples contain greatly in excess of 1 per cent. It 
should be noticed that these last three samples were sold as 98 to 
100 per cent sodium cyanids. 
Whenever sodium cyanids have been used in the past, the same 
dosages have been scheduled as for the regular potassium cyanid. 
Inasmuch as decomposition was then unknown, and no allowance 
was made for it, the strength of gas given off was much less than 
was believed to be the case. The result has been poor work. This 
explains the past unsatisfactory work with the "American," or 98 
to 100 per cent, sodium cyanid. 
THE KIND OF CYANID TO PURCHASE. 
The results of these experiments direct attention to a second 
consideration in the purchasing of a cyanid. That a cyanid be of a 
certain grade of purity is no longer the only consideration. It is of 
equal importance that it be practically free of sodium chlorid. The 
writer would condemn as unfit for use in fumigation any cyanid 
containing in excess of 1 per cent of sodium chlorid. 
Returning to a high-grade sodium cyanid, it has been found on 
analysis of several samples that these contain only a fraction of 1 
per cent of sodium chlorid. It generally can be held as a safe con- 
sideration that a cyanid approaching chemical purity will contain 
not more than a trace of sodium chlorid, and that such a cyanid can 
be safely used, even though the degree of cyanid purity is alone kno wri. 
The writer would consider as generally satisfactory for fumigation 
work a sodium cyanid 124 per cent pure or above. A chemical of 
lower purity should never be used. Preferably the grade demanded 
should be a little higher than that given, or 126 to 130 per cent pure. 
Absolute chemical purity in a commercial cyanid can not be expected, 
but cyanids of the degree of purity recommended herein not only 
are within reasonable limits of expectation but should be demanded. 
When chemicals of this degree of purity are used, analysis for sodium 
chlorid is unnecessary. It is the lower grade of sodium cyanid — the 
grade " 100 per cent pure" or less, which contains the large amounts 
of sodium chlorid. 
DOSAGES WITH SODIUM CYANID. 1 
All recent dosage recommendations in fumigation have been based 
on a high-grade potassium cyanid. Such a situation renders it neces- 
sary to revise our present schedules should we desire to use sodium 
i Whenever sodium cyanid is mentioned in this bulletin, a high-grade article, one 124 to 130 per cent 
pure, is meant unless otherwise specified. 
