SUBDIVISION OF SAMPLE 9 



least a sample taken from every tenth bag. If there are less 

 than ten bags, however, not less than three or four of the bags 

 should be sampled. 



In regard to the preservation of samples after they are secured, 

 ordinary fruit jars which are furnished with rubber gaskets may 

 be used for liquids without any fear of loss. In the case of liquids, 

 where a narrow-necked receptacle is employed, and especially 

 where it is necessary or advisable to secure a small volume of 

 sample, a bottle which is closed with a rubber stopper may be 

 used. A cork stopper which has been coated with paraffin and 

 afterwards secured with sealing wax may be substituted some- 

 times to advantage for a rubber stopper. Of course, in many 

 cases the presence of paraffin is objectionable, and in such cases 

 it should not be used. 



13. Subdivision of Sample. The extent of the subdivision 

 of the sample depends entirely on its nature and the 

 character of the examinations to be' made. In general 

 it may be said that the finer the subdivision the better 

 the analytical results. When substances are dry and can be easily 

 pulverized, they should be powdered and passed through a sieve 

 with a millimeter or, better still, a half millimeter mesh. The 

 sample may be selected advantageously from a large amount of 

 material by repeated quartering, the subsamples being passed suc- 

 cessively through the crusher from time to time so as to have only 

 a small amount of the sample in a fine state of subdivision when 

 the final grinding occurs. In the case of a tough and difficultly 

 reduced substance like meat, as large a quantity as possible should 

 be passed repeatedly through a sausage mill, mixing the whole 

 at once for each grinding, quartering the residue and regrinding, 

 and mixing the subsamples. 



Many products which consist of relatively small particles which 

 can not be ground may be thoroughly mixed together and sub- 

 divided by means of quartering until a sample of proper size is 

 obtained. If this material is soluble in water, the whole of the 

 sample may be weighed, dissolved in water and an aliquot por- 

 tion of the mixture taken for analysis. If soluble in other solvents 

 than water, a similar process is to be employed. It appears that 



