Note on costing

Such evaluation should be adopted in all the simpler preparations. In this way the student will become acquainted with the elements of costing which play such an important part in his later life in the factory. He should hardly wait until he enters the factory to appreciate the cost of such common substances as sulphuric acid, benzene, aniline, naphthalene he should be able to estimate roughly the cost of derivatives such as dinitrobenzene, p-nitroaniline, etc. Even should he not take up the industrial side of his profession, he should be acquainted with the relative value of the more common products, and trained to decide for himself whether, for example, it would be more economical to extract with ether or benzene, taking into consideration the relative efficiencies of the two processes. 

Moreover, he should not use chemically pure products for his preparations, unless for research purposes, lie ordinary technical qualities supplied by the well-known manufacturers are quite suitable for most preparations, and are, of course, much cheaper It should be remembered that the facilities for the purification of many organic products are much greater on the large scale than in the laboratory, and that these technical products are often therefore of remarkable purity. It is a valuable 

The authors would not stress the point further in a book of this kind. Their experience teaches them that too often do students look upon such things as gas and power, bench reagents, and the commoner organic chemicals supplied from the departmental store, as commodities which have no actual value. It is a moot point as to whether educational authorities would not render much greater service to the student by charging more moderate fees for instruction, and thereafter charging for all materials used in the course of his work. 

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