CI1. VI} MICRO-CHEMISTRY 177 



indicate that in every research laboratory of chemistry the micro- 

 scope will become as familiar as it now is in research laboratories of 

 biology. Its proper place in chemistry has been admirably stated 

 by Chamot: 



" It is rather remarkable how slow American chemists have been in re- 

 alizing the importance of the microscope as an adjunct to every chemical 

 laboratory. This is, perhaps, largely due to the fact that few of our students 

 in chemistry become familiar with the construction and manipulation of this 

 instrument, just as few of them become sufficiently familiar with the spectro- 

 scope and its manifold uses; and doubtless also because of the prevailing im- 

 pression that a microscope is primarily an instrument for the biologist and is 

 of necessity a most expensive luxury. The fact is, however, that this instru- 

 ment is now far from being a luxury to the chemist, and the time is not far 

 distant when it will be conceded to be as much a necessity in every analytical 

 laboratory as is the balance. 



" Nor is the apprenticeship to its use in chemical work long or intricate. 



" Micro-chemical analysis should appeal to every chemist because of its 

 neatness, wonderful delicacy, in which it is not excelled even by the spectro- 

 scope, and the expedition with which an analysis can be made. A complete 

 analysis, intricate though it may be, is a matter of a few minutes rather than 

 of a few hours. 



" While there is no good reason to believe, as do some enthusiasts, that 

 this new system is to displace the old analysis in the wet way, every chemist 

 should, nevertheless, familiarize himself with the microscope, its accessories, 

 and the elegant and time-saving methods of micro-analysis, thus enabling him 

 to examine qualitatively the most minute amounts of material with a rapidity 

 and accuracy which is truly marvelous; not to speak of the many substances 

 for which no other method of identification is known. 



" At present the greatest bar to its general use is the absence of any well 

 defined scheme, and the absolute necessity of being well grounded in general 

 chemistry. There are no tables which can be followed in a mechanical way by 

 the student, but on the' contrary he is obliged to exercise his knowledge and 

 judgment at every step. For this very reason the introduction of this subject 

 into the list of those now taught is greatly to be desired." 



The microscope is used by the chemist to follow reactions in 

 minute quantities of material. This is done by examining the 

 crystals which separate on the addition of a drop of reagent to a 

 drop of solution containing the unknown substance. 



252. Experiment. To a drop of distilled water on the 

 corner of a slide add a piece of calcium chlorid about half a milli- 

 meter in diameter. When it is dissolved place a minute drop of 

 dilute sulphuric acid (about ro%) near the drop of solution. With 



