l'.V CHRISTOPHER JOB N 



II 



very small dimensions, as we Bel aside the result of so uracil 

 labor. 



Finally, in reviewing the work done, let as have in mind the 

 intention of each of the acids employed, and remember that 



NO 1 boils at a moderately high temperature, which, as in other 

 fluids, is decreased by the presence of pebbles, bits of glass, or 

 coarse sand: that HC1 passes into ebullition at a comparatively 

 low indication of the thermometer; and, lastly, that the boiling 

 point of SO is very high indeed, — so elevated, in fact, as to 

 jeopardize all inferior glassware. 



The foregoing process is open to the charge of being time- 

 consuming, — as are all other methods, — but we have invariably 

 found the results to be excellent. The same success is claimed 

 for a different procedure, practiced and recommended by F. G. 

 Stokes,* and which may be here briefly set forth. 



Provide a beaker glass of six or eight ounces 1 capacity, in 

 which place about two teaspoonfuls of guano, and then fill to 

 near the top with a saturated solution of carbonate of soda. 

 Boil for half an hour, wash well with w r ater, and, after stand- 

 ing, pour off the supernatant fluid very close. 



Add now of chlorhydric acid two ounces, boil also for a half- 

 hour, wash well, and pour off very close once more. 



Treat the sediment with one ounce of strong sulphuric acid. 

 Let it act for ten minutes, and then add bicarbonate of soda 

 cautiously, either in solution or suspension. Shake well during 

 effervescence, wash well, and, with great caution, add two 

 ounces of nitric acid. After effervescence, drop in two pinches 

 of chlorate of potash, boil a half-hour, or until the deposit be- 

 comes white, and, finally, wash the sediment thoroughly. 



From what precedes, it must appear that the aim of the 

 operator is the removal of all inorganic substances, either 

 originally soluble or artificially made so. prominent among 

 which is lime, and of all organic matters reduced by a destructive 

 process to a soluble or gaseous form. And it is also evident 

 that when certain of these stranger elements are known to be 



absent, such parts of the proa BSeS SS are applicable to them 



ought t<> be omitted, so that fewer steps arc nec essa ry to attain 



•F. O. Stokes. On Cleaning Diatoms, "Quarterly Jonrnal Microscopical 

 Botenoe, M v.»i. xv, ,,. 2& 



