54 PRACTICAL AGRICULTURAL CHEMISTRY [147-150 



sodium sulphate, the sodium (Na) would first be tested for 

 by the sodium test (186), and then the acid radical (S0 4 ) 

 would be tested for by the sulphate test (194). 



147. It will be noticed that the name of a suitable sub- 

 stance for performing the tests upon is given at the head 

 of each series of reactions. Thus, when testing for sodium, 

 the most suitable substance to use is sodium chloride 

 (NaCl). The reagent to be added is given immediately 

 after the paragraph number. 



148. Entry in Note-book. — A note-book of quarto 

 size should be used. A concise account of each experiment 

 or test should be entered directly it is made. Neat pencil 

 entry will suffice. The entry should not be considered 

 complete until after it has been examined and initialled by 

 the teacher. 



The following tests for sodium will serve for an example 

 of entry : — 



Sodium (Na). Used NaCl. 



% 

 Dipped a platinum wire into the solution and held in Bunsen flame : 



golden-yellow flame-coloration ; not seen through prism. 



Heated the solid in ignition-tube : decrepitated and finally fused ; 



no sublimate formed. 



General Rules to be Observed whilst Working 



149. Before commencing work see that the reagent- 

 bottles are full ; filter any liquids that require it. Clean the 

 apparatus if necessary. It is far better to put everything 

 away clean. Keep the bench scrupulously clean during 

 work. 



150. In cleaning apparatus, glass and porcelain can 

 usually be cleansed by washing with a brush. If this fails 

 caustic alkalies or acid may be requisite. Failing these, 

 rubbing or shaking with a little sea-sand will usually suffice. 



