§ 28. REAGENTS. 21 



]^Hp,E[0, PO^.)— This should, give a colorless bead when 

 fused on platinum wire. 



d. Sodic bisulphite.— HNaS03. (Bisulphite of soda. 

 NaO,HO,S02.) — This should give a residue when heated 

 with sulphuric acid, whose solution is not changed by 

 hydrosulphuric acid or amnionic molybdate. Dissolve in 

 10 parts of water. 



e. Sodic carbonate. — Na.CO^. (Carbonate of soda. 

 NaOjCO^.)- — This should be perfectly white, and the solu- 

 tion obtained after supersaturation with nitric acid should 

 give no precipitate nor color with baric chloride, argentic 

 nitrate, or potassic sulphocyanate, nor any reaction with 

 ammonic molybdate, nor any insoluble residue of silicic 

 acid w^hen evaporated to dryness. Dissolve the crystal- 

 lized salt in 3 parts of water, or the anhydrous salt in 5 

 parts. Keep some of the ignited salt in the dry form. 



/. Sodic hyposulphite.— Na.SJI^O^. (Hyposulphite 

 of soda. NaO,HO,S,0,.) 



<7. Hydric di sodic phosphate. — ^N^a^HPO^. (Phosphate 

 of*^ soda. 2]SraO,HO,PO,.)— This should not be made 

 turbid when heated with ammonia, and the precipitate 

 produced by argentic nitrate, or baric chloride, should be 

 dissolved completely and without effervescence by dilute 

 nitric acid. Dissolve in 10 parts of water. 



Ji, Sodic nitrate. — XaNOg. (Nitrate of soda. NaO-, 

 KO^.) — This should give no reaction with argentic nitrate 

 or baric chloride, nor with sodic carbonate. 



28. Starch-paper. — Boil starch with 25 parts of w^ater, 

 saturate strips of paper with the liquid, and dry them. 



Tannin. — See acid^ tannic. 



29. Tin.— Sn.— Get the best tinfoil of the druggists, 

 or pure tin in small sticks. 



Turmeric-paper. — See curcuma-paper. 



30. Franic acetate. — (U,0) C,H30,. (Acetate of 



