170 



BORACIC ACID. 



b. Purified by crystallization from alcohol. 



c. Ditto, by recrystallization from water. 



SILICON. Si. 



33. METALLOID. 



f a. In crystals, 

 t b. Amorphous. 



34. SILICIC ANHYDRIDE. Si 2 . (Silica, Silicic Acid, Silicic Oxide.) 



a. Precipitated. 



Note. This specimen was obtained by passing gaseous fluoride of 

 silicon into water. 



For various specimens of crystallized silica, see the collection of minerals 

 in case No. 8, ire the centre of the Chemical Museum. 



b. Prepared by calcination of flint. 



PHOSPHORUS. P. 



35. CRYSTALLINE. 



a. Commercial specimen, fused into sticks. 



b. Ditto, coated with white opaque phosphorus. 



c. Ditto, ditto, red ditto. 



d. Ditto, ditto, black ditto. 



36. AMORPHOUS. 



a. Commercial specimen. (Tfed Amorphous Phosphorus.) 



b. Pure, for medicinal purposes. 



c. Impure, partially decomposed into phosphatic acid. 



37. PHOSPHORIC ANHYDRIDE. P 2 5 . (Pentoxide of Phosphorus, Anhy- 



drous Phosphoric Acid, Phosphoric Oxide.") 

 a. Commercial specimen. 



38. PHOSPHORIC ACID. HP0 3 . (Glacial Phosphoric Acid, Metaphos- 



phoric Acid.) 

 a. Commercial specimen. 

 * l>. Very fine specimen, presented by Mr. Morson. 



39. PHOSPHORIC CHLORIDE. P C1 5 . (Pentachloride of Phosphorus, 



Per chloride of Phosphorus.) 

 a. Commercial specimen. 



MONAD METALS. 



POTASSIUM. K. 



40. METAL. 



a. Preserved from oxidation in Persian naphtha. 



41. ACETATE. K C 2 H 3 2 . (Potassce Acetas, B.P., Diuretic Salt.) 



a. In fused masses. 



42. BIN-ANTIMONIATE. K 4 Sb 3 ? . (Calx Antimonialis .) 



a. Powder. 



