The mode of sub-dividinir entries made uader any element in 

 each numbered division shall be as follows: — 



(a) All entries relating either to the element itself or of a 



g-eneral character shall come immediately under the 

 number. 



(b) Salts are to be indexed under the registration number of 



the metal, and. in general, compounds are to be 

 indexed under the registration number of the most 

 characteristic element in them. 



The registration number must be immediately followed 

 by the symbol of the characteristic element, followed 

 by that of the other element or elements. Where one 

 compound only is dealt with, its formula may be given 

 immediately after tiie registration number. 



Thus, after each metal, its compounds with the following 

 elements would be placed in the followino- order in the 

 Catalogue : As. B. Br. C. CI. F. H. I. X, 0. P, S, Si, 

 these, and any other elements being taken in the 

 order in which they occur in the preceding table. 



(c) References to hydroxides, acids, and salts that contain 



oxygen shall be entered under the oxide : the corre- 

 sponding sulphur compoimds under the sulphide. 



Thus, under 0420 KO would be placed the followmg 

 compounds of potassium (among- others) : oxides, 

 hydroxide, nitrate, nitiite, hypophosphite. phosphate, 

 hypochlorite, hypobromite. chlorite, chlorate, per- 

 chlorate, bromalo, iodate, sulphite, sulphate, silicate, 

 manganate, permang:a!iate, &c. 



Under U420 KS would be placed any compound containing 

 sulphur that may be considered to be derived by the 

 substitution of sulphur for one or more atoms of 

 oxygen, e.y., sulphide, sulph-hydrides. thiocarbonates, 

 dithiocarbonates, trithiocarbonates. thiosulphates, 

 thionates, thioarsenites, &c. 



{d) In each subdivision the entries may be arranged in such 

 order that those relating, a, to the history or origin of 

 the suUstance come first, and following these, those 

 relating, /3, to its physical properties ; 7. to its pre- 

 paration or manufacture ; c, to its structure, or of a 

 theoretical nature; €, to its interactions or use ; g'j to 

 its compounds. 



It will, as a rale, be unnecessary to repeat a reference to any 

 one substance under each of the sub-sections, o — ^ ; it would suffice 

 to enter the reference in one of these (say /i), and to append at 

 the close of the entry, 7, c, &c., if statements of special impor- 

 tance falling under these headings are made in the commuuica 

 tion. 



(D-3218) B 2 



