and Notice of a nevo analytical Scale oj Equivalents. 431 

 SoSAq™, sulphate of soda, crystallized, 10 atoms of water; 



* s 



T Aq\ tartaric acid, crystallized, 1 atom of water. The simple 

 bodies are designated in that massive letter, called by printers 

 " Egyptian." 



Oxides being also distinguished by superimpressed dots, 

 expressing the number of atoms of oxygen, thus leave the 

 substances without a generic sign, so reduced in number, as 

 to make the privation almost answer the purpose of one. 



The following arrangement, added to these distinctions, 

 render this scale (with a little practice, for chemists not fami- 

 liarized to the symbols) easier of reference than others much 

 less comprehensive; so at least it is found in my own prac- 

 tice. 



The scale is the same length as Wollaston's, but double, 

 opening, bookwise, on hinges, and having of course two 

 sliders, which are on the outsides. Within, is on one side a set 

 of index-tables illustrative of the symbols; on the other, a let- 

 ter-press explanation of the distinctive objects and use of the 

 instrument. 



The principal working scale is occupied entirely with the 

 tests, salts and precipitates, arranged in four columns as fol- 

 lows ; each column being headed with the generic symbols of 

 its contents. 



In the column left of the slider, — muriates, nitrates, borates, 

 and a few sulphites, arsenites and silicates. 



In the outer column on the left, — sulphates, arseniates, phos- 

 phates, and a few tungstates. 



In the first column on the right of the slider, — carbonates, 

 acetates, and a few chromates and chlorates. 



In the outer column on the right, — tartrates, oxalates, ci- 

 trates, and a few ferro-prussiates and benzoates. 



Triple, quadruple and compound salts, being heavy, fall 

 near the bottom; and their long symbols crossing two co- 

 lumns, readily strike the eye. 



The other scale contains the simple bodies, binary com- 

 pounds, and multiples, having four columns on the right of 

 the slider, and five. On the left, each column being headed 

 with its contents. 



On the right side are negative substances, chlorides, bro- 

 mides and the multiples. On the left, neutral and positive sub- 

 stances, and iodides. 



Simple bodies are on the columns next the slider (except a 

 few displaced to prevent crowding) ; oxides in the two suc- 

 ceeding columns to the left; and sulphurets, phosphurets, &c. 

 in tlf^two columns furthest left. 



Acids 



