24 E. DIVERS AND T. HAdA. 



process is no longer, we consider, of any value, the two alkaline salts 

 being- readily obtainable from tlie neutral salt. 



Prepanition of the neutral sodiuiii (Miniidosulphonate hy the, sidplnir- 

 dioxide melliod. — Tlie stdts are to be in the proportion of two molecules 

 of sodium nitrite to one of sodium carbonate or to two of sodium 

 hydroxide, but with about a tenth extra of the carbonate or hydrox- 

 ide, (called for by the unavoidable* conversion of about a tenth of the 

 nitrite into nitrile). In our experience this proportion gives about 

 the highest yield of oximide along with decomposition of all the 

 nitrite. Suppose the nitrite used to be 9() per cent, pure, and the 

 quantity ttiken 50 grams. Then this is put with 110 grams of sodium 

 carbonate crystals, or 80.8 grams of real sodium hydroxide, a piece 

 of lacmoïd ])a]ieï-. and 150 cub. cents, of water when carbonate is 

 taken, or 200 cub. cents, when hydroxide is taken, into a 500 cub. 

 cents, tiiisk. firted with cork carrying inlet and exit tubes and, if con- 

 venient, a thermometci-. Tiie inlet tube dipping into the solution is 

 connected with the sulphur-dioxide apparatus, and the exit tube with 

 a washing bottle of water, by (^aoutchouc tubes of adequate length 

 to allow of free movement of the flask. The stream of sulphur dioxide 

 may be r.apid (in the case of the carbonate being used, very rapid), but 

 not so as to cause any fumes either wliite oi* red in the flask ke])t in 

 active motion and immersed in water with ice floating in it. Hardly 

 any sulj)hur dioxide at all will escape consumption. In about 70 

 minutes the sohition will have become acid or nearly so, if the sulphur 

 dioxide have been passed in at a, good rate. Notice of the remote 

 approach (^f neutralisation of the sohition is gi^^en, when carbonate is 

 being used, by the disa])pea ranee <^f the last of the sodium hydrogen 

 carbonate which has heevi ])reci{)itated previously by the sul])hur 

 dioxide and, when sodium hydroxide has been used, by the disa)»- 



* No lon^-er nuavoidable -, March, 1894. 



