1871.] 



Dr. Divers on Salts of Nitrous Oxide. 



427 



with hydrochloric acid. The silver chloride weighed '3386 grm. = '2549 

 grm. silver. 



II. *5703 grm. of some of the salt which had been dissolved in ammo- 

 nia, filtered, and precipitated by acetic acid, was dissolved in dilute nitric 

 acid and treated with hydrochloric acid. It yielded *5858 grm. silver 

 chloride = '44 10 grm. silver. 



III. -9462 grm. of some of the salt which had been dissolved in nitric 

 acid, filtered, and reprecipitated by ammonia, was dissolved in very dilute 

 nitric acid and precipitated by hydrochloric acid. It gave '9722 grm. 

 chloride ='7318 grm. silver. 



IV. '6111 grm. of the same preparation as the last was heated at first 

 moderately and then to redness. It left '4737 grm. silver. 



V. "3685 grm. kept for sixty hours at a temperature varying from 100° 

 to 175°, left a residue weighing "2921 grm., of which *2775 grm. was metallic 

 silver and the rest silver nitrate ='0093 grm. silver. 



VI. -5937 grm. heated moderately till red fumes ceased to appear yielded 

 •4274 grm. silver and '0557 grm. silver nitrate = '0354 grm. silver. 



The percentage numbers for the silver found and that required by the 

 formula NOAg are : 



Calc. I. II. III. IV. V. VI. 



78-26 76-85 77'33 77'34 77'48 77'83 77*95 



so that there can be no doubt as to the composition of the salt, although 

 the silver comes out about one per cent, too low. But in several of the 

 samples traces of brownish or black matters were detected on solution ; and 

 in the last preparation analyzed, the presence of a little moisture was de- 

 tected, an attempt to expel which in some of the unused salt by a stronger 

 heat caused partial decomposition. 



6. If the product of t the ultimate action of sodium on the nitrate be 

 treated with acetic acid, as directed, until it is neutral to test-paper, it gives 

 no precipitate with any metallic solution except that of silver, so far at 

 least as trial has yet been made. But the precipitation of the silver-salt 

 leaves the solution of an acid reaction to litmus ; and even if the solution 

 before precipitation be rendered a little alkaline to litmus, it will, after 

 precipitation, generally react slightly acid. The reason of this is clearly 

 that the sodium salt has a markedly alkaline reaction ; and this is further 

 shown to be the case by adding some of the washed silver-salt to a solu- 

 tion of potassium or sodium chloride, which it at once renders alkaline in 

 reaction to litmus. To obtain a solution of the salt free from acid or 

 caustic alkali, the original alkaline liquid is to be treated with acetic acid 

 in successive quantities until it just ceases to yield a brown precipitate with 

 silver nitrate. Such a solution will yield the yellow silver-salt with silver 

 nitrate as before, and also precipitates with the salts of most of the com- 

 mon metals. Instead of acetic acid dilute nitric acid may be used in this 

 method for thus neutralizing the caustic soda, with the same result as to 



