Method of preparing Black Oxide of Mercurt/. 225 



the gray salt of Brouage : however, for this very reason 

 some people think it is advantageous to mix some of it with 

 that of Brouage, when the herrings are fat and oily. Some 

 use the salt brought back from Newfoundland. The reader 

 may see what we shall say of this salt in the Essay on Cod 

 Fish. Provided it be not old salt that fell from the heaps 

 of cod, it may do very well, particularly if care has been 

 taken to dry it well in the sun upon sails. 



The neighbouring nations use white Spanish and Portu- 

 guese salt, in which the English and Dutch carry on a con- 

 siderable trade. The greatest part of the salt used by the 

 northern nations is brought from St. Ubes in Portugal. 



This salt looks infinitely finer than that of Brouage, but 

 is of a much inferior quality ; and the Dutch, who know 

 this well, sometimes mix Brouage salt with Spanish or Por- 

 tuguese salt, which mixture is allowed to be preferable to 

 pure Brouage salt, when the fish is fat and oily ; and it is 

 said that it contributes to the superiority of the Dutch salt 

 herrings. This may be true : we shall see, hov/ever, in the 

 sequel, that the perfection of the Dutch herrings in general 

 is owing to the great care they take during the whole pro- 

 cess of curing them. 



In Holland all the salt to be used in curing herrings must 

 be examined, before it is embarked, by juries of the respec- 

 tive places, to show that it is of a good quality and clean. 

 The fishermen must get a certificate to this purpose, under 

 the penalty of paying a fine of twenty-five florins. 



Of the Barrels for Salt Herrings. 



There is an order in Holland that the barrels must bf 

 marked with the cooper's mark, and then examined in pub- 

 lic by juries, who reject such as are not of good wood, or 

 which might give a bad taste to the fish ; after which the 

 mark of the city is put upon them. There are also in 

 France many regulations relative to the size, condition of 

 barrels, &c, 



[To be continued.} 



XXXVIII. Improved Method of preparing Black Oxide of 

 Mercurt/. By M. Schulzk, of Kiel f» 



X HOUGH several methods have been proposed for pre- 

 paring black oxide of mercury since that substance wa^ 



* From Schcrer's AUgrmdncs Journal iLr Ctcmit', no. 47. 



Vol, XVII. No. 67. P used 



