64 COMPOSITION OF AMERICAN WINES. 



pose carbonates, filtered, and the insoluble portion again burned, 

 extracted with dilute acetic acid, and again filtered. The insoluble 

 portion now contains calcium silicate and fluorid, while the filtrate 

 will contain as a calcium salt all the boric acid present. 



First method. l The filter containing the insoluble portion is again 

 incinerated, mixed with a little precipitated silica, and placed, with the 

 addition of 1 or 2 cc of concentrated sulphuric acid, in a short test tube, 

 which is attached to a small U-tube, containing a few drops of water. 

 The test tube is now placed in a beaker of water, which is kept hot on 

 the steam bath for a few minutes. If any fluorid be present the silicon 

 fluorid generated will be decomposed by the water in the U-tube and 

 will form a gelatinous deposit on the walls of the tube. 



The filtrate is now tested as directed under boric acid. If both 

 hydrochloric and boric acids be present, it is evident that they were 

 combined as borofluorid. If, however, silicon fluorid be detected and 

 not boric acid, the operation is repeated without the introduction of 

 the silica, in which case the formation of the silicon skeleton is con- 

 clusive of the presence of silicofluorid. 



/Second method. The filter containing the insoluble portion is again 

 incinerated in a platinum crucible, mixed with a little precipitated 

 silica, and 1 cc of concentrated sulphuric acid added. The crucible is 

 covered with a watch glass to whose underside a drop of water is sus- 

 pended, and heated an hour at the temperature of 70 or 80. The 

 silicon fluorid which is formed is decomposed by the water, leaving a 

 gelatinous deposit of silica. 



TABLES USED IN EXAMINATION OF WINES. 



The following tables are for use in the analysis of wines. For con- 

 venience of reference the tables are numbered: 



1 Neviere and Hubert, Mon. sci., 1895 [4], 9, 324, 



