366 APPENDIX 



of alcohol and pour the rinsings in the bottle; then add 

 alcohol, shaking occasionally until the iodin and potassium 

 iodid are all dissolved and the finished tincture measures 

 1000 c.c. 



SOLUTIONS FOR CLEANING GLASSWARE 

 Chromic acid cleaning solution for cleaning glassware: 



Potassium or sodium dichromate 60 gms. 



Commercial sulphuric acid 60 c.c. 



Water 1000 c.c. 



Prepare in a flask resistant to heat, never in a heavy 

 glass jar. 



Add the potassium dichromate to about 500 c.c. water; 

 shake well and add the sulphuric acid gradually, continually 

 shaking with a rotary motion. The remaining water may 

 then be added. The potassium dichromate should be all 

 dissolved before using the solution. 



This solution may be used repeatedly until oxidized 

 to a dark green color. Heat will hasten its action. 



Chromic acid cleaning solution is especially valuable 

 for removing traces of oxidizable organic matter and neu- 

 tralizing ' any free alkali adhering to glassware. However, 

 effort should be made to previously remove as much extrane- 

 ous matter as possible with water and a suitable brush 

 before treating with this solution. This will economize 

 time. 



Caution. This solution contains sufficient sulphuric acid 

 to destroy fabrics, bristles of brushes, and corrodes metal 

 quickly. For this reason neither cloth nor brushes should 

 be used as an immediate aid to this cleaning agent, nor 

 should this solution be placed in agateware utensils if the 

 enamel is chipped, exposing the metal. 



If this solution is used cold, leave the glassware contain-^ 

 ing it, over night on top of desk, never inside of desk. 



