Polytechnic Association Proceedings. 579 



an rwpeoved whitewash. 

 Dr. Jacobson has made a whitewash which is said, to be almost 

 as durable as paint, by dissolving fifty parts of glue into one hun- 

 dred and fifty parts of water, and adding two parts of caustic soda; 

 after boiling, a flocculent precipitate separates, which may, how- 

 ever, be disregarded. After the mixture has cooled, he adds fifty 

 parts of water-glass (sodemakit), and stirs in enough oxyd of zinc 

 (ztnoamat), to make it of the proper consistence for painting. Two 

 coats should be applied, and when diy, a solution containing ten 

 per cent of choloride of zinc (zincamed) should be laid on, which 

 gives it a beautiful gloss and great durability. It is well suited 

 for wood, metal or brick, but should be applied as soon as made, 

 for it cannot be kept long in the proper state. 



NEW DEVELOPER. 



Mr. H. T. Anthony, of this city, has given to photographers the 

 following recipe for a new developer: To a saturated solution of 

 iron, add, drop by di-op, a weak solution of tannin in alcohol, the 

 mixture soon assumes a blue color; add acetic acid until that color 

 disappears and afterward a few drops (about five to ten per ounce) 

 of a two-grain solution of gelatine; finally add as much acetic acid 

 as may be proper, Mr. Anthony has lately found that white 

 loaf-sugar may be substituted for the gelatine, and will produce 

 very brilliant negatives without the necessity of intensifying by 

 redevelopment or otherwise. The keeping quality of this developer 

 is said to be all that can be desired. 



ADULTERATION OF SAFFRON. 



At a late meeting of the Chicago College of Pharmacy, an inte- 

 resting examination was made of safii-on. All the samples exhibited 

 were proved to be adulterated, some containing as little as forty per 

 cent of genuine saffi'on. The latter yields, with sulphuric acid, a 

 bright purple color, while the adulterated becomes slightly brown. 

 The darker hue, as well as the characteristic aromatic, acrid safii'on 

 taste is hardly perceptible in the adulteration, which has an insipid 

 taste, owing probably, to the maceration or boiling resorted to, to 

 color it yellow. The latter seemed to have been done by means 

 of saffron. Our colleges of pharmacy, can render no higher ser- 

 vice to the whole community, than to continue the investigation 

 aiid exposure of adulterated drugs and medicines. 



Dr. Feuchtwanger said marigold flowers had long been used 

 to adulterate safl5.'on. 



