432 Progress in Science . [July, 1876. 
bell and the plate after the combustion. Thus all the arsenic combined with 
the potash is dissolved, and not the oxides of chrome, copper, aluminium, and 
of tin and lead if present. This colourless solution, filtered, and mixed with 
sulphuric acid till a slight acid reaction is distinguished, is then introduced 
in f o a Marsh’s apparatus which has been submitted to a blank test, and found 
free from arsenic. 
It was observed by Kcechlin that woollen cloth dyed blue with indigo was 
notably decolourised by being allowed to freeze. This result, according to 
the experiments of Goppelsrceder, was due to ozone present in the air, which 
ads even at temperatures below o' 1 , but only when the tissue is wet. 
Cochineal reds on wool were decidedly impoverished by exposure to the 
adion of ozone for eight days, but were not discharged. Aniline-black was 
unchanged ; aniline-brown on cotton was turned an orange-yellow ; magenta, 
aniline-blues and violets, coralline, and iodine green were discharged, as were 
also lakes of the dye-woods, and even Turkey-red. Ozone is of great 
importance in the development of certain colours. Aniline-black, made up 
with hydrochlorate of aniline, sal-ammoniac, thickening, sulphide of copper, 
and chlorate of potash, was developed by the aid of ozone in i to hours. 
For the development of ozone on the large scale Goppelsrceder proposes 
Gramme’s machine, in which the eledric spark passes through a condudor 
repeatedly interrupted. The injurious effeds of frost upon alizarin paste, 
alumina, gelatin, cochineal lakes, mordanted tissues, &c., are well-known, but 
by no means thoroughly understood. 
MM. E. Fremy and PP. Deherain, in their researches on the sugar beet, 
show that saline solutions identical in composition ad very differently upon 
beets accordingly as the roots plunge into the solutions themselves, or as the 
latter merely occupy the pores of the soil. On planting beets of different 
origin in identical conditions as to soil, manure, and watering, roots are 
obtained differing in their yield of sugar. An excess of nitrogenous manure 
lowers the percentage of sugar in all beets, but those of a superior strain 
preserve still such a quantity of sugar that they may be advantageously 
treated. To produce from a given surface the maximum of sugar under 
conditions advantageous alike for grower and manufadurer, we must depend 
above all on a judicious seledion of the seed. 
