CHEMISTRY. 



147 



ion, li in common with other crops," depends 

 upon the soil for its supplies of nitrogen. The 

 mean composition of air-dried onions growing 

 on unraanured land was found to be: 



Water S94'S 



Com bustible matter (N = 2'37) 101 '0 



Ash 42 



Total 1,000-0 



The total nitrogen and mean composition of 

 ash show that an average crop of, say, eight 

 tons will remove from an acre : 



LU. I Lbs. 



X 42-48 PoO 5 10-88 



K..O 29-36 Cf. O'SO 



Na.,0 1 -v > S0 3 22-90 



CaO 6-52 SiOj VT2 



MtrO - 



Fe 2 3 0-30 Total 119'54 



The total sulphur in air-dried onions was 

 found to average O'Ool per cent. 



The presence of aluminum was supposed to 

 be peculiar to Lycopodium among plants; but 

 Prof. Church has found traces of it in the ash- 

 es of many other plants. It occurs in all the 

 species of Lycopodium which were examined, 

 except those which are of epiphytic habit, but 

 not in the allied genus Selaginella ; and in the 

 ashes of some but not all tree-ferns, in large 

 proportions. 



Domestic Chemistry. The results of observa- 

 tions of the effect of free carbonic acid in po- 

 table water on leaden pipes have been summa- 

 rized by E. Reichardt. Only water containing 

 free carbonic acid has been found to attack the 

 pipes. The view that lead pipes conducting 

 such water become incrusted gradually, and 

 thereby capable of resisting corrosion, has not 

 been proved. Except with hard waters hold- 

 ing much lime, no deposit has been observed, 

 even after years of use. Mountain spring* do 

 not usually contain more than enough free car- 

 bonic acid to dissolve the monocarbonate of 

 lime present, often hardly enough to form bi- 

 carbonate ; but sometimes waters holding much 

 lime in solution have more. Experiments thus 

 far show that these spring-waters do not attack 

 lead in more than the most minute degree. 

 River- waters more frequently contain free car- 

 bonic acid than spring-waters, but in far small- 

 er quantity. It has thus far been found that 

 waters containing bicarbonates do not attack 

 lead, and even free carbonic acid, in small 

 quantities, is without effect in the presence of 

 much lime and magnesia. But the less min- 

 eral matter a water contains, or the " softer " it 

 is, the more readily is lead dissolved. Distilled 

 or carbonic-acid-free water dissolves lead slow- 

 ly with separation of oxyhydrate : distilled wa- 

 ter holding carbonic acid in solution dissolves 

 lead in much larger quantity, with a separation 

 of basic lead carbonate, which can be very 

 complete. Water to be conducted through lead 

 pipes should, under all circumstances, be ex- 

 amined for free carbonic acid and the amount 

 determined. Its action on lead plates should 

 also be noted. 



In the experiments of J. H. Long, made in 



July and August. 1886, to determine the rate 

 of oxidation or destruction of the sewage of 

 the city of Chicago, which is carried through 

 the Illinois and Michigan Canal to the Illinois 

 river, examinations were made of the dilute 

 sewage at the point (Bridgeport) where it is 

 pumped into the canal, and of specimens of the 

 water taken on the same day at stations select- 

 ed at intervals through a distance of 159 miles, 

 in which a total descent of 1,467 feet occurs. 

 The conditions of the tests were variously 

 complicated at the several stations, so that no 

 absolute result was possible ; but the experi- 

 ment as a whole was interpreted as showing "in 

 a fair and unmistakable way the general fact 

 of the gradual purification of a highly contami- 

 nated water by what may be broadly termed 

 oxidation " ; and importance is claimed for the 

 investigations " as showing pretty fully the 

 rate at which a city's sewage is destroyed un- 

 der certain conditions of temperature, dilution, 

 and velocity of flow." Investigations were also 

 made in the succeeding winter December, 

 January, and February to ascertain the effect 

 of cold. The results were marked by perplex- 

 ing irregularities, but tended to show a slow 

 rate of change at that season. 



Prof. Atwater has published seme of the 

 results of his analyses of the flesh of American 

 in tables which give severally the proxi- 

 mate ingredients, as directly determined, of 

 the flesh, and of the water-free substance of 

 the flesh ; the percentages of phosphoric acid, 

 sulphuric acid, and chlorine in the flesh ; classi- 

 fication of fish by percentages of flesh, chiefly 

 muscular tissue, in the entire body ; classifica- 

 tion by proportions of water-free substance in 

 the flesh ; classification by proportions of fat in 

 the flesh ; composition of water-free substance 

 in flesh of preserved fish ; composition of flesh 

 in preserved fish; and composition, including 

 both flesh and refuse. Other analyses have been 

 reported of cod by Prof. Chittenden, and of 

 menhaden by Prof. G. H. Cook : comparisons of 

 the groupings made by the author according to 

 the percentages of the different classes of con- 

 stituents with the classification by families as 

 practiced by ichthyologists, show no very defi- 

 nite connection between the two. In the analy- 

 ses of preserved fishes, the replacement of the 

 water in the flesh by salt is remarked upon as 

 a matter of physiological inter. 



As a simple and inexpensive freezing-mixt- 

 ure, J. A. Baohman has used the spent nitro- 

 sulphuric-acid mixture which had been em- 

 ployed in a Grove battery, with snow. At tem- 

 peratures of about zero Centigrade, this acid, 

 with various proportions of snow, gave a fall of 

 from thirty to thirty-two degrees of tempera- 

 ture, or nearly the same as that obtained when 

 simple hydrochloric acid is employed. As there 

 Avas so little difference in the result when the 

 enow was used within considerably wide limits 

 of proportion, it was found most satisfactory to 

 mix the snow with the acid until it reached the 

 consistency of a thin mush, dispensing with 



