T H E J O U R N A L OF I N D U S T R I A L A N D EIVGI~VEERIA-GC H E . I I I S T R Y .
328
2 . Samples separated in the laboratory from the milk collected by the inspectors of the department (recorded with a circle). 3. Commercial samples found free from cane sugar by the Baier and Neumann test1 and also found free from preservatives (recorded with a triangle). I n making the analyses the fat was determined by the Babcock method and the calcium, and also the alkalinity of the ash, a s follows : Weigh 2 5 grams of cream into a platinum dish, place in a n oven a t about 125-15oO C. over night and b u m t o a n ash in a muffle a t a low red heat. Dissolve the ash in 2 0 cc. N / I O sulphuric acid, boil to expel the carbon dioxide and titrate back with N/ IO sodium hydroxide, using phenolphthalein as the indicator. Express results as cc. N / I O acid required t o neutralize the ash of IOO grams of cream. Make the final solution of the above determination acid with acetic acid, heat to boiling, add I gram of sodium acetate, and t o the clear solution add a n excess of ammonium oxalate, boil for a few minutes, filter and wash with water. Dissolve the calcium oxalate in hot dilute sulphuric acid and titrate hot with N / I O potassium permanganate. cc. N / I O permanganate multiplied by 0 . 0 1 1 2 (41x 0.0028) gives the percentage of CaO in the sample.
July, 1910
For example, if a quantity of calcium sucrate sufficient to thicken were added to a sample of cream having 30 per cent. fat and 0.085 per cent. calcium oxide, the calcium would be increased to about 0 . 1 1 per cent. or 0 . 1 3 per cent., or less than 0.144 per cent., which is the maximum amount which could be present in natural cream: The fcllowing table shows the maximum amount of calcium oxide corresponding to the fat content in pure cream: Maximum Fat. Per cent. 15 16 17 18 19 20 21 22 23 24
CaO.
Per cent. 0.181
SIaximum Fat. Per cent.
0.178
0.175 0.173 0,171 0.169 0.166 0.164 0.161 0.158
CaO.
25
Per cent. 0.1.56
26 27 28 29 30 31 32 33 34
0.151 0.149 0.146 0.144 0.141 0.139 0 137 0.134
0.154
Fat. Per cent. 35 36 37 38 39 40 41 42 43 44
Axaximum CaO. Per cent. 0,132 0.129 0,127 0.124 0.122 0.120
0.118 0.115 0.113 0.110
Fat. Per cent. 45 46 47 48 49 50 51 52 53 54
Maximum CaO. Per cent. 0,108 0.106 0.103 0.100 0.098 0.096 0.093 0.090 0.088 0 . ~ 8 5
FURTHER STUDIES O F THE REACTIONS OF LIMESULFUR SOLUTION AND ALKALI WATERS ON LEAD ARSENATES. I3y C.
E. BRADLEYAND H. V. TARTAR. Received April 18, 1910.
caO% 0.20
0.19 0.18 0.17
0.16 0.lj
0.14 0.13 0.17.
0.11 0.10
0.09 0.08 0.07
5
IO
15
20
30 F a t %.
25
3j
40
45
j0
j5
It will be seen from the plot that most of the known purity samples and those separated in the laboratory were relatively higher in calcium than the commercial samples. This is probably due to the fact that commercial cream is, as a rule, pasteurized, or is made from pasteurized milk. It is a well-known fact that pasteurizing milk renders some of the calcium insoluble, and experiments made in this laboratory show t h a t cream of the same fat content made from the same milk, part of which has been heated, will contain less calcium in the heated portion. The presence of calcium in less quantity than that shown by the maximum figures does not necessarily mean that the sample is free from calcium sucrate. 12.Nohr.-Genussm., 16, 51.
It was shown by us1 that only very small quantities of arsenic were rendered soluble on mixing a neutral lead arsenate and commercial lime-sulfur in a combined spray. More recently we have noticed that the residue from the mixture of a n acid arsenate was much darker in color than that from the neutral indicating that considerable decomposition or interreaction had taken place in the former instance. It was thought advisable, therefore, to make a comparati\-e study of the reactions taking place and the product formed when either the acid or neutral arsenate of lead is mixed with the lime-sulfur solution under spraying conditions X sample of Niagara lime-sulfur having a specific gravity of 32’ B. was selected for the tests. Bean’s ortho arsenate of lead was taken as a representative of the neutral and Hemingway’s arsenate as a type of the acid arsenate. Analysis in our laboratory had shown these arsenates t o have the following composition : LEAD ARSENATES. Hemingway’s. Per cent. Moisture., . . . . , , . , . , . . , , , . . . . 32.46 Total PbO., , , , , . , , , . . . , . , 42.64 Total Asnos.. . . . . , . . . . , . . . . . 21.45 0.31 Soluble AszO5. . , , . . , . . . 0.93 Soluble impurities. . . . . C03lPCSITION O F
.
. .. . . . ... . .. . . . . .. . . Total. . . , . , . . . . . . . , . . . . . . . ,
~
97.48
Bean’s. Per cent 41.68 42.19 13.47 0.10 1.60
98.94
The arsenates were in each instance added in the proportion of four pounds of the moist arsenate t o 1
THISJOURNAL. 1, 8,610.
SUTHERST ON T H E EFFECT OF GYPSUAW O X A L K A L I I S S O I L S . one hundred gallons of the lime-sulfur diluted I to 30. The mixtures were agitated occasionally for twenty-four hours, then filtered and the residue washed and dried a t Soo C., then a t 100’. The residue from the acid arsenate was very dark in color from the lead sulfid present, while t h a t from the neutral was gray, indicating but slight decomposition. A partial analysis of the filtrate from each arsenate gave results as follows, a blank consisting of untreated lime-sulfur being run for comparison : COMPOSITION
OF THE
LIME-SULFUR SOLUTION BEFORE LEADARSENATE.
AND AFTER
ADDI-
TION O F
Grams per 1000 cc. Filtrate from Filtrate from acid arsenate neutral arsenate Blank and limeand limelime-sulfur. sulfur. sulfur. 10,750 10.256 4.380 4.060 0,095 0.012
......... ....... ...............
Total S.. Total CaO.. AseOs..
... ...
The above results indicate that eight times as much arsenic is rendered soluble from the acid arsenate a s from the neutral, or calculated to the original material this would be equivalent to 0.25 per cent. of soluble As,O, from the neutral and 1.98 per cent. from the acid. Distinct losses of sulfur and lime have also taken place in the acid arsenate mixture and it is evident t h a t there is a mutual decomposition when lead acid arsenate is mixed with the limesulfur solution. Analysis of the dried residues gives further evidence of the breaking down of the acid arsenate under these conditions : ANALYSIS OF
THE
Free S. PbS CaO.
RESIDUE FROM THE MIXTURE O F L I M E - S U L F U R AND LEADARSENATE. Neutral arsenate Acid arsenate residue. residue. Per cent. Per cent.
.......................
0.70
.......................... 1.47 .............................
20.80 14.80 10.40
Sulfur was determined by extracting the dry residue with CS,; the lead sulfid b y extracting the remaining residue with HNO, I : I O ; the lime by precipitation as oxalate after removing lead and arsenic with hydrogen sulfid. A study of the reactions involved in the above mixtures indicates t h a t there is a partial interchange of the lime and lead resulting in the formation of calcium arsenate and lead sulfid respectively, free sulfur being a t the same time deposited. The soluble arsenic is then derived from partial solution of the calcium arsenate thus formed. Sulfids of arsenic are not formed, as these sulfids are soluble in the alkaline lime-sulfur forming sulpho salts, and sulpho salts are not present in the solution. The reactions as shown above are much more pronounced with the acid than with the neutral arsenate and i t is therefore advisable to employ the neutral form when desiring t o combine lime-sulfur and lead arsenate. Having found t h a t the alkaline lime-sulfur solution
329
reacts quite readily with the acid lead arsenate, the tests were extended to determine the comparative solvent action of alkaline and saline waters on these arsenates. Haedden has stated‘ that lead arsenate is more soluble in waters containing alkali salts than in normal water. I n the tests which are reported in the succeeding table a quantity of the moist arsenate, equivalent to ten grams of the dry arsenate, was treated in each case with two liters of solution, except in case of the CO, test, in which two grams of the moist arsenate were used. The solutions were kept a t room temperature (about 17’ C.) for twentyfour hours with occasional shaking, then filtered and the filtrate analyzed for soluble arsenic by the modified method of Gooch and Browning,’ 500 cc. equivalent to 2 . 5 grams of the arsenate being used in each determination. The alkali water used in the tests was the extract from a natural alkali incrustation containing 50 per cent. Na,SO,, 18 per cent. NaC1, 13 per cent. Na,CO,, and 2 per cent. NaHCO,. The arsenic is reported as per cent. of the original material : SOLUBLE
ARSESIC PENTOXIDE
FROM
NEUTRAL
AND
ACID LEADARSENATES.
Bean’s ortho arsenate. Sol. As23j. Per cent. of moist arsenate. 0.073 C 0 2 for two
Solution used. Distilled water.. Distilled water hours.. ... . : 0 . 2 3 per cent. NaCl, 0.46 per cent. CaCI,. 0 . 1 0 per cent. Nag304.. . . . . . . . . Alkali water, 40 grains to gal..
............... +
...............
Hemingway’s acid arsenate. Sol. Asz06. Per cent. of moist arsenate. 0.108
0.125
...
................ 0.201
0 310
0.106 0,536
0.155 1.833
...
It appears from the above resuLts that both forms of the lead arsenate are more soluble in saline waters than in pure waters. Alkaline carbonate waters especially exert a solvent action on these arsenates and the reaction is much more pronounced in the case of the acid arsenate. This is perhaps due t o the fact that lead carbonate is extremely insoluble and t h a t a base with which arsenic forms a soluble salt is present. It is evident t h a t waters containing considerable quantities of alkali carbonates should be avoided in mixing lead arsenate for spraying purposes, as their tendency is to render the arsenic soluble. Tests for lead in the alkaline solutions failed to show its presence therein. AGRICULTURAL EXPERIMEST STATION, ~ C O R V A L L IOREGON. S,
THE EFFECT O F GYPSUM ON ALKALI IN SOILS. B y W. F. SUTHERST. PH.D.. F.I.C. Received April 14. 1910.
One of the remedies suggested for the removal of “alkali” from the soil is to add gypsum, whereby the morezdetrimental ingredient is supposed to be 2
Bull. 131, Col. Exp. S t a . Lac. cit.
