December, 1929
INDUSTRIAL AND ENGINEERING CHEMISTRY
The solvents and the extracts were tested against aphids (Mytus persicae Sulz.) on cabbages. Potted cabbage seedlings in the greenhouse harboring the aphids were sprayed from an atomizer of about 40 cc. capacity. The aim was to cover the leaf and stalk, as well as the surface of the soil. The spray material was usually a clear solution, but in some cases, those of the more difficultly soluble extractants, it was shaken up into an emulsion, without, however, the addition of an emulsifier, and applied as such. The number of aphids to each test ranged usually from 100 to 250, infesting two or three plants. Observations were made 24 hours later to determine the mortality of aphids. Among the aphids counted as dead are included the few insects repelled from the plants in the manner peculiar to pyrethrum. This number varied slightly, not with the extracts, but with the concentrations. A second examination to determine injury to the cabbage plant was made five days after the spraying. This injury is classed as slight, moderate, severe, or very severe. Slight injury is either faint spotting on the leaf or localized curling of the leaf edge. Moderate injury is more pronounced discoloration, often extending through the leaf tissue to form window-like spots. Severe injury is the crumpling or discoloration of whole leaves and wilting of stalks. Very severe injury is destruction of the plant. Plants injured to x slight or moderate extent made normal subsequent growth. Those severely injured made subnormal subsequent growth and were feeble. Where injury to the plants was severe enough to cause aphids to leave from lack of food it was difficult to determine the actual mortality. This was more pronounced when the injury appeared immediately after the spraying. The results of these tests are shown in Tables I1 and 111.
1253 Results
Methyl, ethyl isopropyl, normal butyl, secondary butyl, and tertiary butyl alcohols, as well as benzene, xylene, carbon tetrachloride, chloroform, ethylene dichloride, amylene dichloride, tetrachloroethylene, and diethyl carbonate, completely remove from pyrethrum the insecticidal principles effective against the aphid M y - u s persicae Sulz. Kormal and secondary butyl alcohols a t 10 per cent concentrations in water and benzene, carbon tetrachloride, ethylene dichloride, tetrachloroethylene, and diethyl carbonate a t 5 per cent concentrations in ethyl alcohol kill 50 per cent or more of these aphids without injury to cabbage. At 5 per cent concentrations all the extracts except xylene and amylene dichloride give effective control against Mytus persicae Sulz. without injury to cabbage. Normal and secondary butyl alcohols show markedly greater toxicity to these aphids than tertiary butyl and isopropyl alcohols, which, in turn, show markedly greater toxicity than methyl and ethyl alcohols. Roark and Cotton (2) found the butyl alcohols and isopropyl alcohol to be more toxic than methyl and ethyl alcohols, in the vapor phase, to rice weevils. If cost is taken into account, denatured ethyl alcohol appears to be the best of the solvents tried for extracting pyrethrum when the extract is to be diluted with water for application upon plants. There is no advantage in the extraction of pyrethrum with these solvents a t their boiling point temperatures over that a t room temperature. Literature Cited (1) McDonnell, Roark, LaForge, and Keenan, U S Dept Agr.. Bull 824 . (1926) (2) Roark and Cotton, U S Dept Agr , Tech Bull. 162 (In press).
Ratio of Fluorine to Phosphoric Acid in Phosphate Rock' D. S. Reynolds, K. D. Jacob, and W. L. Hill FERTILIZER AHD FIXEDNITROGEN INVESTIGATIONS, BUREAUOF CHEMISTRY AND SOILS,WASHINGTON, D. C.
I
N A recent paper Jacob and Reynolds (9) have s h o r n that
the commercial types of phosphate rock produced in the United States usually contain about 3.2 to 4 per cent fluorine. Results given by these writers indicate that an approximately constant ratio may exist between the fluorine and phosphoric acid in most of the domestic types of phosphate rock, the ratio, however, apparently varying somewhat with each type of rock. If a more or less definite ratio exists between the fluorine and phosphoric acid in a given type of phosphate rock, its determination will have a practical application in that it will permit the calculation of the approximate fluorine content of a sample of rock from its phosphoric acid content. The determination of fluorine requires special reagents and apparatus which are not always readily available, while the accurate determination of phosphoric acid is a comparatively simple operation requiring no special equipment. A careful investigation of the relation between the content of fluorine and of phosphoric acid would undoubtedly assist in deciding many uncertain points relating to the chemical composition, constitution, and origin of phosphate rock. Received August 9, 1929. Presented before the Division of Fertilizer Chemistry at the 78th Meeting of the American Chemical Society, Minneapolis, Minn., September 9 to 13, 1929. I
The present paper gives the results of a study of the fluorine-phosphoric acid ratios in the commercial types of phosphate rock now mined in the United States. Types of Phosphate Rock in United States
I n the order of their present commercial importance, the domestic types of phosphate rock are: Florida land-pebble (13, 15); Tennessee brown-rock (15); Florida hard-rock (13, 1 5 ) ; Tennessee blue-rock ( 1 5 ) ; the phosphates of Idaho, Montana, Utah, and Wyoming (11, 15); the soft and waste-pond phosphates of Florida (IS); and South Carolina phosphate (15). The general characteristics of the phosphates and the nature and extent of the deposits are discussed in the publications cited.2 The South Carolina deposits were formerly an important source of phosphate rock in the United States. Exploitatios of these deposits ceased, however, several years ago, owing t o the low grade of the rock and the cost of mining in competition with Florida land-pebble phosphate. As the name implies, Florida soft phosphate is a soft, clay-
* Statistics relating to the production of the different types of phosphate rock are given in "Mineral Resources of the United States," publishes annually by the U. S. Bureau of Mines, and in "The Mineral Industry," published annually by the McGraw-Hill Book Co.
1254
INDUSTRIAL AND ENGINEERING CHE:MISTRY
Vol. 21,
KO,
12
like material. It is nearly always closely associated with of fluorine, respectively, are both relatively low in phosphoric both the Florida land-pebble and hard-rock phosphates, but acid. In this respect Florida land-pebble differs from all it occurs to a greater extent in the hard-rock than in the land- other commercial domestic types of the hard phosphates, pebble deposits. Individual deposits of variable size are with the possible exception of South Carolina phosphate. found in both districts. During the process of preparing The average fluorine content of the twenty-two samples of Florida hard-rock phosphate for the market, the soft phos- commercial rock is 3.94 per cent, and this figure may be phate present in the matrix is washed into waste ponds, where taken as the approximate fluorine content of practically all it settles out along with the clay and other impurities, the the commercial grades of land-pebble phosphate produced a t finer particles concentrating a t points farthest from the en- the present time. The low fluorine-phosphoric acid ratio in trance to the ponds. sample 442, which is run-of-mine material, is due to the The "waste-pond'' phosphate and the soft phosphate from presence of the soft clay-like phosphates, which, in general, which it is derived are usually composed of very fine particles, have comparatively low ratios. a large percentage of which are colloidal in size ( I O ) . The HARD-ROCK PHOSPHATE-The results (Table 11) obtained abandoned waste ponds in the Florida hard-rock phosphate on nine samples of commercial hard-rock phosphate show district contain several million tons of this material, which is that the ratio of fluorine to phosphoric acid is approximately used to some extent as a fertilizer for direct application to the constant in this type of phosphate. The ratios vary from soil. The waste ponds in the Florida land-pebble district 0.1038 to 0.1124 with an average of 0.1083. contain a much smaller perS O F TA N D WASTE-POND c e n t a g e of finely divided P H 0 S P H A T E s-An a 1y S e S phosphates than those in the (Table 111)of three samples A study has been made of the fluorine-phosphoric hard-rock district. of n a t u r a l soft phosphate acid ratios in the domestic types of phosphate rock. and nine samples of wasteApproximately constant ratios exist in the different Analytical Methods p o n d phosphate, all from commercial grades of Florida hard-rock, Tennessee Unless stated otherwise, the Florida hard-rock disbrown- and blue-rock, and Western phosphates, the all the samples of phosphate trict, show that the ratio of ratios varying somewhat with the different types of rock were taken from matefluorine to phosphoric acid rock. The approximate fluorine content of samples of rial that had been prepared is n o t c o n s t a n t in these these types of phosphate may be calculated from their f o r c o m m e r c i a l use. A types of phosphate. The phosphoric acid content by the use of the ratios given number of the samples repratios vary from 0.0157 to in this paper. resented shipments of 30 to 0.0798 in the w a s t e - p o n d The fluorine-phosphoric acid ratio in Florida land5000 tons each and, in most phosphates and from 0.0417 pebble phosphate is not constant, but varies inversely cases, they were taken by to 0.1084 in the soft phoswith the phosphoric acid content. The percentages of means of automatic samphates. It should be noted, fluorine are very constant in the different grades of pling devices. however, that in two samthis type of phosphate. The volatilization method ples of the soft phosphate Figures are given on the fluorine-phosphoric acid as outlined by R e y n o l d s , the ratio is quite close to ratios in Florida soft and waste-pond phosphates, and Ross, and Jacob (14) was the average ratio for hardthe relation between the fluorine content and the geoused for the determination r o c k phosphate. O n t h e logical age of phosphate rock is discussed. of fluorine. This m e t h o d other hand, the ratios in all a c c o u n t s f o r a b o u t 93.5 the samples of waste-pond per cent of the f l u o r i n e phosphate are considerably present in phosphate rock. Consequently, all the figures for below the ratios found in any of the other domestic types of fluorine given in the tables are calculated to 100 per cent phosphate rock examined during this investigation. recovery on the basis of an actual recovery of 93.5 per cent of t o Phosphoric Acid in Florida Landthe fluorine in the moisture-free sample. The tabulated Table I-Ratio of Fluorine Pebble Phosphate figures are averages of two or more analyses checking within FLUORINE- LOCATION OF SAMPLE P20a FLUORINE P201RATIO DEPOSIT 0.10 per cent in all cases, and usually within less than 0.05 Per cent Per cent per cent. 442a 32.05 3.19 0 0995 Mulberry 567 30.52 3.86 Mulberry 0.1264 The phosphoric acid was determined by the gravimetric 618 31.06 Pierce 3.92 0.1262 method of the Association of Official Agricultural Chemists 617b 31.16 Brewster 4 01 0 1286 Brewster 615b 31.25 3.96 0.1267 (1). The figures given in the tables are the averages of two Nichols 619 31.29 3.98 0.1271 616b 3 1 , 3 5 4 . 0 8 0 , 1 3 0 1 Brewster or more analyses, checking within 0.15 per cent and are 790 31.40 3.97 0.1264 ,.... calculated to the moisture-free basis (105" to 110" C.). 4361, 31.42 3.91 0,1244 Mulbeiiy Mulberry Florida Phosphate Rock
LAND-PEBBLE PHOSPHATE-TWenty-three samples of landpebble phosphate were analyzed. The results (Table I) show that the ratio of fluorine to phosphoric acid is not even approximately constant in this type of phosphate. The ratios, excluding Sample 442, vary from 0.1090 to 0.1301 and decrease inversely with the phosphoric acid content. The fluorine content of the twenty-two samples of commercial rock is remarkably constant, the extreme figures differing by only 0.22 per cent, although the phosphoric acid content varies from 30.52 to 35.96 per cent. Furthermore, there is not the slightest tendency towards an increase in the fluorine content of the higher grades of rock. I n fact, the two samples containing the highest and the lowest percentages
437b 628b 620 568 438b 621 622 43Qb 627 440b 570 89s 441b 569
32.21 32.31 32.32 32.63 33.1s 33.27 33.56 33,62 33.70 34.64 35.50 35.59 35.63 35.96
3.94 3.97 3.92 3.97 3.90 3.96 3.96 3.87 3.90 3.88 3.95 3.95 3.93 3.92 3.94
0.1223 0,1228 0,1212 0.1216 0.1175 0.1190 0.1179 0,1151 0.1157 0.1120 0.1112 0.1109 0.1103 0,1090
Bartow Mulberry Nichols Mulberry Nichols h'ichols Mulberry Lakeland Mulberry Lakeland Mulberry Mulberry
Av. Run-of-mine material. b Sample representing large shipment. a
Tennessee Phosphate Rock
BROWN-ROCK PHOSPHATE-hlalySeS (Table Iv) Of Sixteen samples of Tennessee brown-rock phosphate show that an a p
December, 1929
I,VD UXTRIAL AND ENGINEERING CHEAVISTRY
proximately constant fluorine-phosphoric acid ratio exists in the various commercial grades of this type of phosphate, The ratios, excluding sample 585, which is run-of-mine material and contains considerable clay-like phosphate$,vary from 0.1064 to 0.1160, with an average of 0.1112. Soft claylike phosphates are always present in the Tennessee brown-rock deposits. They have not yet been investigated to any extent, but the comparatively low fluorine- phosphoric acid ratio in sample 585 indicates that in this respect they are similar to the Florida soft and waste-pond phosphates. T a b l e 11-Ratio
of F l u o r i n e t o P h o s p h o r i c Acid in F l o r i d a H a r d Rock Phosphate
FLCORINFI CALCD. AV.
FROM
FLUORISEFLUORIXESAMPLE 771 5905 5910 589a 434 5880 623a 6250 6240
PlO,
PZOS
FLUORIXE R.4TIO Per cent
PiOa Per cent 31.25 33.52 33.52 34,68 35.33 35.70 35.74 35.75 35.86
RATIO Per cent 3.38 3.63 3.53 3.76 3.83 3.87 3.87 3.87 3.88
3.35 3.48 3.77 3.79 3.76 3.86 3.93 3.95 3.85
0.1072 0.1038 0.1124 0.1093 0,1064 0,1081 0.1099 0.1104 0,1073 Av. 0.1083 a Sample representing large shipment.
LOCATION DEPOSIT
OF
.......
Benotis Inverness Floral City Dunnellon Floral City Hernando Dunnellon Dunnellon
1.23 3.33 3.79
826 581 828 727 827 726 825 824 725
15.19 18.18 19.41 21.63 22.29 23.4s 23.48 24,24 25.31
Western Phosphate Rock
The western phosphates are grouped into two general divisions based on their geological age (12). The deposits that are now being exploited in Idaho and Wyoming belong to the Permian epoch of the Carboniferous period. Phosphates belonging to the Mississippian epoch are found in certain parts of Utah. The phosphates of these epochs have not been divided into types, but it is probable that divisions could be made on the basis of general physical characteristics. For the purpose of the present paper the western phosphates are grouped according to the states in which the deposits occur. IDAHO PHOSPHATE-The average fluorine-phosphoric acid ratio in eight samples of Idaho phosphate rock (Table V) is 0.10i6, the ratios varying from 0.1051 to 0.1107. It will be noted that the average ratio is very close to the average ratio for Florida hard-rock phosphate. T a b l e V-Ratio
of F l u o r i n e t o P h o s p h o r i c Acid in W e s t e r n P h o s p h a t e
FLUORINE CALCD.
..........
0.0417 0,1047 0.1084
Juliette Gilchrist County
SAMPLE
P.06 PZOS FLUORINE RATIO
Per cent
Per cent
30.15 31.08 31.97 31.97 32.21 32.24 34.40 34.96
3.34 3.39 3.49 3.36 3.43 3.40 8.76 3.70 Av.
T a b l e IV-Ratio
0.0157 0.0571 0.0644 0.0665 0.0632 0.0771 0.0674 0.0614 0.0798
Dunnellon
..........
Hernando Dunnellon Dunnellon Herriando Dunnellon Dunnellon Juliette
of F l u o r i n e t o P h o s p h o r i c Acid in T e n n e s s e e Phosphate
FLUORIXE CALCD.
FROM
AV.
FLUORINEFLUORINE-
SAMPLE PZO6 Per cent
PZOS FI.UORINE RATIO P e r cent BROWN-ROCK
PlOS
RATIO
LOCATION OF DEPOSIT
Per cenl
PHOSPHATE
5855 573b 575b 587
...
25.74 29.40 29.90 30.17 31.34
2.62 3.22 3.32 3.24 3.56
0.1017 0.1095 0,1109 0,1073 0.1135
577b 5786 574b 564 566 586 762 584 565 774 583
31.57 32.37 32,80 32.85 33.30 33.62 33.73 34.18 34.80 35.01 37.51
3 48 3 60 3.49 3 62 3 72 3 89 3.87 3 78 3 94 4 02 4 08 Av.
0.1102 0.1112 0.1064 0.1102 0.1117 0.1160 0.1147 0.1105 0.1132 0.1148 0.1087 0.1112
571b 572b 772 5766 445 449
27.90 29.16 30.45 31.22 32.03 33.65
3:26 3.32 3.35 3.48 3.51 3.60 3.64 3.65 3.70 3.73 3.75 3.80 3.87 3.89 4.17
M t . Pleasant M t . Pleasant M t . Pleasant Wa!es Bur. Standards. standard sample 5fi Mt. Pleasant M t . Pleasant M t . Pleasant Wales M t . Pleasant M t . Pleasant M t . Pleasant M t . Pleasant M t . Pleasant Wales M t . Pleasant
BLUE-ROCK PHOSPHATE
Q
b
3.29 3.37 8.49 3.71 3.67 3.95 Av. Run-of-mine material. Sample representing large
0.1179 0.1155 0.1146 0.1188 0.1145 0.1173 0.1164
3.26 3.39 3.54 3.63 3.73 3.91
Gordonsburg Gordonsburg Glover Gordonsburg Gordonsburg Gordonsburg
shipment.
BLUE-ROCKPHOSPHATE-The ratio of fluorine to phosphoric acid in Tennessee blue-rock phosphate (Table IV) is quite constant in the six samples analyzed. The ratios vary
P2OS RATIO P e r cenl
LOCATION OF DEPOSIT
3.24 3.34 3.44 3.44 3.46 3.47 3.70 3.76
Montpelier Montpelier Georgetown Conda Paris Conda Paris Georgetown
3.11 3 37 3.48 3.48
Cokeville Cokeville Cokeville Cokeville
I D A H O PHOSPHATE
492 493 489 773 550 454 490 494
WASTE-POND PHOSPHATE
0.24 1.04 1.25 1.44 1.41 1.81 1.52 1.49 2.02
AV.
FLUORINEFLUORINB-
SOFT PHOSPHATE
29.49 31.80 34.94
from 0.1145 to 0.1188, with an average of 0.1164. I n general, the ratios are appreciably higher in blue-rock than in brownrock phosphate.
FROM
T a b l e 111-Ratio of F l u o r i n e t o P h o s p h o r i c Acid in W a s t e - P o n d P h o s p h a t e a n d S o f t P h o s p h a t e f r o m t h e Florida H a r d - R o c k Phosphate District FLUORINE-PZOS LOCATION OF SAMPLE PZOS FLUORINE RATIO DEPOSIT Per cent Per cent 580 728 443
1265
WYOMING
4670 491a 469. 468
26.60 28.84 29.75 29.79
3.10 3.39 3.51 3.44
0,1107 0.1090 0.1091 0.1051 0,1064 0.1064 0.1093 0.1058 0,1076 PHOSPHATB
0.1165 0.1175 0.1179 0,1156 Av. 0.1169 a Sample representing shipment of 30 tons.
WYOMIKGPHOSPHATE-^^ the four samples of phosphate from Cokeville, Wyo. (Table V), the fluorine-phosphoric acid ratio varies from 0.1156 to 0.1179. The average ratio, 0.1169, is very close to the average, 0.1164, found in Tennessee blue-rock phosphate, and is considerably higher than the average for the samples of Idaho phosphate. Except for color, the Idaho and Wyoming phosphates examined during this investigation seem to have approximately the same physical characteristics, the Idaho phosphates, in general, being a dark brown while the Wyoming phosphates are almost black. Referring to the results given in Tables 11, IV, and V, it is evident that, by the use of the average values for the fluorinephosphoric acid ratios, the fluorine content of the commercial grades of Florida hard-rock, Tennessee blue- and brown-rock, and western phosphate may be calculated directly from the phosphoric acid content with a fair degree of accuracy. In forty-two samples of these phosphates the fluorine content as calculated from the average fluorine-phosphoric acid ratios differs from the fluorine content as found by analysis, by an average of *0.06 per cent, the maximum deviations being $0.15 and -0.16 per cent, respectively. The fluorine-phosphoric acid ratios in the land-pebble, soft, and waste-pond phosphates of Florida vary so widely that the approximate fluorine content of these types of phosphate cannot be calculated from their phosphoric acid content. It should be noted, however, that in twenty-two samples of commercial grades of Florida land-pebble the average fluorine content is 3.94 per cent, as determined by analysis. The average deviation from the figure is only *0.035 per cent, the
INDUSTRIAL A N D ENGINEERING CHEMISTRY
1256
maximum deviations being +0.14 and -0.08 per cent fluorine, respectively. The relation of fluorine to the composition, constitution, and origin of the domestic types of phosphate rock is now being investigated in this bureau through the medium of chemical, microscopical, and x-ray studies. Miscellaneous Natural Phosphates
The fluorine-phosphoric acid ratios in several miscellaneous samples of natural phosphates are given in Table VI. The ratios in all the samples from the island deposits are considerably smaller than the ratios in the varieties of hard phosphate rock produced in the United States. The same is also true of the fossil materials from the Florida land-pebble phosphate deposits. of Fluorine to Phosphoric Acid in Miscellaneous Natural Phosohates FLUORINESAMFLUOR- PnOs LPE PsOa INE RATIO COMMENTS Per cent Per cent Table VI-Ratio
SOUTH CAROLINA PHOSPHATE ROCK
495 650
16.07 2 . 2 0 0.1367 Museum sample of land rock 28.86 3.43 0,1188 Museum sample of land rock ISLAND PHOSPHATE ROCK
450 451 452 943 8570
38.92 40.32 39.46 40 66 35.87
2.62 2.97 1.32 0.38 Trace
0.0673 0.0736 0,0334 0.0094
Commercial material from Nauru Island Commercial material from Ocean Island Commercial material from Christmas Island Commercial material from Curacao Island Commercial material from Connetable Island
633 646 647 648 649 905
39.88 39.63 39.77 38.58 40.86 40.30
3.88 3.84 3.89 4.24 3.44 3.26
0.0972 0.0969 0,0978 0,1099 0.0841 0.0809
Large crystal Renfrew Co. Ontario Large crystal: Renfrew Co.: Ontario Large crystal, Renfrew Co., Ontario Large crystal, St. Lawrence Co., N. Y. Crystalline material, Durango, Mexico Crystalline material, Quebec Province
. .. .
FLUORAPATITE
FOSSIL MATERIAL FROM FLORIDA LAhD-PEBBLE PHOSPHATE DEPOSITS
643 644 645
37.16 3 . 4 8 0.0936 Fish teeth 38.91 1 . 7 6 0.0452 Animal teeth 37.29 3.29 0,0882 Animal bones 0 Hydrated iron-aluminum phosphate containing Fez03 11.58, AhOs 28.48, and Hz0 at 105’ C., 17.02 per cent.
The writers were unable to obtain samples representing commercial shipments of South Carolina phosphate. The results given in Table VI were obtained on two museum specimens, one of which, Sample 650, is probably representative of the commercial material. The fluorine-phosphoric acid ratio, 0.1188, in this sample is close to the average ratios in Tennessee blue-rock and Wyoming phosphates. Fluorapatite is the most abundant and the most widely distributed of the crystalline phosphates. Although the formula 3Ca3(P04)2.CaF2 is usually ascribed to this mineral, Carnot (5, 6),and others (8) have shown that in many specimens the fluorine may be partially replaced by chlorine, oxygen, carbon dioxide, or the hydroxyl group, which would indicate that the fluorine-phosphoric acid ratios in samples of fluorapatite from different localities may vary widely from the theoretical ratio, 0.0891. This is borne out by the results (Table VI) obtained on six samples of fluorapatite from four localities, four of the samples containing more fluorine than corresponds to the fluorapatite formula. The other two samples, 649 and 905, contain less fluorine than corresponds to fluorapatite, but they contain 0.38 and 0.16 per cent chlorine equivalent to 0.20 and 0.086 per cent fluorine, respectively. Replacing the chlorine by fluorine, the fluorine-phosphoric acid ratios for samples 649 and 905 become 0.089 and 0.083, respectively. Qualitative tests showed that sample 905 also contained a small quantity of carbon dioxide. The commercial domestic types of hard phosphate rock, in general, contain considerably more fluorine than corresponds to the fluorapatite formula. Relation between Fluorine Content and Geological Age of Phosphate Rock
The fluorine in phosphate rock seems to be combined almost entirely in the form of complex fluorphosphates. Car-
Vol. 21, No. 12
not ( 4 , 7) advances the theory that these complex fluorphosphates are formed by reaction between the calcium phosphates and fluorine compounds dissolved in water, particularly sea water. Carnot’s theory is the most logical one that has been advanced to account for the high fluorine content of phosphate rock. On the basis of this theory it might be expected that some relation exists between the fluorinephosphoric acid ratios in the rock and the geological age of the deposits, since the process of formation of the complex fluorphosphates, in this manner, would probably be quite slow. The data given in Table VI1 show that in the domestic types of phosphate rock, older than the Quaternary period of the Cenozoic era, there is no considerable variation in the fluorine-phosphoric acid ratio, although there is a definite tendency toward higher ratios in the older types of rock. The peculiar nature of Florida land-pebble phosphate is again brought out by the fact that it shows a marked deviation from this general tendency. The high ratio for South Carolina phosphate is not conclusive evidence that this type is an exception, since only one sample was examined. Age a n d Fluorine-Phosphoric Acid Ratio of Natural Phosphates FI.UORrNE-PaO6 TYPEOF PHOSPHATE GEOLOGICAL Acg RATIO Fresh bird uano (2) A4 oderri < 0.40’X F Bones (3, 47 Modern 0 , 0 0 2 to 0.008 Cenozoic Era Curacao Island rock Quaternary period 0.0094 Christmas Island rock Quaternaiy period 0.0334 Nauru Island rock Quaternary period 0.0673 Ocean Island rock Quaternary period 0.0736 Tertiary period: Florida land-pebble Pliocene epoch 0,1090 to 0.1301 South Carolina rock Miocene epoch 0.1188 Florida hard-rock Oligocene epoch 0.1083 Paleozoic Era Carboniferous oeriod! ~ . ~ ~ ~ = ~ ~ -~ - - ~ Idaho rock Permian epoch 0.1076 Wyoming rock Permian epoch 0.1169 Tennessee blue-rock Devonian period 0.1164 Tennessee brown-rock Ordovician period 0.1112 Table VII-Geological
In the case of the island phosphate deposits, which are of comparatively recent origin and may be grouped together in the Quaternary period, the fluorine-phosphoric acid ratios vary considerably and are much lower than the ratios in the older types of continental phosphate. Carnot found no definite relation between the fluorine content and the geological age of phosphate rock ( 5 ) , but the fluorine content of fossil bones (3, 4 ) tended to increase with their age. The phosphate deposits of more recent origin seem to have been exposed to fluorine-bearing waters for an insufficient time t Q attain the maximum fluorine content. Acknowledgment
The writers wish to express their appreciation of the kindness of a number of phosphate mining companies, fertilizer manufacturers, and interested individuals who supplied the samples of phosphate rock used in this investigation. Literature Cited Assocn. O5cial Agr. Chem., Methods, p. 2 (1925). Braun, Chem. Ind., 19, 181 (1896). Carnot, Compt. rend., 111, 243 (1892). Carnot, A n n . mines, [SI S, 155 (1893). Carnot, Ibid., [9] 10, 137 (1896). Carnot, Comfit. rend., 12’2, 1375 (1896). Carnot, Ibid., 1’28, 724 (1896). Dana, “A System of Mineralogy,” p. 762, 1914. Jacob and Reynolds, J . Assocn. Oficial A g r . Chem., 11, 237 (1928). Jacob, Hill, and Holmes, Colloid Symposium Monograph, 1929. Mansfield and Girty, U. S. Geol. Survey, Professional Paper 162 (1927). Mansfield and Girty, Ibid., p. 208. Matson, U. S. Geol. Survey, Bull. 604 (1915). Reynolds,Ross, and Jacob, J. Assocn. Oficial Agr. Chem., 11, ZZS(l928). Waggaman and Easterwood, “Phosphoric Acid, Phosphates, an$ Phosphatic Fertilizers,” 1927.
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