&lay, 1916
T H E J O C R Y A L OF I N D C S T R I A L A N D ENGINEERIXG CHEMISTRY
all calculations, a considerably greater accuracy was maintained. I n t h e case of Vc, however, a certain amount of difficulty arises. Vc represents approximately 9 j t o I O O per cent of V . T o maintain the desired final accuracy, requires t h a t F. No. I be obtained with an accuracy corresponding t o a maximum error of approximately onet e n t h of one per cent, and consequently t h a t Fig. I be plotted on a scale capable of reading to this degree of accuracy. While such a scale is quite possible, it is quite inconvenient and t h e writer would recommend in cases where extreme accuracy is desired t h a t t h e value F. No. I be determined from t h e table for “Determination of Areas of Circular Segments” given in Kent’s ‘‘ hTechanica1 Engineering Handbook,” page I z I. The factor under t h e heading “Area” represents t h e desired value F. S o . I and is given t o very great accuracy. I n general, however, t h e above Fig. I plotted o n scale 0.1t o t h e inch is sufficiently accurate for most manufacturing calculations. 17
T H E BARRETTCOMPAXY NEW YORK
BATTERY PLACE,
THE UNIT OF VISCOSITY MEASUREMENT By P B R K B R
c. MCILHINEY
Received March 1, 1916
The scientific world expresses the results of measurement of viscosity in terms of absolute viscosity of which the units are directly related to t h e fundamental units of mass, length, and time. The practical world speaks of Saybolt seconds, Engler numbers, etc. The absolute C. G. S. unit of viscosity is a relatively large one so t h a t water a n d similar liquids have absolute viscosities which are inconveniently small numbers, and furthermore, without giving it a name it is impracticable t o use such a unit in commercial testing. Many people have t h e idea t h a t absolute viscosities cannot be determined except when t h e viscosity is deduced from the absolute dimensions of t h e instrument and t h a t t h e practical instruments are not adapted t o determine absolute results. The fact is t h a t there are many practical methods by which viscosity may be measured, some of them better t h a n others, all of them subject t o disadvantages which differ according t.o the circumstances of their use, but all of t h e m giving results capable of being translated into t h e common language of absolute viscosity. The study of this important physical property of liquids has been seriously hampered by t h e lack of any kind of uniformity in its measurement. The principal use which is made of viscosity measurements to-day is in the case of lubricating oils, but their use is not more widely extended because workers in different countries with different kinds of instruments think they are unable t o obtain anything by their work but results of merely personal interest. Few of them know how t o translate t h e results which they obtain into results comparable with those obtained with another instrument. This state of affairs would be radically improved if there were some unit of measurement of viscosity which was generally intelligible and in which t h e results of any determination with any instrument might
433
be expressed. The absolute unit as already mentioned is inconveniently large and i t has no name. The suggestion has been made b y Deeley a n d Parr’ t h a t t h e unit of viscosity expressed in C. G. S. units should be called t h e “poise” in honor of Poiseuille, but t h e suggestion has not been adopted generally and it is customary t o simply speak of t h e “absolute” viscosity of a liquid. If t h e “poise” is adopted as t h e name of t h e absolute unit, i t has been suggested t h a t we might use t h e decimal multiples and submultiples of this c p = 0.01 9unit, a n d t h a t then t h e centipoise-1 would be almost exactly t h e viscosity of water a t 2 0 ’ C. or 68” F. Thus for all practical purposes in t h e lubricating oil business, i t would be sufficiently near t h e t r u t h t o say t h a t the viscosity expressed in centipoises is t h e specific viscosity, t h a t is, the viscosity as compared with water a t 2 0 ’ C. or 68” F. as a standard liquid. There are, as is well known, a Gariety of instruments with which t h e viscosity of liquids generally may be determined. There are three of these instruments which are in commercial use largely for the examination of lubricating oils, namely, t h e Saybolt Universal, t h e Engler, and t h e Redwood. All three of these instruments are capable, as shown by t h e work done a t t h e Bureau of Standards in of determining t h e viscosity of oils with t h e accuracy usually required in present-day industrial testing. In these instruments, t h e number of seconds required for a given amount of oil t o flow through a small tube or orifice in t h e instrument is measured. Tables have been prepared by t h e use of which the true viscosity may be calculated from the number of seconds required for any one of these three instruments. If these tables could be brought into general use, a determination of t h e number of seconds required by the Saybolt Universal, Engler, and Redwood instruments would be reported in terms of centipoises. If the centipoise is used as a unit, t h e figure obtained will be 1.0042 for water a n d a larger number for all oils, a n d t h e number will represent t h e t r u e relation between t h e viscosity of the oil examined and t h a t of water with sufficient accuracy for commercial purposes, and also t h e true or absolute viscosity. I n scientific work, t h e use either of absolute viscosity expressed in C. G. S. units or o f - t h e centipoise for convenience, will enable t h e workers in all t h e different fields in which viscosity may be determined, t o express their results in a universal language and the result will certainly be t h a t t h e use of viscosity as a valuable physical property will no longer be confined practically t o oils b u t will be extended t o many other lines of work. If, for example, t h e instrument recently described by MacMichae13 should prove serviceable in many fields, investigations in viscosity can be carried on with i t upon materials for which i t is adapted a n d t h e results readily compared with those “The Viscosity of Glacier Ice.” Phil. M a g . , [6] a6 (1913). 8 5 . Dr. C. W. Waidner, “Conversion Tables for Saybolt Universal, Engler, and Redwood Viscosimeters,” Proc. A n . SOL.Test. A!fal.. 15 (1915). 1
2
284. 3
R. F. MacMichael, “ A New Direct-Reading Viscosimeter,” THIS 7 (19151, 961.
JOURNAL,
T H E JOLTRXAL OF I X D G S T R I A L A S D EA7GIXEERISG C H E M I S T R Y
434
obtained by a n y other worker using a different form of apparatus. In order t o facilitate such comparisons as well as t o assist in t h e introduction of a uniform method of expressing results throughout the \\Torld, it would Uncorr. Uncorr. SECONDS viscosity SECONDS viscosity in in Engler Say- Red-' centiEngler Say- Red- centiNO. bolt wood poises wood poises N o . bolt
..
.. .. ,.
.. ..
.. .. .. .. ..
.. .. ..
2:oo 2.02 2.05 2.08 2.10 2.12 2.14 2 1; 2.20 2.21 2.24 2.27 2.29 2.31 2.34 2.36 2.39 2.41 2.44 2.46 2.49 2.51 2.54 2.56 2.59 2.60 2.63 2.66 2.69 2.70 2.73 2.76 2.78 2.80 2.82 2.85 2.88 2.90 2.93 2.96 2.98 3.01 3.04 3.02 3.05 3.08 3.11 3.13 3.16 3.19 3.21 3.24 3.27 3.29 3.32 3.35 3.38 3.41 3.43 3.46 3.48 3.51 3.54 3.57 3.59 3.62 3.65 3.68 3.70 3.73 3.74 3.77 3.79
. , .
... , . .
,..
... , .
... ... ... . .
... ... ... ...
...
... ... ... ...
...
... ... ...
..
.. ..
..
.. ..
... , .
... ... ... ,..
. . ~
...
.. ..
..
.. ... 67,s 59.2 i i 15 59.8 11.7 69 6 0 . I 12.0 70 61.7 12.2 71 62.4 12.4 72 63.0 12.2 73 63.8 12.) 74 64.7 13.1 75 65.8 13.2 76 66.2 13.4 77 67.1 13.6 78 68.1 13.8 79 68.7 14.0 80 69.4 14.2 81 70.3 14.4 82 71.0 14.6 83 14.9 71 .: 84 72.f 15.0 85 15.3 73.6 86 74.3 15.4 87 15 i 75.2 88 75.9 15.9 89 76.8 16,l 90 77.6 16.3 91 78.5 16.5 92 78.8 16.6 93 79.7 16.8 94 80.6 17.0 95 81.5 17.4 96 81.8 17.6 97 82.9 17.7 98 83.9 17.9 99 84.5 18.1 100 85.1 18.2 101 85,7 18.4 102 86.6 18.6 103 87.6 18.9 104 88.2 19.1 105 106 89.2 19.3 90.3 19.5 107 90.9 19.7 108 92.1 19.9 109 110 93.0 20.2 111 92.4 20.0 93.3 20.3 112 94.2 20.5 113 114 95.2 20.7 95.8 20.9 115 116 96.7 21.1 117 97.6 21.4 98.2 21.5 118 119 99.1 21.8 100.4 22.0 120 101 .o 22.1 121 101.9 22.4 122 102.8 22.6 123 103.8 22.9 124 104.7 23,l 125 105.3 23.1 126 106.2 23.4 127 106.8 23.7 128 108.I 23.7 129 109.0 24.0 130 110.0 24.3 131 110.6 24.4 132 111.5 24.7 133 112.4 25 . o 134 113.3 25 2 135 114.0 25.3 136 114.9 25.6 I37 115.1 25.6 138 116.5 2.5, 8 I39 117.1 25.9 I40
...
...
3.82 3.85 3.88 3.91 3.93 3.96 3.98 4.00 4.02 4.05 4.08 4.10 4.13 4.16 4.18 4.21 4.24 4.27 4.29 4.32 4.35 4.37 4.40 4.43 4.45 4.48 4.47 4.50 4.53 4.55 4.58 4.61 4.63 4.66 4.69 4.71 4.74 4.77 4.79 4.82 4.85 4.87 4.91 4.93 4.95 4.98 5.00 5.02 5.05 5.08 5.10 5.13 5.16 5.18 5.21 5.24 5.26 5.29 5.32 5.34 5.37 5.40 5.42 5.45 5.48 5.50 5.52 5.55 5.58 5.61 5.63 5.66 5.68 5.71 5.74 5.76 5.79 5.82 5,84 5 ,87 5.90
5.92 5.95 5.98 6.00 6.03 6.05 6.08 6 .I O 6.13
141 118.0 26.2 142 119.0 26.5 143 119.9 26.8 144 120.8 26.9 145 121.4 27.1 146 122.4 27.3 147 123.0 27.4 148 123.6 27.6 149 125.0 27.7 150 126.0 28.0 151 126.9 28.3 152 127.5 28.4 153 128.4 28.6 154 129.4 28.9 155 130.0 29.1 156 130.9 29.3 157 131.9 29.5 158 132.8 29.8 1.59 133.4 29.9 160 134.4 30.2 161 135.3 30.4 162 135.9 30.5 163 136.8 30.8 164 137.8 30.9 165 138.4 31.1 166 139.3 31.3 167 139.0 31.3 168 140.0 31.5 I69 141.1 31.8 170 141.7 31.9 171 142.7 32.2 172 143.6 32.4 173 144.2 32.5 174 145.2 32.7 175 146.I 33.0 176 146.2 33.1 1 7 7 147.I 33.3 178 148.6 33.6 179 149.2 33.8 I80 150.1 34.0 181 151.1 34.2 182 151.7 34.3 183 152.9 34.7 184 153.6 34.8 185 154.2 35.0 186 155.1 35.2 187 156.0 35.3 188 156.6 35.5 189 157.6 35.7 190 158.5 35.9 191 159.1 36.1 192 160.1 36.3 193 161 . O 36.5 194 161.6 36.i 195 162.6 36.9 196 163.5 37.1 197 164.1 37.3 198 165.0 37.7 199 166.0 37.7 200 166.6 37.9 201 167.5 38.1 202 168.5 38.4 203 169.1 38.5 204 1,o.o 38.7 205 171.0 38.9 206 171.9 39.I 207 172.5 39.3 208 173.4 39.5 209 174.4 39.7 210 175.3 39.9 211 175.9 40.1 212 176.9 40.3 213 177.5 40.4 214 178.4 40.7 215 179,4 40.9 216 180.0 41.0 217 180.9 41.2 218 181 .9 41.5 219 182.5 41.7 220 183.4 41 9 221 184.4 42.1 222 185.0 42.3 223 185 9 42.6 224 186.9 42.8 225 187.8 42 8 226 188 i 43.0 227 189.4 43.2 228 190 3 43.5 229 190.9 43.7 230 191 9 43.9
bring t o the attention of those who are engaged 171 a n y kind of viscosity determinations the desirability of expressing all their results in terms of either t h e centipoise or the poise. The accompanying tables have been prepared as
_---
Uncorr.
SECOXDS viscosity
Engler Say- RedNo. bolt wood
in centiooises
6.16 6.18 6.21 6.24 6.27 6.29 6.32 6.34 6.37 6.40 6.42 6.45 6.48 6.51 6.53 6.56 6.59 6.61 6.64 6.67 6.69 6.72 6.75 6.77 6.80 6.83 6.85 '6.89 6.91 6.93 6.96 6.99 7.01 7.04 7.07 7.09 7.12 7.15 7.17 7.20 7.23 7.25 7.28 7.31 7.33 7.36 7.39 7.41 z.44 I .47 7.49 7.52 7.55 7.57 7.60 7.63 7.65 7.68 7.71 7.73 7.76 7.79 7.81 7.84 7.87 7.89 7.92 7.95 7.97 8.00 8.03 8.05 8.08 8.11 8.13 8.16 8.19 8.21 8.24 8.27 8.29 8.32 8.35 8.37 8,40 8.43 8.45 8.48 8.51 8.53
44.1 44.2 44.5 44.7 44.9 45.0 45.3 45.4 45.6 45.8 46.0 46.2 46.4 46.6 46.8 47.0 47.2 47.4 47.6 47.9 48.1 48.3 48.5 48.7 48.9 49.0 49.2 49.5 49.7 49.8 50.0 50.2 50.4 50.6 50.8 51.0 51.2 51.4 51.5 51.8 52.0 52.2 52.5 52.7 52.7 53.1 53.3 53.4 53.7 53.9 54.0 54.2 54.5 54.6 54.8 55.0 55.2 55.4 55.6 55.7 56.0 56.2 56.3 56.5 56.8 56.9 57.1 57.3 57.5 57.7 57.9 58.0 58.3 58.5 58.7 58.9 59.2 59.4 59.6 59.8 60.0 60.2 60.4 60.5 60,7 60.9 61.1 61 3 61 5 61 7
23 1 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 2.50 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 29 1 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 31 1
312 3 13 314 3 15 316 317 3 18 319 320
therefore seem t o b e a rational procedure to use t h e name "poise" in the n-ay suggested by Deeley and Parr, t o use t h e "centipoise" which is one-hundredth the size of this as a unit for practical measurements, and t o
T'ol. 8 , So. 5
192.8 193.4 194.4 195.3 196.3 196.9 197.8 198.4 199.4 200.3 200.9 201.9 202.8 203.8 204.3 205.3 206.3 206.9 207.8 208.8 209.4 210.3 211.4 211.9 212.8 213.8 214.4 215.6 216.3 216.9 217.8 218.8 219.4 220.4 221.3 221.9 222.8 223.7 224.4 225.4 226.3 226.9 227.9 228.8 229.4 230.4 231.3 231.9 232.9 233.8 234.4 235.4 236.3 236.9 237.9 238.8 239.4 240.4 241.3 241.9 242.9 243.8 244.5 246.0 246.3 247.0 247.9 248.8 249.5 250.4 251.3 252.0 252.9 253.8 254.5 255.4 256.3 257.0 257.9 258.9 259,5 260.4 261 4 262,O 262.9 263.9 264 5 265.4 266.4 267.0
Uncorr. SECONDS viscosity in Engler' S a y - Red- centiNO. bolt wood poises Y---
8.56 321 8.59 322 8.61 323 8.64 324 8.67 325 8.69 326 8.72 327 8.75 328 8.77 329 8.80 330 8.83 331 8.85 332 8.88 333 8.91 334 8.93 335 8.96 336 8.99 337 9.01 338 9.04 339 9.07 340 9.09 341 9.12 342 9.15 343 9.17 344 9.20 345 9.23 346 9.25 347 9.28 348 9.31 349 9.33 350 9.36 351 9.39 352 9.41 353 9.44 354 9.47 355 9.49 356 9.52 357 9.55 358 9.57 359 9.60 360 9.63 361 9.65 362 9.68 363 9.71 364 9.73 365 9.76 366 9.79 367 9.82 368 9.84 369 9.87 370 9.89 371 9.92 372 9.95 373 9.97 374 10.00 375 10.03 376 10.05 377 10.08 378 10.11 379 10.13 380 10.16 381 10.19 382 10.21 383 '10.24 384 10.27 385 10.29 386 10.32 387 10.35 388 10.37 389 10.40 390 I O , 43 391 10.45 392 10.48 393 10.51 394 10 53 395 10.56 396 10.59 397 10.61 398 10.64 399 10.67 400
267.9 268.9 269.5 270.4 271.4 272.0 272.9 273.9 274.5 275.4 276.4 277.0 278.0 278.9 279.5 280.4 281.4 282.0 283.0 283.9 284.5 285.5 286.4 287.0 288.0 288.9 289.5 290.5 291.4 292.0 293.0 293.9 294.5 295.5 296.4 297.0 298.0 298.9 299.5 300.5 301.4 302.0 303.0 303.9 304.5 305.5 306.4 307.4 308.0 308.9 309.6 310.5 311.4 312.1 313.0 313.9 314.6 315.5 312.4 311.1 318.0 318.9 319.6 320.5 321.5 322.1 323.0 324.0 324.6 325.5 326.5 327.1 328.0 329.0 329.6 330.5 331.5 332.1 333.0 334.0
61.9 62.1 62.4 62.2 62.i 62.8 63.0 63.3 63.4 63.6 63.8 64.0 64.2 64.4 64.6 64.9 65.1 65.3 65.5 65.7 65.9 66.1 66.3 66.5 66.7 66.9 67.0 67.2 67.5 67,6 67.8 68.0 68.2 68.4 68.6 68.8 69.0 69.3 69.3 69.5 69.8 69.9
338.0 319.0 339.6 340.9 341,s 342.1
78.4 78.6 78.8 79.2 79.R 79.J
20.1
,0.4 70.5 70.8 71.1 71.3
71.5 71.7 i1.8
72.0 z2.2 12.4 72.6 22.8 13.0 73.2 73.4 73.5 73.8 74.0 24.1 (4.3 74.5 74.7 74.9 75.1 75.3 75.5 75.7 75.8 76.1 76.3 76.4 76.6 76.8 77.0 77.2 77.4
10.69
10.72 10 75 10.77 10 80 10.83 10.85 10.89 10.91 10 93
405 406 407 408 409 410
Uncorr. SECONDS viscosity in Engler Say- Red- centiNo. bolt wood poises
10.96 10.99 11.01 11.04 11.07 11.09 11.12 11.15 11.17 11.20 11.23 11.25 11.28
411 412 413 414 415 416 417 418 419 420 421 422 423 1 1 . 3 1 424 11.33 425 11.36 426 11.39 427 11.41 428 11.44 429 11.47 430 11.49 431 11.52 432 11.55 433 11.57 434 11.60 435 11.63 436 11.65 437 11.68 438 11.71 439 11.73 440 11.76 441 11.79 442 11.81 443 11.84 444 11.87 445 11.89 446 11.92 447 11.95 448 11.97 449 12.00 450 12.03 451 12.05 452 12.08 453 12.11 454 12.13 455 12.16 456 12.19 457 12.21 458 12.24 459 12.27 460 12.29 461 12.32 462 12.35 463 12.37 464 12.40 465 12.43 466 12.45 467 12.48 468 12.51 469 12.53 470 12.56 471 12.59 472 12.61 473 12.64 474 12.67 475 12.69 476 12.72 477 12.75 478 12.77 479 12.80 4x0 12.83 481 12.85 482 12.88 483 12.91 484 12.93 485 12.96 486 12.99 487 13.01 488 13.04 489 13.07 490 13.09 491 12 12 492 13.16 491 13 l i 494 13.20 495 13.23 4961 13.25 497 13.28 498 13.31 499 13 33 500
343.0 79.7 344.0 79.Y 344.6 80.0 345.6 80.3 346.5 80.5 347.1 8 0 , 6 348.1 80.8 349.0 81.0 349.6 81.2 350.6 8 1 . 4 351 . 5 81.6 352.1 81.8 353.1 82.0 354.0 82.2 354.6 82.3 355.6 82.6 356.5 82.8 357.1 82.9 358.1 83.1 359.0 83.3 359.6 83.3 360.1 83.7 361.5 83.9 362.I 84.1 363.1 84.3 364.0 84.5 364.6 84.6 365.6 84.9 366.5 85.1 367.1 85.2 368.1 85,: 369.0 85,, 369.7 8s 8 370.6 86.1 371.5 86.4 372.2 86.5 373.1 86.8 374.0 87.0 374.7 87.1 375.6 87,5 376.5 87.2 377.2 87.i 378.1 87.9 379.0 88.1 379.7 88.3 380,6 88.5 381.5 88.7 382,2 88.8 383.1 89,1 384.: 89.3 384.i 89 4 385.6 89.6 386,6 89.9 387,2 90.0 388.1 90.2 389.1 90.4 389.7 90.6 390.6 90.8 391.6 91.0 392.2 91 .2 393.1 91.4 394.1 91.7 394.7 91.8 395,fi 91.9 396.6 92.2 397.2 92.3 398.1 92.5 399.I 92.7 ,399.7 92.9 400.6 93.1 401.6 93.3 402.2 93.5 403.1 93.7 404.1 94.0 404,7 94.2 405.6 94.5 406.6 94.6 407.2 94.8 408 2 94.9 409.0 95.2 409.2 95.4 95.6 410, I 411.9 95.8 412.2 95.Y 413.2 96.1 4 1 4 . 1 96.4 414.7 96.5 411,7
96,1
416.6 96 9 41, , ?
97.0
a help irL such comparisons T hey haT-e as a hasis the n-ork done a t the Bureau of Standards by Dr C. IT. Vaidner in which a careful inrestigation was made of the relation betnTeen readings of t h e Engler,
T H E JOrRAV.4L O F I S D G S T R I A L A iV D E N G I ATE E RI N G C H E M I S T R Y
May, 1916
t h e Saybolt Universal, and t h e Redwood instruments as well as of their reliability. The accompanying conversion tables do not take into account t h e varying specific gtavity of t h e liquids examined. For commercial work with oils this is not done at present with t h e commercial instruments so t h a t no new error or inaccuracy is introduced in such work by comparing t h e results of different instruments with each other or by converting t h e m into true viscosity on t h e assumption t h a t they have a uniform gravity of 1.000,b u t if accuracy is desired, t h e figure found in t h e column headed “Uncorrected Viscosity in Centipoises” should be multiplied b y t h e density of t h e liquid at t h e temperature of t h e experiment. The density is t h e specific gravity of t h e liquid a t t h e temperature of t h e test in terms of water a t 4’ C. NEWY O R K
43 5
I n order t o compare t h e rates of settling, a 2 per cent solution of calcium chloride and magnesium nit r a t e was prepared. T o aliquot portions of this solution equal quantities of Sample B, unfiltered Sample A, filtered Sample A, and graphite, respectively, were added. T o a fifth portion no preventative was added. To each of these five solutions I g. of sodium carbonate was added to precipitate the carbonates of calcium and magnesium. The ratio of settling was observed, first.from a cold solution, then from one which h a d been boiled for 0
/
2
d
42 .+ 0%
CITY
-
~~~
A METHOD FOR TESTING THE EFFICIENCY OF BOILER SCALE PREVENTATIVES By H. K. BENSON AND 0 . A. HOUGEN Received March 23, 1916
For t h e purpose of selecting a commercial boiler compound, t h e engineers of t h e University of Washington Power Station submitted samples of scale and of t h e feed water together with several boiler compounds. After analytical studies of t h e water, scale, and t h e boiler compounds were made, a method for determining t h e relative efficiency of t h e compounds was devised. F E E D W A T E R A N D SCALE-The feed water contained considerable suspended organic matter, fine silt a n d clay, together with temporary and permanent hardness. The percentage composition of the resulting scale was as follows: Organic Matter .................................... 10.93 Silica (SiOz) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29.70 Iron and Aiumina (FezOs + AlzOs) . . . . . . . . . . . . . . . . . . 7 . 4 2 Lime (CaO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38.09 Magnesia (MgO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.90 BOILER coMPocNDs-Sample A was a liquid consisting of water, sodium carbonate, graphite, a n d a n organic solid. Sample B consisted of sodium phos‘ p h a t e (Na2P04) in t h e solid form. Sample C was a commercial liquid compound of undetermined composition. ExPERIMExTAL-goo cc. of feed water were concentrated t o about 60 cc. A small quantity of solid matter settled out readily. Upon treating t h e clear filtrate with filtered solutions of t h e boiler compounds a large quantity of very finely divided colloidal precipitate was obtained; upon boiling, this coagulated into a flocculent precipitate. Inasmuch as all of t h e boiler compounds formed such a precipitate it is apparent t h a t some other property than precipitation must determine t h e relative efficiency of boiler compounds. From the nature of scale deposition it was assumed t h a t t h e function of boiler compounds is t o form precipitates which do not settle out readily but re main suspended in a colloidal or flocculent condition. Yhile t h e precipitate from concentrated feed water with Sample B settled completely in z hrs., t h a t with Sample A was still partly suspended at the end of 5 hrs.
several hours a t constant volume. shown in Figs. I, 11, and 111.
The results are
CONCLUSIONS
From t h e curves on Fig. I1 it will be observed t h a t t h e filtered compound has very little effect in upholding suspended water while t h e unfiltered compound is t h e most effective. Graphite, likewise, has no effect. While t h e flocculent phosphate precipitate is effective, t h e colloidal organic matter seems t o be most effective
