J u l y , 1917
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERIiVG C H E M I S T R Y
TABLE 1-WATER-SOLUBLE
ARSENIC ON THE
A. 0. A. C. No. 3..
Method 24 hrs. a t 32' C.
. . . . . . trace
Devoe & Raynolds Boiling Method 4.62 0.47 0.06 0.46 0.23
CALCULATED
DRY BASIS
AS
A. 0. A.
PER CENT 4 ~ 2 0 ~
c.
Devoe&
YtkEd
Rg:itgds
No.
at 3 2 3 6. . . . . . . 0.56 7 . . . . . . . 0.23 8 . . . . . . . 0.18
hfethod 0.68 0.30 0.21 0.33 0.46
There is no provision made for t h e removal of lead, as w e have never found water-soluble le,id in more t h a n traces in a n y sample of lead arsenate. Furthermore, as has been pointed out by Gray arid Christie, there is great danger of volatilization of t h e arsenic b y evaporating t h e solution t o sulfuric ;acid fumes, as t h e results given in Table I1 will show. The extractions were made by boiling as in t h e method given above. TABLEII-WVATER-SOLUBLE ARSENIC CALCULATED AS .&s2t3a BASIS
Evaporated to so3 fumes Reduced and Titrated without Evaporation.
683
ON
1x6 DRY
No. 1
. . . . . . . . . . . 2.40 . . . . . . . . . . . . . .3 . .56
No. 2
1.61 2.50
The m~ater-so~uble arsenic in commercial lead arsenate very often is largely in t h e arsenious form. Commercia1 sodium arsenate a n d arsenic acid often contain small amounts of unoxidized arsenic trioxide, and this precipitates with t h e lead arsenate in a form which is very difficult t o wash out with cold water, but which dissolves readily in hot water. This may be t h e reason why t h e boiling methods of Gray and Christie, a n d of t h e writers, and t h e hot water method of Robinson a n d Tartar' give higher results t h a n t h e cold a n d 32' C. methods of t h e A. 0. A. C. By t h e method given a determination of water-soluble arsenic may be made in less t h a n a n hour, which is a very important consideration for factory control work. The same method of extraction may be used for t h e determination Of Other water-so1ub1e impurities* D E V O E AXD
14-16 I
RAYNOLDS COMPANY
W E S T L A K E STREET, C H I C l G O
THISJ O U R N A L , 7 (1915), 499.
1
i
LABORATORY AND PLANT SAFEGUARDING THE EYES OF INDUSTRIAL WORKERS' T h e Seaman Gold Medal, gift of Dr. Louis Livingston Seaman, Trustee, is annually awarded b y T h e American Lluseum of Safety for progress and achievement i n t h e promotion of hygiene and t h e mitigation of occupational disease. This year t h e distinction of t h e Seaman Medal has been conferred upon t h e Julius King Optical Company, of New York, for scientific research and practical achievement in overcoming t h e harmful effects of ultra-violet and infrared rays of light in connection with arc-welding and other industrial processes a t very high temperatures. For a number of years t h e necessity of protecting t h e eyes of workers against chips of steel, splashes of metal and flying particles of emery, concrete a n d other materials, has been recognized, and t h e wearing of a n approved t y p e of safety goggles made compulsory. h far more insidious and hazardous danger t o eyesight is caused by certain invisible rays of light, such as t h e ultra-violet a n d infra-red rays. which are present in injurious quantities in t h e manufacture and working of iron and steel. These rays may cause electric ophthalmia. A4nylight source over zooo' Fahrenheit is a distinct menace and when a temperature of 6400' is reached, such as is encountered in electric carbon arc-welding, t h e volume of ultra-violet radiation is so great as t o impair vision permanently. On account of its destruction of animal tissue, these rays must positively be guarded against. Being invisible, their presence is detected by t h e operator only after h a r m has been done. Until a n investigation was made about three years ago, practically go per cent of all colored glass in goggles for industrial use was incorrect; a n d without a doubt a large number of blind men, or those unfortunates 1 Abstracted and adapted from the May, 1917, issue of ''Safely" (p. 118 and supplement), published by the American Museum of Safety, 14 to 18 West 24th Street, New York City
who are afflicted with cataract, would have their full sight to-day if they had been provided with scientifically correct colored glass. One of t h e first forms of eye protection from glare was t h e wearing of blue glasses in t h e manufacture of steel, particularly in t h e open-hearth process. Glare is made u p of non-injurious rays of t h e spectrum, namely green, yellow, orange, and red rays. As a matter of fact, blue is one of t h e worst colors which could possibly be selected for this process, as it allows ultra-violet, violet, blue and also infra-red rays t o enter t h e eyes freely, cutting out only t h a t part of t h e light which is essential t o vision, but affording no protection from dangerous light. The higher t h e temperature, t h e more rich it is in ultra-violet rays. At t h e temperature encountered in oxy-acetylene welding and cutting, which is about 4350' Fahrenheit, grave danger exists and t h e glasses formerly supplied b y t h e oxy-acetylene companies, who manufactured a n d furnished t h e outfits, were without any scientific value whatever. They were using blue glass, as described, or else smoked lenses, which allowed a large proportion of injurious rays t o enter t h e eye. Where a wrong color is used a much darker shade is necessary t h a n if a correct color is prescribed. All colors have been analyzed a n d tabulated, by spectral photography, so t h e relative value of each is known. A temperature of zoooo requires a lens b u t slightly tinted, while a temperature of 6400' requires a lens so dark t h a t one can barely see t h e sun through it. T h e Julius King Optical Company has plotted all colors on a photometric scale, t h e standard adopted being a white cloud illuminated by t h e sun, which may be looked at indefinitely without eyestrain. A temperature of zooo' of molten iron through a slightly tinted glass has t h e same effect on t h e eye as if t h e
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
684 INVISIBLE
VISIBLE RAYS
INVISIBLE
INVISIBLE
Harmful
Harmless in Moderate Harmful Amounts [B, G, Y, R areas printed Blue, Green, Yellow and Red in Original.]
VISIBLE R A V S
F. such as Gas Heating
Light SANI-WELD Glass Recommended for Temperatures around 3500’ F. Cutting, Pouring Steel, etc.
Oxy-Acetylene
Should Not be Used where Temperature is over 1500° F. I
l
I
1 I
l
Red Glass-Harmful Should Never be Used as it Transmits Infra-Red and is Very Fatiguing t o the Eye.
Green Glass-Incorrect Should Not be Used as it Distorts Colors and is of Low Optical Value.
Dark SANI-WELD Glass Recommended for Temperatures around 4300’ F. Heavy Oxy-Acetylene Welding, Electric Furnaces, etc.
TNVTSTRT.~.
Clear “White” Glass
I
AKOPOS Glass Recommended-for Temperatures around 2000° Furnaces, etc.
Vol. 9, No. 7
Cobalt-Blue Glass-Exceedingly
Dangerous
Transmits Invisible Rays as freely as Clear Glass. Should be Abolished except for Open Hearth Temperature Judging where it is not Practical t o Teach Melters a New Color.
ARK-WELD Glass Smoked Glass-Dangerous
For Temperatures around 6400’ F. in Combination with AKOPOS or SANI-WELD (to eliminate infra-red rays). Correct for Iron or Carbon Arc Welding and for Electric Furnaces: in these Processes Face-burn will Result unless a Helmet is Used.
’
wearer had nothing over t h e eyes, and was looking a t a white cloud. The same photometric standard applies in looking a t a temperature of 6400’ through t h e darkest glass, t h e effect on t h e eye being t h e same. These new values of lenses were determined by flowing colors over photographic plates. Spectral photographs were taken through this medium, t h e efficient ones being tabulated and reproduced in pot glass. All of this research was conducted in what was practically a n unknown field and it will be difficult t o find any other line of work where more good has been accomplished in t h e prevention of ocular diseases, disturbances and actual loss of sight t h a n has been accomplished by this patient research conducted with considerable expense of time, money and material. T h e process of arc-welding requires protection not only for t h e eyes, b u t for t h e entire face and neck. Welders have experienced such intense eyestrain and face burns after a few minutes’ work, t h a t all sorts of crude shields have been devised. The majority of these, however, were heavy and cumbersome, being made of metal and leather; and all were inefficient and uncomfortable. Frequently, t h e workmen themselves selected glass t o reduce t h e light intensity, but they were, of course, wholly ignorant of t h e fact t h a t t h e character of t h e light caused more damage t h a n its brilliancy. Since metal is a conductor of heat and electricity, t h e Julius King Optical Company have constructed a helmet of fiber, finished within and without in dead black so as t o minimize t h e danger from reflected light. T h e t o p of t h e head is protected by a fireproof cap, t o
Reduces Visible but Transmits Invisible Rays; Although sometimes Furnished with Oxy-Acetylene Outfits, it is about the Worst t h a t could be Used for the Process.
which the helmet is pivoted so t h a t i t may be turned back out of t h e range of vision when i t becomes necessary for t h e wearer t o inspect his work or t o move about, The lenses mounted in this helmet are a combination of “Ark-weld” and “Akopos” glass, t h e former t o reduce t h e intensity and t h e latter t o eliminate the injurious rays of t h e arc light. As t h e lenses are of t h e proper scientific color, no danger exists from electric ophthalmia or other diseased condition of the retina or conjunctiva. The accompanying drawing was adapted from t h e special colored supplement accompanying t h e May issue of S a f e t y , and furnished through t h e cooperation of t h e Julius King Optical Company. It indicates quite clearly t h e transmission of t h e invisible dangerous rays of light through t h e ordinary colored glass, and their absorption by t h e “Akopos,” “Sani-weld” and‘‘ Arkweld” glasses. The kinds and proportions of t h e various parts of t h e spectrum transmitted are indicated by t h e shaded areas.
RECOVERY OF MOLYBDENUM RESIDUES By VICTORLENHERAND M. P. SCHVLTZ Received June 6, 1917
A number of methods for t h e recovery of molybdic acid residues have been suggested in the past few years. The scheme of Armstrong’ consists in t h e precipitation of molybdic acid from t h e residues, while the procedures of Brown2 and of Prescottahave in addition t h e removal of. t h e phosphates by means 1 2
8
THISJOURNAL, 7 (1915), 764. Ibid., 7 (1915). 213. T h e Analyst, 40 (1915), 390.
