OTHER DEFENSIVE MEASURES
PROTECTIVE CLOTHING
Protective clothing was an additional feature of the general program
of protection. As far as factory protection is concerned, the use of
protective garments was more or less of a temporary expedient and they
were abandoned as fast as automatic machinery and standard practice
made their use less necessary. It is likewise a question regarding
their value at the front. It is very certain that the garments
developed needed to be made lighter and more comfortable to be of much
value to the fighting unit.
The first development of protective clothing was along the lines of
factory protection. The large number of casualties in connection with
the manufacture of mustard gas made it imperative that the workmen
be protected not only from splashes of the liquid mustard gas, but
also from its vapors. The first suit developed provided protection to
the entire body. The ordinary clothing materials and even rubberized
fabrics offered little protection but it was found that certain
oilcloths were practically impermeable to mustard gas. The suit was a
single garment, buttoning in the back, with no openings in the front,
no pockets and with tie-strings at wrists and ankles. The head was
protected by means of an aluminium helmet, supported by means of a head
band resting on the head like a cap and slung from the inside of the
helmet; this permitted slight head motions independent of the helmet.
In order to provide cooling and ventilating and pure air breathing, the
suit was inflated by pumping a considerable volume of air into the suit
through a flexible hose long enough to permit considerable freedom of
movement.
This suit had the very great disadvantage of limiting the range of
motion to the length of the hose. Because of this, a Tissot type mask
was used in place of the helmet and hose connections. The hood was made
of the same special oilcloth as the suit, enveloped the head and neck
and extended a short distance down the back and over the chest. The
canister was slung on the left hip by an oilcloth harness and was kept
from swinging by an oilcloth belt around the waist. The canister was
much larger than the standard box respirator, had a much longer life
with lower resistance and weighed about 3.5 lbs.
[Illustration: FIG. 80.—Impervious Overall Suit for Mustard Gas.]
Another type of impervious overall suit was developed which protected
against mustard gas for over 100 minutes. The material was a cotton
sheeting which was impregnated with linseed oil containing a suitable
non-drying material, which was thoroughly oxidized in the fabric. These
suits proved to be very uncomfortable, especially in warm weather,
because they entirely prevented the escape of perspiration from the
body.
Semi-permeable suits were then prepared, in which the cotton sheeting
was impregnated or coated with a solution of gelatin and glycerine. The
fabric was then “tanned” to render the gelatin insoluble in water. Such
a suit is valuable for factory wear, but the impregnating material is
easily leached out and the suit is therefore not recommended for field
service.
This was built with an inside layer of dry cloth together with an
outside layer of treated cloth to afford the necessary chemical
protection against mustard gas. Work of fabrication consisted in
treating the cloth with simplexene, cutting the suits to design and
size, and sewing them together.
Treatment consisted in passing the fabric through a dye machine, then
through the wringer rolls where the excess oil was expressed. The
inner layer of dry cloth was found necessary, since the cloth was cut
as soon as treated. Simplexene does not attain the maximum degree of
“tackiness” for two or three days, owing to the presence in the oil of
a small amount of volatile spirits. However, by allowing the cloth to
air for 48 hours before cutting, the inner lining could probably be
dispensed with.
The fighting suits were distributed among various detachments using
mustard gas in field tests, and in other places where protection
against vapor was needed and where field conditions were approximated.
The tests showed that the suit gave satisfactory protection for
considerable periods against mustard gas vapors. No other suit, equal
both in porosity and protection, has yet been submitted, although
samples furnishing better protection with much higher resistance have
been examined. The protection of the simplexene suit is about 30
minutes against saturated gas. A large number of these suits were made
and taken abroad for field tests at the front.
PROTECTIVE GLOVES
Protective gloves have been made with a variety of impregnating agents.
The one which was selected for large scale production was impregnated
with a solution of cellulose nitrate because of the availability of
materials and the protection offered by the finished product. The
material is impregnated after being made up. The one finger type of
glove is used. The gloves are placed on wooden forms and dipped into
the impregnating solution. After draining a few minutes, the gloves
are turned upside down on racks and run through a drying oven. Finally
they are removed from the forms and conditioned by drying at a moderate
temperature for several hours. After being properly cured they are
fitted with two straps on the gauntlet of each glove. They should offer
protection to chloropicrin (standard method of test) for 30 minutes.
When subjected to rough work they will last from one to two weeks.
[Illustration: FIG. 81.—Coated Gloves for Protection against Mustard
Gas.]
PROTECTIVE OINTMENTS
The extensive use of mustard gas on the field caused the men to be
exposed to low concentrations of the vapors for extended periods of
time. Since it did not seem feasible to furnish the men with special
fighting suits, which would protect them against these vapors, it was
desirable to provide protection in the form of an ointment which could
be applied to the body. In order to be satisfactory an ointment should
have the following properties:
(_a_) It should protect against saturated mustard
gas during the longest possible exposure.
(_b_) Its protective action should last as long
as possible after the application of the ointment.
It was felt that the ointment should give protection
for 24 hours after it is applied, even if the body is
perspiring freely.
(_c_) The material should not be easily rubbed off
under the clothing.
(_d_) It should be non-irritating to the membranes
of the body.
(_e_) There should be no likelihood of toxic
after-effects on long use.
(_f_) It should be of a good consistency under a
fairly wide temperature range and give a good coating
at the temperature of the body.
(_g_) Its method of manufacture should be simple
and rapid, and the raw materials required should be
abundant.
(_h_) The cost should not be excessive.
An extensive study of this question was made both in the laboratories
and on the field. At first it was believed that successful results
could be obtained by the use of such ointments. Careful investigation
showed, however, that while these ointments really did protect against
rather high concentrations of vapor for short times of exposure, they
were probably not so valuable when used against low concentrations
over an extended period of time. It was further demonstrated that the
protection furnished by a coating of linseed oil is practically equal
to the best ointment which has been developed. About 150 ointments were
prepared and tested. These consisted of two parts or components, the
metallic soap or other solid material and the oil or liquid part which
bound and held the solid. The latter is called the base. The best base
is lanolin, containing 30 per cent of water. A solution of wax in olive
oil was next best. Of the metallic soaps the oleates and linoleates are
better than the stearates. A satisfactory ointment has the following
composition:
Zinc oxide 40
Linseed oil (raw) 20
Lard 20
Lanolin 20
A modification of this formula is:
Zinc oxide 45
Linseed oil 30
Lard 10
Lanolin 15
The physical properties of this ointment are very good. It forms a
smooth, even coating on the skin, sticks well enough not to rub off
easily on the clothing and yet is not sticky. Its consistency is
such that it can be readily pressed from an ointment tube. A. E. F.
reports indicate that sag paste (zinc stearate and vegetable oil) is as
satisfactory as any of the preparations tried.
The great difficulties of such preparation from a field point of view
are: Extra weight to be carried by the soldiers, necessity for keeping
in tight boxes or tubes, thereby adding to the difficulty of carrying,
and finally, the difficulty encountered when applying it properly to
the body in the field, where gas contaminated hands may cause harm.
The paste was too late a development for thorough field trial. It was
used just enough to cause severe partisan controversies between its
advocates and those opposed to it. Unquestionably, it proved of decided
value in preventing mustard gas burns when properly applied. There are
many authentic cases where men alongside each other were similarly
gassed except as to burns. The difference in burns arose from the use
or non-use of the paste, and in some cases of poor application. Fries
is of the opinion that had the war lasted another year the use of
pastes would have become universal unless some thoroughly successful
substance for impregnating the uniform or underclothing had been
developed. This is likewise his belief for the future.
PROTECTION OF ANIMALS
=Horse Mask.= The need of protection for animals (horses and dogs),
although not as great as in the case of men, was of sufficient
importance so that masks and boots were developed for the horse and a
mask for the dog.
The German horse mask was the first produced. It was of the nose bag
type, enveloping the mouth and nose of the animal. It was fitted with a
complicated drawstring and with snap hooks fastening it to the harness.
The interior contains a plate of stiff material to prevent the collapse
of the bag. The mask itself was apparently not impregnated, but was
used wet or with a filling of wet straw or rags to act as the absorbent.
[Illustration: FIG. 82.—German Respirator for Horses.]
The French had two types of horse masks impregnated with a
glycerine-nickel hydroxide mixture. One type had a closed bottom, while
in the other, the bottom was open.
The British horse mask has a two-layer flannelette bag, with a canvas
mouth pad and elastic drawstring. It was impregnated with a mixture of
phenol, formaldehyde, ammonia, canister soda and glycerine.
The first type of American horse mask was modelled after
the British and was impregnated with the Komplexene mixture
(hexamethylenetetramine, glycerine, nickel sulfate mixture). This mask
had too high a resistance and caused complete exhaustion in running
horses. The second mask was made of a large number of layers of very
open cheesecloth. It consists of two bags, impregnated with different
mixtures (Komplexene and Simplexene). Horses can run two miles with
this mask without showing evidences of exhaustion.
Dewey gives the following method of manufacture:
The chemical employed consisted of a mixture of hexamethylenetetramine
(to give protection against phosgene), nickel sulfate (to protect
against the possible use of hydrocyanic acid), sodium carbonate and
glycerine. This solution was mixed in a heavy steam jacketed mixing
kettle with heavy geared stirrers. The mixture was conducted by pipes
to the impregnating apparatus which consisted of a rotary laundry
washing machine. The masks were treated in this machine for 15 minutes,
and then placed in a power operated wringer and the solution driven off
to a given weight. Following this operation, they were suspended on
wire supports and conducted through a hot air drying machine and dried
to a definite weight. 378,000 horse masks were produced at the rate of
5,000 per day.
[Illustration: FIG. 83.—Horse Mask—American Type.]
Theoretically, horse masks and horse boots are very
valuable,—practically, they did very little actual good in the field,
not that they would not protect or that animals would not wear them.
The trouble was with the riders and drivers. Gas attacks, coming
usually at night, made adjustment of horse masks difficult at best,
while in the confusion of bursting shell and smoke, the drivers
absolutely forgot the horse masks or after putting on their own masks
feared to try putting masks on the animals. This last was natural as
most animals fight the adjustment of the mask and in so doing there is
great risk that the man’s mask may be torn off and the man gassed. In
the future, such masks will have even more importance than in the past,
for the present methods of manufacture of mustard gas coupled with its
all-round effectiveness will cause a use of it ten-fold greater than at
any time in the World War. In such cases, operations will necessarily
be frequently carried on over large areas thoroughly poisoned with
mustard gas. Here the animals will be masked and booted before entering
the gassed area, and remain so until they leave it. In the torn and
broken ground around the front line there will always be need for
animal transportation,—wagon, cart and horse—as in such places it is
far better in nearly all cases than motor transport.
=Dog Mask.= The use of dogs in messenger service and in Red Cross work,
in which gassed areas must be passed, led to the designing of a mask
to give the animals suitable protection. The same materials and method
of impregnation were used as in the horse mask. With eight layers of
cheesecloth, adequate protection against mustard gas was secured with
practically no pressure drop.
The eyepieces were made of thin sheets of cellulose acetate bound
around the edge with adhesive tape and sewed directly over openings
cut through the mask fabric. The ear pockets were made round and full
enough to fit pointed or lop-eared animals. The mask is continued to
form a wide neck band which may be drawn up by two adjustable straps.
It is made sufficiently full to allow a free movement of the dog’s jaws
and yet tight enough around the neck to avoid the possibility of being
pawed off. The dog apparently soon became accustomed to wearing the
mask.
=Horse Boots.= The increasing amount of mustard gas used on the Western
front made it seem necessary to develop some form of protection for the
horse’s hoof and fore-leg. It has been found that mustard gas vapors
attack the fleshy portion of the leg, especially around the coronary
band and causes inflammation of the frog of the foot. The problem was
solved by devising a special hoof pad and a boot. The pad was made of
sheet iron imbedded in a hoof protector (composition rubber) to which
the shoe is applied. The shoe just overlaps the metal plate on the
inside and provides a solid metal surface for the bottom of the foot.
Such a pad not only offers protection against gas but against shell
splinters, barbed wire, etc., and would be useful at all times on the
front.
[Illustration: FIG. 84.—Impervious Boots and Pads to Protect Horses’
Legs and Hoofs against Mustard Gas.]
[Illustration: FIG. 85.—Protective Gas Outfit—Gas Mask, Gas Suit,
Gloves, Boots, Horse Mask, Horse Boots, Horse Pads.]
The boot was made of satin, treated so as to be impervious to mustard
gas. It covers all of the foot except the bottom and extends to just
below the knee. The boot is held in contact with the hoof by a sewed
cloth strap, which passes around the bottom of the hoof and is held in
position by projections extending from the spur or toe clip. Special
care is taken to insure a perfect joint at the rear of the boot since
the small cavity in the back of the hoof is one of the most sensitive
parts. The boot is wrapped about one and a half times around the leg
and is clipped with five loops through which passes a ¾-inch strap.
=Dugout Blankets.= Dugout protection is intended to prevent entrance of
any gases, lethal, lachrymatory or irritant, into the enclosed space.
This has been most efficiently accomplished by means of curtains hung
upon wooden frames and fitting closely against all edges of the opening
to be closed. These curtains have usually been of heavy material and
have generally been spoken of as dugout blankets. Since they were
designed to exclude all toxic gases, they had to be devised upon
general mechanical principles rather than upon principles of chemical
action with specific gases. Permeability to air has not been considered
a necessity, it being held that sufficient ventilation is secured by
means of the air entering through the soil. For large dugouts and
extended use large air filters were designed to draw pure air into the
dugout with a fan.
The qualities aimed at, to which both fabric and treatment should
contribute, are the following:
(_a_) Impermeability to gas.
(_b_) Flexibility, especially at low temperatures.
(_c_) Non-inflammability.
(_d_) Freedom from stickiness and from tendency to lose
material by drainage under action of gravity.
(_e_) Mechanical strength.
(_f_) Simplicity of manufacture and treatment.
(_g_) Low cost.
Army blankets, both those for men and those for horses, proved suitable
materials for curtains, but the scarcity of wool made it desirable to
select an all cotton fabric.
A large number of oils were studied as impregnating agents. The most
satisfactory mixture consisted of 85 per cent of a heavy steam refined
cylinder oil and 15 per cent of linseed oil. This is taken up to the
extent of about 300 per cent increase in weight of the blanket during
impregnation. It becomes oxidized to some extent upon the surface of
the blanket, which becomes less oily than the soft, central core.
The finished blanket possessed the following properties: It resists
penetration of 400-600 p.p.m. of chloropicrin for 8 hours (dugout test)
and mustard gas for 100-400 minutes (machine test). It is sufficiently
flexible after standing for 2 hours at 18° F. to unroll of its own
weight, and may be unrolled by applying a slight force at 6° F.; it is
not ignited by lighted matches and shows but little loss by drainage.
Two types of machines were designed for impregnation, one for use on
large scale behind the line, and a field apparatus for use at the
front.