maximum daily output of about one ton, while along the Rhine
alone the production was more than forty times greater.
The question of German chlorine production was, therefore,
already solved. The lachrymators were mainly raw materials
and intermediates of the dye industry submitted to a process,
the technique of which the German dye factories readily mastered.
Here, again, production presented no real difficulties.
Cylinders were also probably available from the industry.

Field Preparations.--There remains the last question of gas attack
technique and personnel. Those of us who remember the difficulties
involved in creating our own organisation in the summer of 1915
have no illusions on the question of German preparation.
Giving the Germans every credit for their technical and military
efficiency, some months must have been occupied in establishing
and training the special companies required, and in arriving
at a satisfactory design for the discharge appliances.
Schwarte's book, _Die Technik Im Weltkriege_,[1] tells us "specially
organised and trained troops" were required for the purpose.
Prisoners taken later revealed the German methods. Gas officers
and N.C.O.'s, after making a careful survey of the front line trench,
organised the digging of deep narrow trenches at suitable places
below the surface of the main trench, just underneath the parapet.
The heavy gas cylinders, weighing as much as ninety pounds,
were carried to the front line by the unfortunate infantry.
The discharge valves were carefully protected by domes which screwed
on to the cylinder. The latter were introduced into the holes,
tops flush with the trench bottom, and covered by a board
on which reposed the "Salzdecke," a kind of long bag stuffed
with some such material as peat moss and soaked in potash