more baffling than some of these well-known methods in use by our own men.
Mr. Byron R. Newton, collector at the port of New York, gave out a curious story on the work done by the Customs Intelligence Bureau, created as a lookout for smugglers and others. This service was employed in searching ships, examining baggage, looking out for explosive bombs, invisible writing, and so forth. Mr. Newton's story appeared in the New York Herald of July 14, 1918, and from it one incident may be taken.
Through the Boarding Officials, a passenger who arrived the
other day has furnished interesting material for the Intelligence
Bureau investigators. The passenger, who for some
time had been a resident of Germany, although an American
citizen, said he had been approached in Dresden by German
agents and asked if on his return to the United States he
would obtain military and other information of interest to
the Imperial German Intelligence Bureau. He was furnished
with a code to be used by him for forwarding information to
Germany and also with a formula for manufacturing an invisible
ink, and with paper to be treated by a special process
for correspondence. The passenger, in evidence of what he
stated, offered four collars to the customs officials. They appeared
to be ordinary negligee collars of cream-colored material—double,
turn-over collars, medium height, such as many
men wear with sport shirts or for informal occasions. The
passenger explained the purpose of these collars as follows:
"I take a soup plate and I put boiling water in it and let it stand for about a quarter of an hour, after which I throw away the water. The plate being warm, I place one of these collars in it. I pour over the collar one hundred grams of boiling water and let it stand for half an hour. Then I wring out the collar, and the water that remains is my invisible ink. They call it 'pyrogram.' It looks like water, it is not poisonous and it can be drunk.
"I wash my hands, since they are wet with this ink, and take the paper and fold it crosswise and begin the letter, writing two fingers from the edge. I let it dry, and then take a glass of water and put about one teaspoonful of ammonia in it. With a piece of wadding dipped in this solution of ammonia and water, I rub the paper both ways, and thus prepare it on both sides. After this I place the paper in this wet condition between blotting paper and under heavy books or a trunk for three hours. You will not be able to recognize the
