Acid Works

 George M. Mowbray

Photo Paul W. Marino Collection

“It is time that I should now accompany my reader through the Hoosac tunnel Nitro-Glycerin works, of whom (my readers) few have ever ventured to trust themselves within a nitro-glycerin manufactory. The very name is sufficient to make the passer-by quicken his step, till he is a safe distance beyond the dreaded precinct.”  George M. Mowbray 1874

“Perfect system pervades this factory and is absolutely necessary in the manufacture of nitro-glycerin, to ensure safety.

The steadiest men possible are selected for the work. Three are employed in the acid house, working in three shifts of eight hours each, but they do not actually work more than seven hours. Every movement is like clockwork, every man has his place and special duty, which he is expected to perform at the proper time.”

If the success of the completion of the Hoosac Tunnel could be rendered down to three items, they would probably be, the hiring of the Shanly Brothers as general contractors, the use of the Burleigh Drill and the introduction of  Tri-Nitro-Glycerin as blasting agent by Prof. Mowbray.

Prof. Mowbray had become famous in the oilfields near Titusville Pa. by using his perfected tri-nito-glycerin to produce more yield from slow oil wells. Mowbray’s advertisement in Scientific American was read by Thomas Doane who invited Professor Mowbray to come to North Adams.

Professor Mowbray wasted no time in setting up his “manufactory” about a 1000 feet south of West Shaft.

There were a few buildings constructed at the site which included:

The 150 foot long “acid house.”

A 90 foot long building that was used in the manufacture of electric blasting wire insulated with “gutta-percha”, a rubber compound known for its great insulation. There was also an attached house for the Forman’s family.

Two ice houses that were large enough to contain 400 tons of ice used for cooling the tri-nitro-glycerin.

A 100 foot long converting building

The engine house used to supply steam and mechanical power for the works.

Prof. Mowbray’s house.

There were at least two magazine buildings 300 feet further south used to store the finished product.


Accidents at the Works  

There were a few accidents that happened at the Acid Works. As one can imagine, most all had disastrous outcomes.

“The first occurred on the twenty third of December, 1870, to my foreman, who I surmised, in the absence of proof, in removing the clinkers from the heater, may have thrown a red hot coal on the inflammable floor boards of the magazine, moistened with nitro-glycerin spilt during three years use, whilst adding fuel to the parlor stove that warmed it. It was a poor consolation that Mr. Velsor, the foreman, who had been engaged with me during the greater part of the past ten years, had finished his day’s work and was using the magazine for a bath house, probably on account of it’s seclusion.”

“The new magazine had hardly been completed, and stored with nitro-glycerin, when, on Sunday morning, at half past six o’clock, March twelfth, 1871, the neighborhood was startled by another explosion of sixteen hundred pounds of nitro-glycerin. The cause of this last explosion was the continuous overheating of the magazine.”


Discarded Explosives    

During the early days of tri-nitro-glycerin, there were a few comparisons held on the power of tri-nitro and other weaker explosive compounds like dualin.

Getting the contract to supply the explosives used in the tunnel construction could prove to be quite lucrative, so many resorted to exaggerated claims.

“On Tuesday, the twenty eighth of November, the experiments under the supervision of Mr. Dittmar commenced, and were continued on the twenty ninth and thirtieth; but they demonstrated beyond cavil, that there being no nitro-glycerin fired at the same time to assist them, that the dualin was of “no account”….and again the dualin left over from this experiment, thirteen hundred pounds, was thrown out.”

It is still believed that the dualin explosive is still buried somewhere on Hoosac Mountain. It’s location unknown.

Nitro-Glycerin Factory West View







Converting Room







Nitro-Glycerin Factory South View






Electric Wire Factory




Mowbray’s Nitro Works Gate