How To Kill Germs With Violet Rays –

How To Kill Germs With Violet Rays


This article is about removing germs from milk using ultraviolet radiation. That doesn’t sound very exciting on the face of it. Since I couldn’t decide whether or not milk germ eradication is a topic worth posting about, I did a little investigating. When I eventually found myself browsing through a 1917 book called City Milk Supply I decided that I didn’t want all my research going to waste. So here you have this fascinating post about milk, germs, and radiation.

In a nutshell, the main scientist in this article says:

“The pasteurization of milk has been followed by great improvement in conditions, but there is objection to the Pasteur treatment method, because it is claimed that the taste of the milk is changed. The effect of the ultra-violet rays on milk is different, and although it kills all the harmful germs the taste of the milk is not changed.

“So far as I have been able to determine the only noticeable change is that the milk in its new method loses its animate or ‘cowy’ odor, something that will not, in my opinion, cause people to object.”

But this other scientist says:

“It will destroy the micro-organisms without doubt. That has been positively proved. But what chemical changes would take place in the milk we have not yet entirely determined. This is to be found out only by lengthy experiments. There may be such a change brought about by the using of the violet rays that the milk would not be suitable for use. It might develop a disagreeable smell or taste, which would render it impossible to use. These are matters yet to be determined.”

And seven years later, here’s what the book City Milk Supply had to say on page 308 after further research:

When milk was exposed under conditions suitable for a satisfactory reduction of the bacteria by the ultraviolet rays there was also produced an abnormal disagreeable flavor that would render the milk unsaleable… On a commercial scale it would be difficult to control the factors which influence the bactericidal action of the rays and moreover the disagreeable flavor imparted to the milk renders the process impracticable.

So there you go.

HOW TO KILL GERMS WITH VIOLET RAYS: Dr. Frederick G. Keyes Tells of the Important Results of Experiments With Milk Made in the Laboratory of Brown University (PDF)

From May 29, 1910