Almost 150 years ago, in the very first volume of the Journal of the American Chemical Society, issue 6, published in 1879, Henry Morton begins, “There is a piece of recent chemical history which has already become somewhat involved on account of the oversight of some writers.”
Morton, the first president of the Stevens Institute of Technology, had a bone to pick (PDF). “And as the threads happen to be in my hands, I think I shall do a good office to future students by laying them out straight,” he writes. This chemical history involved one of the early synthetic red dyes, alizarin, and another dye from the madder root, purpurin.
“Being able to have that historic side of the work and better appreciate and understand that, together with the chemistry, I found really great.”
William Henry Perkin—who in 1856 accidentally discovered mauveine while still in college and later developed it into the first commercial synthetic dye—studied alizarin himself. BASF beat his patent application for its commercial synthesis by a single day, though.
A secondary colorant is produced during the synthesis of alizarin, which Perkin reported to be anthrapurpurin. In Morton’s simmering JACS article, he argues that Perkin was indeed the first ever to isolate the substance. “As a matter of fact,” Morton continues, the chemist G. Auerbach, who claimed to have isolated the compound earlier, though he called it isopurpurin, had really only made an unpurified mixture and didn’t even know it.
To prove his point, Morton and his friend William E. Geyer repeated both scientists’ work. By Perkin’s methods, they isolated anthrapurpurin. But by Auerbach’s, they obtained a mixture of mostly flavopurpurin with some anthrapurpurin and alizarin. To finally lay straight the threads in his hands, Morton went so far as to have fabric samples dyed with anthrapurpurin and flavopurpurin and inserted into the JACS issues. “The swatches of dyed test cloth accompanying this paper, as illustrations, speak for themselves,” he concludes.
Mary Kate Donais, analytical chemist and professor at Saint Anselm College, serendipitously encountered this combative article. A colleague happened to be waiting for a meeting in the library, “poking around, and noticed that we still have hard copies of a lot of our chemistry journals squirreled away in dark corners of the library basement,” Donais says.
“And she’s just, you know, killing time and looking. She’s like, wow, the original, really old issues of JACS were down there, from the 1800s. . . . And so she’s like, huh, I wonder what they were doing.” The coworker pulled volume I off the shelf, flipped through it, “and then she gets to this weird cardboard divider, and she looks in, and there’re fabric samples in there! What in the world?” Donais recalls. After her meeting, the colleague brought news of this discovery back to the department.
“And that started this whole interesting side rabbit hole,” says Donais, who was already collaborating with a local historical association to study antique fabrics in a color maker’s recipe book using portable spectroscopy tools. The nondestructive devices, including a colorimeter and X-ray fluorescence (XRF) and Raman spectrometers, were also used to examine Morton’s JACS fabric insert. Donais collaborated with analytical chemist Thomas J. Tague on the project.
The fabric insert has five color blocks for each of the two dyes, anthrapurpurin and flavopurpurin. Though the insert does not specify how the colorways were produced, Donais and Tague found that they are chemically distinct, likely because of the mordant metal salts used to bind the dyes to the fabric. “Different metals combined with different organic dyes produce color variations. So that’s where some of the different colors in the JACS fabrics are coming from,” Donais says. “One of them [the red swatch in the center] has tin, and the others don’t.” Iron levels are also elevated in the first two color blocks, as is lead in just the first.
The project has allowed a peek into the mystery of how Morton’s textile conclusion was made. “Being able to have that historic side of the work and better appreciate and understand that, together with the chemistry, I found really great,” Donais says.
The Journal of the Chemical Society of London used fabric inserts too
It’s a wonder that those manuscripts still lived in Saint Anselm’s library and weren’t “just all digital, because then there wouldn’t be a fabric sample to analyze,” Donais says. “So that got me thinking, Well, are there others?”
Indeed there are. Luckily, Perkin’s earlier publication on alizarin, to which Morton referred, had fabric inserts too. Perkin actually had multiple manuscripts published in the Journal of the Chemical Society of London in the 1870s with textile inserts dyed with alizarin derivatives.
But the manuscripts that Donais and Tague were first able to access ended up being mid-20th-century reprints. One had a color copy of the fabrics, while the others had new fabric inserts. So they tracked down the originals to compare the reproductions with Perkin’s work.
“It’s really interesting to see that we’re discovering things that people were doing more than 100 years ago, and it’s as relevant today as it was then, in my opinion.”
“I could definitely say for one of the reproduction journals, they faked it,” Donais says. Both the original 1874 fabric and the later reprint were labeled bromalizarin, but the XRF spectrometer showed that only the original had bromine in it. Donais was able to find Royal Society of Chemistry meeting notes in which the reprint contracts were discussed, but nothing was mentioned about the new fabrics themselves.
In another sample, they found iron in the color Prussian blue in the original but not the reprint, Tague adds, which was “interesting because if I collected the Raman first, I wouldn’t have such a head start, right? I would say, OK, I have some pigment, and I’m not sure of this or that, but then the XRF really clears up the picture so that the two work really well together. You can kind of break it down very nicely.”
More of this colorful story will be revealed, as the team aims to publish an article later this year. For both scientists, working with these materials from so long ago was special. “When you look back at these older textiles and actually see how well they work and how well they retain color, there’s a lot that can be learned there. Sometimes people don’t learn from the past,” Tague says. “It’s really interesting to see that we’re discovering things that people were doing more than 100 years ago, and it’s as relevant today as it was then, in my opinion.”
