From Butterflies to Biochemistry

A teenage interest in butterflies and beetles and a chemical apprenticeship started Hopkins on his biochemical quest. Shortly after leaving school aged 17, Hopkins was apprenticed at a London drug company. He developed excellent analytical skills, invaluable for his future research. The experience also prompted Hopkins to continue his neglected education. He worked as an analytical chemist with Percy Faraday Frankland at the Royal School of Mines and then with Sir Thomas Stevenson, the Home Office forensic pathologist, based at Guy’s Hospital. While working, Hopkins gained a chemistry degree from London University. He then decided to train as a doctor.

 It was during his medical training at Guy Hospital that Hopkins started his own research programmes. His first project was an analysis of the chemical nature of butterfly pigments. Hopkins discovered that the pigments of the Pieridae butterflies were salts of uric acid, and was intrigued by the idea of excretory products being used as ornament. Another project involved Hopkins collaborating with Archibald Garrod and others on clinical research of urinary diseases. In 1898, he wrote the section on The Chemistry of Urine in E.H. Schafer Textbook of Physiology.


Letter of reference from Thomas Stevenson regarding Hopkins' suitability for the Sir William Gull Memorial Scholarship (1891)
Hopkins worked from1882-7 as an analytical chemist for Sir Thomas Stevenson who was both Lecturer in Forensic Medicine at Guy’s Hospital and Principal Analyst and Expert Witness for the Home Office in prosecutions for poisoning. Stevenson supported Hopkins’ candidature for this research scholarship after he had started his medical training. 
(On loan from the University Library, Cambridge)

Gold Medal in Chemistry awarded by London University, 1890
In 1888, encouraged by Thomas Stevenson, Hopkins enrolled as a student at Guy’s Medical School. He qualified in 1894, by which time he had also established a reputation as a gifted researcher. 
(Private collection)

‘On the Estimation of Uric Acid in Urine’ (1892)  
This was Hopkins’ first serious scientific paper, published in the Proceedings of the Royal Society. During the late 19th century uric acid levels in the urine figured prominently in medical speculations on many conditions. Hopkins’ greatly improved method for measuring uric acid levels in urine became the standard for many years.                      

Pieridae butterflies 
As a teenager Hopkins had been curious about the chemical nature of insect pigments. In the early 1890s he identified the white Pieridae pigment as uric acid and the yellow as a derivative of uric acid.
(On loan from the University Museum of Zoology, Cambridge)

Orange Tip (Anthodaris cardamines) butterflies
Hopkins found that the different tones of yellow and orange resulted from variable amounts of pigment and optical effects.      
(On loan from the University Museum of Zoology, Cambridge)

Laboratory Notebook, 1880s 
This notebook contains detailed drawings and observations of both the morphology of Pieridae wing scales and purification procedures of wing pigments. 
(On loan from the University Library, Cambridge) 

Duboscq Colorimeter
Invented by Louis Jules Duboscq in 1854, this instrument could precisely measure the concentration of coloured substances and would have been used by Hopkins in his analytical work. The glass cylinders are both immersed in  two cups, one containing the ‘standard’ solution with a known concentration and the other the test substance at unknown concentration. On looking through the eyepiece, the colour intensities in the two cylinders are equalized by raising or lowering the cylinder in one cup. The extent of this raising or lowering is indicated on a calibrated scale from which the concentration can be read. 
(Oxford H. of Science Museum,).

Hand held Spectrosope  
The spectroscope was a key piece of equipment for Hopkins' analysis of butterfly pigments and in important researches with A E Garrod on urobilin and haematoporphyrin excreted into the urine as the result of certain types of poisoning.
(Private collection)

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