Vintage glucose meter

Here's an article here, it looks like a piece of lab equipment than something the NHS would hand out for home testing.

https://www.flickr.com/photos/heritagefutures/8275133422

 

Carl Zeiss are known for their quality cameras, so my thoughts are also that it's a piece of laboratory equipment, e.g. a microscope with a Zeiss lens for testing blood samples.

(edited for spelling error)

 

One of the last th ings I saw when I had my first cataract removed, was Zeiss as my head went under the microscope so the ophthalmologist could see what she was doing..

 

Which is why I was suggesting the item is a microscope for examining blood samples rather than some sort of blood glucose testing meter.

 

You could always make an offer! It looks very interesting.

 

I had a bit of fun doing some research on this:

From eBay listings:
On box lid: Blutzucker - Kolorimeter nach Crecelius Seifert
Wikipedia's definition of a Kolorinter aka Colorimeter:
A colorimeter is a device used in colorimetry that measures the absorbance of particular wavelengths of light by a specific solution.

Description of our Crecelius Seifert calorimeter from WorldCat:
Colorimeter. Enameled metal base supports mounted circular colorimeter with attached cylindrical ocular lens; colorimeter has square side opening for squared test tube (containing blood sample) and a hinged door and metal rotating disk on underside; glass ocular lens allows viewing of color standard, blood sample, and hemoglobin scale. Round plastic case contains filter paper. Instruction and information booklets are included.

Worthpoint also provides a description and detailed step by step procedures used to check the blood samples, but briefly:
Very simply, a tincture is prepared by mixing a patient’s blood, distilled water and diluted picric acid. After agitation and filtering, sodium hydroxide is added & heated a few minutes. The resultant picramic acid acquires a radish color, the proportional intensity of which can be measured & compared to a color scale in the instrument’s eyepiece, thus the percentage of sugar in the blood is determined.

And more information from Wikipedia regarding picric acid's use in checking blood sugar:
This reduction of picric acid was also formerly used in Crecelius-Seifert's method for measuring blood sugar levels. This is a colorimetric method for determining blood sugar levels. A solution of picric acid is mixed with a blood sample; the protein is then filtered off. By adding caustic soda and heating the sample in a water bath, picric acid is reduced by the blood sugar to picramic acid, which has a red color. After cooling, the blood sugar level can be read in a sugar colorimeter.

And finally, from PubMed some references to various papers on the Crecelius-Seifert method, and an abstract of one of the papers:
Kritik der colorimetrischen Blutzuckerbestimmung nach Crecelius-Seifert (Study of Crecelius-Seifert's colorimetric blood sugar method.) Buttner, H. E. ; Christ, H.; Klinische Wochenschrift 1931 Vol.10 pp.1815-1816 ref.5
Abstract : Crecelius and Seifert's picric acid method is rapid and very simple, but has been adversely criticized. Buttner and Christ showed that by standardizing the conditions, results comparable with those by Hagedorn-Jensen's method might be obtained. The error tended to be of the same order with concentrations of glucose varying from 50 to 500 mg. per 100 c.c., so that the percentage error was much lower in higher concentration. Average deviation on any determination was about 4 mg. (In German)

@Antje77 - there are also a couple more of this Instrument on eBat but much further from home (Kiev & USA), but somehow I don't think we;d be opting to buy use them due to their reliance on explosive picric - which I somehow doubt will be found in our kitchens!

 

In those days I imagine that +/-15% would have seemed impossibly accurate.