[Histonet] Re: discarding old dry chemicals with no expiration date

[Smith, Allen]

The stuff found in the Judean caves is "kal ilan," indigo derived from Indigofera tinctoria.  It is chemically identical to "tekhelet," indigo derived from Murex trunculus by photochemical debromination of Tyrian purple.  Although some second and third century Jews, knowingly or unknowingly, used kal ilan instead of tekhelet, Rabbinic opinion has generally held that only tekhelet is kosher for dyeing the fringes.  However, the Talmud also remarks that, "Only God can tell the difference between tekhelet and kal ilan."  Modern spectrometry can detect traces of cellulose in kal ilan, which are not present in tekhelet.

Allen A. Smith
Professor of Anatomy
Barry University School of Podiatric Medicine
Miami Shores, Florida 

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu [mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Robert Richmond
Sent: Thursday, October 01, 2009 10:57 AM
To: histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] Re: discarding old dry chemicals with no expiration date

Kelly D. Boyd, BS, HTL (ASCP) at Harris Histology Services in
Greenville NC describes having a CLIA inspector ordering that all dry
chemicals older than 10 years be discarded.

Allen Smith sums it up >>The problem is letting people with little or
no knowledge of chemistry make chemical decisions.<< To which I would
add: and a system in which inspectors from agencies accountable to no
one (e.g. JCAHO) are allowed to require summary changes in laboratory
procedures, with no appeal allowed. Thirty years ago most histology
labs did almost all of their own preparations - today making a 1%
solution of periodic acid is considered high-level manufacturing.

Allen Smith goes on to observe that >>Indigo used by Bar Kochba's
soldiers to dye the fringes of their prayer shawls in the second
century has been found in caves in the Judean desert; it is still
indigo.<<
Was this indigo, or was it the indigo-like dyes obtained from
shellfish that they used? This remains a lively subject of debate
among Jewish scholars. Present day Jews do not dye the fringes
(tzitzit) of their prayer shawls (tallit or tallis), thinking that the
technique has been lost (a vociferous fringe group - you might say -
is using shellfish-derived dyes and has a cool T-shirt - I want one).

Bob Richmond
Samurai Pathologist
Knoxville TN

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