(א) איזו מים כשרים ואיזו פסולים לנטילה. ובו טו סעיפים:
מים שנשתנו מראיהן בין מחמת עצמן בין מחמת דבר שנפל לתוכן בין מחמת מקומם פסולים:
(1) Which water is kosher or not for washing your hands with: Water that has had it's appearance changed doesn't work to wash your hands with, whether from itself or from something that fell into it or from it's location.
Introduction:
Mishna Berura discusses three levels of objects which can potentially effectuate a shun mareh to passul the water.
1. Ink
2. Smoke / "Other things"
3. Dust and Dirt
(ג) מחמת דבר שנפל - כגון דיו ושארי מיני סממנים וצבעים ואף שלא נימוח גוף הצבע בתוכן אלא שעל ידי שרייתן נשתנה המראה...
1. Ink
We need to know a little bit more of the metzius to understand this comment of Mishna Berura.
"Deyo"(ink) is actually a solid.
For 5,000 years, artists and writers across Asia have used a glossy, dark black, durable carbon-based ink, first recorded in China’s Neolithic, which is known colloquially as Chinese ink. (Chinese ink is also known as India ink and remains extremely popular for contemporary artists and writers.) Chinese ink has been used from China to Korea to India to South-east Asia, on Buddhist and Jainian scrolls as well as in traditional Chinese calligraphy. Conventional Chinese ink, unlike many other inks throughout history, was made to be stored in a solid form, only to be liquefied into ink when needed.*
In Mishnaic times, it seems like kankantom (copperas) was the main ingredient in ink. (Interestingly, kankantom was not black - it was green, but when mixed with other ingredients, it turned black.)
*Source:
https://www.historytoday.com/history-matters/history-ink-six-objects
This is what the Mishna Berura is saying here. If deyo - a solid - falls into the water and changes its color, even if the entire deyo-solid hasn't completely dissolved (and thereby also adding substance to the color change), even just with a discoloration (from the initial contact of the deyo with the water) and the deyo-stick is left intact*, the water is passul because of the discoloration (shinui mareh) alone.
The reason that Mishna Berura holds that the deyo can be left intact is from the Halacha in the next category below (about smoke) which can passul the water even if there is no tangible item that has dissolved.
(ג) ...וה"ה אם נשתנה ע"י עשן ושום דבר דרק מחמת עצמן כשרים.
2. Smoke / "Other things"
The next "external object" Mishna Berura discusses is smoke and other things, which are less tangible than ink.
The Shulchan Aruch HaRav holds that even this less intrusive object consists a shinui mareh to passul the water.
ואם נשתנו מחמת עשן או דבר אחר פסולים
What exactly is the metzius of this? What is "davar acher" referring to for it to be paired with ashan?
(ג) אכן מה שנשתנה ע"י עפר וטיט שנתערב בתוכו לא חשיב שינוי מראה וכדלקמיה בסעיף ט' משום דדרך גידול המים הוא כן להיות מעורב בעפר וטיט וגם דלבסוף כשישהו אותן דרכן לצול ועיין לקמיה בס"ט: