Almost done. Just need to update reagent vars.

code/modules/reagents/chemistry/holder.dm

@@ -832,10 +832,10 @@
 	if(cached_reagents[reagent])								//if it's already in us, merge
 		var/datum/reagent/R = cached_reagents[reagent]
 
-		WIP_TAG			//check my maths for purity calculations
+		//WIP_TAG			//check my maths for purity calculations
 		//Add amount and equalize purity
-		var/our_pure_moles = R.volume * R.purity
-		var/their_pure_moles = amount * other_purity
+		//var/our_pure_moles = R.volume * R.purity
+		//var/their_pure_moles = amount * other_purity
 		R.volume += amount
 		//R.purity = (our_pure_moles + their_pure_moles) / (R.volume)
 		R.purity = ((R.purity * R.volume) + (other_purity * amount)) /((R.volume + amount)) //This should add the purity to the product
@@ -846,7 +846,7 @@
 			my_atom.on_reagent_change(ADD_REAGENT)
 		R.on_merge(data, amount)
 		if(!no_react)
-			start_reacting()
+			handle_reactions()
 		return TRUE
 
 	else
@@ -863,7 +863,7 @@
 		if(my_atom)
 			my_atom.on_reagent_change(ADD_REAGENT)
 		if(!no_react)
-			start_reacting()
+			handle_reactions()
 		if(isliving(my_atom))
 			R.on_mob_add(my_atom)
 		return TRUE
@@ -897,7 +897,7 @@
 			//clamp the removal amount to be between current reagent amount
 			//and zero, to prevent removing more than the holder has stored
 			amount = CLAMP(amount, 0, R.volume)
-			pH = ((pH * volume)-(R.pH * amount))/(volume - amount)
+			pH = ((pH * total_volume)-(R.pH * amount))/(total_volume - amount)
 			R.volume -= amount
 			update_total()
 			if(!safety)//So it does not handle reactions when it need not to

code/modules/reagents/chemistry/reagents.dm

@@ -36,7 +36,8 @@
 	//Fermichem vars:
 	var/purity = 1
 	var/impureChem = "toxin"
-	var/loc = null
+	//var/loc = null
+	var/pH
 
 /datum/reagent/Destroy() // This should only be called by the holder, so it's already handled clearing its references
 	. = ..()

modular_citadel/code/modules/reagents/chemistry/reagents/fermi_reagents.dm

@@ -8,9 +8,12 @@
 //Naninte chem
 
 /datum/reagent/fermi
-	name = "Fermi"
-	id = "fermi"
-	taste_description = "If affection had a taste, this would be it."
+	name = "Fermi" 	//Why did I putthis here?
+	id = "fermi"	//It's meeee
+	taste_description	= "If affection had a taste, this would be it."
+	var/ImpureChem 			= "toxin"			// What chemical is metabolised with an inpure reaction
+	var/InverseChemVal 		= 0					// If the impurity is below 0.5, replace ALL of the chem with InverseChem upon metabolising
+	var/InverseChem 		= "Initropidril" 	// What chem is metabolised when purity is below InverseChemVal
 
 ///datum/reagent/fermi/on_mob_life(mob/living/carbon/M)
 	//current_cycle++
@@ -22,15 +25,15 @@
 /datum/reagent/fermi/on_mob_add(mob/living/carbon/M)
 	if (src.purity == 1)
 		return
-	if (CR.InverseChemVal > src.purity)
+	else if (src.InverseChemVal > src.purity)
 		holder.remove_reagent(src.id, volume, FALSE)
-		holder.add_reagent(CR.InverseChem)
+		holder.add_reagent(src.InverseChem)
 		return
 	else
 		var/pureVol = volume * purity
 		var/impureVol = volume * (1 - pureVol)
 		holder.remove_reagent(src.id, (volume*impureVol), FALSE)
-		holder.add_reagent(CR.ImpureChem, impureVol, FALSE)
+		holder.add_reagent(src.ImpureChem, impureVol, FALSE)
 
 
 

modular_citadel/code/modules/reagents/chemistry/recipes/fermi.dm

@@ -21,7 +21,6 @@
 	RateUpLim = 5 //Optimal/max rate possible if all conditions are perfect
 	FermiChem = TRUE//If the chemical uses the Fermichem reaction mechanics
 	FermiExplode = FALSE //If the chemical explodes in a special way
-	ImpureChem = "toxin" //What chemical is produced with an inpure reaction
 
 /datum/chemical_reaction/eigenstate/on_reaction(datum/reagents/holder)
 	var/location = get_turf(holder.my_atom)
@@ -50,9 +49,6 @@
 	RateUpLim 			= 5 		// Optimal/max rate possible if all conditions are perfect
 	FermiChem 			= TRUE		// If the chemical uses the Fermichem reaction mechanics
 	FermiExplode 		= FALSE		// If the chemical explodes in a special way
-	ImpureChem 			= "SDGFTox"	// What chemical is metabolised with an inpure reaction
-	InverseChemVal 		= 0.5 		// If the impurity is below 0.5, replace ALL of the chem with InverseChem upon metabolising
-	InverseChem 		= "SDZF" 	// What chem is metabolised when purity is below InverseChemVal
 
 /datum/chemical_reaction/BElarger
 	name = ""
@@ -119,9 +115,6 @@
 	RateUpLim 			= 5 		// Optimal/max rate possible if all conditions are perfect
 	FermiChem 			= TRUE		// If the chemical uses the Fermichem reaction mechanics
 	FermiExplode 		= FALSE		// If the chemical explodes in a special way
-	//ImpureChem 			= "SDGFTox"	// What chemical is metabolised with an inpure reaction
-	//InverseChemVal 		= 0.5 		// If the impurity is below 0.5, replace ALL of the chem with InverseChem upon metabolising
-	//InverseChem 		= "SDZF" 	// What chem is metabolised when purity is below InverseChemVal
 
 
 /datum/chemical_reaction/enthral/on_reaction(datum/reagents/holder)

modular_citadel/code/modules/reagents/objects/items.dm

@@ -0,0 +1,67 @@
+/obj/item/pHbooklet
+    name = "pH indicator booklet"
+    desc = "A piece of paper that will change colour depending on the pH of what it's added to."
+    icon_state = "pHbooklet"
+    icon = 'modular_citadel/icons/obj/FermiChem.dmi'
+    item_flags = NOBLUDGEON
+    var/numberOfPages = 100
+
+/obj/item/pHbooklet/attack_hand(mob/user)
+	if(numberOfPages >= 1)
+		var/obj/item/pHpaper/P = new /obj/item/pHpaper
+		//P.add_fingerprint(user)
+		P.forceMove(user.loc)
+		user.put_in_hands(P)
+		to_chat(user, "<span class='notice'>You take [P] out of \the [src].</span>")
+		numberOfPages--
+	else
+		to_chat(user, "<span class='warning'>[src] is empty!</span>")
+	add_fingerprint(user)
+	return ..()
+
+/obj/item/pHpaper
+    name = "pH indicator strip"
+    desc = "A piece of paper that will change colour depending on the pH of a solution."
+    icon_state = "pHpaper"
+    icon = 'modular_citadel/icons/obj/FermiChem.dmi'
+    item_flags = NOBLUDGEON
+    color = "#f5c352"
+    var/used = FALSE
+
+/obj/item/pHpaper/attack_hand(mob/user, obj/I)
+	if(!I.reagents.pH)
+		return
+	if(used == TRUE)
+		to_chat(user, "<span class='warning'>[src] has already been used!</span>")
+		return
+	switch(I.reagents.pH)
+		if(14 to INFINITY)
+			src.color = "#462c83"
+		if(13 to 14)
+			src.color = "#63459b"
+		if(12 to 13)
+			src.color = "#5a51a2"
+		if(11 to 12)
+			src.color = "#3853a4"
+		if(10 to 11)
+			src.color = "#3f93cf"
+		if(9 to 10)
+			src.color = "#0bb9b7"
+		if(8 to 9)
+			src.color = "#23b36e"
+		if(7 to 8)
+			src.color = "#3aa651"
+		if(6 to 7)
+			src.color = "#4cb849"
+		if(5 to 6)
+			src.color = "#b5d335"
+		if(4 to 5)
+			src.color = "#b5d333"
+		if(3 to 4)
+			src.color = "#f7ec1e"
+		if(2 to 3)
+			src.color = "#fbc314"
+		if(1 to 2)
+			src.color = "#f26724"
+		if(0 to 1)
+			src.color = "#ef1d26"

tgstation.dme

@@ -2901,7 +2901,6 @@
 #include "modular_citadel\code\modules\client\verbs\who.dm"
 #include "modular_citadel\code\modules\clothing\clothing.dm"
 #include "modular_citadel\code\modules\clothing\neck.dm"
-#include "modular_citadel\code\modules\clothing\fermichemclothe\fermiclothes.dm"
 #include "modular_citadel\code\modules\clothing\glasses\phantomthief.dm"
 #include "modular_citadel\code\modules\clothing\head\head.dm"
 #include "modular_citadel\code\modules\clothing\spacesuits\cydonian_armor.dm"
@@ -2987,6 +2986,8 @@
 #include "modular_citadel\code\modules\reagents\chemistry\reagents\fermi_reagents.dm"
 #include "modular_citadel\code\modules\reagents\chemistry\reagents\other_reagents.dm"
 #include "modular_citadel\code\modules\reagents\chemistry\recipes\fermi.dm"
+#include "modular_citadel\code\modules\reagents\objects\fermiclothes.dm"
+#include "modular_citadel\code\modules\reagents\objects\items.dm"
 #include "modular_citadel\code\modules\reagents\reagent container\cit_kegs.dm"
 #include "modular_citadel\code\modules\reagents\reagent container\hypospraymkii.dm"
 #include "modular_citadel\code\modules\reagents\reagent container\hypovial.dm"